EVA-CM-001 01/28/2020

EVA-EXP-0042

REVISION B 

National Aeronautics and

Space Administration

EFFECTIVE DATE: OCTOBER 19, 2020

EXPLORATION EVA SYSTEM

CONCEPT OF OPERATIONS

“This document has been reviewed for Proprietary, SBU, and Export Control (ITAR/EAR) 

and has been determined to be non-sensitive. It has been released to the public via the 

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Verify that this is the correct version before use
Revision: B Document No: EVA-EXP-0042 

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Title: Exploration EVA System Concept of Operations

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Prepared by: 

___________________________________________________

XX/David Coan, EVA Operations & Engineering Specialist 

Concurred by: 

______________________________________________________

XX/Lori Crocker, EVA Strategic Integration Office, Manager 

Approved by: 

____________________________________________

XX/Christopher P. Hansen, EVA Office, Manager 

David Coan 

(affiliate)

Digitally signed by David Coan 

(affiliate)

Date: 2020.10.16 10:29:48 -05'00'

LORI

CROCKER

Digitally signed by LORI 

CROCKER

Date: 2020.10.16 11:06:58 

-05'00'

CHRISTOPH

ER HANSEN

Digitally signed by 

CHRISTOPHER HANSEN 

Date: 2020.10.19 09:19:13 

-05'00'
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REVISION AND HISTORY PAGE

Revision

No.

Change 

No. Description Release

Date

B Revision B (Reference EVA-CR-00082) 

New template (change in section numbers)

Section 1: Updated with Artemis Program

Section 2: Updated references

Section 3: Added Artemis Program and phases

Section 4: Consolidated information, incorporated 

information from EVA-EXP-0075, community work on 

xEVA System, the Artemis Program, Gateway, HLS, 

and LTV

Section 5: Minor cleanup and updates

Section 6: Minor cleanup and updates

Section 7: Updated per Artemis Program

Section 8: Minor cleanup and updates

Section 9: Minor cleanup and updates

Appendices: New appendices with details and information 

from revision A, along with architecture information 

moved to annexes

10/07/2020

A Revision A (Reference CR EVA-CR-00048 dated 

07/03/2019) 

Section 1: Updates and clarifications

Section 2: Clarifications and formatting updates

Section 3: Most of section moved to EVA-EXP-0041

Section 4: Content reduced and simplified 

Section 5: Updates to xEVA System overview

Section 6: Minor cleanup

Section 7: Minor cleanup

Section 8: Updated lunar details per Artemis and EVAEXP-0075

Section 9: Minor cleanup

07/03/2019

Baseline Baseline (per EVA-CR-00032) 12/20/2017

EVA-REF-004 Revision History

Initial Draft Preliminary Baseline 05/17/2016

Pre Baseline 07/07/2014
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TABLE OF CONTENTS

SECTION PAGE

1.0 INTRODUCTION.............................................................................................. 11

1.1 PURPOSE........................................................................................................ 11

1.2 SCOPE............................................................................................................ 11

1.3 CHANGE AUTHORITY/RESPONSIBILITY ........................................................ 12

2.0 DOCUMENTS .................................................................................................. 13

2.1 APPLICABLE DOCUMENTS ............................................................................ 13

2.2 REFERENCE DOCUMENTS............................................................................ 13

3.0 EXPLORATION PROGRAM & ARCHITECTURE GOALS................................. 15

3.1 RETURNING TO THE MOON........................................................................... 15

3.1.1 Space Policy Directive – 1 .................................................................. 15

3.1.2 5th Meeting of the National Space Council .......................................... 15

3.2 ARTEMIS LUNAR PROGRAM.......................................................................... 15

3.2.1 Artemis Phase 1................................................................................. 15

3.2.2 Artemis Phase 2................................................................................. 16

3.3 INTO THE PROVING GROUND (AND ON TO MARS)...................................... 17

4.0 EXPLORATION EVA AND MISSION SYSTEMS OVERVIEW............................ 20

4.1 EXPLORATION EVA OVERVIEW..................................................................... 20

4.1.1 xEVA System Definition ..................................................................... 20

4.1.2 Exploration EVA System Strategy ...................................................... 22

4.1.3 Phases of Operations for xEVA System.............................................. 26

4.1.4 Frequency and Duration of EVAs ....................................................... 29

4.1.5 EVA Tasks for Exploration Missions ................................................... 30

4.2 XEVA SYSTEM KEY CAPABILITIES & FEATURES.......................................... 35

4.2.1 xEVA Suit and Ancillary xEVA Equipment........................................... 36

4.2.2 VISE .................................................................................................. 49

4.2.3 xEVA Accessories ............................................................................. 50

4.2.4 EVA Task Tools & Equipment ............................................................ 50

4.3 AUXILIARY SUPPORT SYSTEMS FOR XEVA ................................................. 52

4.3.1 Navigation & Tracking........................................................................ 52

4.3.2 EVA Mission Support System............................................................. 55
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4.4 EGRESS/INGRESS METHODS ....................................................................... 57

4.5 SPACECRAFT................................................................................................. 58

4.5.1 Orion ................................................................................................. 58

4.5.2 Gateway ............................................................................................ 59

4.5.3 HLS (Human Landing System)........................................................... 61

4.6 SURFACE MOBILITY....................................................................................... 63

4.6.1 Lunar Terrain Vehicle (LTV)............................................................... 63

4.6.2 Crewed Pressurized Rovers (CPR) .................................................... 64

5.0 CONCEPT OF OPERATIONS FOR EVA ON A SPACECRAFT ........................ 66

5.1 CON OPS FOR EVA ON ISS (MICROGRAVITY EVA IN LEO).......................... 66

5.1.1 Demonstration of xEVA Suit (xEMU) on ISS........................................ 66

5.1.2 ISS Nominal Operations with xEVA Suit ............................................. 67

5.2 CON OPS FOR EVA ON GATEWAY (MICROGRAVITY EVA IN CISLUNAR SPACE)

................................................................................................................. 68

5.2.1 General Aspects of EVA on Gateway ................................................. 68

5.2.2 Road-to EVA (Gateway)..................................................................... 70

5.2.3 EVA Prep & Prebreathe (Gateway) .................................................... 71

5.2.4 EVA (Gateway).................................................................................. 73

5.2.5 Post EVA (Gateway).......................................................................... 74

6.0 CONCEPT OF OPERATIONS FOR EVA ON A SMALL NATURAL BODY......... 75

6.1 CON OPS FOR EVA ON A CAPTURED ASTEROID......................................... 75

6.1.1 Road-to EVA (Captured Asteroid) ...................................................... 75

6.1.2 Prep & Prebreathe on EVA Day (Captured Asteroid).......................... 76

6.1.3 EVA (Captured Asteroid) ................................................................... 77

6.1.4 Post EVA (Captured Asteroid) ........................................................... 78

6.2 CON OPS FOR EVA ON A NEAR EARTH ASTEROID (NEA) ........................... 78

6.2.1 Road-to EVA (NEA)............................................................................ 79

6.2.2 Prep & Prebreathe on EVA Day (NEA) ............................................... 79

6.2.3 EVA (NEA)......................................................................................... 80

6.2.4 Post EVA (NEA)................................................................................. 82

6.3 CON OPS FOR EVA ON THE MOONS OF MARS............................................ 82

6.3.1 Road-to EVA (Moons of Mars)............................................................ 82

6.3.2 Prep & Prebreathe for EVA (Moons of Mars) ...................................... 82
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6.3.3 EVA (Moons of Mars)......................................................................... 83

6.3.4 Post EVA (Moons of Mars) ................................................................. 83

7.0 CONCEPT OF OPERATIONS FOR EVA ON THE MOON................................. 84

7.1 SCIENCE OBJECTIVES & REGIONS OF INTEREST....................................... 85

7.1.1 Science Objectives for the Lunar Surface........................................... 85

7.1.2 General Regions of Interest ............................................................... 87

7.1.3 Lunar South Pole Region................................................................... 88

7.2 CON OPS FOR EVA ON LUNAR SURFACE (ARTEMIS PHASE 1).................. 89

7.2.1 Preflight and Earth Launch ................................................................ 90

7.2.2 On-Orbit Operations (Crew Arrival) .................................................... 91

7.2.3 Descent to Lunar Surface .................................................................. 92

7.2.4 Lunar Surface EVA Operations.......................................................... 93

7.2.5 Road-to EVA (Lunar) ......................................................................... 93

7.2.6 Prep & Prebreathe for EVA (Lunar).................................................... 94

7.2.7 Egress and Setup .............................................................................. 95

7.2.8 EVA Surface Operations.................................................................... 95

7.2.9 Cleanup and Ingress.......................................................................... 99

7.2.10 Post EVA Operations......................................................................... 100

7.2.11 Maintenance...................................................................................... 100

7.2.12 Ascent from Lunar Surface ................................................................ 100

7.2.13 On-Orbit Operations (Crew Return).................................................... 101

7.2.14 Design Reference EVA for Artemis III.................................................. 101

7.3 CON OPS FOR EVA ON LUNAR SURFACE (ARTEMIS PHASE 2).................. 108

7.3.1 Sustained Mission – Short Stay.......................................................... 108

7.3.2 Sustained Missions – Extended Stay.................................................. 108

7.3.3 Design Reference EVA for Artemis Phase 2 ....................................... 110

8.0 CONCEPT OF OPERATIONS FOR EVA ON MARS......................................... 119

8.1 GENERAL CONSIDERATIONS FOR MARS..................................................... 119

8.2 CON OPS FOR EVA ON MARS ....................................................................... 121

8.2.1 Road-to EVA (Mars)........................................................................... 121

8.2.2 Prep & Prebreathe for EVA (Mars) ..................................................... 121

8.2.3 EVA (Mars)........................................................................................ 122

8.2.4 Post EVA (Mars)................................................................................ 123
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9.0 CONTINGENCIES & CREW RESCUE.............................................................. 124

9.1 SELF-RESCUE................................................................................................ 124

9.1.1 Microgravity Self-Rescue................................................................... 124

9.1.2 Lunar Surface Self-Rescue and Rover Rescue .................................. 124

9.2 INCAPACITATED CREWMEMBER RESCUE................................................... 124

9.2.1 Microgravity EVA Rescue................................................................... 125

9.2.2 Partial-Gravity Surface Rescue.......................................................... 125

9.3 EMERGENCY RECOMPRESSION................................................................... 126

9.4 CONTAMINATION............................................................................................ 127

9.5 LOSS OF COMMUNICATION........................................................................... 127

9.6 LOSS OF TRANSPORTATION......................................................................... 128

9.7 RADIATION...................................................................................................... 128

9.8 VEHICLE CONTINGENCIES............................................................................. 128

9.8.1 Orion ................................................................................................. 128

9.8.2 Gateway ............................................................................................ 128

9.8.3 HLS ................................................................................................... 128

9.8.4 Pressurized Rover ............................................................................. 128

APPENDIX

APPENDIX A ACRONYMS AND ABBREVIATIONS AND GLOSSARY OF TERMS............. 129

APPENDIX B OPEN WORK............................................................................................... 135

APPENDIX C ADDITIONAL REFERENCES........................................................................ 141

APPENDIX D KEY FIGURES OF MERIT (FOM)................................................................. 146

APPENDIX E NEXTSTEP APPENDIX H: HLS.................................................................... 152

APPENDIX F EVA TASKS FOR EXPLORATION MISSIONS............................................... 157

APPENDIX G EVA TOOLS & EQUIPMENT......................................................................... 161

APPENDIX H INFORMATICS............................................................................................. 165

APPENDIX I PRE-ARTEMIS LUNAR MISSION SCENARIOS.............................................. 167

APPENDIX J DOCUMENT TREE & INFORMATION FLOW FOR XEVA SYSTEM CON OPS

.................................................................................................................... 174

TABLE

TABLE 2.1-1: APPLICABLE DOCUMENTS LIST ..........................................................13
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TABLE 2.2-1: REFERENCE DOCUMENT LIST.............................................................14

TABLE 4.2.4.1-1: TYPES OF GEOLOGY SAMPLING TOOLS......................................50

TABLE B1.0-1: TO BE DETERMINED ITEMS ..............................................................135

TABLE B2.0-1: TO BE RESOLVED ISSUES................................................................136

TABLE B3.0-1 FORWARD WORK..............................................................................136

TABLE D-1: KEY FOMS FOR A MICROGRAVITY EVA ON ISS...................................146

TABLE D-2: KEY FOMS FOR EVA ON GATEWAY (MICROGRAVITY IN CISLUNAR 

SPACE).....................................................................................................146

TABLE D-3: KEY FOMS FOR EVA FROM DEEP SPACE TRANSIT (DST) VEHICLE IN 

CISLUNAR SPACE ...................................................................................147

TABLE D-4: KEY FOMS FOR EVA FROM DST VEHICLE IN TRANSIT TO/FROM MARS

.................................................................................................................147

TABLE D-5: KEY FOMS FOR EVA ON A CAPTURED ASTEROID...............................148

TABLE D-6: KEY FOMS FOR EVA ON A NEA.............................................................148

TABLE D-7: KEY FOMS FOR EVA ON THE MOONS OF MARS..................................149

TABLE D-8: KEY FOMS FOR EVA ON THE LUNAR SURFACE ..................................149

TABLE D-9: KEY FOMS FOR EVA ON MARS .............................................................150

TABLE F-1: ENGINEERING TASKS ............................................................................157

TABLE F-2: SCIENTIFIC TASKS .................................................................................158

TABLE G-1: GEOLOGY SAMPLE TYPES....................................................................163

FIGURE

FIGURE 3.2.1-1: ARTEMIS PHASE 1 ...........................................................................16

FIGURE 3.3.2-1: ARTEMIS PHASE 2 ...........................................................................17

FIGURE 4.1.1-1: SYSTEMS UTILIZED TO EXECUTE EXPLORATION EVAS...............20

FIGURE 4.1.1-2: XEVA SYSTEM SUIT CONCEPT .......................................................21

FIGURE 4.1.2.1-1: EXPLORATION XEVA SYSTEM CAPABILITY BOUNDARIES.........24

FIGURE 4.1.2.1-2: XEMU CAPABILITIES.....................................................................25

FIGURE 4.1.5-1: EMUMICRO-G EVA ON ISS (L) AND SURFACE EVA DURING APOLLO 

(R)..............................................................................................................31

FIGURE 4.1.5.1.3-1: CONTINGENCY BMRRM R&R ON ISS DURING US EVA 14 (L) AND 

UNFORESEEN SOLAR ARRAY REPAIR DURING STS-120 ......................32

FIGURE 4.1.5.1.4-1: EVA ENGINEERING TASKS FOR SURFACE OPS.....................33

FIGURE 4.1.5.2.1-1: EVA SURFACE SCIENCE OBSERVATION & DATA COLLECTION 

TASKS.......................................................................................................34

FIGURE 4. 4.1.5.2.1-2: EVA SCIENCE SAMPLE ACQUISITION TASKS......................35
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FIGURE 4.2.1.1-1: XEVA SYSTEM SUIT CONCEPT ...................................................37

FIGURE 4.2.1.2-1: APOLLO 10 CREW TRAINING FOR LUNAR DESCENT IN SUITS.37

FIGURE 4.2.1.2.1-1: XEMU VEHICLE LOOP MODE CONFIGURATION......................38

FIGURE 4.2.1.3-1: XEVA SUIT CONDUCTING TASKS STANDING AND KNEELING ..39

FIGURE 4.2.1.3.1.1-1: LUNAR SURFACE EVA EXCURSION RANGES.......................41

FIGURE 4.2.1.4-1: GENERAL SCIENCE REGIONS OF INTEREST FOR LUNAR 

SURFACE MISSIONS ................................................................................42

FIGURE 4.2.1.4.1-1: DUST CONTAMINATION DURING APOLLO 17..........................43

FIGURE 4.2.1.5-1: XEVA SUIT LIGHT AND VISOR NOTIONAL CONCEPTS...............45

FIGURE 4.2.1.6-1: XEVA SUIT CAMERA NOTIONAL CONCEPT .................................46

FIGURE 4.2.4.1-1: SCIENCE SAMPLING TOOLS (RAKE)...........................................51

FIGURE 4.2.4.2-1: CARRYING TOOLS ON APOLLO SUITS ........................................52

FIGURE 4.4-1: EVA EGRESS/INGRESS METHODS....................................................57

FIGURE 4.4.-2: SUITLOCK (REAR-ENTRY AIRLOCK) CONCEPT ...............................58

FIGURE 4.5.1-1: ORION...............................................................................................59

FIGURE 4.5.2-1: GATEWAY.........................................................................................59

FIGURE 4.5.2-2: GATEWAY PHASE I ..........................................................................60

FIGURE 4.5.2-3: GATEWAY PHASE II .........................................................................61

FIGURE 4.5.3.1-1: HLS REFERENCE CONCEPT ........................................................62

FIGURE 4.6.1-1: UNPRESSURIZED ROVER CONCEPT VEHICLE..............................64

FIGURE 4.6.2-1: PRESSURIZED ROVER CONCEPT ..................................................65

FIGURE 5.1-1: EVA OPERATIONS ON THE SPACE SHUTTLE AND SPACE STATION66

FIGURE 5.2.1-1: EVA INTERFACES SUPPORTING NOMINAL EVA CAPABILITY .......69

FIGURE 5.2.2-1: ROAD-TO EVA REFERENCE BASED ON ISS EMU EVA ..................71

FIGURE 5.2.3-1: DAY OF EVA EXAMPLE TIMELINE BASED ON ISS EMU EVA..........72

FIGURE 6.1.1-1: CONCEPT FOR EVA ON A CAPTURED ASTEROID .........................76

FIGURE 6.1.3-1: EVALUATING ASTEROID EVA BOOM OPERATIONS IN THE NBL AND 

DURING NEEMO 20 ..................................................................................77

FIGURE 6.1.3-2: ASTEROID SAMPLE COLLECTION CONCEPT (ARCM) AND 

EVALUATIONS DURING NEEMO 20 .........................................................77

FIGURE 6.1.3-3: ASTEROID SAMPLE STOWAGE CONCEPT (ARMC) AND 

EVALUATIONS DURING NEEMO 20 .........................................................78

FIGURE 6.1.3-4: BRINGING ASTEROID SAMPLE INSIDE VEHICLE ...........................78

FIGURE 6.3-1: MOONS OF MARS (PHOBOS AND DEIMOS) ......................................82
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FIGURE 6.3.3-1: EVALUATING SCIENCE EVA TASKS FOR PHOBOS DURING NEEMO 

20...............................................................................................................83

FIGURE 7.0-1: LUNAR EVA DURING APOLLO 16.......................................................84

FIGURE 7.1.2-1: POTENTIAL LUNAR SCIENCE LANDING SITES...............................88

FIGURE 7.2-1: PHASE OF XEVA OPERATIONS FOR LUNAR SURFACE MISSIONS..90

FIGURE 7.2-2: LUNAR SCIENCE EVA OPERATIONS DURING APOLLO 17 ...............90

FIGURE 7.2.14-1: NOTIONAL LUNAR LANDING SITE AT CONNECTING RIDGE.......102

FIGURE 7.2.14.1-1: NOTIONAL DESIGN REFERENCE EVA SERIES FROM EVA-EXP0075..........................................................................................................102

FIGURE 7.2.14.2-1: DESIGN REFERENCE EVA OUTLINE FROM EVA-EXP-0075 .....104

FIGURE 8.1-1: EVALUATING SCIENCE TEAM INTERACTION WITH MARS EVA DURING 

NEEMO 20................................................................................................120

FIGURE 8.1-2: EVALUATING MULTI-DAY CREW SELF-SCHEDULING OF EVAS......121

FIGURE 8.2.3.2-1: EVALUATING SCIENCE SAMPLE ACQUISITION ON MARS DURING 

NEEMO 20................................................................................................122

FIGURE 8.2.3.2-2: EVALUATING SAMPLE MARKERS NAVIGATION METHODS TO 

IDENTIFY ZONES.....................................................................................123

FIGURE 9.3-1: ISS EMU CHECKLIST DCS CUFF CLASSES......................................127

FIGURE G-1: UTILIZING THE PISTOL GRIP TOOL (PGT) DURING AN ISS EVA........162

FIGURE G-2: POWERED AND MANUAL EVA SAMPLE ACQUISITION TOOL CONCEPTS 

(CORE, CHIP, SOIL, SURFACE)...............................................................163

FIGURE H-1: CAPABILITY CONCEPT FOR AN AUGMENTED HEADS-UP DISPLAY 

SYSTEM ...................................................................................................166

FIGURE H-2: TESTING AN EVA ELECTRONIC CUFF DURING STS-69.....................166

FIGURE J-1: XEVA SYSTEM DOCUMENT TREE PER EVA-EXP-0045.......................174

FIGURE J-2: XEVA SYSTEM INFORMATION FLOW FOR THE CON OPS..................175
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1.0 INTRODUCTION

The Exploration Extravehicular Activity (xEVA) System concept of operations (con ops) 

captures the National Aeronautics and Space Administration’s (NASA’s) current aims

future missions to all potential Exploration destinations. This document captures the 

mission architectures, stakeholder expectations, and high level definitions of the 

capabilities and interfaces associated with the xEVA System. This includes missions to 

Gateway in cislunar space, the lunar surface, a redirected asteroid in cislunar space, Near 

Earth Asteroids (NEA), Mars’ orbit, the moons of Mars (Phobos and Deimos), and the 

surface of Mars. These missions, which include microgravity, milli-gravity, and partialgravity surface EVAs, will involve a variety of engineering (maintenance, contingency, 

pioneering, construction) and science tasks. This document also captures information 

concerning vehicles and habitats with which the xEVA System will interface. The concepts 

of operations (con ops) detailed in this document are informed by the Artemis Program 

and a multitude of Exploration studies, and are also influenced by various integrated 

operational analog testing.

1.1 PURPOSE

This EVA Office document captures the xEVA concepts of operations for a wide range of 

destinations. It focuses on the lunar surface in order to support the Artemis Program, 

including the science goals driving the missions and the xEVA System capabilities needed 

to successfully complete the operations. The concepts of operations detailed in this 

document are intended to inform the development of the xEVA System, including the xEVA 

Suit, the current design solution for which is the Exploration Extravehicular Mobility Unit 

(xEMU), and the Vehicle Interface to Suit Equipment (VISE). 

EVA-EXP-0042 describes the xEVA System operations and the tasks that will be 

accomplished during missions on the International Space Station (ISS), on Gateway in 

cislunar orbit, and on the lunar surface as part of the Artemis Phases. It also includes con 

ops for missions to asteroids and to Mars. This document is intended for Program concept 

of operations development and Exploration spacesuit suppliers. EVA-EXP-0042 provides 

the EVA Office standard for conducting EVA in a multitude of environments and locations, 

and new Programs working with the EVA Office will utilize this con ops as the basis for 

how EVAs will be conducted, tailored as needed to meet the objectives and goals of that 

Program. For spacesuit developers, this document provides the basis of what is 

operationally expected of the spacesuit in a given environment. If there is a conflict 

between EVA-EXP-0042 and other con ops involving EVA operations, EVA-EXP-0042 

takes precedence. An exception is a program specific con ops tailored with support and 

approval by the EVA Office will take precedence over EVA-EXP-0042.

1.2 SCOPE

It is intended that the content contained in this document is to enable the development of 

more refined concept of operations for Exploration missions and architecture (e.g., 

Gateway, the Artemis Program, and the Human Landing System), for the xEVA system
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(e.g., SSP 51073), and for the subsystems (e.g. xEMU ConOps Ref#) and associated 

requirements (e.g. xEMU PTRS ref#) and provide the motivating/supporting rational and 

context for system verification.. The con ops will continue to mature as the Exploration 

architecture missions evolve, and this document will continuously evolve and be updated 

accordingly. 

This document includes the information contained in EVA-EXP-0075, Exploration EVA 

System Concept of Operations Summary for Artemis Phase 1 Lunar Surface Mission, 

presented at the EVA Exploration Workshop on 18 February 2020. Results from pertinent 

integrated operational tests (analogs) were utilized to provide relevant data for informing 

concepts, flushing out capabilities, and evolving systems. Finally, the xEVA Concepts of 

Operations Working Group (xEVA Con Ops WG) was utilized to consolidate and finalize 

the high level definition of the mission architecture, capability needs, and concepts of 

operations associated with conducting EVA operations.

Specifically for the xEMU project, that suit is intended to have the capability to support 

missions from the ISS, to the lunar vicinity (on Gateway), and to the lunar surface as a key 

component of Artemis. The capabilities needed for that suit and associated equipment 

are described in Section 4.1.2, initial lunar mission parts of Section 4.2 (specifically Section 

4.2.1 for the spacesuit), Section 5.1.1, and Section 7.2.

1.3 CHANGE AUTHORITY/RESPONSIBILITY

Proposed changes to this document shall be submitted by an EVA Office Change Request 

(CR) to the EVA Configuration Control Board (EVA CCB) for consideration and disposition.

All such requests will adhere to the EVA Office Configuration Management Change 

Process (EVA-PLN-012).

The appropriate NASA Office of Primary Responsibility (OPR) identified for this document 

is EVA.
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2.0 DOCUMENTS

2.1 APPLICABLE DOCUMENTS

The following documents include specifications, models, standards, guidelines, 

handbooks, and other special publications. The documents listed in this paragraph are 

applicable to the extent specified herein.

TABLE 2.1-1: APPLICABLE DOCUMENTS LIST

Document 

Number

Document 

Revision/Release 

Date

Document Title Applicability

Alternative 

Documents

(allowed/not 

allowed)

JSC-48538 07/16/2007 ISS EVA Systems Checklist

SSP 51073 / 

EVA-RD-001

B

04/10/2020

xEVA Suit Systems 

Requirements Document

SSP 51080 / 

EVA-EXP0037

Baseline

12/04/2018

xEMU-ISS Interface 

Requirements Control Document

EVA-EXP0031

Baseline

04/04/2018

EVA Airlocks and Alternative 

Ingress/Egress Methods

EVA-EXP0032

Baseline

606/05/2018

EVA-ISS Interface Definition 

Document (IDD)

EVA-EXP0034

B

07/31/2020

Exploration EVA System 

Technical Standards

EVA-EXP0035

Baseline

09/12/2018

Exploration EVA System 

Compatibility

EVA-EXP0039

A

11/29/2017

Exploration EVA System 

Destination Environments 

Specifications

EVA-EXP0041

Baseline

12/18/2018

Exploration EVA System 

Architecture Description

EVA-EXP0043

Baseline

10/25/2018

NASA Project Management Plan 

for the Exploration EVA System

EVA-EXP0046

TBD-2.1-014 Exploration EVA Suit-Airlock 

Interfaces, Ops Con and 

Objectives

2.2 REFERENCE DOCUMENTS

The following documents contain supplemental information to guide the user in the 

application of this document. Additional reference documents utilized to develop the xEVA 

con ops are listed in an appendix. 
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TABLE 2.2-1: REFERENCE DOCUMENT LIST

Document Number Document 

Revision Document Title

EVA-EXP-0075 Baseline

03/17/2020

Exploration EVA System Concept of Operations Summary for 

Artemis Phase 1 Lunar Surface Mission

EVA-PLN-012 A

10/02/2019

EVA Office Configuration and Data Management Plan

HLS-CONOPS-001 Baseline (draft)

05/21/2020

Human Landing System (HLS) Program Concept of 

Operations – Initial Phase

Artemis-CONOPS001

Draft Artemis Concept of Operations

GP 10027 Baseline

05/07/2020

Gateway Concept of Operations

https://www.nasa.go

v/sites/default/files/a

toms/files/a_sustain

ed_lunar_presence_

nspc_report4220fina

l.pdf

04/02/2020 NASA’s Plan for Sustained Lunar Exploration and 

Development

https://www.nasa.go

v/sites/default/files/a

toms/files/artemis_pl

an-20200921.pdf 

09/21/2020 Artemis Science Plan

HEOMD-005 Concept of Operations

HEOMD-006 Exploration Utilization Plan

AES-50002 Baseline Artemis Sustained Lunar Exploration Requirements

AES-50010 Baseline Advanced Exploration Systems Lunar Terrain Vehicle (LTV) 

Concept of Operations
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3.0 EXPLORATION PROGRAM & ARCHITECTURE GOALS

The United States (U.S.) Executive Branch and the NASA administration have released 

several policies and documents that outline returning to the moon and eventually landing 

on Mars. Those documents make up the basis for the xEVA con ops. 

3.1 RETURNING TO THE MOON

Through Space Policy Directive – 1 and the 5th Meeting of the National Space Council, the 

United States set in motion plans to return humans to the surface of the moon. 

3.1.1 Space Policy Directive – 1

On 11 December 2017, Space Policy Directive – 1 was updated to redirect the nation’s 

spaceflight efforts to returning humans to the lunar surface. In part, this policy states: 

“Beginning with missions beyond low-Earth orbit, the United States will lead the return of 

humans to the Moon for long-term exploration and utilization, followed by human missions 

to Mars and other destinations.”

3.1.2 5th Meeting of the National Space Council

On 26 March 2019, discussions at the National Space Council provided further direction 

and details on the lunar surface mission plans. In part, it was stated:

• “Fifty years ago, “one small step for man” became “one giant leap for mankind.” 

But now it’s come the time for us to make the next “giant leap” and return American 

astronauts to the Moon, establish a permanent base there, and develop the 

technologies to take American astronauts to Mars and beyond.”

• “...it is the stated policy of this administration and the United States of America to 

return American astronauts to the Moon within the next five years.”

• “And today, the National Space Council will recommend that when the first 

American astronauts return to the lunar surface, that they will take their first steps 

on the Moon’s South Pole.”

3.2 ARTEMIS LUNAR PROGRAM

In response to the new Executive Branch direction, NASA implemented the Artemis 

Program. 

3.2.1 Artemis Phase 1

Per “Forward to the Moon: NASA’s Strategic Plan for Human Exploration”, 4 Sept 2019, 

Artemis Phase 1 builds up to the first crewed mission to the lunar surface.
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FIGURE 3.2.1-1: ARTEMIS PHASE 1

3.2.2 Artemis Phase 2

Per “Forward to the Moon: NASA’s Strategic Plan for Human Exploration”, 4 Sept 2019, 

Artemis Phase 2 continues the lunar surface missions into sustainable capabilities and 

exploration.
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FIGURE 3.3.2-1: ARTEMIS PHASE 2

3.3 INTO THE PROVING GROUND (AND ON TO MARS) 

Prior to Artemis, the Human Exploration and Operations Mission Directorate (HEOMD) 

released several Level 1 documents which lay out objectives, concept of operations, and 

utilization plans pertaining to EVA through crewed missions to Mars. 

Per the paper entitled ISS, SLS, Orion: Into The Proving Ground presented by the Human 

Exploration and Operations (HEO) Associate Administrator at the International 

Astronautical Congress in Adelaide, Australia in September 2017, the current long term 

goal for NASA is a crewed mission to the Martian system by 2033 with a human landing 

later in the decade. This led to the release of HEOMD-001 Human Exploration and 

Operations Exploration Objectives document, and the high level description of the phases 

of exploration.

The goal of landing humans on the surface of Mars will be accomplished through five 

phases. Phase 0, involves continuing to use the ISS for research and as a testbed. Per 

the IAC 2017 paper, the remaining phases are as follows:

In Phase 1, NASA will use the Space Launch System (SLS) and the Orion capsule 

in the early and mid-2020s to deploy a Deep Space Gateway in cislunar space, 

comprising a habitation and in-space propulsion capability. In-space power and 

propulsion, including solar electric propulsion, and deep space habitation are central 

to future human exploration. Development and deployment of these capabilities will 

be a focus of the early-to-mid 2020s. The Gateway provides a space infrastructure 
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enabling missions—NASA, commercial, and international—to a variety of 

destinations, including the surface of the Moon. It will be the next step in expanding 

human presence into the solar system.

Phase 2, in the mid-to-late 2020s, will see NASA using the SLS, Orion, and the 

Gateway to outfit the Deep Space Transport, which will be used to fly crews to the 

Martian system in the 2030s. The Deep Space Transport will be launched without 

fuel and supplies in single SLS launch. The fuel, supplies, and outfitting will occur 

over a series of SLS and Orion missions. The Deep Space Transport can benefit 

from the avionics and computer systems being developed for Orion. The Transport 

represents not only the realization of a robust habitation capability that will keep 

crews healthy on two-year Mars missions, but also the development of a reliable 

propulsion system that will be used to fly crews safely across interplanetary 

distances, and then back to the Earth-Moon system. The Deep Space Transport will 

be reusable for multiple missions and can be maintained at the Gateway. Phase 2 

will culminate in a crewed one-year shakedown cruise or verification mission aboard 

the Deep Space Transport in cislunar space to validate its readiness to conduct 

missions beyond the Earth-Moon system. At this point, we will have the knowledge 

and the infrastructure in place for the voyage to the Martian system.

In Phase 3, NASA will conduct humanity’s first missions to another planet, with the 

initial crewed flight of the Deep Space Transport to the Martian system in 2033, and 

a potential rendezvous with the Martian moon Phobos. Astronauts will thus gain 

experience with interplanetary spaceflight and operations, and will fully utilize the 

cislunar infrastructure that has been developed to support such missions.

During the decade of the 2030s and beyond, in Phase 4 NASA will develop and 

deploy the systems to land cargo and crews on Mars, sustain crews on the surface, 

and return them safely to Martian orbit, where they will re-board the Deep Space 

Transport for the journey back to the Deep Space Gateway, and then home to Earth.

The main Objective Category pertaining to EVA is working in space. Deep space 

operations focus on providing capabilities in the areas of EVA, staging, logistics, humanrobotic integration, and autonomous operations. Objectives for phases 0 and 1 include:

• Phase 0: P0-04 Demonstrate in-space exploration class EVA technologies

• Phase 1: P1-13 Validate ability to conduct EVA in deep space

HEOMD-005, Concept of Operations, includes a description of Gateway (further detailed 

in a later section of this document) which includes an airlock capability to enable EVAs. 

Each of the Gateway elements will be designed to not require on-orbit EVA maintenance 

but will provide EVA translation paths in order to accommodate contingency EVAs or future 

utilization. The Airlock Module will provide secondary ingress capability to allow EVA 

crewmembers to safely ingress the stack in the event of a contingency without causing the 

depressurization of critical stack elements such as a habitat.
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HEOMD-006, Exploration Utilization Plan, also includes near term planned EVA 

technology demonstrations on ISS and xEVA providing for exploration of deep space 

destinations/environments and contingency EVAs during transit. 
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4.0 EXPLORATION EVA AND MISSION SYSTEMS OVERVIEW

A multitude of mission systems are required in order to successfully execute Exploration 

missions and the EVA operations included in those missions. 

4.1 EXPLORATION EVA OVERVIEW

The following subsections provide an overview of the xEVA System and other 

systems/vehicles that will be utilized during Exploration missions. 

4.1.1 xEVA System Definition

The xEVA System works in conjunction with the larger mission architecture and systems 

to conduct EVA operations at Exploration destinations. Figure 4.1.1-1: Systems Utilized 

to Execute Exploration EVAs shows the constituent elements that comprise the xEVA 

Mission System. There are elements that exist at the mission destination (and/or leveraged 

in transit from Earth to that particular mission destination) as well as elements that remain 

on Earth. While the details of each of these elements will differ between mission types, the 

fact remains that there will remain a connection to some extent between crew/local 

elements and Earth. 

FIGURE 4.1.1-1: SYSTEMS UTILIZED TO EXECUTE EXPLORATION EVAS

As NASA aims to shift from an Earth-reliant mindset to one that is independent of Earth, 

what will fundamentally drive the success of this shift is how the concepts of operation for 

a particular mission are established. In other words, who (crew and their local systems or 

Earth-based personnel) will be responsible for what to satisfy mission objectives. The 

inclusion of more advanced systems that afford crew the ability to become more self-reliant 

will become critical for mission success. 
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The xEVA System allows crewmembers to conduct excursions outside a habitable vehicle 

in order to perform exploration, science, construction, servicing, and repair operations. 

The xEVA System includes the following elements:

• Spacesuit (xEVA Suit)

• Vehicle Interface to Suit Equipment (VISE) 

• Flight Support Equipment (FSE)

• Tools and equipment necessary to perform EVA tasks

The xEVA Suit (e.g., xEMU) provides life support, environmental protection, and 

communications capability to the crewmember while allowing sufficient mobility to perform 

dexterous EVA tasks. The primary functions of the xEVA Suit are to provide a habitable, 

anthropomorphic, pressurized environment that allows crewmembers to perform work 

outside of the spacecraft or habitat in hazardous external conditions. The habitable 

environment is maintained by using suit components such as an outer pressure garment 

to maintain survivable pressure on the crewmember’s body, including boots and gloves, a 

helmet that allows suitable visibility for tasks, a thermal micrometeoroid garment to protect 

against thermal extremes and micrometeoroid impacts, a garment to prevent overheating 

in the suit, and a life support system to provide the necessary consumables (oxygen, 

water, and power) and remove carbon dioxide and contaminants.

FIGURE 4.1.1-2: XEVA SYSTEM SUIT CONCEPT

The VISE provides the interfaces necessary between the xEVA suit and the host vehicle. 

These interfaces will enable recharge of consumables and checkout the xEVA equipment. 

VISE performs that functions that are currently done on ISS by the Exploration Servicing, 
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Performance and Checkout Equipment (SPCE). At a high level, VISE can supply various 

consumables or resources used by xEMU, but also includes physical structures used to 

support/restrain the suit. VISE core functions are broken down into the following:

• Power and Data Communication

• Battery Charging

• Suit Loop Ventilation

• Vacuum Access

• High Pressure O2

• Cooling H2O

• xEMU Don/Doff Support

• HLS Descent/Ascent Crew Restraint

The FSE includes the additional equipment and ancillary hardware to support xEVA 

operations, such as the xEVA suit umbilicals. 

The xEVA Tools will interface with a suited crewmember to enable a range of specialized 

tasks. These include both tools for engineering tasks on vehicles and infrastructure, and 

tools for science. 

The xEVA System will enable and help accomplish the Exploration goals for lunar surface 

missions, including science. 

The remaining elements that support the mission system include:

• Assets could include the addition engineered devices leverage by the mission

such as rover vehicles, robotic assistants, and engineering packages

• Additional crewmembers who remain inside spacecraft, known as

intravehicular crew, are also another important element of the xEVA Mission

System.

