2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 1

T/D/K Enabling/

Enhancing

Gap Name Description Status

D Enabling Dust Tolerant 

Bearings

Need pressure enclosure rotating bearings that prevent surface 

dust and regolith from entering the bearing race over extended 

hours and EVAs of long duration surface missions in order to 

preserve. After dust exposure, mechanism must fail gracefully, not 

catastrophically so as to maintain the torque and range of motion 

of the bearing within acceptable limits for use.

5/31/2016: A test procedure and setup has been developed to test the 

torque variance in wrist bearings when exposed to dust; it still needs to be 

validated. The High Performance Glove Disconnect (HPGD) System was 

developed in FY14 and included a dust seal. A revised dust-tolerant wrist 

bearing design is included in the ILC HPEG glove and will undergo testing 

in the summer of FY16. 

7/18/17: Dust tolerant bearings are part of the space suit RFI being 

released in summer 2017. Must track EVA-RD-001 updates to understand 

whether this requirement will be enabling or enhancing for xEMU. FY18 

plan includes refinement of test methodology.

9/11/2018: Dust-proof shoulder and upper arm bearings with dust-proofing 

are being procured for the xEMU Demo effort through phase III SBIR. 

Significant testing required to see if gap is closed with current design.

11/22/2019: Dust tolerant bearing designs are being incorporated in the 

xEMU design for 2024. Design Verification Testing to be performed in 

FY20 and FY21 will inform NASA as to any design changes that may be 

required to best mitigate dust intrusion into the bearing races.

12/10/2019: Delta SRR next week, confirm logic and future iterations on 

design may be needed to support later missions.

T Enhancing Plasma 

Protection

Need an integrated suit design that can withstand the plasma 

environment and protect the crewmember at each destination. 

System plasma shock dissipation and protection is used in 

conjunction with operational constraints. While the EMU is capable 

of operating in some cislunar plasma environments, enhanced 

capability is required for operational flexibility in more 

environments.

5/30/16: Phase II SBIR to address anti-shock coatings on suit hardgoods. 

CxP DSNE describes lunar environment with some limited maturity; 

document not finalized. Both AES EVA and CSSS have draft environment 

spec books that have been compiled from agency resources. Neither book 

is complete, nor endorsed. Neither project has significant resources 

available to finalize the books. We have had initial discussions with SERVI 

to address the knowledge gap/requirements definition. At this point we do 

not know how/if they will be able to help though. 

8/8/17: SBIR Phase II completed and hardware is at JSC ready for testing. 

There is potential collaboration w/ EMU for testing and early demo/cert on 

ISS. TRL 3

9/11/18: Self-healing anti-shock coating for bearings developed on SBIR is 

part of the xEMU demo effort at this time. The gateway environment 

passes into the solar wake behind the moon and the plasma charging 

environment may become more pronounced. SSERVI DREAM 2 team 

recommended making the space suit exterior conductive, though this 

poses potential problems. IRD Funding awarded for partially conductive 

fabric coating in FY19 for potential use in plasma charge dissipation. 

Knowledge gaps exist in this area as well. 

11/22/19: The need remains for effort to be dedicated to development of 

integrated plasma protection. A promising technology exists, but limited 

resources has resulted in lack of progress to date. The xEMU team is 

attempting to include an integrated plasma protection solution by 

qualification testing for 2023 suit deliveries.

Closure Duration: 3-7 years.

K Enabling Inspired CO2 

requirement

Need validated inspired CO2 limits that are relevant to suited 

operations. The current requirement set is based on wall-mounted 

sensors with no correlation to inspired vales.

10/24/2016: SA is aware of this disconnect and is tracking it on list of 

NASA-STD-3000 forward work. Some funding had been provided by HRP 

for this work.

9/11/2018: No census exists on the requirement, but research is ongoing. 

12/10/2019: HSB discuss this tomorrow based off significant research and 

discussions on this requirement. EVA community has made great progress 

and could potentially close this gap soon.

Closure Duration: 1-3 years.
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 2

T/D/K Enabling/

Enhancing

Gap Name Description Status

D Enabling Mass/Strength 

Optimized 

Composites

Need mass/stress-optimized structures for upper torso and brief. 

Surface impact and fall requirements in conjunction with optimizing 

mass are the key driving requirements when selecting a 

technology.

10/24/2016: A small amount of effort has been allocated un FY17 to 

assess HUT redesign efforts to improve packaging and reduce mass. A 

proposal was submitted to GCD Program to request funds to specifically 

evaluate high strength, low-mass composite structures. Waiting to hear 

back on award. Additionally, this could also be addressed as part of overall 

EVA architecture trades on suit pressure, suitport/suitlock interfaces, prebreathe time, etc. 

7/18/17: Waiting to hear back on GCD seedling proposal evaluation. 

Currently have 3 Phase I SBIRs working on this topic. Phase I concludes 

in FY18 and will likely result in at least 1 Phase II proposal.

9/12/2018: STMD GCD seed funding awarded for FY19 for composites 

development using new/optimized materials. Z-2.5 HUT is aluminum, 

xEMU DVT HUT may be S-glass until new composites setup is optimized.

11/22/19: There is an effort funded by GCD that is testing material 

samples and is returning promising results. Funding for the effort ends 

after FY20. Without continued research a new material will not be 

available by 2028 for infusion into the xEMU.

Closure Duration: 3-7 years.