• Spacecraft are an obvious component of a mission but must be considered in

the context of supporting xEVA which will require interactions with these other

identified elements.

• Finally, remote support consists of the entire enterprise of people and

technologies that remain on Earth and support the mission objectives

remotely. For the entire history of US EVA, ground-based support have play

an integral and mission dependent role in successful EVA operations.

4.1.2 Exploration EVA System Strategy

While there is a wide array of possible and feasible variations across the spectrum of 

conceptual human spaceflight architectures, there exists a limited set of overarching 

destination classes. For EVA, these destination classes are defined as follows:
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• EVA on a Spacecraft (Micro-Gravity on an Engineered Surface)

• EVA on a Small Natural Body (Milli-Gravity on an Asteroid or Moons of Mars)

• EVA on the Moon (Partial-Gravity Planetary Surface in a Vacuum)

• EVA on Mars (Partial-Gravity Planetary Surface in a Partial Atmosphere)

When considered in abstract terms, all human spaceflight EVAs would be conducted within 

the context of one or a combination of these destination classes. For example: EVA tasks 

supporting construction of a multi-element spacecraft in Low Earth Orbit (LEO) (such as 

Mir or ISS) or EVA servicing, maintenance or repair of satellites or launch/entry spacecraft 

are all particular activities conducted by an EVA System designed to operate in microgravity on engineered objects built by humans (spacecraft or habitat), within a vacuum 

environment. Similarly, the particular details about EVA environments for specific

destinations will vary, especially parameters like thermal and radiation, but these too may 

be enveloped.

Similarly, it is recognizable that although there are large numbers of NEAs and Near Earth 

Objects (NEO) that may at some point be accessible to human spaceflight missions, in 

general terms an EVA System designed to conduct activities on or immediately near the 

surface of a NEA (the “natural” surface) is simply an EVA System capable of performing 

tasks in milli-gravity within a vacuum environment and withstand intentional or inadvertent 

contact with material/debris not configured by human hands. Thus, despite the varying 

chemistries and compositions of the wide array of NEAs, an EVA System compatible with

activities on a NEA would consider particular items such as abrasion, sharp edges, dust, 

and incidental contact temperatures. Instead, EVA activities would utilize varying amounts 

of engineered crew aids and drive the design of the EVA System, along with operational 

procedures, to accommodate the reality that the natural surface is a source of potential 

hazards. This logic is extendable to a NEA and to the Moons of Mars, which may ultimately 

be shown to be relatively large captured asteroids. Thus, though Phobos and Deimos are 

massive enough to provide milli-gravity level g-values of concern for spacecraft, the 

fundamental nature of EVAs done on them is still classifiable as small natural bodies within 

a vacuum environment with as far as the EVA crewmember is concerned, there is 

insufficient gravity to provide ground reaction force, though that milli-gravity level may 

increase the likelihood of contact with the surface such that it is not considered microgravity.

The remaining two destination classes must acknowledge a common theme: any other 

EVA operation must be considered as occurring on a body so massive that it possesses 

a non-trivial gravitational field, i.e. Earth’s Moon and Mars. Though their specific g-values 

differ by meaningful amounts when it comes to the resulting on-back mass experienced

by the EVA crewmember, they are common in that the nature of EVA activities and tasks 

are significantly different than in microgravity or milli-gravity. Next, these two destinations 

each possess their own particular natural surface characteristics which will lead to 

potentially different concerns for abrasion, sharp edge tolerance, dust mitigation, chemical 

compatibility, planetary protection, etc. However, many of these concerns are similar

between the Earth’s Moon and Mars, and the particular design solutions may be driven 
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just as much by human choices such as EVA frequency, duration, and total quantity of 

EVA as it is the singular interaction with the natural surface and environment. The 

difference in gravity levels between the Moon and Mars is significant. Thus, at a 

destination class level, the biggest differentiator between the two partial-gravity 

destinations is the g-value, the specific geo-technical properties of the surface, 

contamination concerns, thermal environment, and the atmosphere or lack thereof.

Details of the xEVA System architecture are in EVA-EXP-0041, xEVA System Architecture 

Description.

4.1.2.1 xEMU and mEMU

The current design concepts for the xEVA System suit are the xEMU and follow-on Mars 

Extravehicular Mobility Unit (mEMU). The xEVA System will be capable of operating 

anywhere in the range from the Venus halo orbit to the asteroid belt, and from microgravity 

environments to the planetary surface of Mars.

FIGURE 4.1.2.1-1: EXPLORATION XEVA SYSTEM CAPABILITY BOUNDARIES

The xEMU will be a fully outfitted deep space exploration suit that will be utilized in LEO, 

cislunar space (on Gateway), and possibly Mars orbit, along with transit between the two, 

in addition to the lunar surface as a key element of Artemis. The xEMU will utilize a lower 

torso assembly that allows for ambulation on the lunar surface, performance of tasks in a 

non-neutral posture (e.g., kneeling, squatting, bending, stooping, sitting, lying, crawling, 
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etc.), and recovery from the non-neutral positions. It will include features such as dust 

tolerance and informatics. The mEMU will incorporate some aspects of the xEMU, but will 

be modified for operations on the surface of Mars and the different environment 

encountered there.

The future xEVA Suits will have the capabilities listed in Section 4.2 (specifically Section 

4.2.1 for the spacesuit), including (but not limited to) increased mobility & surface 

ambulation (including kneeling), enhanced consumables capabilities beyond the current 

EMU, operability at higher and variable suit pressures, advanced integrated informatics, 

compatibility with a rear-entry airlock (depending on the final mission architecture and 

programmatic phase), and the ability to attach and transport tools in both microgravity and 

surface environments.

FIGURE 4.1.2.1-2: XEMU CAPABILITIES

4.1.2.2 Single Suit Architecture

In order to save on mass and conserve volume, the xEVA Program is examining utilizing 

a single suit system architecture for Human Landing System (HLS) operations during 

dynamic flight phases on descent, EVA, and dynamic phases during ascent.

The Orion Crew Survival System (OCSS) Earth Launch Entry Abort (LEA) suit will be used 

during launch from Earth and Earth landing, but will not be used for the lunar portions of 

the HLS missions. With the single suit architecture concept, the xEMU would be utilized 

for lunar descent/ascent in Vehicle-Loop Mode (VLM) and on the surface in EVA mode. 

This means it will have both the capability to be pressurized via the VLM umbilical, without 

the Exploration Portable Life Support System (xPLSS) backpack during any required 
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dynamic phases, descent, jettison EVA, and ascent, and to operate pre and post EVA with 

the xPLSS on EVA umbilical. 

xEMU suit checkout will be done in the HLS, prior to lunar descent. The HLS will 

accommodate volume and equipment to stow, assemble the suits, don/doff the suits, and 

support on-orbit fit checks and xEMU checkout prior to descent. After checking out each 

xEMU, the crew will then reconfigure the suit for lunar descent by removing the suits rearentry Hard Upper Torso (HUT) hatch and xPLSS from the Exploration Pressure Garment 

System (xPGS) and replacing it with a HUT hatch designed for VLM umbilical operations. 

The xPLSS will be stowed for lunar descent. Upon landing the crew will then reconfigure 

their suits to EVA mode with the xPLSS attached. If the xPLSS will be left on the lunar 

surface for mass savings, the xPLSS and HUT hatch will be removed and the xEMU will 

be reconfigured to VLM mode for lunar ascent. 

See Section 4.2.1.3.1 for further details on the single suit configurations. 

4.1.3 Phases of Operations for xEVA System

Operations of the xEVA System are separated into the following phases:

1. Preflight Testing, Processing, and Training

• Ground operations including manufacturing and acceptance testing, fleet and

mission-specific sizing

• Crew training on the xEVA system and the mission

• Mission planning (including environmental constraints)

2. Earth Launch

• Launch stowage and logistics prepare the hardware for launch and

configuration for transportation to host vehicle

3. Suit Assembly & Checkout

• On-Orbit Suit Assembly - Operations to assemble the components of the

xEVA Suit in preparation for checkout and use

• Full System Checkout - Operations describing the comprehensive checkout

and evaluation of suit systems done prior to first use and after reassembly

following a reconfiguration or a period of quiescent stowage

• On-Orbit Fit Verification - The process of ensuring a good fit for the planned

crewmember including necessary adjustments

4. Suited Dynamic Flight Events (traveling to destination)

• Phases of the mission associated with dynamic vehicle flight and higher risk

times

• Includes planetary descent, planetary ascent, undocking, and certain orbital

maneuver burns

• Prebreathe for initiation of saturation (if required, dependent on lander

atmosphere)
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• xEMU System is utilized in VLM

5. Prep for Operations (Road-to EVA)

• The "road-to EVA" is a comprehensive list of all the activities that occur

before and up to the day prior to the start of a planned series of EVAs

• Typical activities include:

o Suit assembly or reconfiguration

o Suit checkout

o Fit verification

o Consumables recharge (O2, H2O, etc.)

o Battery recharging

o Liquid Cooling Ventilation Garment (LCVG) fill (if required)

o Airlock configuration

o Tools and task equipment configuration

o Filling and installing drink bags in suit

o Preparation of biomedical and radiation monitoring equipment

o Configuration of communication system

o Timeline review

o Briefings from MCC and the Science Team

o Uploading of data into the informatics system (as applicable)

6. Pre EVA Operations (Prep & Prebreathe)

• On the day of the EVA, the crewmembers begin final prep activities and the

prebreathe protocol (as applicable)

• General day-of-EVA activities include, but aren’t limited to, the following:

o EVA prep – activities which occur the day of a planned EVA, just prior

to donning the xEVA Suit for EVA

o Configure vehicle and suit communication

o Verify the appropriate equipment is in the airlock before isolating the

module

o Activate the Carbon Dioxide (CO2) removal system (if applicable)

o Prepare for mask prebreathe (if applicable)

o Power up the xEVA Suits and verify system functionality, and

configure for suit donning

o Verify xEVA Suit communication and data with IV and/or MCC

o IVA crew performs any remaining airlock configuration tasks (if

applicable)

o Suit Donning - Operations that occur in the xEVA Suit, but prior to

disconnecting from the umbilical tied to host vehicle resources

o xEVA Suit manned checkout

o Depress to 10.2 psia (if applicable)

o o Mask prebreathe (if required)

o Donning of suits

o In-suit communication and leak checks

o Prebreathe protocol – Prescribed prebreathe period in order to

decrease the risk of Decompression Sickness (DCS)
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o Depress to 10.2 psia (if applicable)

o Mask prebreathe (if required)

o Purge nitrogen

o In-suit prebreathe on umbilical

7. EVA Operations

• Once the prep and prebreathe procedures are completed, the EVA crew will 

depress the airlock, switch over to suit systems, egress, and begin their tasks

• The “EVA” phase begins when the spacesuit is switched from the vehicle 

provided power source to internal suit power (batteries), and officially ends

when repressurization has begun after ingress 

8. Post EVA Operations

• Post EVA operations commence with reconnection to umbilical and airlock 

repress; and include doffing the xEVA Suit, servicing, disassembly, and 

stowage

• Consumables are recharged

9. Maintenance 

• Periodic maintenance of the suits may be required, in addition to changing out 

some of the more consumable aspects, such as the gloves

10. Departure Prep & Quiescent Stowage

• Quiescent stowage refers to both the period of time EVA hardware is predispositioned at a destination prior to human interaction and the period 

between crewed presence at the destination

• Prior to crew departure from the destination, hardware that is to be reused 

and not returned to Earth for refurbishment will be prepared for quiescent 

stowage, where the hardware will not be accessed by crewmembers or 

remotely actuated from the ground for up to three years

• Suit reconfiguration (if xEMU is needed in VLM for ascent)

11. Suited Dynamic Flight Events (leaving destination)

• Phases of the mission associated with dynamic vehicle flight and higher risk 

times

• Includes planetary ascent, certain orbital maneuver burns, and docking

• xEMU System is utilized in VLM

12. Post Docking Operations

• Disassemble xEVA suit for long term stowage in Gateway or leave in lander 

for disposal

• Transfer samples and returning xEVA hardware to Gateway and Orion

13. Post Flight

• Post-flight testing consists of flight hardware returned from orbit for 

examination of system and component function, health and life

• Evaluations include failure investigations
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• A thorough set of lessons learned, anomaly reports, and failure investigation 

reports will lead to action plans to improve the xEVA system design, 

processes, team communication, training, procedures, etc.

• This may include discarding and/or returning the xEVA Suit for ground 

processing.

4.1.4 Frequency and Duration of EVAs

The xEVA suit will support EVAs of up to 8 hours in duration (6±2 hours). How long EVAs 

are and at what frequency they are conducted will depend on the destination, phase, 

mission needs, and vehicle capabilities. 

4.1.4.1 ISS EVAs

EVAs conducted on ISS will be the same duration and frequency of those that are currently 

done utilizing the EMU. Typically, EVAs on ISS are planned for 6.5 hours, but have 

frequently exceeded 7 hours, and on occasion been over 8 hours in duration. 

4.1.4.2 Gateway EVAs

EVAs on Gateway will be treated similar to EVAs conducted on ISS in terms of duration. 

4.1.4.3 Lunar Surface EVAs

EVAs on the lunar surface will vary according to lander capabilities, surface assets, and 

program phase. EVAs will be between 4 and 8 hours in length (6±2 hours). The duration 

will also take into account a number of factors, such as lighting and the time of year. 

During the Apollo missions, the crew conducting EVAs ranging from two hours 32 minutes 

to seven hours 37 minutes. Out of the 14 EVAs conducted on the lunar surface, six of 

those were over seven hours long.

4.1.4.3.1 Artemis Phase 1 (Artemis III & IV Missions)

EVAs on the lunar surface will vary according to lander capabilities, surface assets, and 

program phase. EVAs will be between 4 and 8 hours in length (6±2 hours). Artemis III 

will have between 2 and 5 EVAs. A supplemental EVA may be allocated to dispose of 

trash and equipment not being brought back up from the surface, and may or may not be 

executed on umbilical (in VLM). 

4.1.4.3.2 Artemis Phase 2 (Sustained Missions)

For Rover and EVA ops during a seven to fourteen-day short stay mission, the crew will 

have the capability to perform daily 8-hour EVAs in order to take advantage of the short 

period on the surface. Crewmembers will conduct the EVAs paired together to maximize 

boots on the ground time and for safety. However, there may be a rest day after three or 

four days of EVA, depending on the duration of the EVAs. 
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For Rover and EVA ops during a 42-day mission, operations will differ between lunar day 

and lunar night. During lunar day, EVAs will be conducted three to four days per week 

and be two to eight hours in duration (hour for egress/ingress and 1.5 - 7.5 hours of tasks) 

with one to two per day. EVAs may extend an additional hour for emergency and offnominal situations. 

For days involving two EVA excursions per day, the EVAs will be treated as if a single EVA 

is conducted in two parts, and therefore the suit consumables won’t be required to be 

recharged between excursions (though some will be recharged simply by plugging in the 

umbilical, such as O2). The total amount of planned EVA Phased Elapsed Time (PET) 

time within a crew wake period will stay within the constraints of a single 8-hour EVA. The 

time between the two EVAs will be considered a ‘break’ in EVA more than a second EVA. 

In other words, the crew will be able to take an 8-hour EVA and conduct it in two parts, 

with the sum of the parts not exceeding what would have been done for a single EVA.

For all rover-based EVA operations on Phase 2 missions with two pressurized rovers, the 

rover pairs will work together. Both crew in one rover will conduct the EVA together, while 

the other rover is nearby. Alternately, one crewmember from each rover may conduct the 

EVA together, still enabling two crewmembers to act as buddies, although this requires 

the rovers to be parked next to each other and requires two separate and simultaneous 

airlock operations. The surface teams will have the capability to conduct EVA with all four 

crewmembers simultaneously, if needed. 

4.1.4.4 Mars Surface EVAs

EVAs on Mars are still in work, but will likely have at least the frequency and duration of 

those for the sustained lunar missions in Artemis Phase 2.

4.1.5 EVA Tasks for Exploration Missions

All future exploration missions include EVA operations that will comprise both engineeringfocused tasks for constructing and maintaining infrastructure and assets, as well as 

science-driven tasks for exploration of the natural environment. Exploration missions will 

include EVA operations for maintenance, construction (pioneering), science, transfer

between vehicles, and contingency. These tasks will largely be planned, but unplanned 

EVAs may occur for a contingency to repair something that has broken
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FIGURE 4.1.5-1: EMU MICRO-GEVA ON ISS (L) AND SURFACE EVA DURING APOLLO (R)

4.1.5.1 Engineering EVA Tasks

Engineering-focused EVA operations and tasks can be generally categorized as 

maintenance, construction/pioneering, or contingency. 

4.1.5.1.1 Maintenance

These engineering-focused EVAs are used to conduct proactive maintenance on any 

vehicle or habitat prior to a failure or the end of life on particular hardware. Maintenance 

EVAs are used to reduce the likelihood of a vehicle failure that would have driven the need 

to execute a contingency EVA. Whether in microgravity or partial gravity, these EVAs will 

be conducted in a similar same way as those on ISS. 

4.1.5.1.2 Construction & Pioneering

Construction EVAs are nominal planned events to perform or assist in vehicle or 

infrastructure assembly. Construction EVAs may be done in a microgravity environment, 

much like assembly of the ISS, and will be done on any planetary surface mission for 

sustained operations. Pioneering EVA is the term sometimes used for those specifically 

that will build up the infrastructure at the partial-g surface destinations. The terms 

construction and pioneering are essentially interchangeable. Like ISS EVAs, construction 

and pioneering EVAs will be planned in advance to utilize the maximum available EVA 

period. Construction tasks may range from connection of lines and driving fasteners in 

microgravity, to placement of anchoring technology on NEAs, to setting up communication

antennas and grading regolith in preparation for habitat construction on a partial gravity 

planetary surface. 

4.1.5.1.3 Contingency

Contingency EVAs include those required to deal with spacecraft, vehicle, and habitat

issues and failures, and those needed to rescue crewmembers on planetary surfaces. 

Vehicle failures can include known possible failures or unexpected and unforeseen events. 

Contingency EVAs are activated to mitigate the consequence of a vehicle failure. 

Depending upon the failure, a Contingency EVA may be required and plan-able for an 
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explicitly limited window, such as docking or loss of spacecraft/vehicle power or thermal 

control. This means that each spacecraft/vehicle must consider its own specific failures to 

determine if and how EVA will be used. All missions will need to account for Contingency 

EVAs for those situations such that a next worst failure (i.e., system is now zero-fault 

tolerant) will result in critical vehicle loss of functionality, an emergency vehicle undocking 

(crew hazard), or loss of EVA capability to enact repair (loss of vehicle with next worst 

failure). 

FIGURE 4.1.5.1.3-1: CONTINGENCY BMRRM R&R ON ISS DURING US EVA 14 (L) AND 

UNFORESEEN SOLAR ARRAY REPAIR DURING STS-120

4.1.5.1.4 General Types of Engineering Tasks

General engineering tasks, especially those on the lunar surface, will be for preparation of 

equipment for Exploration (such as offloading and loading equipment, maintaining 

equipment, and maintaining vehicles and transport system), construction of surface 

infrastructure (transporting tools and equipment, deploying and aligning antennas and 

comm repeaters, routing and connecting power and communication lines, connecting 

modular elements, installing/removing fasteners, electrical connectors, and fluid 

connectors, and preparing surfaces), for assembly and maintenance of equipment 

(installing/removing fasteners, electrical connectors, and fluid connectors, removing dust 

and cleaning equipment, and repairing equipment), and preparing ascent vehicles 

(offloading equipment, transferring equipment and samples from transport system to 

ascent vehicle, and cleaning equipment and vehicle). 
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FIGURE 4.1.5.1.4-1: EVA ENGINEERING TASKS FOR SURFACE OPS

4.1.5.2 Science EVA Tasks

A primary focus of the Exploration missions will be science-driven EVAs and tasks. These 

EVAs will enable the science at each destination and focus on evaluations and 

characterizations of the natural features of the destination. A variety of science-driven 

tasks will be conducted at any natural environment destination, including observations and 

imagery, acquisition of data, deployment and retrieval of instruments, and acquiring 

physical samples for return to Earth. The science tasks may include the operation of novel 

EVA hardware and instruments. Sample acquisition will include loosely adhered particles 

(surface, regolith, float), rock chip samples broken from larger boulders or outcrops, 

subsurface samples exposed in trenches, samples from permanently shadowed regions 

(possibly including volatile samples requiring cold curation), and subsurface (core) 

samples. Science tasks will also involve deploying handheld instruments, larger stationary 

instrument packages, and instruments requiring prolonged astronaut or rover interaction.

4.1.5.2.1 General Types of Science Tasks

General tasks include making contextual observations at the macro-scale (regional) and 

micro-scale (local) context, conducting photo and video documentation of the 

observations, collecting instrument data from handheld instruments and geochemical, 

geophysical, and geotechnical instruments, deploying science payloads, and acquiring 

rock, regolith, and specialized samples.
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FIGURE 4.1.5.2.1-1: EVA SURFACE SCIENCE OBSERVATION & DATA COLLECTION 

TASKS

Science sample return is a top priority for missions to natural planetary bodies, including 

the Moon. Those will include rock, regolith, and specialized (volatile) samples. Rock 

sample types include float (rocks laying on or loosely adhered to the surface, collected via 

tongs and rakes), rock chip (fragments forcibly removed from a larger rock/boulder, 

typically with a hammer and/or chisel), and rock core (cylindrical subsurface sample drilled 

from a rock). Regolith sample types include bulk (loose surface material collected with a 

scoop), core (subsurface samples collected with a drive tube and drill), and surface 

samples (the top ~1mm of undisturbed material). Specialized samples include volatiles 

and atmospheric samples, both of which require specialized tools and containers. 
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FIGURE 4. 4.1.5.2.1-2: EVA SCIENCE SAMPLE ACQUISITION TASKS

4.1.5.3 Resource Utilization EVA Tasks

In-Situ Resource Utilization (ISRU) is the practice of collection, processing, storing and 

use of materials found or manufactured on other astronomical objects (the Moon, Mars, 

asteroids, etc.) that replace materials that would otherwise be brought from Earth. These 

activities could represent hybrid tasks between the defined Engineering and Science 

Tasks. 

4.2 XEVA SYSTEM KEY CAPABILITIES & FEATURES

The xEVA System includes the xEVA spacesuit, the IVSE, the FSE, and the tools. 

The following sections describe some of the high-level key aspects and capabilities of the 

xEVA System, with a focus on the xEVA lunar surface suit and equipment to needed 

enable the Artemis missions. The entire system is highly integrated between the 

spacesuit, ancillary equipment, tools, lander, and other assets, however, these sections 

attempt to group capabilities in order to assist with comprehension of the overall system. 

Capabilities and features are separated into Artemis Phase 1 and Gateway (which 

encompasses ISS) and Artemis Phase 2, where applicable. 
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4.2.1 xEVA Suit and Ancillary xEVA Equipment

The following are key capabilities and features that are primary encompassed in the xEVA 

suit. There may be ancillary tools and equipment that are not directly a part of the suit 

needed in order to enable these capabilities. 

4.2.1.1 General xEVA Capabilities

The xEVA System includes, but is not limited to, the following general key capabilities and 

features for Artemis Phase 1 (including Gateway):

• Perform engineering-focused tasks (contingency, maintenance, and 

construction/pioneering) in microgravity and partial-gravity surface 

environments

[Reference Section 4.1.5.1]

• Perform science tasks in microgravity and partial-gravity surface 

environments

[Reference Section 4.1.5.2]

• Support EVAs of up to 8 hours in duration (6±2 hours), with an additional 1 

hour of secondary/backup O2 for off-nominal operations

• Suit pressures range from 0.4 psid to 8.2 psid, with a nominal EVA pressure 

of 4.3 psid

• Rear-entry spacesuit

• Compatibility with a traditional airlock and/or vehicle cabin as an airlock

• Crew able to “self-don/doff” suit (nominal ops efficiency and contingencies 

associated with incapacitated crew or failure to repress the vehicle cabin)

• Dust mitigation capability

The xEVA System includes, but is not limited to, the following general key capabilities and 

features for Artemis Phase 2 (sustained missions):

• Everything from Artemis Phase 1

• Compatibility with a suitlock (rear-entry airlock) (TBD-4.2.1.1-004
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FIGURE 4.2.1.1-1: XEVA SYSTEM SUIT CONCEPT

4.2.1.2 Single Suit Configurations

The xEVA System supports two different suit configurations for operations during dynamic 

flight phases on descent, EVA, and dynamic phases during ascent.

FIGURE 4.2.1.2-1: APOLLO 10 CREW TRAINING FOR LUNAR DESCENT IN SUITS

4.2.1.2.1 Suit VLM (Vehicle Loop Mode)

Key attributes for vehicle loop mode including:

• Use during dynamic flight phases during descent and ascent operations

• Crew removable Exploration Primary Life Support System (xPLSS) and 

installable VLM umbilical(s) between the Exploration Pressure Garment 

System (xPGS) and host vehicle for power, data, communication, ventilation, 

and thermal control

• xPGS will protect astronauts during unexpected depress events (lunar 

ascent/descent) 

• Crew are not expected to be suited for longer than 12 hours at any one time 

during nominal operations, therefore they may not be suited during the full 

duration of the descent or ascent
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• A Crew Restraint System (CRS) may be used during certain dynamic phases 

in order to safely stabilize the crew and relieve some loads

• xEMU (including gloves and helmet) will be compatible with the HLS controls, 

systems, and cabin environment that are required to be actuated during 

dynamic operations

• Crew will be able to conduct a jettison EVA in VLM mode

FIGURE 4.2.1.2.1-1: XEMU VEHICLE LOOP MODE CONFIGURATION

4.2.1.2.2 Suit EVA Mode

For the EVA Mode, the suit is configured with the xPLSS attached to the xPGS to provide 

life support during lunar surface excursions. Umbilicals are provided by the host vehicle 

for recharge of the xEMU consumables and support during pre- and post-EVA operations. 

4.2.1.3 Suit Mobility

The xEVA System includes, but is not limited to, the following key mobility capabilities and 

features for Artemis Phase 1 (including Gateway):

• Mobility & surface ambulation during partial-gravity surface operations

• Translation via walking, crawling on hands and knees (short distances with 

slow controlled motions, scrambling (traversing sloped terrain while using 

one's hands), and climbing steps and ladders 

• Walking up/down/across a slope of up to 20° 

[Note: Apollo 15 traversed on slopes of ~17°]
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• Ambulating on traverses of up to 2 km away from the lander (depending on 

terrain)

[Note: Apollo 14 walked ~1.45 km from the lander]

• Traversing across regolith and scree, down into and out of craters, volcanic 

terrains (including lava tubes), and shadowed regions (with the appropriate 

equipment and assets)

• Performing tasks while standing and non-neutral postures (e.g., kneeling)

• Mobility allows crewmembers to stand up unassisted after a fall

• Mobility to egress/ingress a 40 x 40 inch hatch in microgravity

• Mobility to step through (egress/ingress) a 40 x 60 inch hatch in partial-gravity

(surface operations)

• Ability to sit on a seat, such as on an unpressurized rover

• Ability to safely carry equipment, including pushing/pulling a carrier (reference 

4.2.3 Tools & Task Equipment)

The xEVA System includes, but is not limited to, the following key mobility capabilities and 

features for Artemis Phase 2 (sustained missions):

• Everything from Artemis Phase 1

• Walking back from a failed rover to a safe haven on ambulating traverses of 

up to 12 km

FIGURE 4.2.1.3-1: XEVA SUIT CONDUCTING TASKS STANDING AND KNEELING
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4.2.1.3.1 Walk Back for Planetary Surfaces

The xEVA suit will enable EVA crew the ability to ambulate (walk) on planetary surfaces. 

This includes being able to support a walking traverse of up to 2 km away from the 

lander on the lunar surface (radial distance) and a total cumulative distance of 16 km 

during an EVA, though that exact distance depends on the local terrain. Utilizing rovers 

will extend the ranges that EVA crew will be able to explore the surface. Traverse 

ranges account for the xEVA suit secondary O2 system providing an additional hour of 

gas. These ranges also do not stack any failures, meaning that if the vehicle fails, the 

suit is presumed to function nominally, and vice-versa. Actual distances traveled will 

need to account for terrain and time for ingress. 

4.2.1.3.1.1 Lunar Surface Excursion Ranges

For lunar surface operations, there will be a goal to maximize the distance possible for 

science exploration to the greatest extent possible. They will always stay within a range 

that allows them to get to a safe haven (lander, habitat, or pressurized rover) in the event 

of a contingency. Depending on the assets on the mission (e.g., rovers), the distance the 

crew travels from the lander (or habitat) will change. This will be a combination of the EV 

crew staying within appropriate walk back and/or driving distances. Smart traverse 

planning tools will be utilized to calculate the appropriate distance during any given day. 

The assumptions for defining EVA ranges are provided below. 

EVA range for lunar surface walking: Traverses assume an ~2 km/hr walking pace over 

relatively level regolith, yielding a walking distance of 2 km away from the lander (safe 

haven), while factoring in the time to ingress and attach to vehicle consumables. This 

does not account for slope or obstacles (e.g., boulders), so distances may decrease due 

to terrain or operational considerations. Note that the Apollo 14 crew walked 1.45 km from 

their lander. 

EVA range with lunar surface unpressurized rover: The rover will stay within less than a 

5-hour walk back to the lander, which equates to approximately 10 km when walking at a 

pace of 2 km/hr [TBR-EVA-EXP-0042-001]. This protects for a rover failure that drives the 

EV crew to walk back to the lander. This distance must be balanced with suit consumables

remaining, and does not account for slope or obstacles (e.g., boulders), so distances may 

decrease due to terrain or operational considerations. This range does not stack system 

failures. Giving the rovers the capability of fully recharging the EVA suits before attempting 

any walk back would help extend this range. During the Apollo missions, the crew got as 

far away from the Lunar Module as 7.63 km while driving the unpressurized Lunar Rover 

Vehicle (LRV), which was designed to operate within a 5-mile (~8 km) radius of the Lunar 

Module. 

EVA range with a single pressurized rover range: It is assumed that there is time available 

for the crew to rest and recharge their suits before they walk back to the lander/habitat, 

providing a maximum walk-back time of 8 hours (nearly a full EVA). Given a pace of 2 

km/hr, a walk of 8 hours could be upwards of 16 km. However, a more conservative 
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approach would be to use a more nominal EVA length of 6 hours, with an associated walk 

back distance of 12 km. Note, as failures are not stacked, if the suit experiences a failure, 

the crew simply ingresses the rover, and then drives back to the lander/habitat. 

For dual pressurized rover range, the two will be capable or rescuing the other crew. 

Therefore, the crew essentially have a mobile safe haven, which could extend their 

excursion range to 100 km or more. The second rescuing rover will stay within less than 

an 8-hour drive of the EV crew [TBR-EVA-EXP-0042-002]. This protects for the situation 

in which a rover has been compromised, and they must abandon the vehicle in their EVA 

suits. Future refinement and testing will determine if this distance should be shortened in 

order to reduce the amount of time the EV crew may be in their suits, while still striving to 

provide the greatest range possible for science exploration, especially if a rover failure 

happens at the end of an EVA.

FIGURE 4.2.1.3.1.1-1: LUNAR SURFACE EVA EXCURSION RANGES

4.2.1.3.1.2 Mars’ Surface Excursion Ranges

Development of the mEMU and associated walk back ranges are forward work. 

4.2.1.4 Environmental

The xEVA System includes, but is not limited to, the following key environmental 

capabilities and features for Artemis Phase 1 (including Gateway):

• Conduct microgravity operations on the ISS and Gateway (cislunar orbit)
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• Conduct partial-gravity operations on the surface of the Moon, including near 

the south pole 

• Operate during lunar day (near continuous light)

• Function for up to 2 hours of contiguous exposure in a shadowed area, 

including Permanently Shadowed Regions (PSRs)

o Factors in translating into and out of the shadowed area

o Crew will return to lit area in order to warm up before going into 

another shadowed region

• Function within vehicles with the potential following nominal saturation 

atmosphere set points (note: it is important to recognize that spacecraft 

design implementation may involve design uncertainty that adds margin to 

these values and must be considered in requirements for materials 

compatibilities):

o 14.7 psia with 21% O2

o 10.2 psia with 27% O2

o 8.2 psia and 34% O2

The xEVA System includes, but is not limited to, the following key environmental 

capabilities and features for Artemis Phase 2 (sustained missions):

• Everything from Artemis Phase 1

• Operate during lunar night (near continuous dark)

For lunar surface missions, the general regions of interest for Exploration include cratered 

terrain, permanently shadowed regions, and volcanic terrain. The xEVA System will 

enable exploration into those regions, and return of science samples from them.

FIGURE 4.2.1.4-1: GENERAL SCIENCE REGIONS OF INTEREST FOR LUNAR SURFACE 

MISSIONS
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Mission to the lunar surface will require xEVA Suits that operate in and survive in the harsh 

lunar environment. The Pressure Garment System components such as bearings, boots, 

and gloves must provide a higher level of protection against a dusty environment, higher 

abrasion resistance, higher cycle life and longer mission durations before refurbishment 

than the ISS EMU was required to survive. Dust tolerant electrical connectors are also 

necessary to prevent shorts and mechanical failure of connectors. 

The xEVA Suit will enable the crewmembers to ambulate over a variety of terrain. The 

crew will need to scramble up and down steep slopes, down/up rom and explore craters 

and lava flows, and possibly down into and back up out of lava tubes and pits (likely 

involving belaying/rappelling). The EVA Suit must be robust enough to maintain suit 

pressure and functionality during and after crew falls and impacts with sharp rocks.

Reference the latest version of EVA-EXP-0039, xEVA System Destination Environments 

Specifications for detailed information on the environments in which the xEVA system will 

operate.

4.2.1.4.1 Dust Mitigation

The removal of dust from the suits (dust mitigation) is a multi-phase operation to preclude 

or limit dust introduction into the suit interior, life support system, or into the crew cabin. 

Dust can damage suit components and can become a crew health hazard if introduced 

into the crew cabin in sufficient quantities. 

FIGURE 4.2.1.4.1-1: DUST CONTAMINATION DURING APOLLO 17

xEVA surface operations include multiple strategies for reducing the amount of lunar dust 

that is released into the HLS habitable volume. The theme of the overall strategies can 

be separated into three processes:

• Prevention (reducing the amount that adheres to the suit)

o Improved mobility to reduce contact points with regolith during the 

EVA
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o Reducing dust capture points on the suit based on lessons from 

Apollo

o Reducing the amount that adheres to the suit outer layer and surfaces

• Reduction

o Removing dust that has been captured by the suit

o Removing dust while minimizing dust that re-adheres to the suit

• Mitigation & Contamination Control

o Preventing dust from spreading from the suit to the cabin

o Cleaning up areas that have become contaminated with dust

4.2.1.5 Visibility and Lighting

The xEVA System includes, but is not limited to, the following key visibility and lighting 

capabilities and features for Artemis Phase 1 (including Gateway):

• Suit-mounted lights will support visual sight of suited astronaut boots, ground 

ahead including the immediate walking path (and hazards and obstacles 

therein), EV partner in a PSR, lander, and the EV worksite

• Primary lights are helmet-mounted to illuminate the standard microgravity 

work envelope

• Crew visibility and lights may need to support color-critical tasks

• Ancillary lights and/or lights on surface assets or other parts of the suit (e.g., 

hands-free flashlight strapped to the forearm or mounted near the waist) may 

supplement the helmet lights

The xEVA System includes, but is not limited to, the following key visibility and lighting 

capabilities and features for Artemis Phase 2 (sustained missions:

• Everything from Artemis Phase 1

• Lighting to support up to a 12,000 m contingency walk-back from a failed 

pressurized rover 

Lighting will be critical for lunar surface missions, especially for those near the lunar South 

Pole where constant long shadows will be prevalent. Sufficient lighting for walking over 

rough slopes and conducting science tasks will be required for any incursion into a PSR. 

Those lights will need to allow the crew to walk hands-free (as much as possible) and 

perform tasks with tools in both hands. 
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FIGURE 4.2.1.5-1: XEVA SUIT LIGHT AND VISOR NOTIONAL CONCEPTS

4.2.1.6 Communication and Data

Exploration EVAs require high data rate and high bandwidth communication and data for 

voice, suit data, scientific data, video, and still imagery, in addition to augmented reality 

cues. Critical services, such as voice communication and suit telemetry, will be 

transmitted over UHF. Non-critical services will be transmitted primarily over Wi-Fi.

The xEVA suit will be capable of transferring data and communications through a Radio 

Frequency (RF) Spectrum Management approved wireless system and a hardline 

umbilical. For exploration, new protocols will be developed that will be needed for 

spacecraft proximity (e.g. asteroid mission, Mars moons/orbit) and for surface deployment. 

Some missions may involve both microgravity and planetary surface EVAs in the same 

mission. On-orbit updates of software and complex programmable logic devices will allow 

changes to be made during the mission if necessary. If a hardware change out is required, 

then the component will have to be an ORU. A special antenna may be required.

Limited or delayed communications coverage may prohibit the Mission Control Center 

(MCC) from providing guidance to the crew during real-time EVA life support system 

anomalies. Therefore, the pertinent suit caution and warning alarms, including those 

sounded, enunciated, and displayed, from one suit will be directly transferred to all other 

crewmembers on the EVA and in close proximity vehicles, identifying the originating suit, 

and allowing the crew to immediately respond to a suit failure. For this to be possible, the 

network coordinator rebroadcasts the warning messages received from one suit to the 

other suits and users on the network. Alternatively, when generated, the suit Caution and 

Warning System (CWS) messages may be sent as broadcast or multicast packets. It is 

envisioned that this type of crew autonomy is eventually provided via an in-suit CWS 

capable of providing spoken descriptions of the problem, a crew locator system (e.g., 

transponder system), and an electronic display. The IV crewmember aboard a habitat 

element or exploration vehicle has communications with the EVA crew as long as the EVA 

crew is within the line of sight, even when coverage with the MCC is not available, up to a 

range of 10,000 m on surface missions, which may require relays or other assets.
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For lunar surface missions, current plans utilize Ultra-High Frequency (UHF) and Wi-Fi for 

voice communication and data. This is also a potential to expand to other systems (e.g., 

LTE or 5G) for lunar surface operations. An Acquisition of Signal (AOS) state from the 

EVA crew to the HLS is presumed to be the nominal operational condition for EVA, 

however, there will likely be lower signal strength due to distance or blockage, including 

up to LOS, which will be addressed by mission rules. Indication of this signal strength to 

EV crew and MCC will help the team anticipate LOS. During EVAs, the xEVA Suits will 

have a direct UHF and Wi-Fi communication link to the HLS landed element, enabling the 

crew to communicate with the Gateway/Orion crew and Earth via KA-band radio. Because 

HLS will be concurrently communicating with both Gateway/Orion and Earth, it means the 

xEVA Suits will be able to communicate with both Earth & Gateway.

The xEVA System includes, but is not limited to, the following key audio communication 

and data capabilities and features for Artemis Phase 1 (including Gateway):

• UHF and Wi-Fi for voice and data

• Ability to record communication and video onboard the suit in case of loss of 

signal with the MCC

• All audio, video, and integrated xEVA suit still imagery will be recorded with 

timestamp

• Ability to communicate up to a range of 10,000 m on surface missions

o Hills, boulders, craters, and other natural obstacles may require the 

use of EVA-deployable communication repeaters

The xEVA System includes, but is not limited to, the following key audio communication 

and data capabilities and features for Artemis Phase 2 (sustained missions):

• Everything from Artemis Phase 1

• Ability to communicate up to a range of 12,000 m on surface missions during 

a contingency walk-back (with appropriate ancillary equipment)

FIGURE 4.2.1.6-1: XEVA SUIT CAMERA NOTIONAL CONCEPT
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4.2.1.7 Imagery

Exploration will require high definition video, some amount of transmission and storage on 

the suit, and enhanced informatics. The imagery aspects of xEVA overlap with the 

informatics capabilities. 

The xEVA System includes, but is not limited to, the following key imagery capabilities and 

features for Artemis Phase 1 (including Gateway):

• Integrated high-resolution imaging capability in the xEVA suit (i.e., high 

definition helmet cameras)

• Still photography is required and will be completed by the xEVA suit helmet 

camera and supplemental equipment as necessary (e.g., a hand-held 

camera)

4.2.1.8 Informatics

Informatics required for the Artemis III mission include the following for Artemis Phase 1 

(including Gateway):

• Cameras (video)

o Obtaining and transmitting high-resolution video and still imagery from 

the suit integrated camera and other hand-held cameras 

• Lights

o Enables visibility for viewing the ground ahead while walking, the 

worksites, and tasks

o Needed to ensure safe return from shadowed regions and to the 

lander

o May be integrated into the suit or ancillary lights hands-free lights 

(reference 4.2.1.5 for details on lighting)

For Artemis Phase 2, the xEVA suit will include an integrated informatics system with a 

heads-up display type of capability that will allow for both increased autonomy and 

enhanced ability of the flight control and science teams to interact with the EVA 

crewmembers. The informatics display and processor are anticipated to be a non-critical 

system and should be distinguished from the Caution & Warning System that monitors 

safety critical functions of the suit. The xInformatics display system will be used to 

enhance communication with MCC, along with increasing crew efficiency and autonomy 

when performing tasks. In the event that data on the xInformatics system does not match 

information on the Caution and Warning System, the crew will be trained to use the Caution 

and Warning System information because of its higher reliability.

In addition to lights and cameras, the xEVA suit will have an external power and data 

interface for ancillary equipment (sensors or devices). This connection could be utilized 

for integration of data from xEVA tools and instruments, including (but not limited to) handheld cameras, power tools, and hand-held science instruments.
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Informatics systems will need to take into account lighting conditions. Reference the latest 

version of EVA-EXP-0039, xEVA System Destination Environments Specifications for 

detailed information on the environments in which the xEVA system will operate.

Beyond the basic informatics capabilities required for Artemis Phase 1, the xEVA System 

will eventually include, but is not limited to, the following key informatics capabilities and 

features in Artemis Phase 2 (sustained missions):

Suit System Monitoring

• Suit systems monitoring and consumables displays

o Enhanced awareness of suit functions for the crew

o Caution and warning auditory tones and displays will still be controlled 

by the CWS

• Consumables calculation

o Allows for real-time timeline adjustments (similar to dive computers)

o Primary is CWS and MCC monitoring

o Crew should be trained to check Display and Control Unit (DCU)

and/or with MCC before reacting off suit data displayed on any 

informatics system, which provides situational awareness

Conducting Tasks and Traverses

• Procedure and cue card viewing

o Down-mode is verbal directions from MCC and/or an IV (as is done 

today on ISS)

• Viewing of diagrams, photographs, annotated images, and videos

o Down-mode is verbal direction from MCC/IV

• View timeline status, including time ahead/behind and consumables margin 

• Navigation and tracking

o Safe return to lander (or other safe haven)

o Transmission of crew and asset positions 

o Marking of science sample locations

o Down-mode is crew understanding the terrain and manual land 

navigation with maps

• Augmented reality graphics and cues

o Includes pre-planned waypoints for navigation and science regions of 

interest into environment

o Down-mode is maps, images, or verbal direction from IV/MCC

Capturing data

• Verifying helmet camera video framing and quality

o Looking at imagery before/during transmission 

o Down-mode is verbal direction from MCC/IV or best effort
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• Interface with and transmission of scientific instrument, sensor, and camera 

data

o Down-mode is best effort with instruments storing data themselves

Communicating with MCC

• Text communication from both MCC and an IV

o Down-mode (and nominally primary) is voice comm

• Ability to receive near real-time updates and content from MCC during the 

EVA

4.2.2 VISE 

The VISE consists of equipment required for EVA preparation and post EVA activities. It 

includes the equipment for recharging consumables on the xEVA suit, providing 

resources directly from the vehicle, communication systems, the Exploration Don/Doff 

Assembly (EDDA), and crew restraint system.

The VISE provides for the following:

• Lander descent/ascent vehicle loop mode

o Breathing gas

o Suit ventilation

o Cooling water

o Communication

• Suit servicing (refill/recharge) and prep/prebreathe activities

o Oxygen (O2) recharge

o Water recharge

o Battery recharge

• Data/Communication

• Don/doff assembly

• Crew restraint for HLS descent/ascent

Reference the VISE Project for details on the EVA interface equipment planned for use on 

HLS and Gateway for the Artemis Program. 

4.2.2.1 Consumables Recharging

Consumable recharging will nominally be completed prior to the start of the EVA day and 

will nominally occur while the suit is doffed. 

1. Oxygen Recharging – nominally, oxygen tanks will be filled prior to the start of the 

EVA day. During umbilical operations, the oxygen tanks will remain topped-off prior 

to disconnection from the vehicle/rover/habitat interface panel.
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2. Battery Recharging – the battery can be recharged while installed in the Exploration 

Portable Life Support System (xPLSS). The power charging equipment also 

provides a battery discharge capability. The capability to discharge a battery is 

needed for long-term surface operations (to maintain battery capacity). The suit 

may be powered while recharging the batteries. 

3. Water Recharging – recharging of the water tanks on the xEVA Suit will be provided 

by host vehicle or habitat. Support equipment will pump feed water into the xEVA 

Suit water tanks prior to the start of the EVA day.

4.2.3 xEVA Accessories

The accessories include all of the other hardware and equipment not considered part of 

the xEVA suit, VISE, or Tools. 

4.2.4 EVA Task Tools & Equipment

The xEVA System includes a variety of tools and equipment that are critical for 

accomplishing EVA tasks. Tools will be provided to support exploration science, vehicle 

assembly and maintenance, inspection, crew safety, and equipment transport. This 

includes a tool & sample management system, and equipment for rescuing an 

incapacitated crewmember. 

Reference Section 4.1.3 for the tasks that will be done with tools, and reference the 

Artemis Geology Tools Project for details on the tools planned for the Artemis Program. 

4.2.4.1 Tools

The general types of tools include those for:

• Mobility/transportation

• Construction

• Science sampling (e.g., hammer, tongs, scoop, rake, etc.)

• Contingency

Tools utilized during microgravity operations on ISS and Gateway will be similar to, if not 

the exact same, as the tools currently utilized on ISS during EMU EVAs. 

Tools utilized on planetary surfaces will largely focus on construction and science 

sampling. Construction tools will be modified for use in the partial-g lunar environment. 

Science tools will be used for achieving scientific objectives and sample acquisition. 

TABLE 4.2.4.1-1: TYPES OF GEOLOGY SAMPLING TOOLS

Sampling Tool Sample Type Sample Description

Tong Rock float Rocks that are loosely adhered to the surface
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Rake

Hammer (with Chisel) Rock chip Piece of rock forcibly removed from a larger 

rock

Core Drill and Bit Rock core Cylindrical samples of a rock

Scoop Regolith bulk Representative loose surface material

Drive Tube with Drill Regolith core Cylindrical sample of regolith at depth

Surface Sampler Surface Undisturbed material from the top ~1mm of 

surface

Specialized Tools and 

Containers

Volatile

Specialized Tools and 

Containers

Atmospheric

FIGURE 4.2.4.1-1: SCIENCE SAMPLING TOOLS (RAKE)

The tool kit for surface operations will likely include portable lighting. 

Powered tools will utilize a common battery architecture that will allow tools to utilize 

batteries based on the xEVA suit batteries. 

4.2.4.2 Tool & Sample Management

The xEVA System includes, but is not limited to, the following key capabilities for tools and 

sample management:

• Ability to transport tools (microgravity and surface)

• Capacity to carry some tools on the suit (attached directly or via a harness)

• Capability to pull/push an equipment carrier during surface operations

• Capability of interfacing with equipment utilized assist with traversing into and 

out of challenging terrain (e.g., lava flow) and descending/ascending steep 

slopes (e.g., craters and lava tubes), such as a belaying device and/or winch
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FIGURE 4.2.4.2-1: CARRYING TOOLS ON APOLLO SUITS

As was done during the Apollo missions, some smaller set of tools will be carried on the 

suit. For Apollo, those included a hammer, sample collection bags, and cameras. For the 

xEVA suit and the Artemis missions, tools that may be carried on the suit include, but are 

not limited to the following:

• Hammer

• Chisel

• Scoop

• Handheld Camera

• Documented Sample Bag

• Sample Collection Bag

• Cuff Checklist

4.2.4.3 Incapacitated Crewmember Rescue Equipment

Planetary surface missions will need equipment and interfaces to transport an 

incapacitated crewmember from a work zone to a safe haven (e.g., lander), and then into 

the safe haven. 

4.3 AUXILIARY SUPPORT SYSTEMS FOR XEVA

The following aspects of missions help enable safe and successful EVA operations.

4.3.1 Navigation & Tracking

The capability to track EVA crew and for the EVA crew to navigate will become critical in 

future missions for safety, science, and operations. This is especially true for planetary 

surface missions to the moon and Mars. Any navigation solution will likely involve an 

integrated and distributed system, with components on the suit, ancillary accessories, the 

rover (if applicable), and the lander.
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4.3.1.1 ISS and Gateway

The xEVA System may include, but is not limited to, the following key navigation 

capabilities and features for microgravity operations on ISS and Gateway for 

demonstration and possibly nominal ops:

• Navigation (location) tracking, with real-time data to the Flight Control Team 

(FCT)

• Orientation tracking on ISS, with real-time data to FCT

• Path to safety tether anchor

• Path to airlock

4.3.1.2 Planetary Surface

In order to support the Artemis mission goals of returning the crew safely and completing 

the science objectives, there is a need for EVA navigation capabilities on the lunar surface. 

A navigation system(s) will enable the crew to find and document the science objectives, 

and will allow them to safely return to their vehicle. Navigation capability for Artemis will 

likely evolve in a phased approach, with basic capabilities for Artemis III (e.g., something 

handheld) and more advanced systems coming online in Phase 2.

Early xEVA System navigation solutions are envisioned to be independent of space suit 

or spacecraft utilities/consumables and operated as a hand-held relative-navigation device 

available to the EVA crew member. Relative navigation support is intended to provide real 

time position/heading integration sufficient to return the crewmember to the general vicinity 

of the lander sufficient for the crew member to obtain visual indication of lander location 

within expected lighting conditions. From an infrastructure perspective, xEVA will assume 

the primary responsibility of deriving an adequate navigation capability without use of any 

other infrastructure. In other words, no assumption is made for supporting capabilities 

such as range beacons, satellite constellations providing Position/Navigation/Time (PNT) 

data, or any other form of information. This ensures safe operation/safe return of the crew 

without interdependence from other assets.

This relative navigation solution may also be used to document approximate locations of 

surface activities such as science sampling worksites, payload deployments, etc. 

However, such information will by design be referenced to the starting point (the lander 

itself) and must be interpreted after the fact to understand/estimate absolute surface 

location in any broader coordinate system.

As missions and capabilities evolve, these features may be incorporated directly into the 

suit itself.

4.3.1.2.1 Safety-focused Navigation Capabilities

Safety navigation capabilities for the xEVA System include, but are not limited to, the 

following for planetary surface operations for Artemis Phase 1 (including Gateway):
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• Crew must always be able to safely find the lander, even when out of line-ofsight or in shadows

• Crew will require a system/method for ensured safe return within 2 km of the 

lander (e.g., a transponder)

Safety navigation capabilities for the xEVA System include, but are not limited to, the 

following for planetary surface operations for Artemis Phase 2 (sustained missions):

• Crew will have systems to enable navigation when greater than 2 km of the 

lander that ensures safe return to the lander

• EVA crew must be able to safely return to the lander on their own in the event 

of a contingency with any rover failure (i.e., not fully dependent on the rover 

for navigation)

4.3.1.2.2 Science-Focused Navigation Capabilities

Science navigation capabilities for the xEVA System include, but are not limited to, the 

following for planetary surface operations for Artemis Phase 1 (including Gateway):

• Science objectives will require crew to precisely locate sampling targets within 

a few meter precision

• Science objectives will require crew/science support to precisely document 

where samples and data are being collected

• Accuracy required for science:

o 0.5 m for subsurface instrument emplacement

o 3-5 m for samples

o 10 m for general context

4.3.1.2.3 Operations-Focused Navigation Capabilities

Flight operations and flight control navigation capabilities for the xEVA System include, 

but are not limited to, the following for planetary surface operations for Artemis Phase 1 

(including Gateway):

• EVA crew must know their location in order to find worksites, accomplish 

tasks, rendezvous with pre-deployed assets, and return to the lander

• MCC must know the location of the crew for situational awareness (SA), 

directing the crew, calculating consumables, and tracking and replanning the 

timeline

• Traverse path data utilized post-processing for planning the next EVA and 

understanding sample acquisition locations

• Enables navigation during lunar day and in shadowed areas, including PSRs
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Flight operations and flight control navigation capabilities for the xEVA System include, 

but are not limited to, the following for planetary surface operations for Artemis Phase 2

(sustained missions):

• Everything from Artemis Phase 1

• Navigation tracking on lunar surface, with real-time data to FCT

• Functions both independently of the vehicle when out of line-of-site or range, 

and also transmits data to the vehicle for relay to MCC for situational 

awareness (e.g., a transponder system) 

• Enables tracking and navigation in lunar daylight, in shadowed areas and 

PSRs, and during lunar night

• Transmits navigation data to the xEVA suit informatics system Heads-Up 

Display (HUD) real-time, allowing the EVA crew to navigate 

independently/autonomously

• Increased visibility of terrain in low-light/shadowed regions, via additional 

hands-free lighting and/or augmented views that utilize imaging systems (e.g., 

active infrared night vision system used terrestrially)

• Functions both independently of the vehicle when out of line-of-site or range, 

and also transmits data to the vehicle for relay to MCC (for situational 

awareness)

• Resources once identified and characterized will need to be re-located for 

utilization

4.3.2 EVA Mission Support System

At destinations with long signal latencies and/or blockages (non-continuous links), the IV 

crewmember directing EVA operations will be more heavily loaded than in current realtime communication operations, and will have the primary responsibility of receiving and 

addressing EVA suit data along with replanning the timeline during the EVA. Essentially, 

the IV will perform the roles of a Shuttle-era IV, partial Flight Director, partial EVA Officer, 

and partial Biomedical Engineer (BME). The IV will utilize an EVA Support System in order 

to effectively handle the large amount of information and tasking that must be contended 

with while actively directing an EVA. This system enable the IV to performreal-time 

timeline tracking and will simplify status monitoring. It will automate relevant analysis tasks 

wherever possible to offload work from the IV crew member. It will incorporate EVAtask 

progress, incorporating EVA suit data, consumables usage, and crew location to inform 

the presentation of high level and low level information about the status of past, current, 

and future tasks. It will display of actual and planned traverses using geoinformatics 

systems (GIS) tools. Minimal hardware will be required for operations to reduce space 

and launch mass, and the system may possibly incorporate augmented reality.

The xEVA System includes, but is not limited to, the following key general capabilities and 

features:

• Communication with MCC and EVA - both voice and text
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• Display of real-time and previously acquired crew video and still images

• Display of procedures and cue cards

• Real-time EVA timeline management and automated analysis

• Monitoring of suit data and telemetry

• Spatially and temporally relevant links to all data products (i.e. pictures, notes 

on samples, video, locations of interest)

• Real-time update of procedures

• Dynamic prioritization of science candidates

• Image annotation

• Display of crew and asset location

• Display of actual and planned traverses in both distance and time

• Creating and sending augmented reality cues and visuals

• Display of real-time and previously acquired in-situ instrument and sensor 

data

4.3.2.1 Data Sources

In order to support crew autonomy, data from the following sources must be accessible to 

the EVA Mission Support System. When applicable, data must be accessible in real-time. 

All as-executed data must be timestamped and stored in an accessible long-term storage 

medium as well.

• Task cue cards, descriptions, and supporting imagery

• Planned task durations

• Planned temporal relationships between tasks (ie. the ordering of tasks)

• As-executed task durations, eg. the start and end time for each task

• xEMU suit telemetry, including limiting consumables statuses

• Planned traverse routes

• Crew locations

• Potential scientific sample locations

• Collected scientific sample locations

• Equipment and asset locations

• In-situ sensor and instrument data, including data from scientific instruments

• All EVA-related audio, video, and still imagery sources, including but not 

limited to:

o EV, IV, and ground voice

o EV-handheld still and video imagery

o xEMU helmet cameras

o Situational awareness cameras

o Vehicle cameras

• If possible: the location and heading of still and video imagery sources
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4.4 EGRESS/INGRESS METHODS

Many of the possible mission architectures for human exploration depend heavily on EVAs 

to achieve mission objectives upon arrival at the destination; they include science-focused 

EVAs that increase EVA frequency and require a paradigm shift from heritage programs. 

For these heritage programs, NASA has used tightly controlled and highly scripted EVA 

timelines at a relatively low annual rate (about eight EVAs/year on average in the ISS 

Program) and relied heavily on interaction between the EVA crew and ground team. Some 

cislunar and/or transit phases assume an even lower annual rate for contingency only 

EVAs. For exploration missions, a flexible operational paradigm is needed so that the 

crew can make changes to their activities in near real-time to satisfy science and 

maintenance objectives. These include both nominal maintenance and science-based 

EVAs as well as contingency repair EVAs.

EVA-EXP-0031, EVA Airlocks and Alternative Ingress/Egress Methods discusses the 

details of multiple ingress/egress methods. 

FIGURE 4.4-1: EVA EGRESS/INGRESS METHODS

Currently, traditional dual chamber airlocks and/or suitlocks (rear-entry airlocks) are the 

prime egress/ingress methods and/or concepts for all microgravity and planetary surface 

EVA operations. These type of airlocks provide an area for preparation and suit-up, an 

area for suit maintenance, a reduced volume for depress, and a means for mitigating dust 

and minimizing forward (planetary protection) and backward (crew health) contamination. 

A suitlock (rear-entry airlock) provides the best solution for the EVA System on surface 

habitat and surface rover for dust mitigation, though it does involve some upcoming design 

challenges for the suit and vehicle. The Artemis Phase 1 missions will utilize a depressed 

lander cabin or an airlock, and Artemis Phase 2 may include suitlocks or suitports. 
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FIGURE 4.4.-2: SUITLOCK (REAR-ENTRY AIRLOCK) CONCEPT

4.5 SPACECRAFT

The following constitute some of the primary vehicles utilized by Exploration crew and for 

which the xEVA System interfaces in some manner. 

4.5.1 Orion

The Orion is a pressurized, crewed element that transports two to six crewmembers from 

the Earth’s surface to destinations beyond LEO and brings them safely back to the Earth’s 

surface at the end of a mission. The Orion provides all services necessary to support the 

crewmembers while onboard for shorter duration missions (up to 21 days) or until they are 

transferred to another vehicle. The Orion Multi-Purpose Crew Vehicle (MPCV) consists of 

a Crew Module (CM), a Service Module (SM), Spacecraft Adaptor (SA) and a Launch 

Abort System (LAS). The CM provides a habitable pressurized volume to support 

crewmembers and cargo during all phases of a given mission - from launch operations to 

Earth Entry, Descent, Landing (EDL) and Recovery. The SM provides services to the CM 

in the form of propulsion, consumables storage, heat rejection and power generation. The 

LAS provides an abort capability to safely transport the CM away from the launch vehicle 

stack in the event of an emergency on the launch pad or during ascent. The crew size 

and mission duration can be adjusted by changing the vehicle configuration. Reducing 

the crew complement from four to two provides additional internal stowage and mass 

capability. 
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FIGURE 4.5.1-1: ORION

4.5.2 Gateway

A Gateway stack/space station (including an airlock providing EVA capability) will be 

positioned in a Near Rectilinear Halo Orbit (NRHO). It will allow for crew presence of at 

least 30 days (possibly up to 45 days). Crew in Gateway will tele-robotically operate 

surface vehicles, including rovers and landers. The stack will include an airlock for science 

and utilization to transfer sample containers from the ascent module to the interior of the 

habitat and Orion while maintaining scientific integrity. It will also include a robotic arm for 

operations

FIGURE 4.5.2-1: GATEWAY
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Per “Gateway Program” presented at the 2020 EVA Exploration Workshop, “Gateway 

will be a sustainable outpost in orbit around the Moon, which will serve as a platform for 

human space exploration, science, and technology development”, including the 

following:

• The Gateway shall be utilized to enable crewed missions to cislunar space 

including capabilities that enable surface missions to the lunar South Pole by 

2024 (Crewed Missions)

• The Gateway shall provide capabilities to meet scientific requirements for 

lunar discovery and exploration, as well as other science objectives(Science 

Requirements)

• The Gateway shall be utilized to enable, demonstrate and prove technologies 

that are enabling for lunar surface missions that feed forward to Mars as well 

as other deep space destinations (Proving Ground & Technology 

Demonstration)

• NASA shall establish industry and international partnerships to develop and 

operate the Gateway (Partnerships)

As stated in “Gateway Program”, the Gateway will not have EVA capability during 

Artemis Phase 1, but will add that capability for Phase 2. 

FIGURE 4.5.2-2: GATEWAY PHASE I
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FIGURE 4.5.2-3: GATEWAY PHASE II

4.5.3 HLS (Human Landing System)

The HLS will allow for crewmembers to descend to the lunar surface. It may include a 

descent stage and a potentially reusable ascent module. 

4.5.3.1 Selected Key Attributes for EVA:

• Capability to support up to 5 EVAs during the lunar surface stay

• Capability to support EVAs of up to 8 hours (6±2 hours) in duration each

• Appropriate volume to don, doff, and maintain the suits

• A minimum EVA hatch opening of 1.02 x 1.53 m (40x60 in)

• Allowance for performing incapacitated crewmember operations

• A cabin atmosphere that would allow for the shortest prebreathe and require 

the least amount of crew time (likely 8.2 psi and 34% O2)

• Layered engineering defense protocols for lunar dust

• Volume and mass launch capacity for returning collected samples

• Margin to bring back as much EVA equipment from the lunar surface (e.g., 

the entire xEVA suit)

• Total crew time in space, from Orion launch to landing, is expected to fall 

within 25-34 days, based on vehicle performance and launch opportunities
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FIGURE 4.5.3.1-1: HLS REFERENCE CONCEPT

Per Next Space Technologies for Exploration Partnerships (NextSTEP) Appendix H 

(Human Landing System), the following subsections outline some of the details of HLS 

that impact EVA:

4.5.3.2 General

• Orion will dock to the Gateway with four crew members

• Some portion of mission logistics (GFE or other) may be launched on a 

logistics module that would arrive at Gateway before the crew

o This can include xEMUs, logistics, spares, xEMU tools, etc.

• If in initial missions, HLS bypasses Gateway to dock directly to Orion, all 

logistics must be launched with HLS

• The total crew time in space, from Orion launch to landing, is expected to fall 

within 25-34 days, based on vehicle performance and launch opportunities

• Within 1km of Gateway, the HLS may have the option to concurrently utilize 

dual-band Wi-Fi for non-critical voice, data, and video

• Plan for best-case round trip latencies of slightly under six seconds for voice 

communications and for low-data rate critical telemetry

4.5.3.3 Assumptions for Initial Mission Capability in 2024

• Crew transfer into the HLS may be achieved either by docking directly to 

Orion or through the use of the Gateway.

• Two crew members will transfer to the HLS for transport to and from the 

surface, while two will remain with Gateway/Orion

• Two astronauts land on the Lunar South Pole

• Astronauts live and work out of the HLS during their surface stay
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• Pre-deployed surface assets are not required

• Hardware reuse is not required

• xPLSSs may be left on the surface

4.5.3.4 Assumptions for Sustainable Missions

• Four crew land on the Lunar Surface

• Pre-deployed surface assets are available

• The Gateway will be used to facilitate crew and cargo transfers to HLS

• Some or all of the HLS is reusable, depending on sustainability analysis to be 

performed

• Refueling element enables reuse of elements if required for sustainability and 

to address disposal of elements for multiple missions.

Reference Appendix E for more details on HLS based on the NextSTEP Appendix H: 

Human Landing System. 

4.6 SURFACE MOBILITY

At some point in the Artemis program, crew will utilize rovers, both unpressurized and 

pressurized, to extend their range on the planetary surface. 

EVA suit can use rovers as a communication relay to other assets. Rovers will take into 

account visibility issues, such as glare from the sun, lighting in shadowed regions, and 

dust being kicked up by the wheels. Rovers will aid in navigation to/from the regions of 

interest, and will incorporate the capability to aid in incapacitated crew rescue. 

4.6.1 Lunar Terrain Vehicle (LTV)

For initial missions to the lunar surface, the crew will live in and work out of the lander. In 

Artemis Phase 2, an unpressurized rover (UPR) allows for longer traverses within an EVA 

day, as long as the distance is balanced with suit consumables. During these missions, 

they’ll utilize an LTV to extend their traverse range, allowing them to get at least 7.5 km 

away from their lander. 
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FIGURE 4.6.1-1: UNPRESSURIZED ROVER CONCEPT VEHICLE

Having EVA consumable resupply capability on the rover would ensure that the EV crew 

has the necessary consumables for a contingency walk back to the lander. Analysis of 

Apollo Lunar Roving Vehicle (LRV) exploration indicates that approximately 20% of the 

total EVA time was spent by the crew on the LRV moving from site to site. Thus the EVA 

team would have sufficient time for recharge of xEVA suit consumables or switching to 

rover-based support systems to preserve suit consumables. Providing multiple sources 

of consumables and support systems while on excursions also enhances crew safety by 

providing contingency options should xEVA suit systems degrade or fail. 

A second rover would help mitigate the risk and extend the range.

Reference AES-50010 (LTV Con Ops).

4.6.2 Crewed Pressurized Rovers (CPR)

For living and surface mobility in Artemis Phase 2, crew will have pressurized rovers, also 

known as the Habitable Mobility Platform (HMP). A single pressurized rover allows for 

multi-day excursions, with distance limited by a fully recharged suit walk back and the type 

and number of mobility assets on the surface (e.g., LTV or dual pressurized rovers for 

drive-back). Dual pressurized rovers allow for multi-day excursions well beyond a suit 

walk back constraint, presuming one rover can rescue the other.

These will nominally house two crewmembers but will be able to hold four in a contingency 

situation. They will give the crew an extended range, speed, and payload capability. From 

an EVA perspective, the vehicle should consist of a habitable crew compartment and one 

for EVA egress/ingress (e.g., a suitlock or functional equivalent with a minimum of a 40x60 

inch external hatch to walk through). The suitlock/airlock portion will be utilized as a suit 

maintenance area. 

However, per the rover team, the vehicle may consist of a habitable crew compartment 

and suitports for EVA egress/ingress, in addition to a minimum of a 40x40 inch external 

hatch. The cabin can be depressed in bring suits in for maintenance or in the event of a 
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suitport failure or other contingency. The differences and final concept will be worked out 

as the rover and xEVA System align. 

Note that discrepancies between the xEVA System and the pressurized rover for egress 

method will need to be worked out. 

The rover will be capable of operating at the following nominal cabin atmosphere 

saturation set points:

• 14.7 psia with 21% O2

• 10.2 psia with 27% O2

• 8.2 psia and 34% O2

The pressurized rovers will have the capability of being controlled autonomously or by the 

crew and will initially be controlled from the MCC in order to perform sampling and other 

investigations. Remote control of the rover will be possible from MCC, from a cislunar 

space station (Gateway), the lander, and while EVA. 

FIGURE 4.6.2-1: PRESSURIZED ROVER CONCEPT

Rovers will be able to navigate slopes of varying soils, and able to handle local slopes of 

up to 20° and rock sizes of up to 30 cm (per International Space Exploration Coordination 

Group (ISECG) May 2018 draft con ops). Various equipment will deploy from the rovers, 

including solar arrays, K-band antennas, panoramic cameras, and robotic arms.
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5.0 CONCEPT OF OPERATIONS FOR EVA ON A SPACECRAFT

All future mission vehicles will have the capability for conducting EVAs in a microgravity 

environment, whether planned or as a contingency. The current concept of operations for 

an EVA on an engineered surface focuses on the ISS and proving grounds, where systems 

will be demonstrated, evaluated, and evolve to progress further towards independence 

from Earth.

These microgravity EVAs may occur in LEO, cislunar space, and during Mars transit. In 

transit to Mars, there is a possibility for a Venus transit. Any contingency EVA done during 

transit will need a system/suit that is capable of withstanding the environment near the 

Venus fly-by.

5.1 CON OPS FOR EVA ON ISS (MICROGRAVITY EVA IN LEO)

Microgravity (Micro-g) EVA operations on any future vehicle will be very similar to those 

done on the Space Shuttle and on ISS.

FIGURE 5.1-1: EVA OPERATIONS ON THE SPACE SHUTTLE AND SPACE STATION

The ISS will serve as a test bed for demonstration of the xEVA suit in a microgravity 

environment. The primary objective is to demonstrate the xEVA suit system and 

operations in the near term at a known LEO destination. This con ops assumes that all 

safety-critical functionality has been completed and demonstrated in ground-based testing 

and that the xEVA Suit will be certified for flight prior to this demonstration test series on 

ISS.

5.1.1 Demonstration of xEVA Suit (xEMU) on ISS

Initial uses of the next generation xEVA suit (xEMU) will be conducted on the ISS. A 

demonstration of the xEMU is planned at ISS prior to first use of the suit on the lunar 

surface to gain experience with the hardware and operations of the suit.
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Mission objectives/evaluations:

• Suit prep and post EVA operations, including checkouts of the suit

• Rear entry suit donning and doffing

• Umbilical connection and crew positioning in the crewlock

• Operation of suit systems (Power, Oxygen [O2], CO2 and contaminant 

scrubbing, cooling)

• Operation of the variable O2 pressure regulator and prebreathe protocol

• Operation of UIA, Depress Valve, and other airlock switches

• Hatch opening and egress

• Translation

• Use of basic EVA tethers and tools

• Articulating Portable Foot Restraints (APFR) operations

• Reach and access to various ISS worksites including CCE worksites

Mission parameters/capabilities:

• Destination: ISS in LEO

• Mission duration: 2-6 months

• Number of crew: 6

• Number of EVAs: 2-6

• Types of EVAs: Nominal microgravity

• EVA egress method: ISS Joint Airlock (Quest)

• Vehicle systems and configuration:

• ISS O2 system for recharge 

• ISS power system for battery recharge and direct powering of suit

• ISS water system for water bladder recharge

• ISS waste water system and bags for water dump

• ISS hardline system for communication and data

• ISS wireless system for communication, data, and video

• ISS cooling water system (cooling loop and heat exchanger)

• Vacuum access

Reference CTSD-ADV-1639, Exploration Extravehicular Activity Mobility Unit (XEMU) 

International Space Station (ISS) Flight Demonstration Objectives for specific details on 

the demonstration EVAs on ISS. 

5.1.2 ISS Nominal Operations with xEVA Suit

Once the xEVA Suit is proven to safely and successfully operate on the ISS, it may be 

certified for EVA system functions so that it may be utilized in a more routine manner in 

conjunction with or instead of the EMU. As such, the xEVA Suit would perform all of the 

tasks currently done by the EMU. Potential task operations include Critical Contingency 

EVAs (CCE) and other maintenance tasks to keep ISS habitable.
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Operations on the ISS will follow a similar timeline to that of the EMU for road-to activities, 

day of EVA preparations and prebreathe activities, timeline execution, and post EVA 

activities. 

The CCEs are a group of hardware failures on ISS which result in a zero-fault-tolerant 

system for ISS survival, and are recovered by EVA or Extravehicular Robotics (EVR). 

When needed, the xEVA Suit will complete the CCE tasks as listed in the appendix. The 

xEVA Suit may conduct maintenance and other EVA tasks that allow ISS to continue 

operating. 

5.2 CON OPS FOR EVA ON GATEWAY (MICROGRAVITY EVA IN CISLUNAR 

SPACE)

Microgravity EVA operations in cislunar space will take place on small space stations, such 

as Gateway. EVAs will utilize the xEVA Suit. It is assumed that EVA will not be utilized 

as the primary means for construction of Gateway, but instead will be available for 

utilization and mission success, and possibly as a backup for contingencies. 

Operations in cislunar space on a small spacecraft stack/space station, such as Gateway, 

will follow a similar approach to those done on the Space Shuttle and ISS. There will be 

a series of road-to-EVA activities in order to gather and prepare the appropriate equipment 

and plans. Within a day or two of the spacewalk, EVA preparation activities will begin, 

with appropriately configuring the airlock beforehand and some focused on crew suit-up 

and prebreathe. Following completion of the prebreathe portion of EVA prep, the crew will 

egress the airlock and conduct the required tasks. Upon completion of the EVA, the crew 

will ingress, doff their suits, and perform the necessary post EVA activities.

5.2.1 General Aspects of EVA on Gateway

EVA operations on a spacecraft in cislunar space will share many similarities with those 

done on the Space Shuttle and Space Station. Egress and ingress will be performed via 

a dual chambered airlock, and many of the same or similar tools will be used to perform 

any tasks - including (but not limited to) safety tethers, waist tethers, Body Restraint 

Tethers (BRTs), equipment tethers (Retractable Equipment Tether (RET) and Adjustable 

Equipment Tethers (AETs)), a Modular Mini Workstation (MMWS) equivalent, various 

bags (crewlock, ORU, trash), drivers (powered and manual wrenches) and associated 

sockets, torque wrenches, pliers, cutters, wire ties, scissors, cameras, and contamination 

detection kits. Possible maintenance tasks include (but are not limited to) science payload 

deploy and retrieve, science instrument data acquisition, leak detection and isolation, 

Orbital Replacement Unit (ORU), Micro Meteoroid Orbital Debris (MMOD) penetration 

location and repair, solar array repair, and robotics repair. 

For consumables and logistics estimates, these missions are assumed to be a minimum 

of 30 days with four crewmembers and will allow for up to two 2-crewmember EVAs per 

mission. Gateway uncrewed periods may be as long as three years; however, this is still 

to be resolved, as well as how and for how long suits are stowed [TBD-6.2.1-001].
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EVA availability begins with the launch of a dedicated Airlock element with the EVA 

System components. For EVAs to occur from the Airlock, permanently mounted hardware 

and plumbing, such as interfaces to vehicle supplied high pressure O2 (3000 psia), water 

(iodine or silver impregnated), vacuum (for CO2 removal if utilizing an amine swing bed 

system), power, data transfer, and communications are in place to enable crew to perform 

prebreathe and suit checkouts prior to switching to xPLSS services. VISE and a common 

Umbilical Interface Panel (UIPs) - also known as an Umbilical Interface Assembly (UIA)

on ISS – will provide general airlock utility services to the EVA suit. Airlock functionality 

for US EVA includes xEVA Suit donning and doffing interfaces, suit servicing and recharge 

interfaces, communication, prebreathe capability, depress and repress, egress and 

ingress, and tools. While some equipment must be hard-mounted in the Airlock to enable 

EVA, other equipment may be launched and stowed separately to increase operational 

flexibility, and the crew would transfer the equipment to the Airlock as needed to support 

an EVA.

FIGURE 5.2.1-1: EVA INTERFACES SUPPORTING NOMINAL EVA CAPABILITY

The dual chamber airlock provides the volume for two crewmembers to perform on-orbit 

suit maintenance and all of the EVA prep and post activities, including suit donning/doffing 

and prebreathe. It is assumed that xEVA rear-entry suits require two donning/doffing 

fixtures to allow crewmembers to self-don and self-doff their rear-entry suits. Airlock 

equipment is designed to function nominally while exposed to vacuum or operate after 

being exposed to vacuum (e.g., battery chargers). This allows airlock equipment to stay 

in the depressurizable volume.
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Servicing and checkout of the suits are performed between EVAs, including recharging 

consumables (such as batteries and thermal system water) using suit servicing vehicle 

interfaces, cleaning the suit interior, replacing biomedical sensors, and checkout of xPLSS 

components in preparation for the next EVA. Vehicle services to the suit are included 

through an umbilical interface panel and umbilicals in the Airlock. Each suit requires its 

own dedicated umbilicals (O2 and vacuum).

EVA wireless radio, cabling, and antenna for two-way communications of EVA voice/data 

as well as downlink of EVA Video are provided by the vehicle.

Spares and logistics will be required for on-orbit suit maintenance (dependent on manned 

pressurized time). Some spares may be equipment left over from previous flights, such 

as is done on ISS, while others may be launched in logistics modules.