D Enabling Dust Tolerant 

Mechanisms

Need protection of relief valves, purge valves, disconnects, 

actuators and other mechanisms to preclude dust from hampering 

motion / function. These types of functional mechanisms are 

required for long-duration EVA operations on the planetary

surface.

10/24/2016: Active dust clearing function (forced gas) was assumed during 

early connector designs for CxP. This feature is not currently included in 

the xEMU SCU connector. Two Phase 1 SBIRs (Airlock, Inc. and 

Honeybee) were funded this year to investigate possible design solutions. 

PGS has not yet invested much effort in this area to understand 

scope/difficulty of this problem. It may require actual technology 

development to solve.

9/11/2018: SBIR work for dust-proof connectors completed (insert more 

information). PGS is currently revising designs for dust-proof interfaces 

and bearings as part of the xEMU Demo effort. Current mechanism 

designs must be tested for dust compatibility.

11/22/19: Limited effort on this area is included in the xEMU 2024. xEMU 

DVT Testing will identify design and technology sensitivities for the focus 

of future work.

K Enabling Gateway 

Contingency 

EVA 

Requirements

What is needed to use a LEA suit for EVA, as is being discussed 

for Lunar Architecture or Gateway Internal EVA?

Given standard hatch diameters, assuming an xEMU does not fit, 

what LEA capabilities are needed to perform these EVAs?

Determination of the hardware solution requires expected EVA 

duration, CO2 washout, task performance etc. Capsule-based 

EVA on a limited-duration or contingency basis is more readily 

achievable. There would be significant challenges in meeting ISSstyle EVA requirements with an OCSS-style system.

EC5 performed significant initial work toward LEA EVA capability in 

support of the ARCM concept in 2013 and 2014 use. Crew consensus 

memo indicates the MACES architecture is acceptable for use in 

contingency scenarios with some modification. These comments are 

largely applicable to the OCSS system as well. The OCSS team believes 

that for contingency EVAs under 4 hours with no liquid cooling 

requirements, the system design could be very simple and potentially 

similar to the Gemini configuration. There are no open technology gaps 

required to meet properly constrained contingency EVA requirements.

12/10/2019: Gateway IAC4 analysis is being done to provide contingency 

EVA capability to Gateway. Until Gateway airlock arrives (2028) there are 

concepts to utilize the lunar lander for microgravity EVA at Gateway. 

Further work needs to be done on this topic.

T Enabling Tool Transport 

on Surface 

EVAs

Need EVA tools caddy device for each destination based on 

results of a trade study to determine if, and what type of, a tool 

caddy is needed, as compared to leaving EVA Tools on the local 

vehicle (rover, truss-mounted tool box, etc.) and having the crew 

translate/walk back and forth with tools in hand.

NEEMO 18-19 evaluated a prototype EVA Sample Bag Dispenser. 

NEEMO 20 evaluated an Integrated Geology Sampling System that 

included a “briefcase” that housed various sampling end effectors. NEEMO 

20 evaluated utilizing a robotic asset (ROV) to carry tools and samples for 

the EVA crewmembers. NEEMO 21 took initial look at sled/cart options for 

large equipment transport using several variations: No wheels, 2 wheels, 4

wheels, rope handle, and solid handle (handles were an issue). Tool caddy 

worked well, but adjustability will be a critical feature to accommodate 

different crew preferences; packing plan for caddy was critical. Evaluated 

sling bag options for small items and easy access (sample markers, hand 

tools, electronics, etc.) - conceptually good, but challenging to use with the 

dive system. Need to determine the tool compliment for each phase of the 

EVA operations, and how those tools are best transported and stowed. 

NEEMO 22 evaluated Modular Equipment Transport System (METS) for 

large and small equipment transport. Included includes 4-wheeled 

transporter and crew-worn tools on forearm and thigh.

Recommendations/Forward Work: Look into developing a harness that 

could be attached to the suit or worn over the suit in order to carry tools.

Knowledge gap for Mars environment: Need definition for amount of in-situ 

analysis to be performed on samples. Need definition of level of 

containment for samples and need programmatic definition of 

contamination limits for forward and reverse contamination. Need EVA 

Tools to perform in-field sample assessment (high grading). Need EVA 
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 3

T/D/K Enabling/

Enhancing

Gap Name Description Status

Tools to package and label samples for return to Earth. Need an EVA Tool 

set to store and manage volatile samples.

K Enabling Incapacitated 

Crewmember 

Operations

Integration: Need to develop methodology for transfer/transport of 

an incapacitated crewmember at each destination and how to 

transfer them onto the ingress/egress hardware, or through side 

hatch, and doff suit. Knowledge: Rescue protocol has not been 

identified for each destination. Determine how to address rescue 

of incapacitated crewmember on single person EVA scenarios. 

How does a 5th percentile strength crewmember rescue a 95th 

percentile mass crewmember?

Past analogs have assessed portions of rescue (Devon Island/Haughton 

Mars Project 2006, NEEMO 14, LER testing in JSC B9, DSH testing). 

During LER timeframe, work was done for crew rescue in lunar scenarios; 

however, preliminary assessments of ingress via suit port vs. side hatch 

showed suit port ingress as more acceptable. SEV design changes were 

implemented in aft cabana based on analog testing to assist in lifting and 

aligning incapacitated crew with suitport in partial gravity. Needs further 

work geared toward different DRMs and looking at varying numbers of 

crew, surface assets, and surface terrain types. NEEMO 20: Add results 

from N20. Add findings from NEEMO 21 and 22; LESA. Add 

recommendations (if agreed upon) for next steps from Incapacitated Crew 

Rescue EEWG presentation by S. Chappell Unfunded.