5.2.2 Road-to EVA (Gateway)

The "Road to EVA" is a comprehensive list of all the activities that must be completed prior 

to and following an EVA or series of EVAs. It includes tasks such as the following:

• Suit assembly and sizing

• Pressurized On-Orbit Fit Verification 

• Pre-EVA xPLSS consumables charging (e.g., water)

• Battery recharging

• LCVG fill (if required)

• Airlock configuration (items not certified for vacuum are removed)

• Tool and equipment configuration in bags or on suit

• Filling and installing drink bags in suit

• Preparation of biomedical monitoring equipment

• Configuration of communication equipment

• Pre-EVA unmanned automated suit checkouts

• Timeline review
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FIGURE 5.2.2-1: ROAD-TO EVA REFERENCE BASED ON ISS EMU EVA

5.2.3 EVA Prep & Prebreathe (Gateway)

On the day of the EVA, the crewmembers begin final prep activities and the prebreathe 

protocol. These general day-of-EVA activities include, but aren’t limited to, the following:

• Non-EVA crew transfer to separate element for duration of EVA activities

• EVA prep 

• Mask prebreathe (if required)

• xEVA Suit manned checkout 

• Suit donning

• In-suit communication and leak checks

• Prebreathe protocol

• Purge nitrogen

• In-suit prebreathe on umbilical

• IVA crew performs any remaining airlock configuration tasks
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FIGURE 5.2.3-1: DAY OF EVA EXAMPLE TIMELINE BASED ON ISS EMU EVA

5.2.3.1 Prep for EVA (Gateway)

A multitude of activities occur on EVA day in order to prepare the crew and suits. These 

include, but are not limited to, the following types of activities:

• Configure vehicle and suit communication

• Verify the appropriate equipment is in the airlock before isolating the module 

• Activate the CO2 removal system

• Prepare for mask prebreathe (if applicable)

• Power up the xEVA Suits and verify system functionality, and configure for 

suit donning

• Verify xEVA Suit communication and data with IV and/or MCC

• Depress to 10.2 psia (if applicable)

• Don suits

• Perform xEVA Suit checkout

General clean-up and stowing of non-EVA equipment is needed to prepare for depress 

and vacuum operations. Any items that cannot withstand vacuum or require special 

stowage should be moved to other elements of the stack. Airlock equipment in the 

depressurized portion must be designed to function nominally while exposed to vacuum. 

Some exception may include battery chargers, which may not be used during 

depress/vacuum operations but would be designed to operate after exposure to vacuum. 

The timing of EVA and cabin preparations will be determined with human-in-the-loop 

stowage studies. 

5.2.3.2 Prebreathe (Gateway)

Once the crew performs suit pressure integrity and system checks, they begin their 

prescribed prebreathe period. Prebreathe protocols decrease the risk of DCS and may be 

different durations depending on suit operational pressure and ppO2 saturation prior to 
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starting an EVA. As a starting point, the intent is that future xEVA systems require prebreathe periods no longer in duration than the current ISS EMU In-Suit Light Exercise 

(ISLE) prebreathe protocol. The current ISLE prebreathe protocol assumes a starting 

point of 14.7 psia (STP) saturation of the crew, which is consistent with the current FCT 

architecture and thus a valid comparison. However, alternate prebreathe protocols, such 

as protocols beginning at 14.7 psia, but beginning the EVA at a higher psid (similar to 

Russian prebreathe) will also be considered in order to minimize prebreathe time and 

reduce stack complexity. Additional analysis and protocol testing are required to verify the 

time required to perform alternate prebreathe protocols.

5.2.3.3 Egress (Gateway)

Once the prep and prebreathe procedures are completed, the EVA crew will depress the 

airlock, switch over to suit systems, egress, and begin their tasks. The “EVA” phase begins 

when the spacesuit is switched from the vehicle provided power source suit batteries, and 

officially ends after the airlock hatch is closed upon ingress.

In order to be “GO for EVA” (approved for EVA operations), xEVA Suit will meet the 

following conditions:

• CO2 levels are verified nominal

• Pressure integrity verified

• O2 pressure nominal

• Cooling system is verified operational

• Communications established

• Secondary Oxygen Regulator (SOR) is verified functional 

• Telemetry is being received by Vehicle and transmitted to Mission Control 

Center -Houston (MCC-H)

Once the crew is given the “GO”, they perform the following steps:

• EVA crew disconnect from don/doff fixture and translate to crewlock

• IVA closes and secures inner hatch

• Crewlock is depressurized

• EVA crew open the EV hatch (prior to transitioning to xPLSS operations)

• EVA crew transition from umbilical to xPLSS (switching to battery power 

starts the PET clock)

• EVA crew egress airlock element through a hatch diameter of at least 

1000mm

• EVA crew is tethered to the spacecraft for safety

5.2.4 EVA (Gateway)

Once egressed, the crew conducts the planned EVA tasks. Examples of potential tasks 

include the following:
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• External payload installation and removal

• Science payload deploy and retrieve

• Science instrument data acquisition

• Vehicle leak detection and isolation

• Vehicle maintenance and repair

• Fluid ORU Remove and Replace (R&R) (e.g., Pump Module (PM) and 

Interface Heat Exchanger (IFHX))

• Electrical ORU R&R (e.g., Multiplex/Demultiplexer (MDM) and Remote Power 

Control Module (RPCM))

• MMOD penetration location and repair

• Solar array repair

• Antenna deploy or repair

• Robotics repair

• Docking contingencies

5.2.5 Post EVA (Gateway)

Crew will conduct post EVA activities immediately after the EVA, and possibly continuing 

into the next day. The general activities include, but aren’t limited to, the following:

• EVA suit are doffed

• Life support units are serviced and recharged

• Suits are soft stowed or stored on the don/doff assembly in the airlock
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6.0 CONCEPT OF OPERATIONS FOR EVA ON A SMALL NATURAL BODY

Missions to asteroids currently under consideration vary in duration and location, as well 

as the assets used and the extent of EVAs involved. There are many challenges 

associated with traveling to asteroids; such as finding an object with appropriate spin 

characteristics, mass, and trajectory. Unlike on the ISS, there is no anchoring, translation, 

and stabilizing EVA hardware built into an asteroid. Due to varying asteroid composition 

(from loosely held together regolith to solid rock), several types of anchors will need to be 

available for installation and various methods assessed to discern the most effective 

technique for anchoring and stabilization. Dust will likely be present on the surface of the 

asteroid. The presence of regolith on the surface poses potential problems with abrasion, 

visibility, and transfer of dust into the habitable volume via adhesion to the spacesuit or 

due to the extended duration that the dust cloud requires to settle in ultra-low gravity 

environment. 

Two basic asteroid missions have been examined to date - one involves manned missions 

traveling to an asteroid and performing EVAs to collect samples, and the other, in order to 

mitigate some of the difficulties with traveling to a NEA, involves capturing an asteroid with 

a robotic vehicle and bringing it to a stable location near the moon, either a 

Lagrangian/Libration point (L2/EML-2) or a Distant Retrograde Orbit (DRO).

Whether conducting an EVA on a captured asteroid, NEA, or a moon of Mars, the EVA 

crew will utilize advanced EVA informatics, the xEVA Informatics designed into their xEVA 

Suit. Utilizing these systems, the EVA crew will navigate themselves to specified worksites 

and mark their location for MCC awareness and future reference. For science activities, 

they will call up cue cards, pictures, and imagery that the Science Team has annotated for 

them. MCC, the Science Team, and IV will also be able to provide the EV crew with 

augmented reality cues in order to guide them through tasks.

6.1 CON OPS FOR EVA ON A CAPTURED ASTEROID

While there are several concepts for working at an asteroid, the EVA Systems architecture 

focuses on having two EVA crewmembers work off of a vehicle that has either captured 

an asteroid or is somehow solidly anchored to one. This maintains the safety of the buddy 

system, and negates the safety and contamination concerns of a small free-flying 

spacecraft. 

Operations during any likely asteroid mission will take place in a relatively micro-g 

environment with the crew retrieving geology samples utilizing tools while based on a 

stabilization boom deployed from a vehicle. If these operations take place in cislunar

space, the operations may likely be directed by a Ground or Flight IV.

6.1.1 Road-to EVA (Captured Asteroid)

A crew task during the approximately 10-day transit time will be preparing the cabin and 

suits for the upcoming EVAs. Shortly after Trans Lunar Injection (TLI), the vehicle cabin 
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will be depressurized to 10.2 psia to facilitate minimal EVA pre-breathe times. The crew 

will then convert the vehicle interior configuration and their OCSS suits from the launch 

configuration to one that supports EVA. The crew will mate the helmet mounted lights and 

cameras (if not integrated), swap gloves, install the xPLSS-to-Hard Upper torso and attach 

the tool mounting hardware. 

FIGURE 6.1.1-1: CONCEPT FOR EVA ON A CAPTURED ASTEROID

6.1.2 Prep & Prebreathe on EVA Day (Captured Asteroid)

On the morning of the first EVA, the crew will complete post-sleep activities and initiate 

EVA preparations with suit donning. The suit will be purged of cabin air and pressurized 

with 100% O2. The crew will then perform suit pressure integrity and system checks 

followed by a prescribed pre-breathe period that is conducted via umbilical from vehicle 

Environmental Control and Life Support Subsystem (ECLSS) system. Based on similarity 

to Shuttle protocols when starting from a saturation pressure of 10.2 psia and 

corresponding cabin air blends, the in-suit pre-breathe duration will be approximately 40 

minutes. Additional analysis is required to verify the time required to perform this task.

When pre-breathe and suit leak checks are complete, the cabin depressurization will be 

initiated by the crew. The performance of the Orion systems will be evaluated during 

depress as well as repress operations. Once at vacuum, the crew will open the vehicle 

hatch and disconnect the umbilicals, marking the formal beginning of the 8-hour EVA time 

as the point where life support is solely provided by the EVA xPLSS. The sequence of 

umbilical disconnection and xPLSS activation will be determined through future integrated 

Orion, xPLSS, & OCSS testing and verification.
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6.1.3 EVA (Captured Asteroid)

If not integrated into the vehicle, the crew will set up a translation path/boom to reach the 

part of the vehicle near the asteroid. There they will retrieve tools and a boom that will 

allow them to reach various places on the asteroid. After configuring the boom and getting 

tools, they will take samples from the asteroid.

FIGURE 6.1.3-1: EVALUATING ASTEROID EVA BOOM OPERATIONS IN THE NBL AND 

DURING NEEMO 20

Once positioned over the asteroid, the crew will utilize specialized sample tools to collect 

and store pieces of the asteroid for return. These tools, currently known as the EVA 

Integrated Geoscience Sampling System (IGSS), allow for taking pristine samples and 

putting them into containers that preserve them for study back on Earth. The IGSS will 

include ways to collect a float sample, surface sample, soil sample, rock chip sample, and 

a core sample, possibly containing volatiles.

FIGURE 6.1.3-2: ASTEROID SAMPLE COLLECTION CONCEPT (ARCM) AND 

EVALUATIONS DURING NEEMO 20

The crew will stow the samples in containers for return to Earth. These containers will 

keep the samples pristine for analysis on Earth.
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FIGURE 6.1.3-3: ASTEROID SAMPLE STOWAGE CONCEPT (ARMC) AND EVALUATIONS 

DURING NEEMO 20

The sample containers will be transferred to the interior of the crewed vehicle at the end 

of each EVA. The EVA crew stows tools and translation aids on the vehicle for use in 

future EVAs, and then ingresses the vehicle for cabin repressurization, suit doffing, and 

preparations for undocking from the Asteroid Retrieval Vehicle (ARV) and return.

FIGURE 6.1.3-4: BRINGING ASTEROID SAMPLE INSIDE VEHICLE

6.1.4 Post EVA (Captured Asteroid)

Servicing and checkout of the suits are performed the day between EVAs, including 

recharging consumables (such as batteries and thermal system water), cleaning the suit 

interior, and checkout of the xPLSS components in preparation for the second EVA.

6.2 CON OPS FOR EVA ON A NEAR EARTH ASTEROID (NEA)

A robust NEA mission involves some form of deep space transit habitat and a Space 

Exploration Vehicle (SEV). The mission is one year in duration with a total of four 

crewmembers stationed at the NEA for ~28 days. The stack (some combination of 

transport, habitat, and/or Orion) station-keeps at a safe standoff distance while the SEV 

free-flies to the NEA surface and provides a stable platform for a crewmember to work 

from during an EVA. The two crewmembers in the SEV perform microgravity EVAs from 

a minimal rear-entry airlock, totaling about 192 hours of EVAs over about five or six 3-day 

long SEV excursions from the stack. Surface activities include sample collection, 

deployment of probes (radar, acoustic, seismometer, etc.), experiments, and planetary 

defense devices. The two IV crewmembers in the stack provide support. 
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Crews will require increased autonomy for NEA missions as compared to current missions, 

based partly on communication delays of up to four minutes round trip. An xINFO system 

that enables the crew to capture field notes and contextual observations, and a caution 

and warning system that provides insight into remaining consumables based on use rate, 

information on the other crewmember’s suit health, and information on the vehicle status 

is needed. EVA crewmembers can capture High Definition (HD) video for science and 

public engagement purposes as needed during the EVA. The crew will carry tools and 

sample stowage bags/containers.

While architecture studies have looked at working off of a small free-flying spacecraft with 

a single EVA crewmember on the end of a robotic arm on the front of it, there are multiple 

issues with this sort of con ops, and currently the EVA Office does not have them in the 

official concept of operations. Until the thruster contamination issues (pluming Phobos), 

the safety issues of a solo EVA crewmember (all current con ops maintain having an EVA 

buddy for rescue), and potential problems with having an EVA crewmember on the front 

of a free-flying spacecraft near the surface (stuck thruster crushing EV crew between 

Phobos and vehicle, failed thruster resulting in crash, and pilot error resulting in collision) 

are resolved, the EVA System will focus on working from a non-moving (anchored) 

platform. Also, while there have been discussions of utilizing some sort of jetpack to 

extend translation on a NEA, there are numerous safety issues (stuck thruster sending 

crew to orbit, failed thruster slamming crew into ground, etc.), and the EVA con ops does 

not include this option. 

6.2.1 Road-to EVA (NEA)

Prior to the first EVA, xEVA Suit hardware must be unstowed, and the airlock must be 

configured with the suit, including all umbilicals and adapters. xEVA Suit consumables 

are verified to be charged or are charged/swapped out as needed. The crew installs tools 

and waist tethers on the suit, as required. Depending on the pre-breathe protocol used, 

tool install may be performed prior to pre-breathe or during pre-breathe. Prior to suit 

donning, the crew unstows all ancillary equipment and crew preference items, including 

provisions for biomedical monitoring and crew comfort (e.g. waste collection devices, 

cooling garments, crew preference items, etc.).

6.2.2 Prep & Prebreathe on EVA Day (NEA)

Following donning of ancillary equipment and crew preference items, the crew connects 

the umbilical to the xEVA Suit and powers on the xPLSS. In this configuration, the power 

to the xPLSS and suit electronics, hardline communications, and cooling are provided by 

the vehicle. Ventilation and CO2 scrubbing is supplied by the xEVA Suit PLSS, with O2

and Water (H2O) resupply from the vehicle via the umbilical and associated adapters. Flow 

is circulated through the umbilical to the airlock heat exchanger for cooling.

The EVA crew then powers up and dons their suits. The crew connects the biomed and 

LCVG internally to the suit harness and enables suit ventilation, relying on the xPLSS to 
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provide the ventilation and CO2 scrubbing as the airlock is not tied to the vehicle ECLSS 

for this function. If not conducted previously, verification of biomed function is also done.

Once the suits are donned, the crew then performs a communications check with each 

other and with the vehicle. Upon successful completion of this check, the crewmember in 

the xEVA Suit closes and locks the suit hatch for subsequent pressurization.

After the suit is pressurized to the IVA prebreathe pressure (~0.9 psid - the equivalent of 

the IVA mode on the EMU), the crew member verifies the operation of the SOR, and then

the crewmember initiates an automated suit leak check followed by a nitrogen purge. The 

crew performs a leak check at 4.3 psid. Once the suit has passed the leak check, the 

nitrogen purge is performed as a part of DCS risk mitigation protocols. The nitrogen is 

purged by opening a purge valve on the suit while using the suit O2 regulation to maintain 

a positive pressure in the suit. As the nitrogen is purged, the O2 concentration increases 

until the crew is breathing >95 percent O2 from the primary bottle with makeup from the 

habitat. Duration for the purge will be affected by the flow rate at which gas is purged from 

the suit and the suit internal gas volume. Purge time will further be constrained by oxygen 

concentration limits in the airlock.

Following the purge, the crew performs an in-suit denitrogenation prebreathe at 0.9 psid. 

During this procedure, nitrogen levels in the suit are low enough to cause the crew to 

release nitrogen from their blood, thereby mitigating the risk of contracting DCS once the 

crew is subjected to lower total pressures. The xEVA Suit must maintain a positive 

pressure in the suit to prevent any ambient air (nitrogen) from entering the suit and violating 

the prebreathe protocol. During prebreathe, the EVA crew performs final checks of the 

xEVA Suit and rear-entry airlock. The IVA crewmember closes the IVA hatch to prepare 

for airlock depressurization.

In order to be “GO” for EVA (approved for EVA operations), the xEVA Suit will have to 

show that it meets the following conditions:

• CO2 levels are verified nominal

• Pressure integrity verified

• O2 Pressure nominal

• Cooling system is verified operational

• Communications established

• Secondary Oxygen Regulator (SOR) is verified functional 

• Telemetry is being received by stack and MCC-H

6.2.3 EVA (NEA)

EVA operations for the NEA robust mission will involve two crewmembers in an SEV with 

xEVA Suits. From the SEV, they will perform sampling tasks of the NEA, and eventually 

return to the stack. EVAs are limited to 24 hours per week. Evaluations of NEA missions 

at NASA Extreme Environment Mission Operations (NEEMO) and Research and 
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Technology Studies (RATS) used two 3-hour EVAs each day, with the two pairs of 

crewmembers alternating days, and that’s the EVA frequency assumption that this con 

ops utilizes.

At the completion of prebreathe, the crew will be ready to depressurize the airlock to 

vacuum. This process includes a depressurization hold at 5.0 psia to perform a final suit 

leak check. Following confirmation of suit pressure integrity, the crew enables the 

contingency O2 system (this should not be enabled for IVA operations), which is the 

equivalent of going into the ‘EVA’ mode on the EMU. The airlock is taken to vacuum, and 

the EV hatch is opened by the EVA crew. The crew then reconfigures the suit to 

autonomous operations; power is transferred from umbilical power to suit power and the 

crew switches from hardline communication to wireless communication. The crew 

performs a wireless communication check, and then disconnects the umbilical from their 

suits to initiate use of xPLSS consumables. The crewmember verifies that the suit is 

functioning nominally by viewing their personal suit status list.

Tasks at the NEA will involve both setup and science tasks. The setup tasks may include 

things such as deploying translation booms. The current ops concepts for science 

sampling at a NEA have three methods of conducting the EVA:

1. SEV anchored to the asteroid with the EVA crewmember on the end of an 

Astronaut Positioning System (APS)

2. The EVA crewmember using personal anchors and translation devices to stay 

attached to the asteroid

3. SEV free-flying with an EVA crewmember conducting sampling tasks from an 

APS or similar configurable platform

Note: This option has safety challenges that must be overcome 

Several different types of samples will be taken and instruments deployed, including:

• Float samples picked up off the surface with a tool or bag

• Soil sample taken using a scoop

• Rock chip samples taken from a large rock with a rotary percussion drill, 

powered hammer, or with a manual hammer as a backup

• Core tube sample taken by using a powered driver

• Geophysical array deployed and possibly anchored to the surface

Several types of EVA tools used for different sampling tasks, and they will be stowed on 

the SEV. Samples will be immediately put in individual sample containers, and then those 

will be stowed in a large sample container. The sample container will be stowed in a box 

on the SEV that will eventually be transferred to Orion for return to Earth while maintaining 

scientific integrity. 
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6.2.4 Post EVA (NEA)

Upon return from the EVA, the crewmembers disconnect the recharge umbilicals from the 

jumper plates and attach them to the suits. Once mated, the crew commands repress of 

the crewlock volume. Once equalized, the crew opens the hatches and doffs suits. 

The suits are cleaned, and maintenance performed as necessary.

6.3 CON OPS FOR EVA ON THE MOONS OF MARS

Both the Capability Driven Framework and Evolvable Mars Campaign studies examined 

possible missions to the moons of Mars. EVA operations on the moons of Mars, Phobos 

and Deimos will seem similar to those on a NEA mission, but will differ due to the slight 

milli-gravity environment. This slight gravity level allows for landing, though vehicles and 

habitats will only weigh a few pounds. This milli-gravity complicates the EVA operations 

in that there isn’t enough gravity to walk on the surface, but there is enough gravity to 

cause objects to slowly settle and make contact with the surface. Operations will look 

close to microgravity EVAs, but plans will need to take into consideration that there may 

be more contact with the un-engineered surface.

FIGURE 6.3-1: MOONS OF MARS (PHOBOS AND DEIMOS)

6.3.1 Road-to EVA (Moons of Mars)

The content for this section is TBD. [TBD-7.3.1-008]

6.3.2 Prep & Prebreathe for EVA (Moons of Mars)

The content for this section is TBD. [TBD-7.3.2-009]
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6.3.3 EVA (Moons of Mars)

The current con ops focuses on EVA operations on Phobos, the larger of Mars’ moons. 

The crew will land in their habitat in the area where samples need to be taken. They will 

egress from an airlock in a similar manner to a micro-g EVA. The EVA crew will then 

deploy a boom from the side of the habitat, which will have multiple ways of articulating it 

in order to reach the required area. From the boom, they will retrieve geology samples 

utilizing the EVA IGSS, much like would be done at an asteroid. Missions to Phobos will 

also deploy science instruments, which the EVA crew will do from the boom.

Due to the several minute communications latency, EVA operations on Phobos will be 

directed by an IV crewmember in the habitat, with input from the Science Team on Earth.

FIGURE 6.3.3-1: EVALUATING SCIENCE EVA TASKS FOR PHOBOS DURING NEEMO 20

As with NEA EVA concepts, one of the architecture studies is looking at working off a small 

free-flying spacecraft with a single EVA crewmember on the end of a robotic arm on the 

front of it. There are multiple issues with this sort of con ops, and currently the EVA Office 

does not include them in the official concept of operations. Until the thruster contamination 

issues (pluming Phobos), the safety issues of a solo EVA crewmember, and safety issues 

with having an EVA crewmember on the front of a free-flying spacecraft near the surface 

are resolved, the EVA System will focus on working from a non-moving platform. Also, 

while there have been discussions of utilizing some sort of jetpack to extend translation on 

Phobos, there are numerous safety issues (stuck thruster sending crew to orbit, failed 

thruster slamming crew into ground, etc.), and the EVA con ops does not include this 

option.

6.3.4 Post EVA (Moons of Mars)

The content for this section is TBD. [TBD-7.3.4-010].
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7.0 CONCEPT OF OPERATIONS FOR EVA ON THE MOON

Lunar missions will allow for continued scientific research of the Moon, along with providing 

a critical test bed for concepts of systems bound for Mars. These missions will progress 

with a phased approach, starting with smaller short missions and expanding to a long 

duration sustained human presence on the surface. These missions will initially take place 

at the South Pole, and then at multiple different landing sites spread across the surface of 

the Moon. EVA operations will involve a variety of engineering-focused and sciencefocused tasks.

FIGURE 7.0-1: LUNAR EVA DURING APOLLO 16

Exploration of the lunar surface will involve a variety of architectural scenarios. Assets will 

range from Gateway (with its orbit as a mission length driver), human landers, 

unpressurized rovers, pressurized rovers, habitats, and Exploration spacesuits. Missions 

may range from a few days, to 42 days, to six months or more. They will involve landing 

two to four crewmembers to the surface. Lunar surface missions will build on the heritage 

of Apollo and demonstrate planetary partial-gravity surface exploration, near-term 

capability development, and operations to support the goal of human exploration of the 

inner solar system, including Mars.

The lunar surface con ops will be driven by fulfillment of key lunar science and Mars 

preparation objectives. Mission activities of human lunar return will include addressing the 

high priority objectives of the science community which benefit from human surface 

presence. They will also characterize human health and performance, long distance 

mobility concepts (such as rovers), dust mitigation practices, crew autonomy, concepts for 

human-robotic partnership, utilizing precision landing technologies, and in-situ resource 

utilization.
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The Artemis missions will take place in two general phases, with the following approximate 

years for the crewed missions:

• Artemis Phase 1

o Artemis III (~2024)

o Artemis IV (~2025/2026)

• Artemis Phase 2

o Artemis V (~2027)

o Artemis VI (~2028)

o Artemis VII (~2029)

7.1 SCIENCE OBJECTIVES & REGIONS OF INTEREST

One of the primary purposes for landing on the surface of the Moon will be for science. 

The science community identified a set of primary objectives for lunar missions, and 

regions of interest to achieve those objectives. On Thursday, May 28th, 2020, NASA HQ 

released the high level science objectives (explained in more depth in section 8.1.1) as 

including the Study of Planetary Processes, Understanding Volatile Cycles, Impact History 

of Earth-Moon System, Record of the Ancient Sun, Fundamental Lunar Science, and a 

Platform to Study the Universe.

7.1.1 Science Objectives for the Lunar Surface

In June 2020 NASA outlined the Artemis Science Plan that includes using the Lunar 

surface as a place to study planetary processes, to understand volatile cycles, study the 

impact history of the Earth-Moon system, study the record of the ancient Sun, and serve 

as a platform to study the Universe. In addition, the 2007 National Research Council’s 

(NRC) Scientific Context for the Exploration of the Moon (SCEM) laid out a series of 

science concepts to study during missions to the moon. The 2017 Lunar Exploration 

Analysis Group (LEAG) Advancing Science of the Moon (ASM) Specific Action Team 

(SAT) Report assessed progress made in achieving the science goals laid out in the 2007 

NRC Report, and added additional concepts/objectives.

The NRC-SCEM study identified eight areas of scientific research that should be 

addressed by future lunar exploration. Within each concept was a list of 35 prioritized 

science goals. The eight science concepts were defined and ranked as follows:

• S.1: The bombardment history of the inner Solar System is uniquely revealed 

on the Moon.

• S.2: The structure and composition of the lunar interior provide fundamental 

information on the evolution of a differentiated planetary body.

• S.3: Key planetary processes are manifested in the diversity of lunar crustal 

rocks.

• S.4: The lunar poles are special environments that may bear witness to the 

volatile flux over the latter part of solar system history.
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• S.5: Lunar volcanism provides a window into the thermal and compositional 

evolution of the Moon.

• S.6: The Moon is an accessible laboratory for studying the impact process on 

planetary scales.

• S.7: The Moon is a natural laboratory for regolith processes and weathering 

on anhydrous airless bodies.

• S.8: Processes involved with the atmosphere and dust environment of the 

Moon are accessible for scientific study while the environment remains in a 

pristine state.

The ASM-SAT added three new concepts as follows:

• A.1: The Lunar Water Cycle: while the SCEM report included polar volatiles, 

work over the last decade has pointed to a water cycle with three principle 

components: primordial (interior) water, surficial water (linked to solar wind), 

and polar (sequestered) water.

• A.2: The Origin of the Moon: clues to lunar origin and geologic processes 

that operated during planetary accretion are recorded in the lunar rock record. 

Focused sample studies and sample return could be used to unlock these 

mysteries and test long-standing origin hypotheses.

• A.3: Lunar Tectonism and Seismicity: over the last decade, high-resolution 

imagery has led to a dramatic increase in the number of tectonic landforms 

present on the lunar surface, including wrinkle ridges, rilles, and lobate 

scarps. The interior structure, thermal history, and mechanism(s) of heat loss 

of a planet are all related to the resulting distribution of surface tectonism.

In addition to the Artemis Science Plan, the NRC-SCEM and ASM-SAT reports, the NRC 

Vision and Voyages for Planetary Science, or the Planetary Decadal Survey, identifies key 

planetary science questions and provides a list of prioritized robotic missions to be 

undertaken in the decade 2013-2022. For the Moon specifically, the Decadal Survey 

specifies two high priority missions: 1) South Pole-Aitken Basin sample return, and 2) 

establishing a long-lived global Lunar Geophysical Network. 

The NASA HQ-released Artemis Science Strategy document highlights four advantages 

of Artemis astronauts accomplishing science objectives including an increase in mobility, 

the ability to widely sample the geologic diversity of the Moon, the ability to deploy delicate 

instrumentation, and access to regions with cold temperatures.

Per the 2020 Lunar Surface Science Workshop, the Artemis program has several highlevel objectives for lunar surface missions, and corresponding science requirements. The 

high-level objectives include the following:

• Study of Planetary Processes

• Understanding Volatile Cycles

• Interpreting the Impact History of the Earth-Moon System
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• Revealing the Record of the Ancient Sun

• Observing the Universe from a Unique Location

• Conducting Experimental Science in the Lunar Environment

• Investigating and Mitigating Exploration Risks to Humans

The corresponding science requirements include the following:

• Mobility to visit geologically different features

• EVA traverses & suits designed for sample collection

• Access to persistently shadowed terrain

• Sealed collection canisters designed for cold sample curation

• Collection of several walnut-sized rocks for chronological analyses

• Identification of and collections of rocks from outcrops and boulders

• Collection of core tube samples to capture ancient solar wind trapped in 

regolith layers

• Understanding regolith stratigraphy

• Dexterity to deploy delicate instrumentation

• Characterization of the local environment (dust, RF, plasma)

7.1.2 General Regions of Interest

To accomplish the scientific goals and objectives outlined in the NRC-SCEM, ASM-SAT, 

and NRC-Decadal reports, site selection for lunar surface operations is critical. Prioritized 

scientific goals and objectives will have to be carefully weighed against engineering 

constraints of exploration regions. A number of reference documents and community 

workshops have explored and selected lunar regions of high scientific interest:

• The January 2018 Global Exploration Roadmap (GER) and the May 2017 

draft of the ISECG Human Lunar Exploration Surface Campaign Concept of 

Operations discussed potential lunar landing sites and areas to explore.

• A study entitled A Global Lunar Landing Site Study to Provide the Scientific 

Context for Exploration of the Moon takes the first 7 NRC-SCEM concepts 

and looks at the best lunar regions to accomplish the specified science goals.

• The Lunar Science for Landed Missions Workshop convened at the NASA 

Ames Research Center in January 2018 with the goal to produce a set of 

high-priority landing site targets for near-term lunar missions generated by the 

lunar science community. The workshop defined a set of targets that nearterm landed missions could visit for scientific exploration and commercial 

exploration companies with interest in pursuing ventures on the surface of the 

Moon.
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FIGURE 7.1.2-1: POTENTIAL LUNAR SCIENCE LANDING SITES

This includes the following potential exploration regions and landing sites:

• Volcanic deposits

• Compton-Belkovich Volcanic Deposit 

• Marius Hills 

• Lunar polar regions (north and south)

• Plateau near Shackleton Crater at 88.8°S and 125.5°E

• Schrodinger Basin at 75.40°S and 138.77°E

• South Pole - Aitken Basin Interior at 60.0°S and 159.9°W

• Impact craters and basins

• Lava tubes or pits

7.1.3 Lunar South Pole Region 

The Artemis Program has directed efforts towards the south pole of the Moon. Near that 

area are three general types of regions of interest for scientific exploration. Those include 

craters, permanently shadowed regions, and volcanic terrain. 

Efforts to plan for the Artemis III mission have identified several notional landing sites. 

One of these sites is on Connecting Ridge, between Shackleton Crater and de Gerlach 

Crater. This ridge is ~540 meters wide with slopes that are generally less than 20°. 
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7.2 CON OPS FOR EVA ON LUNAR SURFACE (ARTEMIS PHASE 1)

Artemis Phase 1 is the initial crewed missions returning to the moon. This initial mission 

will focus on demonstrated human operations on the lunar surface, in addition to providing 

science sample return and deployment of long-lived experiment packages. 

Aspects of the first two mission, Artemis III and Artemis IV, include the following aspects 

and parameters:

• Artemis III initial crewed mission in ~2024

• Artemis IV mission in ~2025/2026

• Mission takes place in lunar daylight (i.e., constant light)

• Four crew fly to cislunar orbit, with two crewmembers staying in Orion for 

Artemis III and in Gateway for Artemis IV, and two crewmembers landing on 

the surface

• Surface stay duration: 6.5 days

• Crew on surface live in and conduct EVAs out of lander

• Total number of surface EVAs: 2 – 5 

• Crew on EVA: 2

• EVA duration (PET): 4-8 hour excursions (6±2 hours)

• Egress method: Lander cabin depress, severable airlock, or airlock(s)

• Excursions distances: up to a 2 km radius away from the lander walking

o Based on walking at 2 km/hr over fairly level and clear terrain

o Slopes and other natural features will affect any range

Reference Section 3.2.1 for high-level architecture information for Artemis Phase 1.

Lunar surface missions generally have the following phases with respect to the xEVA 

system.
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FIGURE 7.2-1: PHASE OF XEVA OPERATIONS FOR LUNAR SURFACE MISSIONS

FIGURE 7.2-2: LUNAR SCIENCE EVA OPERATIONS DURING APOLLO 17

7.2.1 Preflight and Earth Launch

7.2.1.1 Preflight Testing, Processing, and Training

A multitude of events occur surrounding the xEVA System before it or the crew are 

launched on a lunar surface mission. The actions before flight include, but are not limited 

to, the following:

• Technique and task development

• Timeline and procedure development
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• Suit sizing

• Flight-specific training

• Assigned astronaut training

• Flight control team training

• Procedure verification testing

• Pre-acceptance testing

• Bench reviews and functional checks

• Readiness reviews

7.2.1.2 Earth Launch & Mission Logistics

Mass allocation and stowage for all spaceflight missions are a challenge. As such, the 

xEVA System will be launched in a distributed manner, with the majority of the hardware 

planned to be launched on the unmanned HLS or in a Gateway logistics module, 

depending on the mission. The xEMU will be launched in a soft stowed configuration. 

This includes, but is not limited to, the xEVA suits, the VISE, tools, and spares. The crew 

may bring some astronaut specific items (i.e., gloves) and any required suit modification 

kits with them in Orion. 

If Artemis IV goes to Gateway (TBD-7.2.1.2-005), logistics may be prepositioned there. 

The xEVA Suit may launch on a cargo mission (no crew) in a quiescent stowage 

configuration. In the quiescent stowage configuration, the xEVA Suit will not require any 

periodic maintenance, and will remain in this configuration until a contingency or planned 

EVA event is imminent.

7.2.2 On-Orbit Operations (Crew Arrival)

Once crew arrives at Gateway or docks with HLS, the crew will prepare for descent to the 

lunar surface, including stowing their EVA suits in the ascent vehicle of the Human Lunar 

Lander. 

7.2.2.1 Suit Assembly & Checkout

In the current single suit architecture, suit configuration and checkout is broken into two 

distinct phases. The first is the initial assembly and checkout into the full EVA mode 

configuration. That involves the following general steps:

• Unpack xEVA equipment from launch stowage containers and assembly in 

HLS

• Checkout xEMU and VISE (e.g., O2, battery, cooling, comm, umbilical power, 

etc.) in HLS

• Gross on-orbit fitcheck verification and sizing adjustments of the xEMUs
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7.2.2.2 Stand-up EVA

Once the suits are successfully checked-out, a “stand-up EVA” may potentially be 

performed (TBD-7.2.2.2-006). This short EVA would allow for an operational verification 

that the HLS system and particular serial number suits are fully functional before landing 

on the lunar surface. This EVA would test the processes for prebreathe, cabin depress, 

hatch opening, suit ops in vacuum, and repress. As the EVA could be conducted from the 

HLS, it is transparent to which vehicle the HLS is docked (Gateway or Orion). 

7.2.2.3 Suit Configuration for Descent

The second phase has the crew reconfigure the suits for vehicle loop mode in preparation 

for lunar descent and landing. That involves the following general steps:

• Configure the xEVA suit into vehicle-loop mode for descent to lunar surface

• Checkout the xEMU xPGS in vehicle-loop mode 

• Complete any stowage tasks or other xEVA hardware activities required prior 

to undock and descent

7.2.3 Descent to Lunar Surface

The suited dynamic flight events include the phases of the mission with the crew traveling 

in the lander from orbit down to the lunar surface. The xEVA suit may be utilized in VLM.

Prior to departure from Gateway/Orion and descent to the lunar surface, the crew begin 

their saturation to a lower pressure environment with higher O2 concentrations. This 

saturation will reduce (or possibly eliminate) any prebreathe required on the lunar surface. 

Considerations for suited dynamic flight phases include the following:

• Some descent profiles last ≥ 24 hours

• Astronauts must be able to sleep during the descent and ascent portions

• xEMU certified for 12 continuous hrs in VLM (dependent on host vehicle)

• Gloves and helmet should be removed when not needed

• Crew will be saturating to vehicle atmosphere during descent

Notional (TBD-7.2.3-007) suited times during lunar descent include the following:

• Fully suited and pressurized for undocking

• Remove suits for/during Descent Orbit Insertion (DOI) burn

• Unsuited for Powered Descent Initiation (PDI) burn 

• Get suited again (no helmets or gloves) during Braking phase

• Partially suited (no helmets or gloves) for Approach Phase 

• Fully suited and pressurized for Terminal Descent 

• Fully suited and pressurized for Touchdown Phase
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For Artemis III and IV, the crew will land in the area targeted for science characterization.

7.2.4 Lunar Surface EVA Operations

EVA operations on the lunar surface include road-to EVA, prep and prebreathe, surface 

ops, post EVA, and maintenance. 

7.2.5 Road-to EVA (Lunar)

Upon touchdown on the lunar surface, crew doff their suits and prepare the HLS cabin and 

xEVA hardware for surface operations, including converting the xEMU from VLM to to EVA 

configuration. The "road-to EVA" is a comprehensive list of all the activities that occur 

before and up to the day prior to the start of a planned series of EVAs. It includes preparing 

the xEVA suit and VISE, the lander/airlock, and the tools and equipment, in addition to the 

crew preparing themselves. 

7.2.5.1 xEVA System Prep

Preparation of the xEVA suit and VISE includes those tasks necessary to convert the suit 

from VLM (descent/ascent configuration) to the EVA mode configuration:

• Configure xEMU with xPLSS (convert from VLM to EVA mode)

• Install the suits on the don/doff assembly

• Configure the umbilicals and connect the suits to the VISE via the umbilicals

• Perform pre-EVA inspection and checkout 

• Conduct fit verification in lunar gravity

• Recharge consumables (O2, H2O, battery power)

• Fill and install drink bags

• Prepare biomedical monitoring equipment (as applicable)

7.2.5.2 Lander/Airlock Prep

Once the suits are checked out, the crew prepares the lander and/or airlock for EVA 

operations. This includes:

• Securing equipment used for descent

• Configuring communication systems

• Activating O2 monitoring systems

7.2.5.3 EVA Tools and Tasks Prep

Preparing the tools, ancillary equipment, and the crew includes:

• Complete EVA tool configuration

o Configure tool and sample bags

o Attach tools to suit
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o Assemble and configure payloads and experiment packages

• Upload data into the informatics system (as applicable)

• Check all ancillary equipment, especially powered devices such as lights

• Conduct pre-EVA conference with MCC and Science Team

• Review and study timeline, procedures, and safety protocols

• Stage ancillary hardware and external hardware to deploy

Once the suits are initially prepped and the crew begins surface exploration, the equipment 

remains at a relative state of being prepared for EVA. This reduces the amount of roadto activities that need to be conducted, but there will still be several things that must be 

done before each EVA. This will include finalizing the tasks and timeline, reviewing the 

approved timeline, briefings from MCC and the Science Team, an xEVA Suit checkout, 

tool configuration, uploading of data into the xEVA informatics system (as applicable), and 

housekeeping duties to prepare the lander cabin for unmanned operations.

7.2.6 Prep & Prebreathe for EVA (Lunar) 

On the day of the EVA, the crewmembers begin final prep activities and the prebreathe 

protocol (as applicable). 

EVA prep includes the following:

• Suit initialization and power up on vehicle power to verify system functionality

• Donning of suits

• Checkout of primary and backup systems

o In-suit communication checks

o Suit leak checks

o Verification of caution & warning system

• Final suit fitcheck

EVA prebreathe actions include the following:

• Purge to remove N2 from the suits

• Prebreathe

o Prebreathe requirements will depend on the saturation atmosphere 

o Surface EVA protocols are in development, and may be different from 

microgravity due to higher metabolic rates, ground reaction forces, 

and musculoskeletal forces

o Protocols may make use of vehicle saturation atmosphere, prebreathe 

time and/or exercise, and the ability of the suit to operate for periods 

at higher delta pressures

During the surface crew prep operations, the crew in Orion (Artemis III) or Gateway 

(Artemis IV) will prepare for monitoring and guiding the EVA operations as the IV when 

needed, along with conducting tasks unrelated to the EVA. 
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7.2.7 Egress and Setup

Once any required prebreathe is complete and the crew are ready to leave the lander, 

they initiate cabin/airlock depress. This will involve a hold, likely around 5 psia, to verify 

the suits are holding pressure with a final leak check. Once that leak check is passed, the 

crew proceed with taking the volume down to vacuum. 

Once the cabin/airlock is at vacuum, the crew switch over to their suit systems and 

disconnect the vehicle umbilicals. The “EVA” phase elapsed time (PET) begins when the 

spacesuit is switched from the vehicle provided power source to internal suit power

(batteries). 

The EV crew open the hatch, and gather any equipment they may bring with them from 

inside the cabin to the surface. This may include some geology tools, such as the 

contingency sampler. Crew will conduct a final check of tools and equipment on harnesses 

attached to their suit and/or in equipment/tool bags. They then egress the hatch and 

descend down to the surface, which may involve a ladder, sled, or elevator, utilizing a fall 

protection system as required. 

Once on the surface, the crew set up the tools and equipment they’ll need for their tasks. 

They will destow any tools and equipment transported on the exterior of the vehicle. This 

will include sample collection tools and instruments, along with equipment to transport 

tools and samples. The EV crew will transport smaller tools and equipment to the worksite 

either directly attached to their suits or with a harness/carrying system. Larger tools and 

storage boxes will be transported with an equipment transportation system (e.g., a 

wheeled cart).

In addition to task equipment, the crew will set up the dust mitigation kit. This set of tools 

will be part of the dust mitigation strategy that the crew will follow during ingress towards 

the end of the EVA. 

7.2.8 EVA Surface Operations

Once on the surface, the crew will conduct a multitude of engineering and science tasks, 

with a primary focus on successful science return. 

7.2.8.1 EVA Traversing – Navigation and Lighting

During Artemis III, the crew will stay within a walking range of approximately a 2 km radius 

of the lander. Within this 2 km radius, they will walk across regolith and around boulders, 

up/down slopes of up to 20°, and in long shadows, and into PSRs. Over the course of an 

8-hour EVA, it is possible that crew may walk a total distance of 16 km on level terrain at 

2 km/hr, but for more challenging terrain, crew may walk or scramble much less at 

significantly slower speeds, though exact total distances are still being determined.
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They will utilize local and accessory navigation systems and/or methods for locating the 

target science zones, allowing MCC to track their location and progress, and always 

maintaining a safe return to the lander both nominally and in a contingency. 

The crew will experience constant long shadows near the lunar South Pole, while also 

looking nearly directly at the sun. In order to safely and effectively traverse through the 

dark shadows and across rough terrain and slopes, in addition to incursions into PSRs, 

they will utilize hands-free lighting (such as lights strapped to their arms or mounted at the 

waist). While in shadows and/or PSRs, the crew will utilize tools to perform the science 

tasks, and will utilize hands-free lighting for visibility. Traverses and tasks will need to take 

into account the full lighting spectrum, from direct sun to dark shadows. 

7.2.8.2 Engineering EVA Tasks

At the landing site, crew will conduct pioneering construction tasks for surface architecture 

and maintenance of the surface assets. This will include, but is not limited to, tasks such 

as:

• Deploy and construct antennas

• Align antennas

• Grade regolith

• Route and connect power and communication lines

• Remove dust

• Clean equipment

• Repair equipment

7.2.8.3 Science EVA Tasks

The first task on the first EVA will be collection of a contingency sample. This will provide 

a small science return in the event of any abort. 

Crew will conduct a multitude of science-focused tasks on the surface. Once in the general 

region of interest, EV crew will utilize geoscience training to explore and characterize an 

area. Guidance and navigation systems/methods will aid crew in autonomously getting to 

destinations and back without IV or MCC support, and guide them to targets specifically 

designated by the Science Team. Reference Section 4.1.5.2 for additional information on 

surface navigation and tracking. 

Some tasks will require the EV crew to scramble up and down steep slopes, traverse down 

into craters and back up out of them, and work near or inside PSRs. Later missions in 

Phase 2 may have the crew also get into and out of lava tubes and pits.. 

Science operations will include the EV crew navigating to Regions of Interest (ROIs) with 

tools and instruments. They will utilize navigation systems and/or methods that allow for 

them to know they are at the right region, allow MCC to track their progress, allow them to 
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safety return to the lander, and allow for the necessary accuracy for the science team to 

have the appropriate data on where samples were collected. 

Along the way and once there, they will conduct initial inspections of the surroundings, 

perform context documentation, and potentially place markers to identify target samples. 

At the work zone, the EV crew will perform a variety of tasks. They will move and assemble 

hardware, make measurements of fields or the environments, set up science experiments, 

and deploy scientific instruments. They will primarily perform geology tasks, characterizing 

the area and acquiring sample materials. These generic tasks include, but are not limited 

to, the following:

• Observations and Documentation (Imagery)

o Regional macro-scale context

o Local micro-scale context

• Sample acquisition

o Rock float samples

o Rock chip samples

o Rock core samples

o Regolith bulk samples

o Regolith core samples

o Regolith surface samples

o Volatile samples

• Data collection

o Geotechnical and subsurface instrument measurements

o Handheld instrument measurements

• Science payload deployment

Sampling may be achieved in several ways. Collecting regolith may include sampling via 

a scoop, rake, core tube, surface contact tool, and/or trench. Rock samples include float, 

chips, and samples from a core drill. Volatiles may be part of a regolith sample or 

contained in a drill tube. In each case, detailed imagery of the sample site before and after 

sample collections is required.

Generic regolith sampling process:

• Surface contact – EV begins with the surface contact tool, stamping the 

ground from a standing position before disturbing the area with other sample 

types. EV closes the door on the end effector, detaches it, and then stows it 

in the sample container bag.

• Scoop – EV attaches the scoop end effector to the tool handle, crouches 

down to collect a sample of regolith, and then stows it in a sealable bag to 

keep it pristine. EV weighs the sample, holds the bag up to the helmet 

camera for recording by the Science Team, and then stows that bag in the 

temporary collection bag.
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• Rake – EV switches the end effector on the tool handle for the rake and 

proceeds to scrape the ground to collect small rocks, which get put into a 

sealable container and stowed in the larger sample bag after being weighed.

• Trenching – EV then uses the trenching tool to expose a lower level of 

regolith, scraping from a standing position and kneeling when necessary. EV

records context descriptions of the trench, takes imagery, and holds 

stationary to allow the Science Team in MCC to get a good view of the trench. 

The Science Team directs EV towards a sample, which EV then acquires with 

the appropriate tool.

• Drive tube – EV completes the sampling suite at the worksite with a drive tube 

sample. EV retrieves the drive tube, manually drives it into the ground from a 

standing position, kneels and pulls the tube out, caps the end, weighs the 

tube with the sample inside, holds the tube up in the field of view of the

helmet camera, and then stows the tube in the vacuum-sealed container.

Generic rock sampling process:

• Float – EV picks out a couple of float (loose rock) samples that appear as if 

they would satisfy the science requirements. EV holds the helmet camera 

steady for the Science Team to review the selection. From a standing 

position, EV uses the float end effector attached to the end of the tool handle 

to collect the float sample. EV holds the sample up to the helmet camera, 

detaches the end effector, weighs the end effector with sample inside, and 

then seals it inside the sample collection bag.

• Chip – EV retrieves the hammer and chisel. The Science Team directs EV 

towards an outcrop. EV proceeds to the desired rock, kneels down, and uses 

the hammer to break a chip off the rock. EV collects the rock chip with a tool 

(as rocks may be sharp and so as not to contaminate the sample), puts it in a 

sealable bag, weighs the bag, holds it up to the helmet cam while reading off 

the bag number, and then stows that bag in the sample collection bag.

• Core drill – EV retrieves the hammer drill and a core bit. EV2 assembles the 

two together, then walks to the outcrop. Using a combination of helmet 

camera video, pointing, and cues from the Science Team, EV determines the 

best location for a core sample. EV kneels down, presses the bit against the 

rock, leans into it to provide reaction force, and then proceeds using both 

hands to hammer drill the core bit into the rock. After reaching the desired 

depth, EV extracts the tool. EV deploys a core sample container tube, 

activates the break off feature of the bit, and slides the core sample into the 

tube. EV carries the sample and drill bag to the tool carrier, kneels down, 

disassembles the core bit from the hammer drill, and then stows them both.
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7.2.8.4 MCC/IV Tasks

During EVA ops, both MCC and the IV in Orion (Artemis III) or Gateway (Artemis IV) will 

monitor and direct the EV crew. When the EV crew are conducting science-driven tasks, 

the Science Team in MCC will provide communications with the crew via the CAPCOM or 

SCICOM (Science Communicator). 

Reference Section 4.1.3 for additional information on tasks performed by the suited 

crewmembers. 

7.2.9 Cleanup and Ingress

Upon completion of tasks at a work zone, reaching a consumables bingo (limit), or running 

out of time, the crew will clean up (gather and stow) their tools and equipment. They’ll 

pack equipment and science samples into the equipment transportation system and begin 

traversing back to the lander.

Back at the lander, the EV crew will stow equipment and samples. In general, tools and 

equipment launched in exterior tool boxes will be stowed back in those boxes between 

EVAs. This protects the equipment, and leaves the lander configured safely in case of an 

unexpected abort from the surface. 

Samples and sample bags will be unstowed from the transportation system and positioned 

near the lander for bring them inside. 

The crew will then start the dust mitigation procedure to reduce what is brought back into 

the vehicle. Dust and contamination accumulated on the surface of the xEVA Suit is 

mitigated prior to ingress of the airlock to limit contamination to the habitable volume and 

is achieved via both EVA system-provided methods and vehicle-based hardware. These 

steps will include cleaning the suits, bags, tools, and hatch in a multi-layer approach. Note 

that in some contingencies dust removal may not be possible prior to ingress. 

Once the ground portion of the dust mitigation process is complete, the crew will begin 

ascending into the lander, utilizing any fall protection that is required. For lander designs 

with a ladder or sled, the crew will work together to get the sample bags up into the hatch. 

For larger landers with an elevator, the crew will carry the sample bags onto the elevator 

and ride up with them. 

At the hatch, the crew may conduct more dust mitigation steps, and then will work together 

to move the sample bags inside and stow them according to the science plan. After the 

2nd crewmember is inside, the crew will connect umbilicals to the xEVA suits and switch to 

vehicle power and consumables. The crew will then close the hatch, and begin repressing 

the lander/airlock. The EVA PET clock officially ends after the lander/airlock hatch is 

closed and repress has initiated. 
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7.2.10 Post EVA Operations

Following ingress, the crew will conduct post-EVA activities. The don/doff aids will provide 

structure for crew to pull themselves up out of the rear entry hatch unassisted. Post EVA 

operations commence with reconnection to umbilical and includes the following: 

• Utilize HLS ECLSS to remove any particulates in the atmosphere

• Doff/egress the suits

• Doff ancillary equipment (such as a Liquid Cooling & Ventilation Garment)

• Clean the suits

• Perform detailed inspection of the suits

• Bag the suits as required to minimize dust migration

• Recharge consumables (O2, H2O, battery power)

• Download required xEVA suit data

7.2.11 Maintenance 

A thorough inspection, with video and photo documentation, of the suit is performed 

between each EVA, with particular attention paid to the gloves, boots, and any suit surface 

that came in contact with the lunar surface. The crewmembers visually inspect the 

bearings and interfaces. While areas covered in dust are wiped and cleaned, it is not 

expected that all dust that has adhered to the suit is removed. However, it is expected 

that a sufficient amount of dust is removed from the suit to allow inspection of damage.

In addition to post-EVA inspections, the EVA suits may require periodic maintenance, 

though no preventative maintenance is foreseen for Artemis III or IV. This may include 

replacement of gloves and boots. 

7.2.12 Ascent from Lunar Surface

7.2.12.1 Departure Prep & Quiescent Stowage

Prior to crew departure from the destination, the crew will reconfigure xEMU into VLM for 

dynamic operations during lander ascent and docking. This may necessitate a suit 

checkout once the xPLSS has been removed. Depending on the specific mission plan, 

the crew may perform an umbilical EVA as required to discard xPLSS, waste, and other 

disposables not required for return. 

7.2.12.2 Suited Dynamic Flight Events (lunar ascent)

During ascent from the surface, the crew will be suited for parts of the profile. This will be 

in the xEMU in VLM for missions utilizing the single suit architecture. 

Considerations for suited dynamic flight phases include the following:

• Astronauts must be able to sleep during the ascent portions
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• xEMU certified for 12 continuous hrs in VLM 

• Gloves and helmet should be removed when not needed

Notional suited times during lunar ascent include the following:

• Fully suited and pressurized during powered ascent/liftoff

• Remove suits during and for phasing orbit for return to Gateway in NRHO

• Unsuited during cruise from phasing orbit to NRHO

• Partially suited (no helmets or gloves) during rendezvous with Gateway

• Fully suited and pressurized during docking phase to Gateway

7.2.13 On-Orbit Operations (Crew Return)

7.2.13.1 Post Docking Operations

Whether docked to Orion or Gateway, the crew will perform the following post-docking 

tasks:

• Disassemble xEVA suit for long term stowage in Gateway or leave in lander 

for disposal

• Transfer samples and returning xEVA hardware to Gateway and/or Orion, per 

science plan

• If the lander is to be disposed of, EVA will advocate for salvage of any 

possible xEVA System hardware Gateway can accommodate

7.2.13.2 Return and Post Flight Processing

The majority of the xEVA system equipment will not return to Earth with the crew. Any 

hardware returned will be examined for system and component function, health, and life. 

A thorough set of lessons learned, anomaly reports, and failure investigation reports will 

lead to action plans to improve the xEVA system design, processes, team communication, 

training, procedures, etc.

7.2.14 Design Reference EVA for Artemis III

This section outlines a notional design reference series of EVAs, and a notional design 

reference EVA for development of the xEVA system. It contains a variety of potential 

example tasks, and is an example of a snapshot of one particular mission scenario. The 

landing zone for this reference is presumed to be near the South Pole Aitken Basin, on an 

area between Shackleton crater and de Gerlach crater known as Connecting Ridge. This 

section outlines a notional series of EVAs for a mission at Connecting Ridge, which 

includes traverses to PSRs that are within 2km of the landing site. 
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FIGURE 7.2.14-1: NOTIONAL LUNAR LANDING SITE AT CONNECTING RIDGE

7.2.14.1 Design Reference EVA Series for Artemis III

Per the current plan for Artemis III, this design reference mission outlines a series of five 

EVAs over the course of a 6.5 day mission on the surface. 

FIGURE 7.2.14.1-1: NOTIONAL DESIGN REFERENCE EVA SERIES FROM EVA-EXP-0075
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After landing on the surface, the crew immediately get to work on the road-to EVA 

activities. By the end of the first day on the surface, all of the xEVA and lander systems 

are prepped for the first EVA the next day. 

On the second day on the surface, the crew conducts their first EVA. This full length EVA 

focuses on gathering the contingency sample, giving them at least one sample in case the 

rest of the EVAs or even surface mission is aborted. They will conduct some public affairs 

activities, deploy science packages, and proceed with nominal traverse activities and 

sample acquisition for the remainder of the EVA. During this excursion, the crew will stay 

relatively close to the lander. 

On the third surface day, the crew conducts EVA 2. As the volatiles are a high priority for 

science return, the crew traverses ~2km towards a PSR, walking down and up slopes of 

up to 20°, collecting traverse data and samples, including samples that could contain 

volatiles. 

On the fourth surface day, the crew take a day off from EVA activities. They focus on 

lander housekeeping and IVA experiments. 

On the fifth surface day, the crew conduct EVA 3. They execute the science plan, 

acquiring samples of the local ejecta blanket. This traverse is also up to 2 km from the 

lander, walking up and down slopes of up to 20°.

On the sixth surface day, the crew heads out on EVA 4. This is their last full length surface 

EVA for this notional design reference series. They will focus on deploying geotechnical 

instruments, experiment packages, and an environmental monitoring station for ISRU. 

The seventh surface day is the last day on the surface. The crew may perform a short 

one-hour EVA in VLM in order to jettison trash and hardware that won’t be returning to 

lunar orbit. They configure their suits for ascent, and take off from the surface on their way 

to meet Orion. 

7.2.14.2 Design Reference EVA for Artemis III

The notional design reference EVA included is likely oversubscribed for any single EVA, 

however it will give the reader an idea of what will need to be performed on the lunar 

surface via EVA. This section does not timeline an actual EVA, but only provides a 

potential example of tasks performed by EVA on the lunar surface, with the goal to help 

the designers and users understand the various movements and interfaces for the xEVA 

suit. The design reference EVA begins with egress and ends with ingress, following the 

path of an EVA crew from the lander at point A to a PSR at point A’ and back. It walks 

through the EVA tasks at a high level in order to provide information without being 

prescriptive. This example will be updated in future revisions as the lunar surface mission 

architecture develops and evolves.
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FIGURE 7.2.14.2-1: DESIGN REFERENCE EVA OUTLINE FROM EVA-EXP-0075

7.2.14.2.1 Egress & Setup

Once depress is complete, the two EVA crewmembers perform post depress actions. 

They will switch from vehicle to battery power, officially starting the PET clock. They 

release themselves from the don/doff assembly, walk to the EV hatch, and open it. The 

EV crew detaches their umbilicals and stows them in the airlock/cabin on dummy 

connectors that protect the interface from dust and debris. Before egressing, the crew 

conduct a final check of tools and equipment attached to their suit on harnesses and in 

bags they’ll hand carry. For the first EVA, this includes the contingency sample tool, which 

will ensure that the mission returns some science in the event of an abort. 

The crew step through the hatch (minimum of 40x60 inches) and attach to any fall 

protection system that’s required. Once safely configured, EV1 descends the ladder to 

the surface. With boots firmly on the ground, EV1 detaches from the fall protection system. 

EV2 begins lowering tools and equipment bags down to EV1, who places them on the 

surface. Once all equipment has been transferred to the surface, EV2 descends to the 

surface and detaches from the fall protection system.

The crew set up the dust mitigation kit that they’ll use before ingressing. 

Before beginning their traverse, the crew collects the contingency sample, documents the 

collection and communicates with the ST. The crew then unstow the remaining required 

equipment from tool boxes on the outside of the lander. Most of the basic geology 

sampling tools will be stored in the external tool boxes. The EV crew transports some 

smaller tools and equipment to the worksite either directly attached to their suits or with a 
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harness/carrying system. Larger tools and bags are taken to the worksites in an 

equipment transport system (e.g., carrier or wheeled cart). 

7.2.14.2.2 Science on Ejecta Blanket

From the lander at point A, the crew begin walking towards the PSR at A’ across an ejecta 

blanket. The PSR is slightly downhill, with an average slope of ~10° and peaks of up to 

~16°, and approximately 2 km away from the lander. 

Approximately a kilometer into their walking traverse, the crew pause on the ejecta blanket

in their first region of interest. There they conduct contextual observations, with in-depth 

verbal descriptions that are transmitted to scientists in MCC and are recorded by the xEVA 

suit. The crew utilize their helmet cameras to give overview video imagery, and take 

pictures with handheld cameras. 

Using the crew’s verbal descriptions, video imagery, and training opinions, the Science 

Team in MCC directs the crew to acquire samples of the ejecta blanket. They deploy the 

required tool for their tool management system, whether attached to the suit or on a carrier, 

kneel down, and take the sample. They put each sample in individual sample bag, and 

put those bags in temporary collection bags. 

The Science Team in MCC notes the location of the samples, utilizing the tracking and 

navigation system incorporated into the architecture (e.g., transponder). 

At the end of sampling tasks on the ejecta blanket, the crew work together to stow the 

temporary collection bags in the larger sample collection bags. Those are attached to the 

carrier or possibly to the xEVA suit PLSS. They clean up their tools, and perform checks 

before proceeding to the next region of interest. 

7.2.14.2.3 Science in Crater

At the rim of the crater, the EV crew begin initial regional context observations. This 

includes visual inspection of the crater and surrounding areas, complete with imagery and 

verbal descriptions. EV1 stands on the rim and locates the specific zone inside the crater 

from which sampling will take place. 

After verifying they are good to proceed and receiving a GO from MCC, the crew continue 

their walking translation towards the PSR at A’. They continue downslope until they reach 

the rim of the crater with the PSR. Once there, they check with each other, and then 

proceed with descending the ~12° slope. 

Before they reach the PSR, the crew stops to conduct local contextual observations of the 

crater, and perform some sample acquisition. At the primary sampling area, the crew set 

down their bags and retrieve photo equipment and context/sampling markers. They both 

conduct detailed visual inspection and examination of the surroundings, recording detailed 

observations, context descriptions, and taking imagery with handheld cameras to fully 
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characterize the area. EV1 takes panoramic photos of the area, while EV2 retrieves the 

context/sampling markers. They both scout the local area, approach and access vertical 

exposures, look for good target samples, and deploy the markers near them. For each 

marker, they stop and provide a verbal description provide helmet cam video for the 

Science Team. During the area context process, the Science Team in MCC listens to the 

verbal descriptions and watches the helmet cam video. They note any marker that is near 

a sample that is worth taking. 

With the verbal descriptions and context imagery completed, the EV crew retrieve the 

handheld instruments from the carrier. Back at the vertical exposures (e.g., cliff face), they 

both proceed with operating their respective handheld instruments. They take 

measurements as high above their heads as they can reach, near chest level, and kneel 

down to take readings at the contact interface between the wall and the crater floor. When 

all instrument readings are completed, the crew stows the handheld instruments back in 

the carrier. 

Both EV crew proceed with acquiring the geological samples. They deploy sampling tools 

from their equipment bags, assembling the ones their going to use first. For the targets 

identified and documented (context description and imagery), they collect various sample 

types. The crew collect regolith samples – including sampling via a scoop, rake, core tube, 

surface contact tool, and trench – and rock samples – including float, chip, and core drill.

While there, they deploy an environmental monitoring station for long duration study of the 

crater region. They deploy the instrument and get confirmation from MCC that it’s 

operating.

They also plan their excursion into the PSR in order to minimize their exposure to the 

shadowed region. Before proceeding, both crew check the timeline and their consumables 

and trends, and ensure that they have enough for continuing the planned mission.

7.2.14.2.4 Science in PSR

With their plan detailed out and reviewed, the crew progress into the shadowed area. At 

this point , they are nearly 2 km away from the lander. This starts their 2 hour thermal 

clock for being in a shadow, and requires the use of helmet lights and possibly ancillary 

lights in order to see their path. As they near their target spot, the slopes increase to nearly 

20°. 

At their stopping point in the PSR, they conduct contextual observations and take imagery 

as best as possible. If required per the plan, the crew operate their handheld instruments, 

accessing as much of any vertical exposure as possible. This involves reaching above 

their head, near chest level, and at the interface of the wall and surface.

Being as efficient as possible with time, the crew set out to acquire a core sample that 

contains volatiles. They drill the drive tube into the ground, extract it, cap the segment in 

order to keep the stratification, and stow it in a vacuum-sealed container. They also 
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acquire float and regolith samples as directed by the MCC Science Team, stowing them 

in the appropriate bags. 

With the container stowed, the crew make their way back upslope out of the PSR. Exiting 

the shadowed area ends the thermal clock. They then proceed ascending out of the 

craters, walking when able and scrambling when needed in order to get out. 

7.2.14.2.5 Traverse back to HLS

The crew make their way back towards the lander, following their tracks as best as 

possible. This 2 km trek is upslope, with slopes hitting near 20° but typically closer to 10°. 

Along the way, they continue to make contextual observations and taking imagery. They 

also stop to take samples of opportunity, based on their own training or something the 

Science Team caught in a helmet camera view. 

Back at the lander, the crew stow their sample collection bags, which hold all of the 

individual sample bags, into a temporary return bag. This bag will be brought inside the 

lander upon ingress. 

7.2.14.2.6 Engineering Construction Task

With their science samples temporarily stowed, the crew conduct a construction task 

before ingress. They retrieve equipment for a communication antenna from a storage 

compartment on the lander. They also retrieve their construction tools from the external 

toolboxes. 

The crew work together to carry all of the equipment and tools far enough away from the 

lander to be out of the ascent engine blast zone. There, they put together and deploy the 

antenna. They run cables to the power source, and give MCC the GO to activate the 

antenna. 

7.2.14.2.7 Cleanup & Ingress

With their science tasks and engineering tasks complete, the crew begin cleaning up. 

They stow all of the tools and equipment that they had retrieved from the external 

toolboxes. 

The crew initiate the dust mitigation procedures, using the kit they deployed after egress. 

The remove the bulk of the dust from their suits and the temporary return bags. 

For ingress to the lander, the crew essentially reverse the actions they performed during 

egress. EV2 ingresses the hatch with the last return bag, and EV1 follows behind. While 

EV2 stows the bags out of the way, EV1 secures the hatch.

Both crew lock themselves in their respective EDDAs, and attach their umbilicals and 

switch over to vehicle consumables. The crew follows the AIRLOCK 

DEPRESS/REPRESS CUE CARD for repress. EV1 then actuates the pressure 
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equalization valve, beginning repress. Part way through, he stops repress to verify the 

airlock is holding pressure. Once a good hatch seal is confirmed, the cabin/airlock is fully 

repressed.

7.3 CON OPS FOR EVA ON LUNAR SURFACE (ARTEMIS PHASE 2)

Artemis Phase 2 establishes longer and sustained mission to the lunar surface, include 

the following:

• Longer excursion ranges: 

o Up to ~10 km radius away from the lander in an LTV

(note that the distance will depend on EVA walk-back limitations)

o Up to ~12-15 km radius away from the lander in a single pressurized 

rover

(note that the distance will depend on EVA walk-back limitations)

o ~200+ km away from the habitat with dual pressurized rovers

• Both longer lunar daylight missions and mission extending through lunar 

night, with four (or more) crew landing on the surface

• Longer extended missions during lunar daylight (~14 Earth days)

• Sustainable long duration missions during lunar day & night (~42 Earth days 

to 6+ months)

• Exploration excursion distances from lander/habitat increased with use of 

unpressurized rovers and eventually pressurized rovers

Reference Section 3.2.2 for the architecture overview of Artemis Phase 2.

7.3.1 Sustained Mission – Short Stay

For Rover and EVA ops during a seven to fourteen-day short stay mission, the crew will 

have the capability to perform daily 8-hour EVAs in order to take advantage of the short 

period on the surface. Crewmembers will conduct the EVAs paired together to maximize 

boots on the ground time and for safety. However, there may be a rest day after three or 

four days of EVA, depending on the duration of the EVAs. The crew will utilize a 

conventional airlock or dual chamber rear-entry airlock (e.g., suitlock) for egress and for 

suit repair/maintenance.

During Artemis V, with an LTV available, the crew will stay within approximately a 10 km 

contingency walk back radius. The EVA crew may utilize navigation systems on the rover, 

however, will always need to be able to return to the lander safely on their own in case of 

a failure of the rover. 

7.3.2 Sustained Missions – Extended Stay

For Rover and EVA ops during a 42-day extended stay (campaign) mission, operations 

will differ between lunar day and lunar night. During lunar day, the two rovers stay in close 

proximity, operating as a pair in case of an emergency. Rovers will notionally travel at 
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max speed of 10 kph with crew inside and 1.5 kph when operated remotely without crew 

inside. The rovers will notionally never travel farther than 100 km from the ascent vehicle 

in case of an emergency abort from the surface situation. During lunar day, EVAs will be 

conducted three to four days per week and be two to eight hours in duration (hour for 

egress/ingress and 1.5 - 7.5 hours of tasks) with one to two per day. EVAs may extend 

an additional hour for emergency and off-nominal situations. Nominally two crew will be 

out on an excursion from the rover, however there is a potential for more or less to go out 

EVA.

For days involving two EVA excursions per day, the EVAs will be treated as if a single EVA 

is conducted in two parts, and therefore the suit consumables won’t be required to be 

recharged between excursions (though some will be recharged simply by plugging in the 

umbilical, such as O2). The total amount of planned EVA PET time within a crew wake 

period will stay within the constraints of a single 8-hour EVA. The time between the two 

EVAs will be considered a ‘break’ in EVA more than a second EVA. In other words, the 

crew will be able to take an 8-hour EVA and conduct it in two parts, with the sum of the 

parts not exceeding what would have been done for a single EVA.

Enabling this EVA frequency may involve logistics to replace suit components or even 

entire suits. Some consumable items, such as gloves and boots, will need to be replaced 

more often than long life components (such as the xPLSS).

For Rover and EVA ops during an extended stay mission in lunar night, there will be limited 

traverse operations. Crew will primarily stay in rovers and minimize energy consumption, 

using the time during lunar night to analyze the samples they collected, perform IVA 

experiments, and complete maintenance and repairs on the rovers. The primary 

challenges for EVA at lunar night will be thermal, lighting, and navigation. EVAs operations 

during lunar night (eclipse) will be similar to EVA operations in shadowed regions, 

including Permanently Shadowed Regions (PSR). The xEVA System will be able to 

function in the PSRs and therefore should be able to operate during lunar night, with 

certain constraints (such as time). .

For all rover-based EVA operations on extended stay missions (42 days), the rover pairs 

will work together. Both crew in one rover will conduct the EVA together, while the other 

rover is nearby. The crew in the non-EVA rover will act as the local IV to help direct the 

EVA operations, and will conduct any rover duties and maintenance, along with performing 

experiments. Crew will don suits in the airlock instead of the cabin in order to mitigate 

lunar dust exposure into the habitable volume. Alternately, one crewmember from each 

rover may conduct the EVA together, still enabling two crewmembers to act as buddies, 

although this requires the rovers to be parked next to each other and requires two separate 

and simultaneous airlock operations. The surface teams will have the capability to conduct 

EVA with all four crewmembers simultaneously, if needed. Aside from egress/ingress of 

the ascent stage, all EVAs will be conducted out of a conjoined dual chamber airlock (or 

functional equivalent) in order to reduce exposure of the crew cabin to dust and provide 

space for suit maintenance.
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Lunar surface EVAs will also require a support system for the IV crewmember helping 

direct the EVA.

7.3.3 Design Reference EVA for Artemis Phase 2

This subsection details an example “design reference EVA” narrative that contains a 

variety of potential example tasks and concepts for the sustained lunar mission phase. It 

is an example of a snapshot of one particular mission scenario. The landing zone for this 

reference is presumed to be near the South Pole Aitken Basin, close to an area known as 

Connecting Ridge. While this reference EVA is likely oversubscribed for any single EVA, 

it will give the reader an idea of what will need to be performed on the lunar surface via 

EVA. This reference EVA calls out some “simulated” specific example tasks, though not 

necessarily actual tasks since those haven’t been developed or planned yet, however 

these are not the full list of things that will be done over the course of missions to the moon. 

This subsection does not timeline an actual flight EVA, but only provides a potential 

example of tasks performed by EVA on the lunar surface, with the goal to help the 

designers understand the various movements and interfaces for the xEVA suit. This 

example will be updated in future revisions as the lunar surface mission architecture 

develops and evolves. This design reference EVA also incorporates a pressurized rover, 

which includes a suitlock for egress. As this reference EVA is notional and the suitlock 

(and suitport) concept have not been fully matured, a more conventional airlock or cabin 

depress may end up being used. 

7.3.3.1 Post Depress and Egress

Once prebreathe and depress are complete, the two EVA crewmembers perform post 

depress actions. They will switch from vehicle to battery power, officially starting the PET 

clock. They release themselves from the suitlock port (if included in pressurized rover 

design) and open the EV hatch. The EV crew detaches their umbilicals and stows them 

in the suitlock on dummy connectors that protect the interface from dust and debris. Before 

egressing, the crew will conduct a final check of tools and equipment attached to their suit 

on harnesses and in bags they’ll hand carry.

The crew step through the 40x60 inch hatch and attach to the fall protection system to 

their suits. Once safely configured, EV1 descends the ladder to the surface. With boots 

firmly on the ground, EV1 detaches from the fall protection system. EV2 begins lowering 

tools and equipment bags down to EV1, who places them on the surface. Once all 

equipment has been transferred to the surface, EV2 descends the ladder and detaches 

from the fall protection system.

7.3.3.2 Setup

The EV crew transports smaller tools and equipment to the worksite either directly 

attached to their suits or with a harness/carrying system. Larger tools and storage boxes 

are transported in a wheeled cart (or functional equivalent) and a pressurized rover. Once 

both EV crew are on the surface, they unstow the modular equipment transport system 
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(cart) for short traverses to nearby worksites, and configure the pressurized rover for the 

longer traverses.

EV1 displays the equipment checklist on his HUD and checks through each item as both 

crew load the cart with maintenance equipment and stow the science tools and payloads 

on the rover. They load the pressurized rover with science equipment, including sampling 

tools, handheld instruments, and instrument payloads.

To minimize their risk posture, the crew start the EVA tasks at the location furthest from 

the lander and work their way back towards their safe haven. As such, they mount up on 

the rover and sit in their seats for their first science task, planning on ending the EVA with 

the maintenance task that’s within close proximity to the lander.

7.3.3.3 Science Task - Crater

With the pressurized rover loaded with the needed science equipment, the EV crew begin 

driving to a crater in their first Region of Interest (ROI) of the day. This crater is 12 km 

from the lander, which extends the Apollo 17 record of 7.6 km for distance traveled away 

from a lunar lander.

At the rim of the crater, the EV crew egress from the rover and begin initial context 

observations. This includes visual inspection of the crater and surrounding areas, 

complete with imagery and verbal descriptions. EV1 stands on the rim and locates the 

specific zone inside the crater from which sampling will take place. The Science Team 

views EV1’s helmet cam video and makes a real-time confirmation of the target area. 

Using the suit display (e.g., augmented reality capability of the suit projected through the 

HUD) and the navigation data, the Science Team indicates the target area (e.g., draws an 

augmented cue circle around the target area) and suggests a path based on precursor 

information (e.g., Lunar Reconnaissance Orbiter (LRO) data).

While EV1 is conducting the visual inspection and receiving instructions from the Science 

Team in MCC, EV2 offloads the rover with the tools and instruments that will be needed 

on the floor of the crater. EV2 also deploys and sets up the belaying equipment that will 

be used to help them descend into the crater.

The EV crew both hook into the belaying system based on the rover, which will provide 

them assistance as they climb down into the crater by providing constant tension to help 

hold them upright on the incline. They both grab bags holding the science equipment, 

then begin their descent. Once on flatter ground, they detach from the belay system and 

continue walking towards their sampling area.

At the primary sampling area, the crew set down their bags and retrieve photo equipment 

and context/sampling markers. They both conduct detailed visual inspection and 

examination of the surroundings, recording detailed observations, context descriptions, 

and taking imagery with handheld cameras to fully characterize the area. EV1 takes 

panoramic photos of the area, while EV2 retrieves the context/sampling markers. They 
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both scout the local area, approach and access vertical exposures, look for good target 

samples, and deploy the markers near them. For each marker, they stop and provide a 

verbal description provide helmet cam video for the Science Team.

During the area context process, the Science Team in MCC listens to the verbal 

descriptions and watches the helmet cam video. They note any marker that is near a 

sample that is worth taking. They screen capture images, annotate them, and then 

transmit them to the crew. The EV crew access those images on their HUD and use them 

to confirm what sample to take. If needed for clarification, the EV crew approaches the 

sampling site, and the Science Team uses the suit display to indicate a target location 

(e.g., draws augmented cues on the EV crew’s HUDs) and guides them to a specific 

sample of interest.