Microgravity knowledge gap: Closed

Surface operations knowledge gap: Open

K Enabling Required Suit 

System Center 

of Gravity and 

Mass

Need to determine the integrated center-of gravity and mass 

limitations for effective planetary exploration. How does the gravity 

field effect the performance of a given suit? Will the same suit 

design work on the surface of the Moon and on the surface of 

Mars?

11/15/2016: Z-2 mobility will be evaluated at reduced gravities at the 

ARGOS facility in 2017.

11/22/2018: Z-2 Testing did not occur at the ARGOS in 2017, there are no 

current plans for ARGOS planetary configuration testing for xEMU.

T Enhancing Alternate 

Pressure 

Garment 

Structural 

System

Need alternates to polyurethane-coated nylon/spectra 

combination. The goal of the effort is to seek improvements to 

manufacturability, cost to produce, durability, and joint torque.

11/22/19: Gap remains with no progress made toward closure.

T Enabling Lunar Surface 

EPG Shell 

Material 

System

Need suit material layups capable of long duration exposure to 

dust, and abrasive activities without compromising mobility 

(walking, kneeling, etc.). Integrated design and constructions 

methodologies should mitigate penetration of abrasive material 

(over-tape out-layer stitch holes, environmental seals, etc.).

5/31/2016: Abrasion testing of the HPEG-ILC prototype layups will occur in 

the summer of FY16. A test procedure and setup has been developed to 

expose materials to wear from abrasive dust. This procedure and setup 

has been demonstrated in one series of tests, but the findings have yet to 

be analyzed in detail. It is anticipated that iterations will be necessary. 

SBIR phase I complete with phase II in progress to address self-healing 

bladder and cut-resistant RTV replacement for glove palms.

7/18/17: HPEG final report expected

9/30/17 Divide this into Moon and Mars specific EPGs

9/12/2018: Phase II STTR for Lunar surface EPG system is in its 2nd year. 

Limited EPG development in xEMU project.

11/22/19: There is an active STTR in this area. xPGS team resources are 

limiting progress made. The baseline for xEMU 2024 is use of the ISS 

EMU materials lay-up. Significant forward work remains to provide new 

materials for lunar missions post-2024.
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 4

T/D/K Enabling/

Enhancing

Gap Name Description Status

T Enhancing Pressurized 

EVA Sizing 

Adjustments

Need ability to adjust fit of gloves and boots while pressurized.

This particularly critical for suitport operations but would benefit 

traditional EVA ops as well.

11/15/16: Z2 includes second generation adjustable boot design that 

works well at 4.3psid but is very difficult above that pressure. Adjustment 

mechanisms are included on HPEG gas-pressurized gloves but have not 

yet been tested (planned for late FY17).

7/18/17: This is an enhancing capability unless suitport concept is 

implemented.

9/12/2018: HPEG final report completed, includes some recommendations 

on sizing. EVA boots are a phase 1 SBIR topic for FY19.

11/22/19: No progress.

T Enabling Body Waste 

Management 

Solutions

During the xEMU ISS Demo SRR there were several RIDs written 

against the NASA-STD-3001 Volume 2 allocation matrix in the 

PTRS with regards to missing flow down of body waste 

management standards. Originally SSP 51073, Exploration EVA 

Suit Systems Requirement Document Baseline listed these 

standards as Applicable, but met through operational 

mitigation. The xEVA System Panel was assigned several actions 

to address the flow down of these standards.

SA assisted in burn down of these action items and brought the 

EVA/SA consolidated recommendations to the FACB on 09/19/18 

for final approval. This resulted in generation of a Memo and 

associated enclosure. An Action was assigned to SA at the 

11/29/18 TCM to review all of the NASA-STD-3001 V2 Body 

Waste Management standards applicable to the EVA Suit and 

reach an agreement on the values associated with EVAs (e.g. for 

a single EVA). These should be updated in the next revision of 

the NASA-STD-3001 V2 Section 11 standards for the suit.

There are a couple items that would lead to an EVA terminate, 

such as vomit and diarrhea. Need to ensure that there is a focus 

urine management.

New Gap per SSP 51073 Revision A process.

K Enabling Orthostatic 

Intolerance 

Countermeasur

es Solutions

It was decided that during the SSP 51073 Exploration EVA Suit 

Systems Requirements Document to Revision A Technical 

Concurrence Meeting (TCM) on 11/29/18 to open a new gap for 

Orthostatic Intolerance Countermeasures solutions. This gap is to 

address a comment received during the CR review that requested 

to change the applicability of the NASA-STD-3001 V2 flow down of 

standard V2 7042 to the PTRS from Applicable to Not Applicable 

as this capability was nominally addressed by the Launch, Abort, 

and Entry (LEA) suit. Orthostatic Intolerance Countermeasures 

are not applicable for microgravity EVA operations.

During the Dec 11, 2018 EEWG, discussion to make this gap 

broader, as Orthostatic Intolerance is just one piece of a bigger 

countermeasure and physiological deconditioning picture.

New Pending Gap per SSP 51073 Revision A process.