With the verbal descriptions and context imagery completed, the EV crew retrieve the 

handheld instruments from the bags they carried down into the crater. EV1 kneels down 

at EV1’s bag and pulls out the contact spectrometer, while EV2 kneels down next to EV2’s 

bag and gets out an imaging spectrometer. Back at the vertical exposures (e.g., cliff face), 

they both proceed with operating their respective handheld instruments. They take 

measurements as high above their heads as they can reach, near chest level, and kneel 

down to take readings at the contact interface between the wall and the crater floor. When 

all instrument readings are completed, the crew stows the handheld instruments back in 

the bags.

Both EV crew proceed with acquiring the geological samples. They deploy sampling tools 

from their equipment bags, assembling the ones required for the first samples. For the 

targets identified and documented (context description and imagery), they collect various 

sample types.

EV1 focuses on collecting the regolith samples. These include sampling via a scoop, rake, 

core tube, surface contact tool, and trench. All samples are documented, and postcollection imagery is acquired at each sampling site.

• Surface contact: EV1 begins with the surface contact tool, stamping the 

ground from a standing position before disturbing the area with other sample 

types. EV1 closes the door on the end effector, detaches it, and then stows it 

in the sample container bag.

• Scoop: EV1 attaches the scoop end effector to the tool handle, crouches 

down to collect a sample of regolith, and then stows it in a sealable bag to 

keep it pristine. EV1 weighs the sample, holds the bag up to the helmet 

camera for recording by the Science Team, and then stows that bag in the 

sample container bag.

• Rake: EV1 switches the end effector on the tool handle for the rake and 

proceeds to scrape the ground to collect small rocks, which get put into a 

sealable container and stowed in the larger sample bag after being weighed.
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• Trenching: EV1 then uses the trenching tool to expose a lower level of 

regolith, scraping from a standing position and kneeling when necessary. 

EV1 records context descriptions of the trench, takes imagery, and holds 

stationary to allow the Science Team in MCC to get a good view of the trench. 

The Science Team uses the suit display to point EV1 towards a sample (e.g., 

augmented cues displayed on the HUD), which EV1 then acquires with the 

appropriate tool.

• Core tube: EV1 completes the sampling suite at this worksite with a core tube 

sample. EV1 retrieves the core tube, manually drives it into the ground from 

a standing position, kneels and pulls the tube out, caps the end, weighs the 

tube with the sample inside, holds the tube up in the field of view of EV1’s 

helmet camera, and then stows the tube in the sample container bag.

EVA 2 focuses on the rock samples. These include float, chip, and core drill. All samples 

are documented, and post-collection imagery is acquired at each sampling site.

• Float: EV2 picks out a couple of float (loose rock) samples that appear as if 

they would satisfy the science requirements. EV2 holds the helmet camera 

steady for the Science Team to review the selection. The Science Team 

picks the final rock and draws a virtual cue in EV2’s field of view to circle the 

rock they want collected. From a standing position, EV2 uses the float end 

effector attached to the end of the tool handle to collect the float sample. EV2 

holds the sample up to the helmet camera, detaches the end effector, weighs 

the end effector with sample inside, and then seals it inside the sample 

collection bag.

• Chip: EV2 then retrieves the hammer drill and chip end effector, assembling 

the two. The Science Team projects cues to EV2’s informatics HUD, 

directing EV2 towards one of the outcrops that was measured with the 

spectrometer. EV2 proceeds to the desired rock, kneels down, presses the 

chisel end of the tool to the surface of the rock, and actuates the hammer drill. 

The rock chip breaks off and is contained within the end effector. EV2 takes 

the hammer drill back to the equipment bags, detaches the end effector, temp 

stows the hammer drill, weighs the end effector, holds it up to the helmet 

cam, and then stows the end effector and sample in the appropriate slot 

within the larger sample bag. For good measure, EV2 walks back to another 

outcrop, deploys the manual hammer from EV2’s tool harness, breaks off 

another rock chip, collects it and puts it in a sealable bag, weighs the bag, 

holds it up to her helmet cam while reading off the bag number, and then 

stows that bag in the sample bag.

• Core drill: EV2 retrieves the hammer drill and a core bit. EV2 assembles the 

two together, then walks back to the outcrop where she took instrument 

measurements. Using a combination of helmet camera video, pointing, and 

augmented cues from the Science Team, EV2 determines the best location 

for a core sample. EV2 kneels down, presses the bit against the rock, leans 

into it to provide reaction force, and then proceeds using both hands to 
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hammer drill the core bit into the rock. After reaching the desired depth, EV2 

extracts the tool. EV2 deploys a core sample container tube from her tool 

harness, activates the break off feature of the bit, and slides the core sample 

into the tube. EV2 carries the sample and drill bag to the equipment bags. 

EV2 kneels down at the bags, stows the sample in the appropriate slot, 

disassembles the core bit from the hammer drill, and then stows both of them 

in the equipment bag.

With the sampling complete, the EV crew collect their equipment and sample bags, and 

proceed to ascend the rocky slope out of the crater. They walk when able, and scramble 

when they need to in order to get out. Back at the rim, then stow their bags on the rover.

They then retrieve the surface instrument payload from the rover and work together to 

carry it down to the floor of the crater. There they deploy the instrument and get 

confirmation from MCC that it’s operating.

With all of the science tasks at this location complete, they scramble out of the crater again, 

and lock into the rover. Before leaving the area, both crew check the timeline and their 

consumables and trends, and ensure that they have enough for continuing the planned 

mission.

7.3.3.4 Science Task - Lava Tube

The crew drive the rover to ROI at lava tube, which is closer to the lander. Navigation 

cues projected on their HUDs help them get to the right location.

At the edge of the lava tube, the EV crew dismount from the rover and begin initial context 

observations. As at the crater, this includes visual inspection of the lava tube and 

surrounding areas, complete with imagery and verbal descriptions. The Science Team 

views EV1’s helmet cam video and makes a real-time confirmation of the target area. 

Using the suit-mounted display (e.g., augmented reality cues projected via a HUD), the 

Science Team indicates a suggested entrance point.

While EV1 is conducting the visual inspection and receiving instructions from the Science 

Team in MCC, EV2 offloads the rover with the tools, instruments, and lights that will be 

needed inside the tube. EV2 also deploys and sets up the belaying equipment that will be 

used to help them descend into the crater.

The EV crew both attach the rappelling equipment and descend the steep slope into lava 

tube. Once on relatively flat terrain, they proceed with their penetration of the tube. Before 

entering, they set up a small communication relay to ensure that they don’t lose 

communication with their rover or MCC. They traverse as far as their comfortable, likely 

staying within visual sight of the entrance point.

The crew work together to deploy and set up freestanding illumination devices. These 

supplement the helmet lights and help illuminate the general area.
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EV2 conducts observations and characterizes the area, recording context descriptions and 

imagery, while EV1 retrieves the handheld instruments from the equipment bags.

Both crew operate their handheld instruments, taking measurements throughout the tube. 

This involves accessing above their head, near chest level, and on the floor of the tube.

With instrument readings completed, both crew set about acquiring geology samples. For 

the lava tube, they focus on float, surface, and a shallow core. As they did in the crater, 

they document sample locations, collect the samples, seal them in containers, weigh them, 

show them to their helmet cameras, and then stow the samples in the larger sample bag.

Before departing, the crew work together to deploy the seismic instrument payload. They 

kneel down next to it, open it up, deploy arrays, and then activate the instrument.

With the science tasks complete, the crew clean up all of their equipment and lights, and 

traverse to the tub entrance. They then ascend the slope out of lava tube with assistance 

from a remotely operated winch on the unpressurized rover.

Back at the rover, they stow samples, instruments, and bags on pressurized rover, and 

lock in.

7.3.3.5 Science Task - PSR

The crew drive the rover to ROI near the targeted PSR, which is on the way towards the 

lander, getting them closer to their safe haven. Navigation cues projected on their HUDs 

help them get to the right location.

At the edge of the permanently shadowed region, the EV crew dismount from the rover 

and begin initial context observations. As at the crater and lava tube, this includes visual 

inspection of the PSR and surrounding areas, complete with imagery and verbal 

descriptions. The Science Team views EV1’s helmet cam video and makes a real-time 

confirmation of the target area. Using the suit display (e.g., augmented reality cues 

projected via a HUD), the Science Team indicates a suggested shadowed area from which 

the crew should acquire a sample.

While EV1 is conducting the visual inspection and receiving instructions from the Science 

Team in MCC, EV2 offloads the rover with the tools and instruments that will be needed. 

These include the instrument bags and the wheeled deep core drill.

When ready, the EV crew will preconfigure their suit thermal setting and begin walking into 

the PSR, approaching a vertical exposure. EV1 pulls the deep core drill along, while EV2 

manages the instrument bags. Due to the colder temperatures, the crew work quickly but 

safely.
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Both crew operate their handheld instruments, taking accessing as much of the vertical 

exposure as possible. This involves reaching above their head, near chest level, and at 

the interface of the wall and surface.

The crew work together to document the sampling location, set up the deep core drill in 

order to acquire volatiles 2-3 meters below the surface on the edge of the PSR. EV1 

kneels down to set the outriggers and feet, while EV2 deploys the drill head to its maximum 

height over her head. Once the drill is configured, they activate the drill process.

While the deep core drill penetrates the ground, the crew work together to deploy the ISRU 

and environmental instrument payloads.

When the drilling has reached its target depth, the crew retract the core bit. They break 

apart the drill stem, compressing and capping each segment in order to keep the 

stratification. The segments are then put into the insulated and sealed volatiles container. 

With the samples safely secured, the crew break down and stow the drill, and document 

the drilling location after sample acquisition.

The EV crew gather their bags and samples and walk out of the colder PSR area. They 

stow the samples and instruments on unpressurized rover.

With all of the science tasks complete, the crew navigate back to lander on their rover.

7.3.3.6 Maintenance Tasks

Back at the lander area, the EV crew park the rover. The unload the rover, stowing the 

equipment bags with non-powered science tools back in the external toolboxes, the 

instrument bag near the ladder, and the samples near the ladder. They stow the deep core 

drill on the decent element, ensuring that it’s receiving recharge power. The crew 

configures the drill with the appropriate socket and load the tool bag in the cart.

As an example to a potential maintenance task and task details, EV1 and EV2 walk to the 

maintenance worksite, a small pump module and remote power control module on a 

surface communication & power station, with EV2 pulling the cart. The Ground IV in MCC 

powers down the station, confirming all inhibits are in place, which EV1 verifies via the 

overlay on the informatics display.

At the worksite, EV1 begins removing and replacing the pump module.

• Demating power connectors: EV1 begins demating the power cables for the 

pump module. EV1 kneels down to reach the low power connectors. For 

each one, he cleans the exterior, removes the MLI sleeve, demates the 

connector, checks the pins and for FOD, mates the connector to a dummy 

location, then recovers the connector. When done with the lower power 

connectors, EV1 stands and begins the process of demating the connections 

that are overhead. EV1 uses pliers (or pin straightener) from the suit-
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mounted equipment carrying system (harness) to fix any bent pins on the 

connectors.

• Demating fluid connectors: EV1 demates the fluid connectors linking the 

pump module to the communication station’s radiator. The process is similar 

to the electrical connectors, working both on the kneeling level and overhead, 

with the female connectors ending up safely covered on male dummy 

connectors.

• Removing fasteners: EV1 retrieves the power tool (hammer drill) and begins 

backing out the fasteners on the pump module. When the fasteners are fully 

released, EV1 stows the power tool.

• Removing/installing module: EV1 removes the failed pump module, carries it

to the METS, and temp stows it. He then removes the spare module from its 

packaging, takes it to the communication station, and soft docks it in place.

• Installing fasteners: EV1 uses the power tool to drive all of the bolts to full 

engagement, verifying torque and turns.

• Mating fluid connectors: EV1 reverses the demating process, moving each 

fluid connector from the male dummy to the new pump module.

• Mating power connectors: EV1 reversed the demating process, moving each 

power connector from the dummy panel to the new pump module.

• With the R&R complete, EV1 notifies MCC and powers up the system.

• While EV1 works on the pump module, EV2 begins connecting the power 

cable from the communication & power station and the lander. This will 

provide extra power to the lander.

• EV2 begins with digging a trench between the lander and the station in order 

to bury the power cable. She uses a shovel/trenching tool from the lander 

external tool box. EV2 digs the trench deep enough to cover the cable and 

have the rover drive over it without damaging the cable.

• EV2 retrieves the power cable and carries it to the interface panel on the 

lander. She dusts off the lid on the panel with a brush from her harness, then 

opens it up. She inspects the lander side connector, and mates it to the 

panel.

• With the lander end secured, EV2 then begins walking towards the 

communication & power station, laying the power cable in the trench.

• At the power station, EV2 cleans off the interface with her brush, inspects the 

connector and jack, and then mates the cable to the station panel.

• EV2 cleans the solar arrays with the brush from her suit-mounted equipment 

carrying system. 

• EV2 contacts the Ground IV in MCC (or IV in Gateway) to remove inhibits and 

verify that the lander is receiving power from the station.

• EV2 walks along the trench, filling it in and covering the power cable with her 

trenching tool. 
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7.3.3.7 Cleanup

When the pump module R&R and power cable installation tasks are complete, the EV 

crew clean up their tools and stow them on the cart. They take the cart back to the lander. 

Tools that don’t have any electronics are stowed in the external tool boxes on the decent 

element. They secure the cart in its temporary stowage area, making sure it’s in a safe 

configuration for any abort ascent scenario.

They take the tools needing conditioning and recharge to the base of the lander ladder.

7.3.3.8 Ingress

With all objectives complete and cleanup done, the crew begin the ingress process. EV2 

attaches to fall protection and climbs ladder to the platform on the ascent element. She 

kneels down on the platform and ensures she’s stable and secure to receive bags. EV1 

begins handing bags (powered tools, instruments, and sample containers) up to EV2. 

When all of the bags are up on the platform, EV2 moves each one in the airlock.

EV1 attaches to fall protection and climbs ladder. On the platform, both crew perform dust 

mitigation tasks.

EV2 ingresses the hatch with the last bag, and EV1 follows behind. While EV2 stows the 

bags out of the way, EV1 secures the hatch.

Both crew back into the xPLSS hatches in suitlock wall, and lock themselves in place. 

They attach their umbilicals and switch over to vehicle consumables.

The crew follows the SUITLOCK DEPRESS/REPRESS CUE CARD for repress. EV1 then 

actuates the pressure equalization valve, beginning repress. Part way through, he stops 

repress to verify the airlock is holding pressure. Once a good hatch seal is confirmed, the 

suitlock is fully repressed.

Once the suitlock is equalized with the lander cabin, the crew commands the suitlock 

hatches open. They then open their xPLSS hatches and egress their suits.
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8.0 CONCEPT OF OPERATIONS FOR EVA ON MARS

One of the primary goals of the human spaceflight program is to land on and explore Mars. 

Current architecture holds that during the decade of the 2030s and beyond, NASA will 

develop and deploy the systems to land cargo and crews on Mars, sustain crews on the 

surface, and return them safely back to the Gateway, and then home to Earth.

Mars provides a unique environment for EVA operations with its partial gravity level (3/8 

that on Earth), partial atmosphere dominated by CO2, issues with dust, and both forward 

(planetary protection) and backward (crew health) contamination concerns. The distance 

between Mars and Earth also means that the communication latency between MCC and 

the crew will range between ~4 and 20 minutes. Given the current development of a xEVA

System that’s focused on the lunar surface, missions to the surface of Mars will involve a 

modified suit that is capable of operating in the higher gravity gradient and partial 

atmosphere. This Mars xEVA Suit will have different methods for thermal protection and 

scrubbing CO2 (among other modifications).

8.1 GENERAL CONSIDERATIONS FOR MARS

Once on the surface and acclimated to the gravity environment, the crew will conduct EVA 

operations in three general categories.

• Pioneering tasks to assemble the base infrastructure

• Maintenance tasks to keep the infrastructure operating

• Science tasks for geoscience and astrobiology sampling, along with 

instrumentation

With such a long signal latency and blockage, EVA operations will be directed by an IV 

crewmember in-situ on Mars, with input from the Science Team both during and between 

EVAs. The crew will also likely utilize their in-situ knowledge to plan some of the EVAs, 

with MCC concurring and putting together the detailed timelines. Many of the science 

operations tasks will likely be far from the habitat, so the EVA crew will rely on a navigation 

system to find the correct sampling area and find their way back to the habitat or rover.

During missions to the surface of Mars, there will need to be an emphasis on the 

informatics system and mission support systems. The EVA crew will utilize xEVA 

Informatics designed into their Mars xEVA Suit. These informatics will grant the EVA crew 

more autonomy with both tasks and suit monitoring. An in-helmet HUD and on-suit 

electronic display system will provide the crew access to digital data/information and 

augmented reality cues. Utilizing these systems, the EVA crew will navigate themselves 

and mark their location for MCC awareness and future reference. The xEVA Informatics 

capability will allow them to pull up procedures, schematics, and videos to assist with 

pioneering, construction, and maintenance activities. For science activities, they will be 

able to call up cue cards, pictures, and imagery that the Science Team has annotated for 

them. MCC, the Science Team, and IV will also be able to provide the EV crew with 

augmented reality cues in order to guide them through tasks.
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EVA science operations on the surface of Mars will involve different ways of 

communicating information between the EV crew and the Science Team (ST) on Earth. 

The ST will provide input to the crew both during the EVA and between EVAs. With such 

a long communication delay, the IV will be prime for directing the EVA. The ST will provide 

the IV input, and the IV will filter and pass it along to the EV crew. This input will likely be 

largely done via text and file transfer to the IV, as opposed to audio communication. The 

IV will talk to the EV crew and possibly send files to electronic displays on their suits. The 

ST may also directly provide files and text to the electronic displays.

FIGURE 8.1-1: EVALUATING SCIENCE TEAM INTERACTION WITH MARS EVA DURING 

NEEMO 20

The crew will be very well trained, such that they can operate mostly autonomously to get 

science samples. However, science ops can be constructed such that a Science Team 

on Earth can provide relevant, timely feedback to influence the plan and sampling tasks 

during an EVA, provided that the EVA is timelined such as to allow the transmission of 

data back and forth (i.e., having multiple sites to move between and having some tasks 

that don’t require MCC input).

The Science Team will be a focal point of the primary MCC team and be fully integrated 

with all other operations taking place.

An EVA mission support system will be utilized due to the amount of information and 

tasking the IV crewmember must contend with (essentially performs the roles of IV, Flight 

Director, partial EVA Officer, and partial BME).

Timelines and tasks will be dependent on precursor data and the ability of the crew to 

collect new data. Interactions with the MCC ST will need to be planned carefully in order 

to allow feedback from the MCC ST.
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Robotic assets will likely assist EVA crewmembers, including the following:

• Area reconnaissance

• IV and ST situational awareness

• EVA tool management

• Sample stowage and transportation

The robotic vehicle will be driven by a 2nd IV crewmember in the habitat for dynamic 

operations and will be controlled by the ST in MCC for things such as camera views and 

photographing an area.

Due to the expense of launching hardware to Mars, and the possibility that more things 

will break than expected or certain things weren’t anticipated ahead of time, a ThreeDimensional (3D) printer will be useful for things such as:

• Designing and printing broken hardware, such as the IGSS end effectors

• Printing missing parts

• Rapid delivery of parts whose need hadn’t been anticipated pre-mission

With long duration missions at destinations with a long communication latency, the crew 

will likely be more involved in planning their EVAs than as is currently done on ISS. Multiday EVA planning will incorporate crew input, ground based planners, and automated 

planning tools. Crew autonomy and planning techniques on Mars should be informed by 

lessons learned from prior Lunar operations.

FIGURE 8.1-2: EVALUATING MULTI-DAY CREW SELF-SCHEDULING OF EVAS

8.2 CON OPS FOR EVA ON MARS

8.2.1 Road-to EVA (Mars)

The content for this section is forward work. [TBD-9.2.1-011]

8.2.2 Prep & Prebreathe for EVA (Mars)

The content for this section is forward work. [TBD-9.2.2-012]
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8.2.3 EVA (Mars)

EVAs on the surface of Mars will involve pioneering (construction and maintenance) and 

science tasks.

8.2.3.1 Pioneering Tasks

EVA will conduct pioneering tasks to assemble the base infrastructure. The number and 

types of tasks involved are still in work.

8.2.3.2 Science Tasks

The primary goal for a mission to Mars is the collection of various science samples, 

including both geoscience and astrobiology. These samples, along with verbal 

descriptions and imagery, will characterize areas on Mars. Specialized EVA tools will 

allow for the collection and storage of pristine samples.

The EVA Integrated Geology Sampling System will house tools for collecting float, surface, 

soil, rock chip, and core samples. It will allow for a strict contamination protocol that is 

designed for sample management, ease of operation, and consistency across sampling 

activities. The IGSS “briefcase” houses various End Effectors (float, soil, surface, chip, 

and core) with two different types of drivers to secure samples manually or with a powered 

device.

Three types of samples will be taken with manual tools, including surface samples, float 

samples, and soil samples. The surface sample captures the very top layer of dust on the 

surface and will likely be the first one taken before it is disturbed. During Apollo, this type 

of tool used a metallic mesh, but missions to Mars may make use of more advanced 

materials, such as aerogels. One of the primary sampling tools will be the float tool. This 

will enable the crew to capture whole small rocks and store them in end effectors to prevent 

contamination. Another tool, that may very well resemble the float tool, is one to collect 

soil samples. It will enable the crew to scoop up a small quantity of the regolith. 

FIGURE 8.2.3.2-1: EVALUATING SCIENCE SAMPLE ACQUISITION ON MARS DURING 

NEEMO 20
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Two different types of samples will likely be taken with powered tools: a rock chip sample 

and a core sample. To aid in chipping off a piece of a large rock for sample return, a power 

tool with a rock chip end effector may be used to chisel off and then contain a small piece 

of the rock. A power tool and core tube may aid in taking a small core sample at the 

location where the EVA crew are walking.

Concepts such as the IGSS may prove feasible for EVA collection of geology and 

astrobiology samples. It provides a viable method for minimizing sample contamination, 

though its size and mass are rather large compared to the actual samples obtained. 

Further work should be done on methods or modifications to keep the EV crew from 

contaminating areas as they arrive to take samples.

A number of handheld and deployable science instruments will also be utilized on a 

mission to Mars. The handheld tools will enable the EVA crew to conduct scientific 

measurements on samples that they collect to provide initial data and will be used to take 

measurements on samples that won’t be collected. 

While surveying an area and making contextual comments, the EVA crew will utilize 

temporary sample markers to both record data in imagery and for communicating sample 

data with IV and ST/MCC.

Since the goal of a planetary science Exploration mission is to characterize an area, not 

simply pick up a specific rock, a navigation system needs to guide the crew close to a 

landmark that indicates an area of interest rather than just locate a specific sample. 

Electronic navigation will be critical in areas where the terrain looks similar, especially 

when marking new locations and returning to a site. Early missions will likely utilize a 

relative navigation system, such as radar. This system, when coupled with a heads-up 

display, will allow EVA crew to navigate themselves to the desired regions.

FIGURE 8.2.3.2-2: EVALUATING SAMPLE MARKERS NAVIGATION METHODS TO 

IDENTIFY ZONES

8.2.4 Post EVA (Mars)

The content for this section is forward work. [TBD-9.2.4-013]
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9.0 CONTINGENCIES & CREW RESCUE

All spaceflight missions entail some risk, and that risk increases when the crew leave the 

relatively safe confines of their vehicle and venture out EVA. The EVA crew and system 

must be ready and capable of handling various contingency scenarios which include, but 

are not limited to an incapacitated crewmember, DCS, loss of communication, loss of 

transportation, and contamination.

9.1 SELF-RESCUE

The xEVA spacesuit will incorporate a secondary life support system that can sustain a 

leak of a specified size (the exact size is still in work). This system will provide an EV 

crewmember with the capability to reach a safe haven (airlock) within a defined minimum 

amount of time.

9.1.1 Microgravity Self-Rescue

In the event of a suit leak during a microgravity EVA, the crewmember will terminate or 

abort the EVA, and translate back to the airlock. At the airlock, the EV crew will perform 

either a nominal, expedited, or emergency repress based on the severity of the situation.

9.1.2 Lunar Surface Self-Rescue and Rover Rescue

For lunar surface operations, the EVA crew is expected to stay within a range that allows 

them to reach a safe haven in the event of a contingency. The EVA suits will provide a 

minimal capacity of eight hours’ worth of primary consumables, plus one hour of 

contingency consumables. The additional hour allows the EVA crewmember to be 

approximately within an hour’s walk from their safe haven (rover). The calculation of this 

distance could be further augmented with implementation of smart traverse planning tools.

For short stay sortie missions, rover-based excursions will stay within less than an 8-hour 

walk back to the lander [TBR-EVA-EXP-0042-001]. In the event of a rover failure, the crew 

would prepare, and don fully charged suits. This gives them the capacity to walk for up to 

8 hours on primary consumables.

For extended stay campaign missions, a second rover will stay within an 8-hour drive of 

the EV crew to maintain rescue capability [TBR-EVA-EXP-0042-002]. If the EV crew 

experiences a suit emergency, they will return to their primary rover. If the EV crew’s 

primary rover suffers a failure, the EV crew will utilize rover consumables until the rescuing 

rover arrives.

9.2 INCAPACITATED CREWMEMBER RESCUE

Each EVA crewmember will be capable of and responsible for rescuing the other in the 

event that one becomes incapacitated for any reason. The xEVA Suit will contain a 

secondary oxygen tank that will allow for an hour of emergency gas.
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9.2.1 Microgravity EVA Rescue

If a crewmember becomes incapacitated during a microgravity EVA, the other EV 

crewmember will initiate and perform a rescue. The rescuing crewmember translates 

along the surface of the vehicle to the location of the incapacitated crewmember (ICM), 

and verifies the incapacitated crewmember is securely tethered to the vehicle. The 

rescuing crewmember secures any equipment not necessary for survival or that might 

interfere with the ability to translate to the airlock, and then tethers the incapacitated 

crewmember to himself/herself. Once the crew are tethered together, the rescuer 

translates to the airlock towing the ICM, and once there tethers and inserts the affected 

crewmember into the airlock. The rescuer then ingresses the airlock, releases external 

safety tethers, and closes and locks the hatch. Umbilicals may be mated as the specific 

emergency and timing permits. Once the hatch is closed, the rescuer initiates an 

emergency airlock repress.

The time between identification of the incapacitated crewmember and connection to the 

umbilical and/or repressurization of the airlock shall not exceed 30 minutes. The airlock 

can be re-pressurized in an expedited manner as required by the situation (which 

bypasses the two-minute airlock leak check) or perform an emergency repress (which can 

repress in ~90 seconds). The affected crewmember is then removed from the airlock first 

by the IV crew who will perform expedited suit doffing and provide any required medical 

assistance.

9.2.2 Partial-Gravity Surface Rescue

Future planetary surface missions will factor in the complexity associated with the 

possibility of having an EVA crewmember become incapacitated in a partial-gravity 

environment, where it will not be as easy to maneuver that crewmember back to an airlock. 

Some type of rescue assist device will be developed that can interface to the EVA suit to 

enable a rescue. The systems and methods for the rescue of an incapacitated 

crewmember during surface operations must consider that there may be times where only 

one crewmember is available to perform the rescue. Current microgravity operations 

protect for one crewmember (of an EVA pair) to save another. However, surface 

operations may also reserve the capability for IV crewmembers (not currently out on EVA) 

to perform rescue operations of the primary EVA crew. The rescuer will need to be capable 

of getting the ICM into a safe haven (rover or habitat) within 60 minutes in an average 

thermally neutral environment.

With two crewmembers out EVA away from the sanctuary of the habitat or pressurized 

rover, the EV crew will need hardware and techniques for rescuing each other in the event 

of a catastrophic incident. On the lunar surface, these techniques will differ from 

microgravity, where the incapacitated crewmember is usually towed behind the rescuer. 

This is also a driver for a winch to be available on surface elements like rovers and airlocks. 

The gravity field and terrain on the moon will require specialized hardware and suit 

interfaces in order to perform a successful rescue with a single crewmember. The EVA 

System will enable rescue of an incapacitated crewmember and get him/her back to a 
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pressurized safe haven, and the suit will have interfaces for rescue equipment and points 

to lift the suit. In addition to getting to a pressurized vehicle, the rescue system will need 

to enable getting the incapacitated crewmember inside.

Any surface rescue entails multiple phases, including stabilization, loading onto transport 

equipment, transport to a safe haven, and ingress to a habitable volume. Methods and 

equipment for stabilization of the incapacitated crewmember depend on the reason for 

incapacitation. Suit malfunctions or ruptures may result in decompression injuries/illness 

that could entail the need for increased suit pressure while still out EVA, and 

musculoskeletal injuries may require limb stabilization to prevent worsening the injury. 

Once stabilization is established, the incapacitated crewmember is loaded onto a transport 

mechanism. Depending on the mission and Artemis phase, transport mechanisms (such 

as a deployable litter) are retrieved from a nearby rover or deployed from accompanying 

storage, and brought to the crewmember. Hard points and soft-goods handles available 

on the exterior of the suit provide attachment and aids for the rescuer crewmember to 

move and position the incapacitated crewmember on the litter. Once in the litter, straps 

secure the crewmember in place for transport. Transport entails dragging or rolling (on 

attached wheels) the deployable litter by the rescuer crewmember to the closest habitable 

volume. Once at the habitable volume, the incapacitated crewmember ingresses the 

airlock. Ingress of the incapacitated crewmember is assisted by haul/winch systems 

designed to lift and translate the crewmember into the habitable volume, and then onto a 

donning stand or rear-entry airlock interface. At any time during the stabilization, transport, 

and ingress, the rescuer crewmember may obtain, control, and monitor suit and life 

support parameters for the incapacitated crewmember via DCU displays.

9.3 EMERGENCY RECOMPRESSION

Decompression sickness/illness is a potential hazard during EVA operations due to 

changes in the pressure environment and operating the suit at relatively low pressures 

(~4.3 psid). The response to DCS symptoms is a function of the severity (cuff class) and 

the treatment protocol varies as a function of how quickly symptoms resolve. In order to 

prevent progression of DCS symptoms or the development of DCS-induced deficits or 

permanent injury during EVA, it is necessary to provide prompt increased pressure to the 

crewmember. Upon detection of Class one or four symptoms as described in Figure 9.3-

1, the suit pressure is elevated as high as possible while EVA (~8 psid) while the 

crewmembers translate and ingress the airlock. Classification of DCS symptoms will 

determine if action is EVA TERMINATE or EVA ABORT. Once the airlock is repressed, 

the suit’s internal pressure is increased above the starting vehicular atmospheric pressure 

without compromising suit integrity. The pressure profile and duration is determined based 

on crewmember symptom resolution and monitored by the Flight Surgeon and/or Crew 

Medical Officer (CMO). The suit consumables sustain the elevated suit pressures for up 

to one hour prior to reattachment of vehicle umbilicals. The one-hour duration provides 

sufficient time for the EVA crewmember to return to the vehicle, connect the umbilical, and 

switch over to the vehicle gas supply. This capability does not assume that the 
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crewmember is on the Secondary Oxygen system. Rapid and appropriate intervention is 

required to optimize the outcome for the affected crewmembers.

FIGURE 9.3-1: ISS EMU CHECKLIST DCS CUFF CLASSES

9.4 CONTAMINATION

Scenarios exist during EVAs on spacecraft that present the possibility of crewmembers 

coming into contact with contaminants, such as ammonia from the thermal loops, thruster 

residue (i.e., hydrazine), paint flakes, or grease. If EVA crew are confirmed or even 

suspected of becoming contaminated, measures are taken prior to ingress of the airlock, 

such as brushing or wiping away the contaminant, or ’baking’ it out. The second suited 

crewmember will assist with brushing and wiping to properly clean the suit.

Contaminants such as ammonia are not easily removed with wipes or brushes, 

necessitating a ‘bake-out’ of the suit. This involves exposing the suit to the sun or putting 

it in a ‘warm’ area in order to allow the ammonia to sublimate off. Operational planning 

minimizes the impact of ammonia bake-outs by planning activities where possible 

ammonia contact can occur earlier in the timeline, allowing a bulk of the bake-out to occur 

during the remainder of the EVA. However, this does not preclude that situations occur 

where contamination occurs later in the EVA and a bake-out must occur prior to fully 

repressing the airlock.

9.5 LOSS OF COMMUNICATION

For loss of communication (LOC) between the vehicle and EV crew, the crewmembers will 

initiate the process of attempting to restore communications. The EVA crew will initially 

attempt recovery by changing position to regain line of sight with the vehicle 

communication antennas, then switch over to alternate radios (or functional equivalent) if 

unsuccessful. If communication is still not restored between the EV crew and the vehicle, 

they attempt to notify the IV crewmember of the situation via hand signals (and possibly 

signs from a cuff checklist page) at a vehicle window or external vehicle camera. After 

notifying the IV crewmember, the IV crewmember and EVA crew coordinate switching over 

to an alternate frequency. If swapping frequencies does not restore communications, the 

crewmembers are expected to terminate the EVA and return to the airlock. If 
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communication is also lost between the EVA crewmembers, the EVA crewmembers 

communicate with each other via hand signals.

On the lunar surface, there are situations where either an IV crewmember is not present 

or the EV crewmember is beyond the field of view of the IV crewmember. In this situation, 

if there is a loss of communication or signal between EVA crewmembers, the EVA 

crewmembers notify each other via hand signals and follow a checklist in the xEVA 

Informatics subsystem or via a hardcopy for restoring communication. If the 

communication loss persists, the crewmembers return to the rover (or habitat).

9.6 LOSS OF TRANSPORTATION

Crewmembers are expected to traverse away from their vehicle or habitat to conduct EVA 

operations on the lunar surface. This creates the possibility of a system failure that can 

strand the rover and crewmembers from other habitable safe havens.

During short stay sortie missions, where there is not a second crew available for recovery, 

the exploring rover won’t exceed a distance from the ascent vehicle that would preclude 

the EV crew from returning on foot using real-time navigational tools within the limiting 

consumables of the excursion crew.

During extended stay campaign missions, two rovers will be positioned within rescue 

distance of each other, and all excursions from the rovers are performed with at least two 

crewmembers. The maximum time it takes for a second rover to respond to the loss of 

another rover and bring the EV crew inside will not exceed the limiting consumables of the 

excursion crew. EVA crewmembers will stay within a one hour walk back to their rover in 

case of any contingency or emergency.

9.7 RADIATION

Crew will respond to Galactic Cosmic Rays (GCRs) and Solar Particle Events (SPEs) as 

appropriate. This includes potential uses of an Active Radiation Dosimeter (ARD).

9.8 VEHICLE CONTINGENCIES

This section is in work with the HLS Program.

9.8.1 Orion

9.8.2 Gateway

9.8.3 HLS

9.8.4 Pressurized Rover
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APPENDIX A

ACRONYMS AND ABBREVIATIONS

AND GLOSSARY OF TERMS

A1.0 ACRONYMS AND ABBREVIATIONS

AET Adjustable Equipment Tether

AOS Acquisition of Signal

APFR Articulating Portable Foot Restraint

APS Astronaut Positioning System

ARCM Asteroid Redirect Crewed Mission

ARD Active Radiation Dosimeter

ARV Asteroid Retrieval Vehicle

ASM Advancing Science of the Moon

ATSC Advanced Television Standards Committee

BME Biomedical Engineer

BMRRM Bearing Motor Roll Ring Module

BRT Body Restraint Tether

CCB Configuration Control Board

CCE Critical Contingency EVA

CM Crew Module

CMO Chief Medical Officer

CO2 Carbon Dioxide

CR Change Request

CRS Crew Restraint System

CWS Caution Warning System

DCS Decompression Sickness

DCU Display and Control Unit

DOI Descent Orbit Insertion

DRO Distant Retrograde Orbit

DSG&T Deep Space Gateway & Transport

DTE Direct to Earth

ECLSS Environmental Control and Life Support System (Subsystem)

EDDA EMU Don/Doff Assembly

EDL Entry, Descent, Landing

EMU Extravehicular Mobility Unit

EV Extravehicular

EVA Extravehicular Activity

EVR Extravehicular Robotics
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FCT Flight Control Team

FOM Figure of Merit

FSE Flight Support Equipment

GCR Galactic Cosmic Ray

GER Global Exploration Roadmap

HALO Habitation and Logistics Outpost

HD High Definition

HEO Human Exploration and Operations

HEOMD Human Exploration and Operations Mission Directorate

HLS Human Landing System

HUD Heads-Up Display

HUT Hard Upper Torso

H2O Water

ICM Incapacitated Crewmember

IDD Interface Definition Document

IGSS Integrated Geoscience Sampling System

ISECG International Space Exploration Coordination Group

ISLE In-Suit Light Exercise

ISRU In Situ Resource Utilization

ISS International Space Station

IV Intravehicular 

IVA Intravehicular Activity

JSC Johnson Space Center

LCVG Liquid Cooling Ventilation Garment

LEA Launch Entry Abort

LEAG Lunar Exploration Analysis Group

LEO Low Earth Orbit

LiDAR Light Detection and Ranging

LOC Loss of Communication

LOI Lunar Orbit Insertion

LOS Line of Sight

LRU Line Replaceable Unit

LRV Lunar Rover Vehicle

LSS Life Support Subsystem

LTV Lunar Terrain Vehicle

MCC Mission Control Center

MCC-H Mission Control Center-Houston
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MDM Multiplex/Demultiplexer

mEMU Mars Extravehicular Mobility Unit

MMOD Micro Meteoroid Orbital Debris

MPCV Multi-Purpose Crew Vehicle

MMWS Modular Mini-Workstation

NASA National Aeronautics and Space Administration

NBL Neutral Buoyancy Laboratory

NEA Near Earth Asteroid

NEEMO NASA Extreme Environment Mission Operations

NEO Near Earth Object

NHRO Near Rectilinear Halo Orbit

NRC National Research Council

O2 Oxygen

OCSS Orion Crew Survival System

OPR Office of Primary Responsibility

ORU Orbital Replacement Unit

PDI Powered Descent Initiation

PET Phased Elapsed Time

PGS Pressure Garment System

PLSS Portable Life Support Subsystem

PM Pump Module

psia pound per square inch absolute

psi pound per square inch

psid pound per square inch delta

PSR Permanently Shadowed Region

RATS Research and Technology Studies

RET Retractable Equipment Tether

RF Radio Frequency

RPCM Remote Power Control Module

R&R Remove and Replace

SA Situational Awareness

SA Spacecraft Adapter

SAT Specific Action Team

SCEM Scientific Context for the Exploration of the Moon

SEV Space Exploration Vehicle

SLS Space Launch System

SM Service Module
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SPCE Servicing, Performance, and Checkout Equipment

SPE Solar Particle Events

ST Science Team

STP Starting Point

TBD To Be Determined

TBR To Be Resolved

TLI Trans Lunar Injection

UHF Ultra-High Frequency

UIA Umbilical Interface Assembly

UIP Umbilical Interface Panel

UPR Unpressurized Rover

VISE Vehicle Interface to Suit Equipment

VLM Vehicle Loop Mode

xEMU Exploration Extravehicular Mobility Unit

xEVA Exploration Extravehicular Activity

xINFO Exploration Informatics System

xPLSS Exploration Portable Life Support Subsystem

A2.0 GLOSSARY OF TERMS

Term Description

Ancillary Hardware Ancillary hardware consists of the following items: 

recharge umbilical, tools, SAFER, and FSE. 