T Enabling Non-vacuum 

Continuous 

CO2 Removal

Need continuous CO2 removal capability that can operate within 

the Martian atmosphere. The Rapid Cycle Amine (RCA) system in 

its current form does not work in the Mars environment, and either 

a new approach, sorbent, boost compressor, or thermal swing is 

required.

7/18/17: This will be brought forward as FY18 SBIR subtopic in EVA area. 

Specific areas of interest include: 

a. Update/supersede SA9T state of the art 

i. Improvements in amine uptake 

ii. Alternative processes such as temperature swing adsorption, 

selective permeable membranes, etc. 

b. Augment SA9T operation using thermal swing adsorption approach 

c. Augment SA9T operating using boost compressor to enable pressure 

swing operation in the Martian atmosphere

12/18. 2019 Phase 1 SBIR was released under the Exploration Portable 

Life Support System (xPLSS) for deep space and surface missions 

subtopic (ID H212). Section 2.0 describes the requirements for a boost 

compressor to enable CO2 removal in partial atmosphere in combination 

with the RCA system.

Estimated gap closure duration 3-5 years.

T Enhancing Trace 

Contaminant 

Removal

Need a continuous trace contaminant removal capability that is 

regenerative (not a routinely consumable item). Activated charcoal 

is the state of the art and provides a logistics hit to all exploration 

reference missions to remove NH3, CO, CH2O, CH3SH, etc. The 

minimum objective would be to remove all of the significant 

compounds that threaten to exceed the 7-day SMAC during an 

EVA with the optimal objective to enable removal of less 

significant compounds. Ideally, this is either a passive membrane 

or actively switched regenerating beds that can be paired with the 

CO2/RH removal approach.

12/2018 Work on regenerable TCCs is currently underway on SBIR 

contracts. A phase one SBIR was completed but a Phase-II was not 

awarded.

Estimated closure duration 3-5 years.
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 5

T/D/K Enabling/

Enhancing

Gap Name Description Status

D Enhancing Radiation 

hardened 

DC/DC 

Converters

Need radiation-hardened, isolated DC/DC converters with an 

efficiency of >80%. This efficiency gain would enhance the 

performance of the PLSS by reducing the power consumption of 

the system as a whole.

For spacesuit life support systems, there are a number of small 

point of load applications such as smart instruments, controllers, 

etc. that require small, low power output, isolated DC/DC 

converters. With derating and the limited offering available from 

existing catalog parts, the available efficiency is often much lower 

than the rated efficiencies advertised for the part of 70-80% as the 

converter losses become a larger part of the overall output 

dropping the realized efficiencies below 65%. Current state of the 

art is ~70% for 28V to 5V DC/DC with MS Kennedy P/N 

BBF2805S as an example.

7/18/17: Initial round of testing on singular COTS components were 

promising (ref. PLSS tech memo) 

9/12/18: Submitted as a 2019 SBIR Phase I topic on H212, proposal call 

attached.

Estimated closure duration 2-3 years.

T Enhancing PLSS Batteries Need safe, high-energy density power sources that are 

rechargeable post-EVA. The current state of the art is Li-Ion 

batteries with cell level energy densities of ~200 Wh/kg but 

packaged energy densities of ~130Wh/kg after addressing 

mitigation for thermal runaway. Enhancing battery performance 

can reduce PLSS mass and volume, or allow for additional power 

capability.

7/18/17: Testing with COTS (same cells as LLB but different packaging) 

with EP; effort is collaborative with SAFER team. Have alternate battery 

designs from ER and AMPS.

12/18: 2018 Phase I SBIR awarded for safe, high energy space suit 

batteries. The proposed system is an ionic liquid-based hybrid electrolyte 

system. 

Estimated Closure duration 3-5 years.

T Enabling Heat Rejection 

for Vacuum 

and Nonvacuum 

Applications

Need heat rejection compatible with vacuum and Martian 

environment. The current state of the art is the Spacesuit Water 

Membrane Evaporator (SWME) with degraded performance under 

Martian conditions. LiCl radiators that capture the H2O vapor from 

the SWME provide a potential solution. A boost compressor on the 

SWME vapor outlet could potentially yield improved cooling.

12/18: An SBIR contract to develop the Lithium Chloride Absorber 

Radiator (LCAR) was completed in 2017 but the technology feasibility was 

not demonstrated. An ICES paper describing the work was published 

(https://ttu-ir.tdl.org/handle/2346/73073). 

Estimated closure duration 3-5 years.

T Enhancing Multi-gas 

Monitoring

Need a system to measure/monitor O2, CO2, H2O, NH3, CO, 

CH2O, CH3SH, etc. Measuring trace contaminants becomes more 

necessary if a pressure or temperature swing adsorption 

continuous removal approach for trace contaminants is 

implemented in an EVA system. This system would replace the 

traditional activated charcoal cartridge from the list of logistics 

items but would require measurement of system performance 

beyond user detection of odor.

7/18/17: JPL and Vista Photonics are doing a combustion products 

monitoring project for Orion and it could potentially be tuned to other 

compounds but it has not been expressly investigated for our applications.

12/18: A Phase I SBIR was awarded in 2018 for multi-gas monitoring using 

chemical sensitive field effect transistors. Intelligent Optical systems has a 

Phase III for luminesce sensors for pO2, pCO2, relative humidity, 

temperature, and pressure in a compact package. 

D Enabling Dust-tolerant 

Quick 

Disconnects

Need low mating force, small, dust tolerant quick disconnects that 

improve on the current state of the art, the EMU Service and 

Cooling Umbilical (SCU). Fluids include (2) 3750 psia oxygen 

ports, (3) 35 psi water, (1) 80pin electrical connection with a 

mandate that the connections be capable of mating/demating 

under all pressure combinations.

7/18/17: Quick disconnect meeting fluid interface requirements is under 

development as part of xEMU Lite project. Dust tolerance is a goal of that 

effort but not actively being worked or required to meet needs of DTO 

(enhancing capability).

T Enhancing Oxygen 

Pressure 

Sensor

Need a pressure sensor which is small form factor, high reliability, 

radiation hardened, and low power consumption.

7/18/17: Have GP50 sensors that can meet minimal requirements but 

improved performance for future missions is desired.

12/18: No current developmental work. 

D Enabling 5th Percentile 

Crewmember 

Fit

Need a suit that accommodates fifth percentile crewmember 

dimensions (minimum) and still accommodates all system required 

services (purge valve, umbilical services, display/control unit, 

positive pressure relief valve, etc.).

10/24/2016: A reduced profile display and control unit (DCU) prototype 

was developed to fit within the chest area of Z-2 (1st percentile female 

shoulder breadth) that accommodates listed features. A high fidelity 

version with functional SCU QD will be tested summer 2017 with Z-2.

7/18/17: HUT is being redesigned in-house to better accommodate Z-2 

size range (5th percentile shoulder breadth) and be inclusive of fluid line 

routings. Anticipate next prototype in FY18.

9/12/2018 A limited fleet sizing study is underway for xEMU, but significant 

further work is required.

11/22/19: xEMU is working toward meeting this requirement. There is an 

xEMU risk on fleet sizing because sizing has not been verified with 

hardware fit checks as yet. xEMU is currently not funded to fabricate 

hardware to cover the full sizing range.
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 6

T/D/K Enabling/

Enhancing

Gap Name Description Status

D Enhancing CO2 Sensor Need CO2/O2 sensor which is sized appropriately for inclusion in 

a PLSS, not susceptible to humidity, has accurate readings in 3 

psia to 23 psia range, and has low time between each sample 

collection and its associated reporting. The sensor should be a 

common sensor & avionics package used by EVA, ECLSS and 

others and capable of sensing a variety of gas (e.g. ammonia, 

CO2, water vapor, O2, etc.).

11/15/2016: Three different CO2 sensor designs are being developed via 

AES efforts. Two are susceptible to humidity; one is not, but it has a low 

TRL. The ISS Program has also initiated an effort to develop a drop-in 

replacement for the EMU sensor using AES technology. Design down 

select is scheduled for end FY2017. 

1. Modified EMU CO2 Sensor - high TRL, can be adapted to Advanced 

PLSS, susceptible to humidity, can be adapted to sense O2, small form 

factor 

2. Moderate TRL, susceptible to humidity, need separate detector to sense 

O2 and humidity, form factor not small Intelligent 

3. Low TRL, impervious to humidity, can sense multiple gases with one 

detector, largest form factor of three detectors 

7/18/17: ISS DTO project for CO2 sensor down selected requirements to 

only measure CO2 and water vapor. For these two aspects, there are two 

sensors at mid-TRL capability. There are no sensors today that meet 

PLSS requirements and provide measures of all listed chemicals.

9/12/18 A CO2-only sensor was selected for both the EMU CO2 sensor 

replacement and the xEMU Demo sensor. The system uses a COTS IR 

source and detector with improvements to condensation mitigation, 

simplified temperature compensation, power, and latch up recovery. 

Multigas capability with smaller form factor is still desired for the future. 

T Enhancing Alternate Suit 

Ventilation 

Circulation

Need a vent loop system with an increased head rise over 

traditional centrifugal fans. The system would ideally needs to 

yield 7-10 inches of H2O of headrise at 4.3 psia suit and provide 

flowrates in the vicinity of 4.5-6 ACFM. There is interest in 

developing ventilation techniques that would move the PLSS away 

from the current high-speed turbomachinery approach.

7/18/17: Increased vent loop fan performance as described is an 

enhancing feature desired for Mars surface missions. The PLSS can meet 

requirements for xEMU with the planned ventilation loop implementation, 

as tested in PLSS 2.0 and planned for PLSS 2.5 testing.

12/18: No current development other than the primary path xPLSS for the 

Demo development. Fan 3.0 is expected to provide 4.9 in H20 headrise 

with a single-stage centrifugal fan optimized for 35,000 rpm and a power 

draw of 10.2 Watts at 5.3 ACFM and 4.3 psia. 

D Enhancing EVA Radio Need a radiation hardened, radio programmable to support highcriticality UHF communication (voice & limited data) while 

simultaneously transmitting on a second frequency with high data 

throughput.

7/18/17: Collaborating with EV on radio (Phase II SBIR ends in FY18)

12/18: Phase III was awarded, and is on contract to deliver a DVT version 

of the system in FY19. The system is planned to be integrated to the 

xEMU Demo system. 

D Enhancing Low-mass 

Bearings

Need high strength to weight ratio pressurized bearings. 

Improvements made over the stainless-steel bearings on the EMU 

can significantly reduce the weight. Most promising current 

candidates are titanium-alloy bearings in combination with 

coatings to control surface wear.