Consumables Resource that is consumed in the course of 

conducting a given mission. Examples include 

propellant, power, habitability items (e.g. gaseous 

oxygen), and crew supplies.

Crew Human onboard the spacecraft or space system 

during a mission

Dry mass Uncharged unit, without water or oxygen, as well as 

without any tools or other ancillary hardware.

Flight This is the sequence of events that takes place 

between liftoff and landing of a transportation vehicle.

Flight Support Equipment All equipment (in-flight check-out hardware, launch 

carriers and enclosures, in-flight stowage containers, 

etc.) required post launch to support in-flight 

operations and logistics. 
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Term Description

Heads-Up Display An electronic display of data from instruments or other 

sources projected at eye level so that an EVA 

crewmember (or driver or pilot) sees it without looking 

away from the task (or road or course)

Microgravity An environment where gravity has little or no 

measurable effect, commonly referred to as 

"weightlessness" or "zero-g”.

Mobility The sum of weight, range of motion, and center of 

mass that affects the performance of a human.

Motion Imagery Transient imagery and sound captured via electronic 

sensors and converted to data for retention and 

observation. Motion imagery may utilize portions of 

what is currently referred to as traditional video or 

television architectures and systems. Future television 

or motion imagery distribution will be required

to be in a digital format that is compliant with the 

Advanced Television Standards Committee (ATSC) 

standard.

ORU A piece of equipment which can be removed and 

replaced with a working spare by a user or operator 

during the mission. This is a subclass of Line 

Replaceable Unit (LRU).

Prep and Post The activities required preparation for and transition 

from an EVA including configuration and checkout of 

EVA hardware, suit donning and doffing, and all other 

procedures required before or after an EVA.

Spacecraft A spacecraft is considered to be any host vehicle such 

as habitats, rovers, landers, as well as orbiting and 

transit vehicles. 

Suitlock (Rear-Entry Airlock) An airlock designed for a rear-entry spacesuit, where 

the suit back extends through the bulkhead of the 

airlock into the habitable volume such that the

crewmember directly ingresses the suit from the 

habitable volume.

Suitport Similar to a suitlock, but the vestibule through which 

the back of the suit penetrates into the habitable 

volume acts as a pressure seal, such that the area 

around the front of the suit can be depressed with the 

suit hatch still open.

Suitport Airlock A suitport inside of a full airlock.
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Term Description

Umbilicals Umbilicals include service umbilicals used for recharge 

before, after, and during EVAs. Vehicle services 

include O2, water, hardline communication, power, 

data, vacuum, and suit to vehicle vent loop pressure 

equalization. The services may be supplied through 

multiple umbilicals as determined by the operational 

need.

Vehicle Often synonymous with the term spacecraft.
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APPENDIX B

OPEN WORK

B1.0 TO BE DETERMINED

The table To Be Determined Items lists the specific To Be Determined (TBD) items in the 

document that are not yet known. The TBD is inserted as a placeholder wherever the 

required data is needed and is formatted in bold type within carets. The TBD item is 

numbered based on the document number, including the annex, volume, and book 

number, as applicable (i.e., <TBD-XXXXX-001> is the first undetermined item assigned in 

the document). As each TBD is resolved, the updated text is inserted in each place that 

the TBD appears in the document and the item is removed from this table. As new TBD 

items are assigned, they will be added to this list in accordance with the above described 

numbering scheme. Original TBDs will not be renumbered.

TABLE B1.0-1: TO BE DETERMINED ITEMS

TBD Section Description

TBD-2.1-014

TBD-4.2.1-004 4.2.1 Compatibility with a suitlock (rear-entry airlock)

TBD-6.2.1-001 6.2.1 How and for how long suits are stowed is still TBD

TBD-7.2.1.2-005 7.2.1.2 If Artemis IV goes to Gateway

TBD-7.2.2.2-006 7.2.2.2 Stand-up EVA

TBD-7.2.3-007 7.2.3 Suited times during lunar descent

TBD-7.3.1-008 7.3.1 Road to EVA for Moons of Mars

TBD-7.3.2-009 7.3.2 Prep & Prebreathe for Moons of Mars

TBD-7.3.4-010 7.3.4 Post EVA for Moons of Mars

TBD-9.2.1-011 9.2.1 Road to EVA for Mars

TBD-9.2.2-012 9.2.2 Prep & Prebreathe for Mars

TBD-9.2.4-013 9.2.4 Post EVA for Mars

TBD-Apx D-002 Appendix D

TBD-Apx D-003 Appendix D Number of EVAs during transit to Mars

B2.0 TO BE RESOLVED

The table To Be Resolved Issues lists the specific To Be Resolved (TBR) issues in the 

document that are not yet known. The TBR is inserted as a placeholder wherever the 

required data is needed and is formatted in bold type within carets. The TBR issue is 

numbered based on the document number, including the annex, volume, and book 

number, as applicable (i.e., <TBR-XXXXX-001> is the first unresolved issue assigned in 

the document). As each TBR is resolved, the updated text is inserted in each place that 

the TBR appears in the document and the issue is removed from this table. As new TBR 
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issues are assigned, they will be added to this list in accordance with the above described 

numbering scheme. Original TBRs will not be renumbered.

TABLE B2.0-1: TO BE RESOLVED ISSUES

TBR Section Description

TBR-10.1.2-001 10.1.2 8-hour walk back to lander from a lander or disabled 

rover

TBR-10.1.2-002 10.1.2 8-hour drive for rescuing rover to reach disabled rover

B3.0 FORWARD WORK

The table Forward Work lists the known issues in the document that are being worked. 

The identifier CR-XXXXX-XXX refers to the CR that the comments was received on and 

the comment number for that review. For example, comment 63 on CR-00032 would be 

CR-00032-063.

TABLE B3.0-1 FORWARD WORK

Forward Work Section Comment

CR-00030-C107 7.4.1 Update ARCM with last ARCM Con Ops information.

CR-00030-C130 Appendix D Entire Appendix as related to ARCM in 7.4.1 -ARCM was a Project 

within Exploration Integration and Science Directorate (EISD) (was 

considered to be a Proving Ground Phase 1: Cis-Lunar Flight 

Testing of Exploration Systems in the 2025 timeframe per 

Exploration Systems Directorate (ESD) 00012 Rev E.

Suggest update Appendix D 7.4.1 to align with information 

contained in the Baseline JSC-66954 document and state that the 

Project was retired.

CR-00030-C211 The document doesn’t provide a lot of detail on what limits are 

needed for an EVA crew to work with robotics. Are there standard 

load limits from robot to crew? Acceleration limits if crew is on the 

end of an arm? These would likely be nominal human factors 

aspects taken from a ‘typical’ human physiology. Are there any 

other aspects that would define or focus the development of the 

robotic assistants or vehicles mentioned throughout to make them 

more useful to EVA?

CR-00030-C216 b. mention is made of a self-rescue jetpack or Simplified Aid For 

EVA Rescue (SAFER) device is TBD-EVA-EXP-0042-004 for NEA 

missions, however no mention is made of true EVA mobility aids 

(e.g. an MMU-like capability) which may be enabling for EVA 

productivity (e.g. avoid time to transit from airlock to worksite).

CR-00030-C217 c. mention is made of “robotic assets” for various EVAs, but no 

mention is made of dedicated EVA robotic free-flyer assistance 

equipment, e.g. for in-space EVAs a robotic inspector could go out 

before the EVA for inspection (better planning and/or substitute for 

the EVA), during the EVA for monitoring (better safety during the 
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Forward Work Section Comment

EVA), and after the EVA for closeout documentation (better use of 

EVA time).

CR-00048-42 5.5.2 Suggest investigating robo-carts, and mentioning that as a 

possibility here.

CR-00048-86 6.2.1.1 Add why an OCSS suit is being used for asteroid missions.

CR-00048-156 6.3.2 I suggest the following text be added to the end of the bullet: "The 

study found that (i) a majority of the objectives could be addressed 

within the Schrodinger impact basin, which is within the South 

Pole-Aitken impact basin, on the lunar farside; that (ii) Amundsen 

basin is a useful target for examining the potential of lunar volatile 

deposits; and (iii) while the highest-priority landing site may be the 

Schrodinger basin, global access to the lunar surface is required 

to address all science and exploration objectives. The landing 

sites in this report are suitable for both robotic and human EVA 

missions.

CR-00048-160 6.3.2 ISECG published a DRM with five landing sites, based on input 

from HEOMD Chief Exploration Scientist Ben Bussey. Thus, one 

might add at the end of the section the following text: "An ISECGdefined DRM published in 2015 contains five landing sites: 

Malapert Massif, South Pole/Shackleton Crater, Schrodinger 

Basin, Antoniadi Crater, and the center of the South Pole-Aitken 

Basin. Crew/rover traverses around each of those landing sites 

have been studied by team managed by LPI and ARES, as well as 

traverses for tele-operated rovers between those landing sites."

CR-00048-161 6.3.5.10 The text indicates EV crew may "rappel into and out of lava tubes 

and pits." That is an issue I would like to discuss. I do not 

anticipate a need to do that for near-term science purposes. On 

the other hand, it may be useful to carry that capability so that it is 

a future option.

CR-00048-163 5.5.1 Do we want to have self-rescue (SAFER) tools added to this list of 

EVA tools and equipment?

CR-00048-169 6.2.3 Better define "numerous safety issues" as they are understood

CR-00048-171 6.3.5.1.2 Paragraph three, better define the 8 hour EVA and how it will be 

conducted in two parts

CR-00048-172 6.3.5.12 "Crew may need to wear PPE

to prevent dust inhalation, but that is still to be determined"

List PPE that has been discussed for dust inhalation

CR-00048-175 6.5.1.1 Add words that a device for self-rescue (i.e. SAFER) will be used 

should the microgravity EVA crewmember become separated from 

the vehicle (ISS/Gateway, etc.)

CR-00048-183 H Mars Surface Mission - Uncrewed Cargo

Better define suit sizing concerns

CR-00048-256 Overall the document should include references for sources of information 

in-line within the text as well as in image/table captions.

CR-00048-260 6.3.5.10 consider changes to this section accounting for more approriate 

methods than rappeling for accessing steep, sloped terrain as well 
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Forward Work Section Comment

as areas such as lava tubes; lowering/raising winches should be 

considered along with associated auxiliary surface hardware

CR-00048-261 6.4.1.1 should include a deeper explanation of designing EVA timelines 

and tasks to allow for interactions with Earth-based scientists; 

should acknowledge that all science tasks and EVA timeline 

designs are dependent on the level of precursor information, 

specific science objectives/tasks, and the communication latency; 

since there are no DRMs that document this, reference the 

historical origin of this approach following from DRATS, to PLRP, 

to NEEMO, to BASALT and the associated publications

CR-00048-262 6.5.2.2 multiple areas cover incapacitated crew rescue on a partial gravity 

surface and this section is more complete; possibly merge this 

section w/ 6.4.1.4.5

CR-00048-264 6.4.1.2 acknowledge that different science objectives may require different 

specialized tools; acknowledge there may be an ability to take 

more samples on EVA than will be taken back to Earth and the 

desire/capability to analyze some samples in between EVAs and 

provide additional data to MSC for considerations; should talk 

about how IV, EV, and MSC coordinate activities and interact; 

include other capabilities such as feature pointers, cameras, etc., 

as ancillary EVA equipment

CR-00048-278 3.2 With future lunar landings using powered landing and larger 

payloads, vertical distance to surface of moon is large 

(Altair/LSAM ~ 30ft). There may need to be a capability for a 

contingency vertical translation on engineered surface.

CR-00048-296 5.6.3 For planetary surface operations, EVA umbilical charging stations 

providing oxygen, water, and power may be available outside 

multiple pressurized elements. These could potentially allow crew 

to optimize suit mass for shorter duration EVAs, but still have the 

ability to recharge or extend an EVA without having to come back 

into a pressure cabin.

CR-00048-298 6.4.1.6 Not sure how to word it but we should say something about 

discarded suits on Mars likely being reused to repair later suits.

CR-00048-301 You can make it forward work, but you should at least have a 

section on planetary protection for the Mars missions. Note that 

there may also be planetary protection restrictions near 

permanently shadowed craters on the moon.

CR-00048-302 2.2 Add Apollo reference materials

CR-00048-307 5.4.1 Update informatics for more possible design solutions

CR-00048-316 2.2 Add Special Issue Papers on D-RATS 2010

CR-00048-317 2.2 Add published paper on field portable instruments ("The 

Incorporation of Field Portable Instruments in Planetary Surface 

Exploration")

CR-00048-352 2.2 References should be applied directly within the manuscript. I find 

it difficult to see which information is pulled from which references. 

This is particularly important for all figures and tables and 'raw' 

data
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Forward Work Section Comment

CR-00048-383 5.1.1 Need to figure out how to reference a public list. Section 5.1.4 

does list contingency EVAs, most of which are also maintenance. 

There is no current consolidated list for just maintenance EVAs, 

though internal FOD EVA dashboards do contain them.

CR-00048-388 5.1.4 "For this Con Ops, EVA will assume that no contingency events 

will require the use of the EVA system with less than 24 hour 

notice."

This is a major requirement/assumption. Needs to be made much 

more explicit. Consider bolding or making a bullet point. There 

should also be a massive list of assumptions somewhere in this 

document that helps 'define' the Con Ops scenarios

CR-00048-391 5.2 Add language that includes Science traceability matrix that links 

these discrete tasks to more abstract Science Objectives

CR-00048-439 5.5.3 This may be another place to include instruments that could be 

integrated into the suit

CR-00048-440 6.3 Create a science traceability document (XI) and reference that 

document somewhere in this section.

CR-00048-586 6.3.5.12 Recommend explicitly stating in various Rescue scenarios what 

kinds of faults you are and are not protecting for. Include in this 

assumptions about the fault tolerance of the systems. For 

example, when you speak of Rover failures driving the need for 

walk-back capability, it seems you are talking simply of a failure of 

Rover drive/steering systems, not a failure of Rover Life support 

systems. Is the fault tolerance of the life-support systems higher 

than that of the drive systems? Is there a need for crew to be able 

to recharge suits even if life support system fails to begin 8-hr walk 

back to lander? Also in failure scenarios it seems to be assumed 

only protecting one failure deep - no tolerance for second failure 

after first occurs (ie, in 8 hr walkback we don't have normal failure 

tolerance to xEMU failure). These types of assumptions should be 

explicitly stated.

CR-00048-600 6.3.5.10 Careful to distinguish what critical information can and should be 

displayed depending on the environment and task. It may not 

"always" need to be displayed depending on the criticality of the 

caution or warning. Priority should be easily understood 

information at readable resolution. Information needs to be simple 

and not cluttered.

CR-00082-001 3.3.3 Is Artemis IV part of Phase 1 or 2

CR-00082-002 6 & 7 these two sections need to be reconciled with content in xEMU 

ConOps Chapter 7 in particula

CR-00082-003 5.2.2 Chart shows things like Metox install, EMU Battery Install, REBA 

Install

CR-00082-004 9 Add EVA responses to program level contingencies, such as the 

following: (1) failure of HLS to repress at the end of an EVA; (2) 

unexpected HLS depress event while in VLM; (3) HLS failure to 

dock to Gateway or Orio

CR-00082-005 4.2.2.1 "Geochemical, geophysical, and geotechnical measurements
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Forward Work Section Comment

CR-00082-006 4.2.1.4 "Cratered Terrain"

CR-00082-007 4.2.1.4 "Circumnavigate, descend into, perform science tasks"

CR-00082-008 4 Current figure does not match the xEMU ConOps figures which 

show a different suit. The verbiage associated with Figure 4.0-1 

mentions the lunar surface and but the picture does not match 

current xEMU documentation. Specifically (and also throughout 

the document) the picture shows current EMU arms and legs but 

these do not match the pictures in the xEMU document for Lunar 

EVAs.

CR-00082-009 6 These concepts seem to be for tasks that are slated far out in 

time. However, there are some long range con-ops development 

goals that need to be considered. External lighting will need to be 

in larger supply and smarter (automated and variable light fields) 

to adapt to changing and unknown environments. Interior lighting 

will need to be able to duplicate earthlike lighting environments, 

not just adding a spectrum shift for circadian countermeasures but 

actually increasing the levels significantly (daylighting) to 

significantly stimulate their circadian system and provide 

subjective worker productivity countermeasures that are similar to 

impacts skylights and windows bring to the business environment.

CR-00082-010 7 These concepts seem to be for tasks that are slated far out in 

time. However, there are some long range con-ops development 

goals that need to be considered. External lighting will need to be 

in larger supply and smarter (automated and variable light fields) 

to adapt to changing and unknown environments. Autonomous 

and robotic centered tasks, which require camera systems for the 

crew to "drive" or control the remote mechanical system, will also 

need smart lighting systems that improve visibility for video feeds. 

Because of the Martian soil and sky color, lighting may need to 

have modified spectrums to provide a white point that is more 

compatible for humans and RGB camera color systems. Interior 

lighting will need to be able to duplicate earthlike lighting 

environments, not just adding a spectrum shift for circadian 

countermeasures but actually increasing the levels significantly 

(daylighting) to significantly stimulate their circadian system and 

provide subjective worker productivity countermeasures that are 

similar to impacts skylights and windows bring to the business 

environment.

CR-00082-011 4.2.1.3.1 If the crew member traverses to the outer 2 km radius of the 

lander, not including walking around completing EVA tasks, they 

will have done a minimum of 4 km in one day. This already will 

cause significant fatigue. Other considerations such as standing 

and kneeling as well as mental workload will contribute to fatigue.

CR-00082-012 3.2 Clarification with regard to the role of Gateway in Artemis Phase I 

would be helpful to those supporting multiple Exploration 

programs. Will the role of Gateway be determine by the HLS 

provider(s) selected?
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APPENDIX C

ADDITIONAL REFERENCES

The following documents contain supplemental information to guide the user in the 

application of this document and were utilized to assist in developing the various EVA 

Concepts of Operations.

1. Eggleston, J. and Paget, M., “Environmental Factors Involved in the Choice of 

Lunar Operational Dates and the Choice of Lunar Landing Sites” 22 November 

1963

2. Lewis, J. and Wheelwright, C., “Lunar Landing and Site Selection Study”, NASA 

TN D-2999, September 1965

3. Binder, A. and Roberts, D., “Criteria for Lunar Site Selection”, P-30, January 

1970

4. Eppler, D., “Lighting Constraints on Lunar Surface Operations”, NASA Technical 

Memorandum 4271, 1991

5. Connors, M., Eppler, D., Morrow, D., “Interviews with the Apollo Lunar Surface 

Astronauts in Support of Planning for EVA Systems Design”, September 1994

6. Orloff, R. W. and Stephen, G., “Apollo by the Numbers: A Statistical Reference,” 

Tech. Rep., 1996.

7. Ewing, D., “External Maintenance Concepts and Requirements”, Revision B, 

March 2006

8. Coan, D., "Essential Commonality for Effective Future Extravehicular Activity 

Operations", AIAA SpaceOps 2006 Conference

9. “The Scientific Context for Exploration of the Moon”, 2007

10. “EVA - Don’t Leave Earth Without It”, 31 August 2010

11. “Radiation Protection Studies of International Space Station Extravehicular 

Activity Space Suits”, NASA/TP-2003-212051

12. 2010 MEPAG Mars Science Goals, Objectives, Investigations, and Priorities

13. “Planning for the Scientific Exploration of Mars by Humans 2008”

14. “Cross-Program Design Specification for Natural Environments (DSNE)”, Rev E, 

SLS-SPEC-159

15. Hodges, K. and Schmitt, H., “A new paradigm for advanced planetary field 

geology developed through analog experiments on Earth”, The Geological 

Society of America Special Paper 483, 2011

16. Bowen, S., and Koehler, O., “EVA SYSTEMS (EVAS) 10 Neutral Buoyancy 

Laboratory (NBL) Test Crew Consensus Report”, CB-11-068, 28 October 2011

17. Coan, D., “Exploration Analogs Overview and NEEMO 15 & DRATS 2011 Post 

Mission Summaries”, EVA-EXP-0050, 13 December 2011

18. Chappell, S., “NEEMO 15 Evaluation of Human & Robotic Exploration Systems 

for Near-Earth Asteroids Detailed Results”, 22 November 2011
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19. “NASA Human Exploration of Mars, Design Reference Architecture (DRA) 5.0” 

(and associated Addendum), NASA/SP-2009-566

20. Abercromby, A., Gernhardt, M., Jadwick, J., “Evaluation of dual multi-mission 

space exploration vehicle operations during simulated planetary surface 

exploration”, Desert RATS 2010, 25 February 2012

21. “NEEMO 15: Evaluation of Human Exploration Systems for Near-Earth 

Asteroids”, GLEX-2012.06.1.6x12286, 2 May 2012

22. “Exploration System Development Concept of Operations”, Baseline, ESD 

10012, 18 May 2012

23. June 2012 MPD Study

24. Abercromby, A., Litaker, C., Chappell, S., Gernhardt, M., “RATS 2012: MMSEV 

Gen 2A Testing Post-Test Quicklook Report”, 26 September 2012

25. Chappell, S., Abercromby, A., Reagan, M., and Gernhardt, M., “NEEMO 16 

Evaluation of Human & Robotic Exploration Systems for Near-Earth Asteroids 

Detailed Results”, 13 December 2012

26. Metcalf-Lindenburger, D., “NEEMO 16 Post-Mission Crew Report”, 17 June 

2013

27. Chappell, S., Abercromby, A., Reagan, M., and Gernhardt, M., “NEEMO 16: 

Evaluation of Systems for Human Exploration of Near-Earth Asteroids”, 22 

February 2013

28. Chappell, S., Buffington, J., Coan, D., Reagan, M., Todd, W., Janoiko, B., 

Johnson, J., Abercromby, A., and Gernhardt, M., “SEATEST 2 (Space 

Environment Analog for Testing EVA Systems & Training) EVA Results 

Overview”, October 2013

29. Chappell, S., Reagan, M., Todd, W., Janoiko, B., and Johnson, J., “SEATEST 2 

Post-Test Quick-look Summary”, January 2014

30. Reagan, M. and Janoiko, B., “Analog Mission Report & Status SEATEST 2 PostTest Summary”, 14 April 2014

31. Buffington, J., “Summary of Recent EVA Tools Development Efforts - SEATEST 

II & ARCM”, 18 February 2014

32. Coan, D., “NEEMO 18 Post Mission Status and NEEMO 19 Pre Mission Status”, 

EVA Exploration Working Group, 19 August 2014

33. Chappell, S., Abercromby, A., Coan, D., Halcon, C., Todd, W., Reagan, M., 

Janoiko, B., and Gernhardt, M., “NEEMO 18/19 Exploration Traverse Post-Test 

Quick-Look”, 30 October 2014

34. Bresnik, R., “NEEMO 19 Post-Mission Crew Report”, 30 March 2015

35. Coan, D., Buffington, J., Reagan, M., Janoiko, B., and Chappell, S., “NEEMO 18 

& 19 Post Mission Summary”, EVA-EXP-0051, EVA Exploration Working Group, 

16 December 2015

36. Reagan, M., “NEEMO 18 & 19 2014 Missions Summary and High Level 

Results”, 10 December 2014
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37. Coan, D., “PLRP 2014 and NEEMO 18-19 Summary”, 14 November 2014

38. Parmitano, L., Aunon, S., Kanai, N., Coan, D., “NEEMO 20 Post-Mission Crew 

Report”, 24 August 2015

39. Chappell, S., Beaton, K., Miller, M., Graff, T., Naids, A., Hood, A.D., Coan, D., 

Todd, W., Reagan, M., Janoiko, B., Abercromby, A., and Gernhardt, M., 

“NEEMO 20 Exploration EVA Research Post-Test Quick-look”, 21 September 

2015

40. Coan, D., Naids, A., Hood, A.D., Reagan, M., Janoiko, B., Chappell, S., Beaton, 

K., Todd, W., Poffenberger, J., Graff, T., Abel, P., John, K., and Miller, M., 

“NEEMO 20 Exploration EVA Integrated Testing Post-Mission Debrief”, 6 

October 2015

41. Reagan, M., Coan, D., Graff, T., Todd, W., and Janoiko, B., “NEEMO 20 Mission 

Overview and High Level Results”, FINAL, 14 October 2015

42. Reagan, M., “NEEMO 20 Post-Mission Report and Preliminary Findings”, 14 

October 2015

43. Coan, D., “NEEMO 20 Exploration EVA Results”, EVA-EXP-0052, EVA 

Exploration Working Group, 9 December 2015

44. “SMT EVA Gap List”, 29 December 2015

45. “Proving Ground Habitation System Concept of Operations”, FCS-15-02, 20 

November 2015

46. Graff, T., Miller, M., Rodriguez-Lanetty, M., Chappell, S., Naids, A., Hood, A.D., 

Coan, D., Abell, P., John, K., Todd, W., Reagan, M., Janoiko, J., and 

Poffenberger, J., “NEEMO 20: Science Training, Operations, and Tool 

Development”, LPSC 2016

47. Coan, D., “Operational Field Testing for Human Exploration (a.k.a., NASA 

Analog Projects)”, EVA Technology Workshop, 14 September 2016

48. “Human Exploration and Operations Exploration Objectives”, HEOMD-001, 7 

September 2016

49. Graff, T., Coan, D., Reagan, M., and Todd, W., “NEEMO 21 Mission Debrief”, 

XA Strategic Council, 22 September 2016

50. Chappell, S., Beaton, K., Graff, T., Coan, D., Young, K., and Miller, M., “NEEMO 

21 EVA Research Post-Test Quick Look: Integration of an Earth Based Science 

Team During Human Exploration of Mars”, October 2016

51. Coan, D., “NEEMO 21 EVA Mission Debrief”, EVA-EXP-0053, EVA Exploration

Working Group, 8 November 2016

52. Coan, D., “Operational Field Testing for Human Space Exploration”, SpaceCom 

2016, 9 November 2016

53. “Human Lunar Exploration Surface Campaign Concept of Operations”, 

December 2016

54. Miller, M., “Design and Development of Support Systems for Future Human 

Extravehicular Activity”, AIAA SciTech 2017, 12 January 2017
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55. Graff, T., Young, K., Coan, D., Merselis, D., Bellantuono, A., Dougan, K., 

Rodriguez-Lanetty, M., Nedimyer, K., Chappell, S., Beaton, K., Naids, A., Hood, 

A., Reagan, M., Rampe, E., Todd, W., Poffenberger, J., Garrison, D., “NEEMO 

21: Tools, Techniques, Technologies & Training for Science Exploration”, LPSC 

2017, March 2017

56. Chappell, S., Beaton, K., Newton, C., Graff, T., Young, K., Coan, D., 

Abercromby, A., Gernhardt, M., “Integration of an Earth-Based Science Team 

during Human Exploration of Mars”, IEEE Aerospace 2017, March 2017

57. “Deep Space Gateway and Transport Concept Maturation”, 27 June 2017

58. “Deep Space Gateway & Transport Overview Summary Status”, 12 July 2017

59. Gerstenmaier, W., “ISS, SLS, Orion: Into the Proving Ground”, September 2017

60. Graff, T., Coan, D., Reagan, M., and Todd, W., “NEEMO 22 Mission Debrief”, 

EISD, 27 September 2017

61. “Asteroid Redirect Crewed Mission Concept of Operations”, Baseline, JSC66954, 17 December 2017

62. Coan, D., “NEEMO 22 EVA Mission Debrief”, EVA-EXP-0054, EVA Exploration 

Working Group, 15 December 2017

63. Coan, D. and Reagan, M., “Enabling Human Exploration Through Integrated 

Operational Testing: NASA’s Exploration & Science Analogs”, EVA Technology 

Conference, 17 October 2017

64. “Exploration Design Concept of Operations”, HEOMD-005, Draft, 2017

65. “Human Exploration and Operations Exploration Utilization Plan”, HEOMD-006, 

Draft, 18 September 2017)

66. “Advancing Science of the Moon”, 2017

67. Miller, M. J., Claybrook, A., Greenlund, S., Marquez, J., Feigh, K., “Operational 

Assessment of Apollo Lunar Surface Extravehicular Activity,” NASA/TP-2017-

219457, July 2017.

68. Graff, T., Miller, M., Rodriguez-Lanetty, M., Chappell, S., Naids, A., Hood, A., 

Coan, D., Abell, P., John, K., Todd, W., Reagan, M., Janoiko, B., and 

Poffenberger, J., “NEEMO 20: Science Training, Operations, and Tool 

Development”, LPSC 2016

69. Miller, M. and Feigh, K., “Design and Development of Support Systems for 

Future Human Extravehicular Activity”, AIAA SciTech 2017

70. Young, K., Graff, T., Bleacher, J., Whelley, P., Garry, W. B., Rogers, A. D., 

Glotch, T., Coan, D., Reagan, M., Evans, C., and Garrison, D., “Collecting, 

Managing, and Visualizing Data during Planetary Surface Exploration”, AGU 

2017

71. Young, K. Graff, T., Bleacher, J., Coan, D., Whelley, P. Garry, W. B., Kruse, S., 

Reagan, M., Garrison, D., Miller, M., Delgado, F., Rogers, A., Glotch, T. Evans, 

C., Naids, A., Walker, M., and Hood, A. D., “Supporting Future Lunar Surface 

Exploration Through Ongoing Field Activities”, LEAG 2017
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72. Graff, T., Young, K., Coan, D., Merselis, D., Bellantuono, A., Dougan, K., 

Rodriguez-Lanetty, M., Nedimyer, K., Chappell, S., Beaton, K., Naids, A., Hood, 

A., Reagan, M., Rampe, E., Todd, W., Poffenberger, J., and Garrison, D., 

“NEEMO 21: Tools, Techniques, Technologies & Training for Science 

Exploration”, LPSC 2017

73. Young, K., Bleacher, J., Rogers, A. D., McAdam, A., Evans, C., Garry, W. B., 

Whelley, P., Graff, T., Coan, D., Reagan, M., Glotch, T., Scheidt, S., Garrison, 

D., Delgado, F., and Noyes, M. “Incorporating Field Portable Instruments into 

Planetary Surface Exploration”, NESF 2017

74. “Global Exploration Roadmap”, January 2018

75. Miller, M., Graff, T., Young, K., Coan, D., Whelley, P., Richardson, J., Knudson, 

C., Bleacher, J., Garry, W.B., Delgado, F., Noyes, M., Valle, P., Buffington, J., 

and Abercromby, A., “Scientific Hybrid Reality Environments (SHyRE): Bringing 

Field Work into the Laboratory”, PSIDA 2018

76. Young, K., Graff, T., Coan, D., Reagan, M., Todd, W., Naids, A., Walker, M., 

Hood, A. D., Dougan, K. E., Bellantuono, A., Merselis, D., Thinesh, T., 

Rodriquez-Lanetty, M., Rampe, E., Evans, C., Pace, L., Garrison, D., Zacny, K., 

Rehnmark, F., Wei, B., and Chu, P., “Conducting Science-Driven Extravehicular 

Activities during Planetary Surface Exploration - The NEEMO (NASA Extreme 

Environment Mission Operations) 22 Mission”, LPSC 2018

77. Naids, A. and Walker, M., “A Modular Equipment Transport System for Planetary 

Surface Operations”, LPSC 2018

78. Young, K., Bleacher, J., Rogers, A., McAdam, A., Evans, C., Graff, T., Garry, W. 

B., Whelley, P., Scheidt, S., Carter, L., Coan, D., Reagan, M., and Glotch, T., 

“Developing Science Operations Concepts for the Future of Planetary Surface 

Exploration”, Planetary Science Vision 2050 Workshop

79. Jawin, E., Valencia, S., Watkins, N., Crowell, J., Neal, C., and Schmidt, G., 

“Lunar Science for Landed Missions Workshop Findings Report”, 7 July 2018

80. “Phase 1 Gateway Concept of Operations”, DSG-CONOPS-001, 2018 (draft)

81. Lawrence, S., Bussey, B., Gruener, J., Coan, D., Hamilton, J., “2018 LAT Task 

Lunar-6: Lunar Surface Operations”, 18 September 2018

82. Coan, D., “NEEMO 23 EVA & Science Operations Summary of Results”, EVAEXP-0071, EVA Exploration Working Group, 17 September 2019

83. Coan, D., “Neoteric eXploration Technologies (NXT) Feasibility Mission (FaM) 

EVA & Science Operations Summary of Results”, EVA-EXP-0072, EVA 

Exploration Working Group, 15 October 2019

84. Coan, D., “Exploration EVA System Concept of Operations Summary for Artemis 

Phase 1 Lunar Surface Mission”, EVA-EXP-0075, EVA Exploration Workshop, 

18 February 2020
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APPENDIX D

KEY FIGURES OF MERIT (FOM)

This appendix contains the key FOM tables for each Exploration destination. 