5/31/2016: Ti bearings were included in the Z-2 construction and will be 

evaluated, for mobility and wear, through FY17. The scope of weight 

reduction includes things such as optimization of stress analysis to lean 

out the designs of composite components and bearing profiles to just meet 

2.0 FOS, for example. Obtaining softgoods that have best available 

function to mass ratio is another aspect of this. From past experience, this 

usually does not become a funding priority until a program has a launch 

mass problem. It will happen, so we would really like to get out ahead of it 

and in the process be able to realize the best possible system level design 

in parallel.

8/8/17: SBIR Phase II with titanium looks promising; concludes in FY18

9/12/2018: Phase II SBIR titanium bearing development completed, and 

Phase-III awarded to build DVT-quality hardware prototypes for the 

shoulder scye and upper arm bearing. Planned infusion to xEMU following 

completion of Phase III. Advancements should be applicable to the other 

bearing locations.

11/22/19: Titanium bearings are being included in the xEMU design where 

able. Challenges remain to meet optimal stiffness/volume/mass 

combinations.

T Enhancing Smart Thermal 

Control

Need system heat rejection method which eliminates the need for 

a separate TCV (autocooling). An ideal cooling system would not 

require user input or active control to maintain the appropriate 

thermal balance of the system.

7/18/17: Enhancing capability. The current PLSS design incorporates an 

autocooling control mode that is algorithm driven. The algorithm is 

analytically derived and should be further refined/validated with HitL 

testing.

12/18: No new status or development in this technology area. Algorithmic 

autocooling based on metabolic rate and environmental heat leakage is 

implemented on the xEMU Demo system. Innovations in this area may be 

coupled with advances to the liquid cooling garment. 
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 7

T/D/K Enabling/

Enhancing

Gap Name Description Status

T Enabling Cut/Puncture 

Resistant 

Softgoods

Need cut and puncture resistant softgoods for space suit pressure 

garment applications for planetary surface environments. Longer 

cycle lives are required than current materials can provide. Gloves 

and knees are particularly susceptible to cuts.

11/15/16: HPEG does not address increased cut/puncture resistance, selfhealing, moisture removal, or active heating components. Phase II SBIR 

investigating self-healing materials ends FY18. 

7/18/17: Phase II STTR awarded to continue investigating puncture 

resistance with Shear-thickening fluid enhanced fabrics.

12/18: Phase II STTR for EPG development ongoing, Phase II SBIR in 

closeout. The developed system was a gel-encapsulated self-healing 

bladder. A silicone RTV replacement for glove padding was also 

developed. 

T Enhancing Heat Rejection 

w/o Dedicated 

Feedwater

Need EVA System heat rejection method that does not require a 

dedicated feed water supply (i.e. runs off of cooling loop water). 

This has the potential of significantly simplifying the thermal 

control system of the PLSS.

7/18/17: Enhancing capability to reduce consumables usage and on-back 

mass.

12/18: No new status or development on this technology area. 

T Enhancing Non-venting 

Heat Rejection

Need heat rejection to function without venting into the local 

environment. Non-venting heat rejection could improve 

consumables usage compared to current technology and also 

reduce microbial contamination of the surrounding environment in 

areas where planetary protection is important.

7/18/17: Capability is expected to be required for Mars surface stays. 

Potential technologies could include further development of the SEAR, 

which combines a lithium chloride absorber radiator with the existing 

SWME radiator. 

8/12: See "Heat Rejection for Vacuum and Non-vacuum Applications" gap 

for an update on the LCAR system. No EVA suit heat rejection system not 

based on the SWME architecture is currently in development. 

T Enhancing Suitport 

System 

Concept 

Development

Need development of suitport-style concepts for planetary EVAs 

from vehicles or Habitats. The NASA suitport concept was 

developed around a rear-entry suit concept with a rigid Suit 

Interface Plate (SIP).

12/18: The current xEMU DEMO architecture is not built around the 

suitport concept and would require substantial redesign to accommodate. 

The suitport architecture should be explored and developed outside the 

xEMU primary path. Potential topics for initial research or collaboration 

might include: 

1. Hatch opening mechanism (hinges, lock/unlock, and self-don/doff), 

2. Elegant integration of SIP (permanent or removable), 

3. Build vibration model for suits dangling off suitport, or 

4. Elegant solutions for heat sink on SIP.

D Enhancing Thermostat 

Glove Heater 

Control

Need a glove heater system that can automatically maintain safe 

operating temperatures in the suit glove. An automatic thermostat 

controlled system could optimize power draw and eliminate the 

bulky user control in the suit gauntlet area.

12/18: No work initiated. Current EMU system uses an on-off pull tab 

actuated switch in the glove gauntlet to active the fingertip heater 

elements. 

T Enhancing Antimicrobial/antifungal bladder 

materials

Need material for use within the TCU, bladder, and LCVG that is 

antimicrobial, antifungal, non-toxic, and O2 compatible. (NASASTD-3001v2: 4.5.2-4)

5/31/2016: CSSS began to address this gap as part of their LVCG 

development effort but the status of that effort is unknown. Internal testing 

was conducted in 2010 and is documented in CTSD-CX-0120.