TABLE D-1: KEY FOMS FOR A MICROGRAVITY EVA ON ISS

Mission Parameters

Mission Duration 2 - 6 months

Total Crew 6

Vehicle ISS

EVA Parameters

EVA Category Microgravity EVA on an Engineered Spacecraft

Type of Suit xEVA Suit

Type of Life Support Subsystem 

(LSS) (PLSS/Umbilical)

xPLSS (part of xEVA Suit)

Informatics xINFO

Egress Method ISS Joint Airlock

Purpose of Typical EVA Demonstration 

Maintenance and Contingency

Number of EVAs Up to 13 per year

Avg Duration of EVA (PET) 6.5 hours

Max Duration of EVA (PET) 8.0 hours 

Number of Crew EVA 2

Quiescent Period 1-6 months

TABLE D-2: KEY FOMS FOR EVA ON GATEWAY (MICROGRAVITY IN CISLUNAR SPACE)

Mission Parameters EVA Parameters

Mission Duration 26-42 days EVA Category Microgravity EVA on 

an Engineered 

Spacecraft

Number of Mission 7+ Type of Suit xEVA Suit

Quiescent Periods

(between missions)

Up to 2 years 

(~1 year & 339 days per 

Deep Space Gateway & 

Transport (DSG&T))

Type of LSS 

(PLSS/Umbilical)

xPLSS (part of xEVA 

Suit)

Total Crew 4 Egress Method Dual chamber airlock

Vehicle Cislunar habitat (Gateway) Purpose of Typical 

EVA

Demonstration

Contingency
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Mission Parameters EVA Parameters

Number of EVAs 2 per mission

Duration of EVA (PET) Up to 8 hours

Number of Crew EVA 2

TABLE D-3: KEY FOMS FOR EVA FROM DEEP SPACE TRANSIT (DST) VEHICLE IN 

CISLUNAR SPACE

Mission Parameters EVA Parameters

Mission Duration 191-221 days in transit 

vehicle docked to hab

300-400 days in transit 

vehicle free-flying

EVA Category Microgravity EVA on 

an Engineered 

Spacecraft

Number of Mission 3+ Type of Suit xEVA Suit

Quiescent Periods

(between missions)

Up to 1 year

(~330 days per DSG&T)

Type of LSS 

(PLSS/Umbilical)

xPLSS (part of xEVA 

Suit)

Total Crew 4 Egress Method Dual chamber airlock

Vehicle Cislunar habitat (Gateway)

Mars transit vehicle (DST)

Purpose of Typical 

EVA

Maintenance

Contingency

Number of EVAs ~1 for each month of 

mission

Duration of EVA (PET) Up to 8 hours

Number of Crew EVA 2

TABLE D-4: KEY FOMS FOR EVA FROM DST VEHICLE IN TRANSIT TO/FROM MARS

Mission Parameters EVA Parameters

Mission Duration TBD for days in Mars 

transit vehicle [TBD-Apx D002]

EVA Category Microgravity EVA on 

an Engineered 

Spacecraft

Number of Mission TBD for number of mission 

[TBD-EVA-Apx D-003]

Type of Suit xEVA Suit

Quiescent Periods

(between missions)

Up to 1 year

(~330 days per DSG&T)

Type of LSS 

(PLSS/Umbilical)

xPLSS (part of xEVA 

Suit)

Total Crew 4 Egress Method Dual chamber airlock

Vehicle Mars transit vehicle (DST) Purpose of Typical 

EVA

Contingency
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Mission Parameters EVA Parameters

Number of EVAs ~1 for each month of 

mission length

Duration of EVA (PET) Up to 8 hours

Number of Crew EVA 2

TABLE D-5: KEY FOMS FOR EVA ON A CAPTURED ASTEROID

Mission Parameters

Mission Duration 25-30 days

Time at Destination ~6 days

Total Crew 2

Crew Vehicle Orion

Habitation Orion

Excursion Vehicle N/A

EVA Parameters

EVA Category Microgravity EVA on Small Natural Body

Type of Suit OCSS

Type of LSS (PLSS/Umbilical) xPLSS 

Egress Method Depressed cabin

Purpose of Typical EVA Science

Number of EVAs 2

Duration of EVA (PET) Up to 8 hours

Number of Crew EVA 2

TABLE D-6: KEY FOMS FOR EVA ON A NEA

Mission Parameters EVA Parameters

Mission Duration ~1 year EVA Category Microgravity on Small 

Natural Surface

Time at Destination ~28 days Type of Suit Microgravity xEVA Suit 

Total Crew 4 Type of LSS 

(PLSS/Umbilical)

xPLSS

Crew Vehicle Orion Egress Method Rear-entry dual 

chamber airlock

Habitation DST Purpose of Typical 

EVA

Science

Excursion Vehicle SEV Number of EVAs 10 per mission

Duration of EVA 

(PET)

Up to 8 hours
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Mission Parameters EVA Parameters

Number of Crew EVA 2

TABLE D-7: KEY FOMS FOR EVA ON THE MOONS OF MARS

Mission Parameters EVA Parameters

Mission Duration ~600 days EVA Category Microgravity (milli-g) 

EVA on Small Natural 

Body

Time at Destination ~30-90 days Type of Suit xEVA Suit

Total Crew 4 Type of LSS 

(PLSS/Umbilical)

xPLSS (part of xEVA 

Suit)

Crew Vehicle Orion Egress Method Dual chamber airlock

Habitation Phobos Habitat Purpose of Typical 

EVA

Science

Vehicle Maintenance

Excursion Vehicle N/A Number of EVAs 10 per excursion

Duration of EVA 

(PET)

Up to 8 hours

Number of Crew EVA 2

TABLE D-8: KEY FOMS FOR EVA ON THE LUNAR SURFACE

Mission Parameters EVA Parameters

Mission 

Duration

Minimal Stay: <1 day

Initial Short Stay: 6.5 days

Short Stay: 7-14 days

Extended Stay: 42 days 

Long Duration: 6 months

EVA Category Partial-Gravity EVA on Lunar 

Surface in a Vacuum

Number of 

Missions

4+ Type of Suit Surface xEVA Suit

Quiescent 

Periods

(between 

missions)

Minimun Stay: N/A

Initial Short Stay: N/A

Short Stay: In work

Extended Stay: Up to 2 years 

(~1 year 339 days per DSG&T)

Long Duration: Up to 2 years

Type of LSS 

(PLSS/Umbilical)

xPLSS (part of xEVA Suit)

Total Crew Minimal Stay: 2

Initial Short Stay: 4 (2 on 

surface, 2 in Gateway)

Short Stay: 4 (all on surface)

Extended Stay: 4 (all on surface)

Number of Crew 

EVA

2-4 for nominal/planned

4 for transfer from/to lander

4 for contingency
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TABLE D-9: KEY FOMS FOR EVA ON MARS

Mission Parameters EVA Parameters

Mission Duration ~1000 days EVA Category Partial-Gravity EVA in 

Partial-Atmosphere on 

Mars’ Surface

Time at Destination ~7-540 days Type of Suit Mars Surface xEVA Suit

Total Crew 3-6 Type of LSS 

(PLSS/Umbilical)

xPLSS (part of Mars 

xEVA Suit)

Crew Vehicle Orion Egress Method Dual Chamber RearEntry Airlock (min hatch 

of 40”x60”) from Lander

Dual Chamber RearEntry Airlock (min hatch 

of 40”x60”) from Habitat

Rear-Entry Airlock (min 

hatch of 40”x60”) from 

Pressurized Rover

Long Duration: 4 (all on surface)

Transport 

Vehicles

Orion (to NRHO)

Human Lander (to surface)

Purpose of EVA Science

Maintenance

Construction/Pioneering

Habitation Gateway (in NRHO)

Lander (surface)

Pressurized Rover (surface)

Habitat (surface)

Number of EVAs

(per mission)

Sortie: 7-24 

Extended Stay: 4-48

Long Duration: 104-208

Excursion 

Vehicle

Unpressurized Rover

Pressurized Rover

EVA Frequency

(nominal/schedule

d)

Minimum Stay: 1

Initial Short Stay: Daily for 5 

days

Short Stay: Daily, with rest 

days after 3-4 EVAs

Extended Stay: 4 days per 

week

Long Duration: 4 days per 

week

Duration of EVA 

(PET)

2-8 hours

Egress Method Cabin depress from Lander 

(min hatch of 40”x60”) 

Airlock/suitlock (min hatch of 

40”x60”) from pressurized 

rover

Dual chamber rear-entry 

airlock (suitlock) (min hatch of 

40”x60”) from habitat
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Mission Parameters EVA Parameters

Habitation Trans Hab, Lander Purpose of Typical 

EVA

Pioneering

Science

Vehicle/habitat 

maintenance

Excursion Vehicle Pressurized Rover Number of EVAs Up to 27 hours/week

Average Duration of 

EVA (PET)

8 hours

Number of Crew EVA 2
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APPENDIX E

NEXTSTEP APPENDIX H: HLS

Per Next Space Technologies for Exploration Partnerships (NextSTEP) Appendix H 

(Human Landing System), the following subsections outline some of the details of HLS 

that impact EVA:

Communication

• On the surface, the crew will need to talk from inside the HLS landed element 

to the ground, and to the crew on the Gateway.

• For EVA crew on the surface, they can communicate to Gateway and/or Earth 

through the HLS landed element.

• There is no direct communication link from an EVA crew member to the 

Gateway or Earth.

• Crew members inside the HLS will need to communicate with the Gateway 

and Earth both suited and in shirt sleeves.

• During sustainable operations, if there are two crewmembers in the HLS while 

the other two conduct an EVA, the EVA crew will need to talk to their two 

surface companions in the HLS.

• EVA crew members may talk directly to each other in their xEMU’s.

• During Lunar Surface Operations, the HLS landed elements will support EVA 

operations via Wi-Fi and UHF Space-Suit communications.

o Other options may be possible in the sustainable mission phase, such 

as 5G or LTE.

• Crew communications during EVA will have Wi-Fi as well as UHF for EVA 

astronaut voice and data.

• An acquisition of signal (AOS) state from the EVA crew to the HLS is 

presumed to be the operational state for EVA, however, mission rules will 

have to determine if any LOS time during EVA, caused by distance or 

blockage, is allowable.

• During EVAs, the HLS will have a direct UHF and Wi-Fi comm link from the 

suits to the HLS landed element to enable the crew to communicate with the 

HLS, and by extension, with the Gateway crew and Earth.

• Because HLS will be concurrently communicating with both Gateway and 

Earth, it means the HLS EVA Suits will be able to communicate with both 

Earth & Gateway.

• Direct to Earth (DTE) communications from lunar polar locations are subject 

to multi-path issues and blockages, due to the low angle of Earth over the 

horizon.

o DTE communications requires line of site from the HLS landed 

element to Earth.

o This condition is highly variable at the lunar poles, with DTE LOS 

periods being a dynamic condition.
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o Communications coverage from Gateway will therefore be crucial for 

providing adequate AOS communication time for the EVA crew.

o It is possible that lunar communications assets may be available to 

mitigate these conditions but those are TBD as of now.

EVA Checkout, Prep, and Prebreathe

• In the initial capability phase the Gateway configuration will not have suit 

servicing hardware, so suit checkout will be done in the HLS, while still 

docked to Gateway, thus providing access to Gateway suit spares and tooling 

if needed.

• HLS will have to provide volume to assemble the suits and support pre-form 

fit and pressure checks prior to descent.

• In the sustainable phase, suit fitting and checks may be done on the 

Gateway.

Configuration for Lunar Descent

• The crew must begin their pre-breathe operations prior to departing for the 

lunar surface, with a total of 36 hours of [saturation] required prior to the first 

EVA.

• Prior to crew ingress of the HLS for descent to the surface, the integrated 

inhabited space’s pressure is reduced to 10.2 psi for a predetermined period 

of time.

• Once the hatch is closed, the HLS cabin pressure will be reduced to 8.2 psi. 

After a successful checkout, HLS cabin saturation operations will begin as 

part of the prebreathe.

• For the initial missions, two crew will descend to the surface, and two will 

remain at Gateway/Orion. For sustainable phase missions, we expect up to 

four crew members on the surface. The HLS must support the crew during 

surface operations, including life support, consumables, power and 

communications and must enable surface access and EVA.

• The initial mission(s) should not exceed 6.5 days of surface stay. Sustained 

missions may be of longer surface stay duration.

Departure from Gateway

• Based on current operational planning, the period between final crew ingress 

and touchdown on the surface is expected to be more than a day.

• As such, the crew will require sleep, and other activities such as meals and 

biological waste elimination.

• Go/no-go calls and vehicle checkout(s) from the ground and/or performed by 

the crew will be determined in mission planning.
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NRHO to Phasing Orbit

• A loiter in low lunar orbit (LLO), up to three revolutions, will likely be needed 

either for crew preparation for descent and/or navigation state updates to

• reduce error after the Lunar Orbit Insertion (LOI) burn.

• A nominal transit of 12 hours from NRHO to a 100 km circular LLO is 

anticipated, but trip time can vary based on final mission designs.

Decent to Surface

• For descent, the crew will wear the xEMU (on umbilicals, without the PLSS).

• The descent from the phasing orbit to the lunar surface will typically consist of 

four distinct phases.

• A DOI burn will place the HLS in an orbit with a perilune sufficiently low to 

perform Powered Descent Initiation (PDI).

• The Powered Descent Initiation (PDI) and Braking phase will slow the HLS 

into a surface-intercepting trajectory and arrest the HLS to a sufficiently low

altitude to begin the approach phase.

•

• The Approach Phase typically consists of a pitch maneuver to allow for crew 

viewing of the landing site.

• The Terminal Descent and Touchdown Phase consists of the final vertical 

descent to the surface achieving the desired velocity/attitude state for

touchdown.

• The duration and profile of these phases will vary with descent trajectory 

design.

EVA Checkout & Prep on Lunar Surface

• Donning the EVA suit is currently anticipated to take approximately one-hour.

• Based on current analysis, once the crew has donned their suits, the halfhour EVA pre-breathe begins, followed by the cabin or airlock 

depressurization process.

Airlock & Depress

• Initial EVA ingress/egress capability can only be achieved through an airlockstyle option (could be main cabin or separate isolated volume).

• Lander Systems with an isolated EVA ingress/egress volume will not require 

entire cabin depress for each EVA cycle.

• However, Lander Systems without an isolated EVA ingress/egress volume 

will require complete cabin depress for each EVA cycle.
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Surface Operations

• The surface mission operational intent is to perform EVA’s.

• Preparation for EVA’s begins before the crew opens the hatch to egress the 

HLS landed element. EVA preparation time is driven by vehicle atmospheres,

oxygen saturation levels, and pre-breath protocols.

• Science EVA plans are in formulation and will grow with capability.

• They are expected to include general scouting, surveying, sampling including 

rocks, volatiles, and subsurface drilling.

• Other possible science objectives include identification and marking of the 

highest local terrain.

Dust Mitigation

• The EVA System and Lander System will share responsibility for maintaining 

dust exposure within the permissible exposure limits.

• Operationally, the crew will perform post-EVA dust mitigation activities 

external and internal to the lander.

• The exact activities are still being developed but likely include coarse cleaning 

with EVA System-provided tools prior to ingress and then stowing the suit in a 

container inside the lander when not in use to minimize loose dust in the 

vehicle.

Post EVA

• Between EVA’s, the suits will have access to HLS resources for maintenance 

and recharge, including power for batteries, O2, water for cooling, waste 

water removal and vacuum.

Ascent Prep

• For ascent, the crew will wear the xEMU (on umbilicals, without the PLSS).

• If possible the PLSS will be returned to the Gateway. If necessary the PLSS 

may be left on the surface.

• These, and any other items that are to be left behind, must be moved to their 

disposal locations.

• The crew will perform any required vehicle reconfiguration and the vehicle 

systems will be checked out prior to ascent. Vehicle checkout may be initiated 

onboard or from the ground, depending on vehicle design, mission planning 

and flight rules.

Ascent

• Upon completion of the surface mission, the crew will use the HLS to ascend 

to the Gateway.
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• This phase will include a powered ascent phase, similar to a launch to orbit 

on Earth, a loiter period in a phasing orbit to target a return to Gateway in 

NRHO, a cruise phase from phasing orbit to NRHO, and a rendezvous and 

docking phase to connect to Gateway.

Abort

• [For] an aborted landing, the HLS will safely return the crew to the Gateway

• A surface abort may require the crew to shelter in place until the Gateway is 

in the correct orbital position for an ascent.
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APPENDIX F

EVA TASKS FOR EXPLORATION MISSIONS

A variety of both engineering (maintenance and construction) and science tasks will be 

completed by EVA crewmembers during Exploration missions with the appropriate 

equipment. These generic tasks include, but are not limited to, the following sections.

TABLE F-1: ENGINEERING TASKS

ET# ENGINEERING TASKS (ET)

1.0 Microgravity Translating

1.1 Egress Airlock

1.2 Attach and Remove/Swap Tethers

1.3 Transporting Tools

1.4 Transporting ORUs

2.0 Microgravity Maintenance

2.1 Removing/Installing Fasteners

2.2 Removing/Installing Electrical Connectors

2.3 Removing/Installing Fluid Connectors

2.4 Unforeseen Repair

3.0 Prepare Rovers for Exploration

3.1 Offload Equipment from Landers

3.2 Load Equipment onto Rovers

3.3 Clean Equipment

3.4 Checkout Rover Systems

3.5 Maintain Rover

4.0 Construct Surface Habitat and Infrastructure

4.1 Transport Tools

4.2 Deploy and Construct Antennas

4.3 Align Antennas

4.4 Grade Regolith

4.5 Route and Connect Power and Communication Lines
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ET# ENGINEERING TASKS (ET)

4.6 Install/Remove Fasteners

4.7 Install/Remove Electrical Connectors

4.8 Install/Remove Fluid Connectors

4.9 Align and Connect Modular Elements

5.0 Assemble and Maintain Equipment

5.1 Install/Remove Fasteners

5.2 Install/Remove Electrical Connectors

5.3 Install/Remove Fluid Connectors

5.4 Remove Dust

5.5 Clean Equipment

5.6 Repair Equipment

6.0 Prepare Ascent Vehicle

6.1 Offload Equipment from Rovers

6.2 Transfer Equipment and Samples from Rover to Ascent Vehicle

6.3 Clean Equipment

TABLE F-2: SCIENTIFIC TASKS

ST# SCIENTIFIC TASKS (ST)

1.0 Conduct Documentation / Perform Context Descriptions

1.1 Conduct Visual Inspection / Examine Surroundings

1.2 Conduct Photo Documentation

1.3 Conduct Video Documentation

1.4 Place Context/Sampling Markers

2.0 Sampling

2.1 Retrieve Sampling Tools and Equipment

2.2 Transport Sampling Tools and Equipment
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ST# SCIENTIFIC TASKS (ST)

2.3 Collect Regolith Samples

2.4 Collect Rock Samples

2.5 Collect Regolith Core Samples

2.6 Collect Rock Core Samples

2.7 Collect Atmospheric Samples

2.8 Collect Surface Samples

2.9 Conduct Trenching for Sub-surface and Wall Sampling

2.10 Collect Volatile and Cryogenic Samples

2.11 Seal/Store Samples

2.12 Transport Samples

3.0 Instrumentation (Smaller - Hand Operated)

3.1 Retrieve Instrumentation

3.2 Transport Instrumentation

3.3 Deploy Instrumentation

3.4 Operate Instrumentation

3.5 Perform Instrument Maintenance 

3.6 Re-stow Instrumentation

4.0 Experimental Packages (Larger - Field Deployed)

4.1 Retrieve Experimental Package

4.2 Transport Experimental Package

4.3 Deploy Experimental Package

4.4 Operate Experimental Package

4.5 Perform Experimental Package Maintenance 

4.6 Re-stow Experimental Package

5.0 Traversing

5.1 Conduct Navigation / Geo-Locate

5.2 Descend Rocky and Scree Slopes
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ST# SCIENTIFIC TASKS (ST)

5.3 Ascend Rocky and Scree Slopes

5.4 Approach and Access Vertical Exposures (ex. Large Boulders / Vertical 

Outcrops)

5.5 Access and Traverse Void Spaces (ex. Lava Tubes)

5.6 Access Permanently Shadowed Regions

5.7 Install Milli-Gravity Anchoring System

Examples of microgravity critical contingency (and maintenance) tasks based on the ISS 

include:

• NH3 Leak Detection and Isolation

• Pump Module (PM) R&R

• Flex Hose Rotary Coupler (FHRC) R&R

• Interface Heat Exchanger (IFHX) R&R

• Electronic Control Unit (ECU) R&R

• Solar Array Wing Manual Positioning

• Bearing Motor Roll Ring Module (BMRRM) R&R

• Ammonia Tank Assembly (ATA) R&R Overview

• Nitrogen Tank Assembly (NTA) R&R

• Main Bus Switching Unit (MBSU) R&R

• External Multiplex/Demultiplexer (EXT MDM) R&R

• DC to DC Converter Unit (DDCU) R&R

• RPCM R&R

• Pressurized Module Micro Meteoroid Orbital Debris (MMOD) Penetration
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APPENDIX G

EVA TOOLS & EQUIPMENT

The xEVA System provides a set of tools which are critical to accomplishing the tasks 

envisioned on an exploration mission. Tools will be provided to support exploration 

science, vehicle assembly and maintenance, inspection, crew safety, and equipment 

transport. Common tools, fasteners and vehicle interfaces should be pursued to limit the 

number of tools required to support all operations. The full tool set will be defined for 

specific tasks as vehicle designs and exploration concepts of operations mature.

MICRO/MILLI-GRAVITY EVA TOOLS AND EQUIPMENT

In the event of a microgravity EVA, a variety of tools and equipment will be needed to 

perform EVAs, including, but not limited to:

• Safety Tether (including crew hooks)

• Retractable Equipment Tethers (RET)

• Adjustable Equipment Tether (AET)

• Waist Tethers

• Body Restraint Tether (BRT)

• Modular Mini Workstation (MMWS) or equivalent

• Crewlock bags

• ORU bags

• Trash bags

• Wire ties

• Scissors

• Camera

• Contamination detection kit

• Power driver - such as the Pistol Grip Tool (PGT)

• Ratchet wrench

• Torque wrench

• Socket kit

• Compound cutter

• Needle nose pliers

• Foot restraints

• Small natural body anchoring system
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FIGURE G-1: UTILIZING THE PISTOL GRIP TOOL (PGT) DURING AN ISS EVA

SURFACE EVA EQUIPMENT AND TRANSPORT

Tools and equipment utilized during surface EVAs will differ from those used for 

microgravity operations. Large, heavy tools, such as the PGT, will need to be lighter when 

used in a partial-g environment. Additionally, science tools will have special cleanliness 

and material requirements to meet science objectives. Furthermore, dust will be a factor 

that needs to be accounted for in tool design and maintenance. There will also be a 

significant difference with how equipment will be transported during surface EVA 

operations as opposed to in microgravity. In microgravity, tools and bags are restrained 

on the crewmember via the MMWS, BRT, and various soft tethers. Equipment on surface 

EVAs will not be able to be carried in that manner due to the effect of the partial‐g 

environment. Surface operations will require EVA crew to transport equipment, especially 

larger items, to and from a worksite via a caddy/cart that is either manually pulled or 

robotically driven. Larger equipment needed for EVA tasks can be grouped and stowed 

together in smaller, detachable transport modules to make operations more efficient. For 

example, a Drilling Module could include the Power Drill, drill bits, core bits, drill guides 

and sample containers. A crew member who needs to perform drilling would be able to 

carry this smaller module to their drilling location and they would have everything they 

needed to accomplish that task. This architecture could provide added efficiency to the 

EVA timelines, as opposed to having to continually go back and forth to the larger 

caddy/cart for each individual tool.

Smaller tools will need to be carried on the EVA suit in a manner that keeps the tools tightly 

restrained, as opposed to flopping around on a tether. Potential options include a harness 

to latch tools onto a module attached to the thigh and a module attached to the forearm of 

the suit. Small tool stowage on the suit would provide fast and easy access to the crew 

member. Examples of potential small tools carried on the suit include, but aren’t limited to 

the following:

• Forceps

• Snips

• Brushes
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• Tongs

• Chisels

• Sample markers

• Zip ties

• Drill bits

• Sockets

• Lights

Longer term exploration of a planetary surface will likely include examination of lava tubes 

due to their potential use as a radiation shelter and geologic interest. This would present 

unique challenges of providing equipment capable of lowering suited crew members down 

into these tubes and safely getting them out. The suit might need to accommodate 

features like mounting points, face shields, and harnessing locations to safely enable such 

an endeavor.

SCIENCE TASK EVA TOOLS AND EQUIPMENT

Various tools and equipment will be needed for scientific sampling in both microgravity 

and partial-g environments. 

FIGURE G-2: POWERED AND MANUAL EVA SAMPLE ACQUISITION TOOL CONCEPTS 

(CORE, CHIP, SOIL, SURFACE)

TABLE G-1: GEOLOGY SAMPLE TYPES

Surface Samples The fine, top layer (~1mm) of a surface.

Regolith Samples Loose conglomerate of fine particulate that can usually be retrieved by a 

scooping action.

Float Samples Rocks that are loosely adhered to the surface

Chip Samples Small pieces of rock liberated forcibly from a parent body.

Core Samples Cylindrical masses of rock drilled out of a parent body.

Trench Samples Regolith from walls of a trench.
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In addition to retrieving and stowing samples, field portable instruments will play a key role 

in helping to provide in-situ scientific data and high grade samples real-time. The future 

tool kit will consist of a multitude of tools and equipment including but not limited to:

• Geologic hammering tool (will require impact containment for micro-g)

• Rotary-percussive drill

• Subsurface sampling tool (core tube) 

• Surface sampling device

• Soil sampling tool (scoop)

• Float sampling tool (tongs/clamshell)

• Shovel

• Rake

• Sample collection bags

• Sample storage and handling device

• Sealable volatiles and cryogenic container

• Handheld X-ray Fluorescence (hXRF) Analyzer

• Handheld Laser Induced Breakdown Spectroscopy (hLIBS)

• Spectrometer

• X-Ray Diffractometer (XRD)

• Visible Near-Infrared Spectrometer (NVIR)

• Magnetometer (Magnetometry/Magnetic Susceptibility)

• Light Detection and Ranging (LiDAR)

• Multi-View Stereo Photogrammetry (MVSP)

• Visible Near-IR Spectrometer

• Ground Penetrating Radar (GPR)

• Seismometers

• Gravity Meter

COMMON TOOLS AND EQUIPMENT

It is envisioned that each vehicle (spacecraft, rover, or habitat) will carry a small set of IVA 

and EVA tools that would be able to service each system. This drives each system to 

design their components with similar fasteners and interfaces to prevent the need to fly 

unique tools that can only be used on one component. Not only does this concept create 

efficiencies in hardware preparation and maintenance but limited mass and volume makes 

this common tool architecture necessary. Each part of the EVA System will adhere to this 

architecture in which integration will be key. Reference EVA-EXP-0035, Exploration EVA

System Compatibility, for a list of common tools.
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APPENDIX H

INFORMATICS

Current EVA operations on the ISS depend on near constant and instantaneous 

communication between MCC and the EV crew. At destinations with signal outages and/or 

long latencies, Exploration crew will need informatics capabilities and support systems in 

order to effectively handle the large amounts of information and tasking while conducting 

efficient EVA operations. The xEVA System will incorporate advanced informatics for 

Exploration missions beyond low Earth orbit. The informatics will take the form of systems 

on the xEVA Suit, and on systems within the spacecraft.

An informatics system with heads-up display and fixed electronic display capabilities will 

ultimately grant the EVA crew more autonomy with both tasks and suit monitoring, and will 

provide astronauts access to digital data/information, including, but not limited to, the 

following:

• Procedures

• Location and navigation

• Text communications with both IV and Mission Control Center (MCC)

• Auditory cues

• Diagrams

• Photographs and annotated images

• Videos

• Augmented reality cues, including pre-planned waypoints for navigation and 

science regions of interest into environment

• Verifying Extravehicular (EV) video framing and looking at EV imagery 

before/during transmission

• Display of calculated consumables levels to inform the crewmember

• Candidate sample locations for navigation 

• Science instrument, sensor, and camera data
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FIGURE H-1: CAPABILITY CONCEPT FOR AN AUGMENTED HEADS-UP DISPLAY SYSTEM

Having real-time operational data enables greater situational awareness allowing for

increased efficiency and safety. The xEVA hands-free advanced informatics system 

(xEVA Informatics) may take on a combination of several potential forms, including things 

such as a heads-up display, a heads-in display, and/or an electronic cuff display mounted 

on the arm of the suit. Utilizing these systems, the EVA crew will be able to navigate 

themselves to specified worksites and mark their location for MCC awareness and future 

reference. The xEVA Informatics (INFO) capability will allow them to access procedures, 

schematics, and videos to assist with pioneering, construction, and maintenance activities, 

in addition to providing the necessary lighting. For science activities, they will be able to 

reference cue cards, pictures, and imagery that the Science Team has annotated for them. 

MCC, the Science Team, and IV will also be able to provide the EV crew with augmented 

reality cues in order to guide them through tasks and point out specific things in the EV 

crew’s field of view. Any informatics system will have to take into account the lighting 

conditions. 

FIGURE H-2: TESTING AN EVA ELECTRONIC CUFF DURING STS-69
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APPENDIX I

PRE-ARTEMIS LUNAR MISSION SCENARIOS

The following appendix contains the lunar missions scenarios from revision A of this 

document. 

MINIMAL STAY MISSION (“FLAGS & FOOTPRINTS”)

The initial lunar mission will return humans to the surface of the Moon and bring them back 

safely. This mission will only be a few hours on the surface (much like early Apollo 

missions) in order to re-rendezvous with Gateway on its current orbit. During this mission, 

all four crew will descend to the surface and live out of the lander.

Mission parameters and capabilities:

• Surface stay duration: ~12 hours

• Crew to surface: 4

• Egress method: Lander cabin depress

• Crew on EVA: 4

• EVA duration (PET): 2-8 hr

• EVA frequency: 1

• Total number of EVAs: 1

• Rover: None

• Traverse distance from lander: ~1.5 km (< 1 hr walk during ICM rescue) 

(Note: Apollo 14 walked 1.45 km from lander)

• LEA (OCSS) Suits down/up: 0/0

• xEVA Suits down/up: 4/4

• Science return:

• Limited sampling

• Some handheld instrument measurements

• Emplace single simple long-lived surface experiment

INITIAL SHORT STAY MISSION (LUNAR DAYLIGHT, TWO CREW)

These initial missions to the lunar surface of 6.5 (~7) days in lunar daylight (i.e., constant 

light) will land humans at high latitude for the first time, explore local features, acquire 

science samples, set up experiments, and inspire future missions. This initial ~156-hour 

mission will focus on demonstrated human operations on the lunar surface, in addition to 

providing science sample return and deployment of long-lived experiment packages. This 

architecture involves having four crewmembers fly to lunar orbit and dock to Gateway. 

Two crewmembers will remain in the Gateway cis-lunar facility, while two crew will 

descend to the surface in the human lander wearing xEVA suits. They will test out surface 

systems, perform EVAs, and address strategic science and engineering objectives, 

allowing for exploration of high-interest science sites and demonstration of technology 

development objectives.The crew on the surface will live in the lander, use the cabin or a 
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severable airlock for egress, and utilize xEVA suits to conduct EVAs of up to 8 hours in 

duration during local excursions. The crew will have the capability to perform daily EVAs. 

On any given day, two crewmembers conduct an EVA, with rest days anticipated after

three or four days of EVAs, depending on the durations of the EVAs. They will utilize the 

lander cabin as an egress or a severable airlock on the lander for egress. The EVA crew 

will traverse on foot nominally up to ~1.5 to 2 km (< 1 hr walk during ICM rescue) from the 

lander (safe haven), which is similar to the 1.45 km distance that the Apollo 14 walked 

from their lander.

This initial short stay two-crew con ops does not presume any pre-positioned assets or 

equipment.

Mission parameters and capabilities:

• Surface stay duration: ~6.5 days (~156 hr during lunar daylight)

• Crew in Gateway: 2

• Crew to surface: 2 to the surface (2 stay on Gateway)

• Egress method: Lander cabin depress or severable airlock

• Crew on EVA: 2

• EVA duration (PET): 4-8 hour excursions (2-crew/EVA)

• EVA frequency: Daily EVAs for 5 days

• Possibility of a rest day

• Possibility of 2 excursions per day (a day’s EVA may be split into 2 parts)

• Total number of EVAs: Up to 5 per mission

• Possibility of 10 excursions out of the vehicle if an EVA is split into two parts 

on a day (10 cycles on suit and airlock)

• Rover: Unpressurized (initial missions)

• Traverse distance from lander: ~7.5-10 km with unpressurized rover (5 hr 

walk from failed rover) (Note: Apollo 17 traveled 7.6 km from lander)

• xEVA suits down/up: 2/2

• Science return:

• Diverse sample set

• In-situ instrument deployment 

• Multiple long-lived experiment packages deployed

• In Situ Resource Utilization (ISRU) demonstration

SHORT STAY MISSIONS (LUNAR DAYLIGHT, FOUR CREW)

This architecture involves having four crewmembers fly to Gateway in lunar orbit, with two 

then landing on the lunar surface. These ~156-336-hour missions will focus on 

demonstrating operations on the lunar surface, in addition to providing science sample 

return and deployment of long-lived experiment packages. Two crewmembers will 

descend wearing the xEVA suits in the human lander to the surface. On the surface, the 

crew will utilize xEVA suits to conduct EVAs of up to 8 hours in duration. The crew will live 
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in the lander, utilizing an airlock (likely suitlock) for egress, an unpressurized rover for 

longer distance excursions from the lander, and a pressurized rover for two crewmember 

to perform even longer multiday excursions.

The crew on the surface will live in the lander and utilize an unpressurized rover for local 

excursions, and a prepositioned pressurized rover to live in and conduct EVAs during 

longer excursions. They will test out surface systems, perform EVAs, and address 

strategic science and engineering objectives, allowing for exploration of high-interest 

science sites and demonstration of technology development objectives.

During a lunar daylight sortie, the crew will have the capability to perform daily EVAs. They 

will utilize a suitlock on the lander or a suitlock on a pressurized rover for egress. 

Unpressurized roving capability may be available for use on any given sortie. The EVA 

crew will traverse on foot nominally up to ~1.5 to 2 km (< 1 hr walk during ICM rescue) 

from the lander (safe haven), which is similar to the 1.45 km distance that the Apollo 14 

walked from their lander. When riding on an unpressurized rover, the crew will travel ~7.5-

10 km from the lander (~5 hr walk from failed rover), which is similar to the 7.6 km that the 

Apollo 17 crew traveled from their lander. During operations with a single pressurized 

rover, two crew will traverse up to ~12 km from the lander (< 8 hr walk back on full suit 

consumables).

Mission parameters and capabilities:

• Surface stay duration: 14 days (336 hours during lunar daylight)

• Crew in Gateway: 0

• Crew to surface: 4

• EVA frequency: Daily, alternating crew

• EVA duration: 6-8 hours (2-crew/EVA)

• EVA egress:

o Suitlock/airlock on lander

o Suitlock/airlock on pressurized rover

• Rover:

o Unpressurized (local daily excursions)

o Pressurized (extended multi-day excursions)

• Crew on EVA: 2-4

• 2 EV crew from lander

• 2 EV crew from pressurized rover

• Possibility of conducting EVAs simultaneously from both the land and 

pressurized rover

• EVA duration (PET): 2-8-hour excursions

• EVA frequency: Daily EVAs during full days on surface

• Possibility of a rest days after 3-4 days

• Possibility of 2 excursions per day (a day’s EVA may be split into 2 parts)

• Notional timeline: Landing day, 3 days of EVA, rest day, 3 days of EVA, rest 

day, 3 days of EVA, rest and ascent prep day, ascent day
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• Total number of EVAs: Up to 10 per EV pair possible for a 14-day mission

• Includes 2 rest days

• Total of up to ~20 EVAs possible for both EV pairs

• Possibility of 20 excursions out of the vehicle if an EVA is split into two parts 

on a day (20 cycles on suit and airlock)

• Traverse distance from lander:

o ~7.5-10 km with unpressurized rover (5 hr walk from failed rover) 

(Note: Apollo 17 traveled 7.6 km from lander)

o ~12 km with a single pressurized rover (< 8 hr walk back)

• LEA (OCSS) suits down/up: 4/4

• xEVA suits down/up: 4/0

• Science return:

o Diverse sample set

o In-situ instrument deployment 

o Multiple long-lived experiment packages deployed

• ISRU demonstration

EXTENDED STAY MISSIONS (LUNAR DAY & NIGHT, FOUR CREW)

Extended stays on the lunar surface will allow for accomplishment of the primary science 

themes. Also, as Mars is the ultimate destination goal for human exploration of the inner 

solar system, an extended stay mission provides risk reduction and capability development 

necessary for a Mars surface mission.

The extended stay lunar architecture assumes 42-day missions, occurring over two lunar 

days and one lunar night (lunar day and night are both approximately equivalent to 15 

Earth days). Two pressurized rovers will be pre-positioned for crew habitation on the lunar 

surface, which allows all four crewmembers to stay on the surface (two each in the two 

rovers). Rovers would allow long range traverses away from the lander. The rover pairs 

will operate together to complete science objectives, while always staying within rescue 

range of each other. This rescue range is the distance from which the rescuing rover can 

reach the EV crew (from other rover) and get them to a safe configuration within one hour 

(capability of secondary suit consumables). Scientific exploration activities, including EVA, 

are expanded to include long-range traverses away from the landing site with the aid of 

surface mobility assets. 

Unlike the short stay missions where EVA dominates the surface operations, a more 

balanced schedule of EVA and IVA occurs during longer duration crew missions. This is 

primarily due to the fatiguing nature of EVA over the long-term, but it is also attributable to 

consumable availability on the surface to support the EVAs. During the surface stay, EVAs 

will nominally be conducted by crews of two, however the crew has the capability to 

conduct EVAs with all crewmembers on the surface simultaneously. EVAs will be 

conducted to gather scientific samples and demonstrate in-situ resource utilization 

techniques.
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Per the ISECG May 2018 draft con ops, a lunar campaign mission scenario is as follows:

• 1st pre-deploy mission lands two pressurized rovers (mobility & habitation)

• 2nd delivers cargo for first human mission

o One large cargo mission

o One small cargo mission

• 3rd mission delivers Human Lunar Lander to Evolvable Deep Space Habitat 

in cislunar space

• Next mission lands four crew in Human Lunar Lander near the two 

pressurized rovers

• 42 days on surface - two lunar days and one lunar night

• Two crew in each pressurized rover

• Stay within 100 km of ascent vehicle during lunar day (exact distance still in 

work)

• Stay within 1 km of ascent vehicle during lunar night (exact distance still in 

work)

• Conduct three - four EVAs each week (per rover crew pair)

• Pressurized rovers are controlled from Earth to autonomously traverse to next 

landing site between crewed missions

Mission parameters and capabilities:

• Surface stay duration: 42 days during 2 lunar days & 1 night

• Crew in Gateway: 0

• Crew on surface: 4

• Egress method:

o Suitlock/airlock on lander

o Suitlock/airlock on rover

• Rover: Pressurize 

• Crew on EVA: 2-4

• 2 EV crew from each rover, alternating EVA days

• All 4 go EVA for transfer from/to the ascent vehicle

• EVA duration (PET): 2-8-hour excursions

• EVA frequency: 3-4 EVA days per week per EV pair for 42 days (6 weeks)

• EV pair alternate EVA days

• Possibility of 2 excursions per day (a day’s EVA may be split into 2 parts)

• Total number of EVAs: Up to 48 EVAs per mission

• Up to 24 EVAs per rover (EV pair)

• Includes 3-4 rest days each week for each rover crew (EV pair)

• Possibility of 48 excursions out of each vehicle/rover if an EVA is split into two 

parts on a day (48 cycles on suit and airlock)

• Traverse distance from lander:

o ~7.5-10 km with unpressurized rover (5 hr walk from failed rover) 

(Note: Apollo 17 traveled 7.6 km from lander)
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o ~12 km with a single pressurized rover (< 8 hr walk back)

o >100 km with dual pressurized rovers

• LEA (OCSS) Suits down/up: 4/4

• xEVA Suits down/up: 4/0

• Science return:

o Diverse sample set

o In-situ instrument deployment

o Multiple long-lived experiment packages deployed

• ISRU demonstration

LONG DURATION MISSIONS (SUSTAINED HUMAN PRESENCE)

A Long Duration Mission is designed to provide additional exploration capability, but may 

also be used for outpost construction, maintenance of outpost or other surface assets, or 

to provide logistics. This mission will involve building an infrastructure and will include a 

habitat and two pressurized rovers for crew habitation on the lunar surface. This type of 

mission will also likely include unpressurized rovers for traverses closer to the habitat, and 

for longer and quicker traverses than can be done on foot. In addition, there may be more 

robotic assets that can assist the EVA crew. EVA tools and sampling protocols would be 

evaluated.

These missions will also act as a “Mars Test on the Moon” and may extend a 42-day 

campaign mission to six months or more. Each crewmember will conduct three to four 

EVAs per week. These missions will likely involve considerable maintenance of the suits, 

and the crew will need an area to perform that work on the suit.

Mission parameters and capabilities:

• Surface stay duration: 42 days during 2 lunar days & 1 night

• Crew in Gateway: 0

• Crew on surface: 4

• Egress method:

o Suitlock/airlock on lander

o Suitlock/airlock on rover

o Suitlock/airlock on habitat

• Rover: Pressurize 

• Crew on EVA: 2-4

• EVA frequency: 3-4 EVAs per week for 6 months

• EVA duration (PET): 2-8-hour excursions

• Total number of EVAs: Up to 48 EVAs per mission

• 1-2 EVAs per day (a day’s EVA may be split into 2 parts)

• Total of 104-208 EVAs per mission (104 for single EVA in a day, 208 if an 

EVA is split into two parts on a day)

• Crew on EVA: Nominally 2 

• Potential to have 1, 3, or 4 crew on an EVA 
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• All 4 go EVA for transfer from/to the ascent vehicle
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APPENDIX J

DOCUMENT TREE & INFORMATION FLOW FOR XEVA SYSTEM CON OPS

This appendix shows both the systems engineering & integration (SE&I) document tree 

and the information flow for the xEVA system concept of operations. 

FIGURE J-1: XEVA SYSTEM DOCUMENT TREE PER EVA-EXP-0045
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FIGURE J-2: XEVA SYSTEM INFORMATION FLOW FOR THE CON OPS