T Enhancing EVA Glove 

Mobility and 

Durability

Current gloves result in approx. 75% loss of functional 

performance (combined strength and mobility) upon donning and 

pressurizing. Gloves have the shortest effective use life of all EVA 

pressure garment components, mostly due to the severity of sharp 

and abrasive hazards found on EVA external interfaces. Glove 

Thermal Micrometeoroid Garments (TMG) are the first pressure 

garment components to wear out and must be frequently replaced 

on the ISS.

11/15/2016: Two new gas pressurized glove prototypes were delivered 

under the HPEG project in FY16. The gloves are being evaluated in the 

glovebox at for mobility at 0, 4.3, and 8.0 psid using the HPEG Glove 

Mobility Protocol. Test results expected to be published Sept, 2017.

9/12/2018: HPEG results published, EMU phase VI is planning an upgrade 

that incorporates some of the recommended changes. 

K Quantifying 

Suited Mobility

A consistent and validated methodology does not exist to assess 

the mobility of a space suit system at the integrated level- neither 

for benchmarking comparisons nor for requirements verification.

11/15/16: The PGS team, in collaboration with HRP, are investigating new 

concepts in suited human performance (energy-mobility and EVA 

benchmarking), which show promise but will require further development 

as part of HRP funded effort in FY16-18. Still require better methodologies 

to decompose suited human performance requirement to component-level 

design. We have good data on single-axis joints and bearings, but 

complex mobility elements pose challenges.

9/12/2018: HRP EVA benchmarking reduced scope to focus on micro-g 

environments. Results pending.

K Enabling External 

Environments 

Handbook

Need properties of dust environment at each destination. Need a 

NASA-endorsed handbook that describes dust environment for 

each destination. Need definition of each destination's 

environmental hazards, including dust constituents. What is the 

chemical composition of the dust and its characteristics, to include 

particle size and shapes? Do the properties change when exposed 

to a habitable environment (pressure, humidity, etc.)? Need 

radiation environments definition at all locations; unknown material 

degradation due to radiation beyond LEO; this applies to 

softgoods, hardgoods, and electronics.

10/12/2016: The EVA Office is attempting to populate and baseline an 

environments standard for community review and buy-in. Initial draft and 

ToC available. CSSS completed TDS #1139, System Level Radiation 

Requirements Analysis which includes cis-lunar and mars radiation 

environments. CxP DSNE describes lunar environment with some limited 

maturity; document not finalized. Both AES EVA and CSSS have draft 

environment spec books that have been compiled from agency resources. 

Neither book is complete, nor endorsed. Neither project has significant 

resources available to finalize the books.

9/12/18 Significant work is still required, DSNE is largely unpopulated for 

these topics.
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 8

T/D/K Enabling/

Enhancing

Gap Name Description Status

T Enabling Mars 

Environment 

Thermal 

Insulation

Need pressure garments with insulation suited for wider range 

thermal environments, particularly in the Martian atmosphere 

environment where vacuum MLI is not effective.

11/15/16: HPEG has Aerogel and hybridshield materials have been 

incorporated into the prototypes to improve thermal performance. Thermal 

testing of the layups is current underway (report end of FY17).

12/18: No new status, significant development required to achieve 

adequate thermal performance without sacrificing mobility. 

T Enhancing Scratch 

Resistant Visor 

System

Need visor that can be on-orbit maintained and potentially repaired 

and reused after use in an abrasive or dusty environment.

5/30/16: Z-2 was delivered with a protective visor that is capable of rapid 

R&R 

7/18/17: Add reference to prior SBIR P1 report and NCSU student report. 

This capability would be enhancing for ISS and DSG.

12/18: Z-2.5 Incorporates a scratch resistant coating, testing is underway. 

This system is not expected to be the ultimate solution.

T Enhancing Reusable Drink 

Bag

Need a reusable drink bag that is not susceptible to biological 

build-up and that requires limited maintenance between EVA uses, 

to decrease the amount of logistics during long duration missions. 

Solutions could include multi-use, cleanable, or extremely 

light/cheap disposable options.

ISS DIDB is disposable, not infinitely reusable. Prior to implementation of 

the DIDB, the EMU utilized a reusable drink bag. This system worked well 

for Shuttle missions with short durations between EVAs. However, due to 

drying and cleaning issues, this was not a practical solution for space 

station. However trade space could be reopened to meet needs without

new tech (just fly more DIDBs).

12/18: There has been no new work or updates in this technology area. 

K Enabling Martian 

Dust/Regolith 

Properties

Will dust that is built up on outer layer of the suit affect thermal 

capabilities? Need properties of dust and dust storms at each 

destination to inform dust resistance requirements for visor. Will 

one scratch resistant solution work for all destinations? What type 

of Mars particulates exist? Are they corrosive to filters? Need to 

know chemical and physical properties of the dust. Mars soil is 

known to contain perchlorates which may have adverse effects on 

materials used in space suit construction, notably stainless steel 

and potentially softgoods.

12/10/2019: No new status

D Seasonably 

Variable TMG

Need appropriate TMG for "seasonal" thermal environment 

changes over course of long duration Mars surface mission with 

quick changeout features at suit interface.

11/15/16: Aerogel being evaluated within the HPEG effort, co-funded by 

OCT and AES. FY12/13 testing of prelim material assessed durability and 

conductive heat transfer. FY14 effort to assess the aerogel thermal 

insulation as stitched into a prototype glove assembly. Thermal evaluation 

of prototype assembly effort ceased due to inability to develop an effective 

test method. FY16 testing of prototype glove layups continues.

D Enhancing Cooling 

Garment

Need cooling garment with improved UA over Shuttle version 

(SotA). Improve the UA such that warmer water can be used to 

sink the waste heat from the human and hence reduce the 

evaporator size or potential need for boost compressor/radiator. 

Drastically alter the human to cooling loop interfaces such as a 

fluid filled suit with pumped directly cooled water.

11/15/2016: CSSS RL-LCVG was tested as part of PLSS 2.0 HITL testing 

but did not show improvement in cooling efficiency over the EMU LCVG. 

7/18/17: For primary cooling, the current LCVG is sufficient. Improved UA 

would be enhancing from PLSS thermal loop power and reliability 

perspective, but is not required. A secondary LCG cooling loop is required 

to meet xEMU-Lite design requirements for abort return capability. HITL

testing of the CSSS concept demonstrated adequate cooling but design 

improvements with respect to PGS interfaces and crew comfort are

warranted.

12/18: Awarded a 2018 Phase I SBIR to investigate ways cooling 

garments could be optimized. 

K Enhancing Defining SuitHuman 

Interactions

Need an in-suit ground sensor package to provide data on humanto-suit interactions and therefore, improve the ability to design 

suits which are less likely to injure suit occupants. Specifically 

desire to understand the ergonomic implications of exploration 

space suit architectures, notably rear-entry, waist belt, shoulder 

straps, PLSS interface, and indexing of the suit to the person 

(sizing, padding, etc.).

5/31/2016: Current scope does not include assessment by an ergonomist

to assess Z-2 during analog operations (ARGOS, rock pile) with geology 

and other exploration tasks. 

8/8/17: HRP has funded MIT to evaluate "shoulder injury" and injury 

countermeasures specifically from 2014-2017.

12/18: Requires update on H3PO work in this area.

T Enhancing Disposable/No

n-Reusable 

EVA Suit 

Concept

Need concepts for reduced-capability, non-reusable EVA systems 

to trade against the current high-performance modular system.

12/18: awarded a 2018 Phase I SBIR to develop a low-cost, non-reusable

PLSS concept. 

K Enhancing EVA Crew 

Required 

Capabilities

The physiological and cognitive performance capabilities that will 

be required of crewmembers during exploration EVA are not 

adequately understood.

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

additional documentation 

at https://humanresearchroadmap.nasa.gov/Gaps/gap.aspx?i=303

.

12/10/2019: No new status

K Enhancing EVA Suit 

Design for 

Human Health 

& Performance

The effects of suit design parameters on crew health and 

performance (physical and cognitive) during exploration EVA are 

not adequately understood.

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

12/10/2019: No new status
2020 EVA System Maturation Team Gap List

Last Update: January 10, 2020 9

T/D/K Enabling/

Enhancing

Gap Name Description Status

additional documentation 

at https://humanresearchroadmap.nasa.gov/Gaps/gap.aspx?i=304

.

K Enhancing EVA Suit Sizing 

& Fit

How does EVA suit sizing and fit affect crew health, performance, 

and injury risk?

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

additional documentation 

at https://humanresearchroadmap.nasa.gov/Gaps/gap.aspx?i=653

.

12/10/2019: No new status

K Enhancing EVA 

Physiological 

Inputs and 

Outputs

The physiological inputs and outputs associated with EVA 

operations in exploration environments are not adequately 

understood.

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

additional documentation 

at https://humanresearchroadmap.nasa.gov/Gaps/gap.aspx?i=306

.

12/10/2019: No new status

K Enhancing EVA ConOps

for Human 

Health & 

Performance

The effect on crew health & performance (physical & cognitive) of 

variations in EVA task design and operations concepts for 

exploration environments are not adequately understood.

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

additional documentation 

at https://humanresearchroadmap.nasa.gov/Gaps/gap.aspx?i=311

.

12/10/2019: No new status

K Enhancing EVA 

Informatics for 

Health & 

Performance

The knowledge and use of real-time physiological, system, and 

operational parameters during EVA operations to improve crew 

health and performance (physical & cognitive) is not adequately 

understood.

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

additional documentation 

at https://humanresearchroadmap.nasa.gov/Gaps/gap.aspx?i=308

.

12/10/2019: No new status

K Enhancing EVA Injury Risk 

& Mitigation

The risk of crew injury due to exploration EVA operations and 

methods for mitigating that risk are not adequately understood.

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

additional documentation 

at https://humanresearchroadmap.nasa.gov/Gaps/gap.aspx?i=312

.

12/10/2019: No new status

K Enabling EVA 

Exploration 

Prebreathe

The DCS mitigation strategies and associated impacts on mission 

timelines, consumables, and the design of EVA and habitat 

systems for exploration missions are not adequately understood.

This is a human health and performance gap shared by the Crew 

Health and Performance SMT and Human Research Program with 

additional documentation 

at https://humanresearchroadmap.nasa.gov/Risks/risk.aspx?i=168

.

12/10/2019: No new status

D Enhancing Bio-med sensor Need a radiation hardened, wearable biomedical system which 

does not require the crew to shave.

11/15/16: Options were evaluated by CSSS. There should be an 

engineering report on the topic but it cannot be located at this time. 

7/18/17: Enhancing capability for xEMU Lite (can meet requirements with 

EMU system). No planned work in this area.

9/12/18: Heart rate only is the planned biomed capability for xEMU. 

Current design is an adapted wireless commercial system that does not 

require shaving.