Conjunction Assessment Process

For Mars Orbiters

Revision 3

Authors: 

David Berry, Mission Design and Navigation Section MADCAP Representative

Joe Guinn, Deputy Division Manager, Division 39, Mission Systems & Operations

May 2022

D-93790, Revision 3

Jet Propulsion Laboratory

California Institute of Technology

© 2022 California Institute of Technology. Government sponsorship acknowledged. 

URS309986 CL#22-3991
This document has been reviewed and determined not to contain export controlled technical data. URS309986 CL#22-3991 ii

DOCUMENT CHANGE LOG

DATE PAGES AFFECTED REASON FOR CHANGE VERSION/

REVISION

5/28/2014 All Initial version Initial

1/31/2015 14-17 Added Appendix 1

1/8/2018 8, 9-10, 13 Clarified Response Process 

Flowchart. Updated monitoring and 

response notification lists. Updated 

Sample Monitoring Message 

2

5/26/2022 All Periodic update for currency, major 

revisions to reflect actual practice

3
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Table Of Contents

1 Introduction and Brief History 1

2 Driving Requirements 2

3 Procedure 3

4 Monitoring Function (Daily*) 4

5 Response Notifications 5

6 Non-NASA Vehicles Considerations 5

7 Inactive Vehicles Considerations 5

8 Natural Body Considerations 5

9 Sample Response Message (Associated w/Next Section) 6

10 Sample Monitor Message: Red Event with 2 Spacecraft 7

11 Sample Monitor Message: Red Event with 1 Spacecraft, 1 Natural Object 10

12 References 13

13 Acknowledgment 13
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1 Introduction and Brief History

In May 2005, Mars Odyssey and Mars Express (MEX) experienced a close approach (<10km with orbit 

crossing <1km). Uncertainties in the MEX trajectory led ESA to perform an avoidance maneuver. No formal 

process was in place at that time. In mid-2006, the MRO navigation team developed a collision avoidance 

(COLA) process that was used initially during aerobraking operations. MRO performed 27 aerobraking 

maneuvers, six of which were executed to avoid possible collisions with other spacecraft. In summer 2011, 

the MADCAP process (MArs Deepspace Collision Avoidance Program) was instituted for regular weekly

monitoring of Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter. [Note: Earlier versions of 

the MADCAP process were referred to as a Mars COLlision Avoidance (COLA) process.] Non-operating 

spacecraft such as MGS and the Viking 1 orbiter were also included. The process was progressively 

formalized. In June 2012, the process was presented at the SpaceOps Conference in Stockholm, Sweden. 

In early 2014, the first version of this document formalizing the process was negotiated (see Document 

"Change Log" above for subsequent revision history). In late 2014, a new release of the MADCAP software 

was produced in preparation for the arrival of MAVEN and MOM at Mars; MADCAP was re-christened

"Multimission Automated Deepspace Conjunction Assessment Process". Since that time, approximately 

annual software updates have been implemented with bug fixes and improvements to 

scheduling, processing, reports, and report distribution lists. Several conference papers have reported 

MADCAP progress (see "References").

This document describes the conjunction assessment process that routinely monitors Mars-orbiting 

spacecraft trajectories for future orbit crossings and close approaches, as it exists today; there have been 

several changes to the initially negotiated process based on the reality of Mars orbiter operations (e.g., the 

original process involved the MPO in setting up meetings to discuss maneuvers upon each "red event"; in 

practice this has not been necessary). The process uses the aforementioned MADCAP automated 

navigation utility that executes on secure flight network computers at JPL. MADCAP is built upon JPL's 

Monte multimission navigation software. Requirements, a technical description, and user guide for 

MADCAP are available in the EPDM. The process takes advantage of and depends on the availability

ephemeris predictions provided to the DSN by flight projects (including non-NASA vehicles) for tracking 

and communications support. Summary Reports are sent to stakeholders by email via tailored email lists.

The process consists of Monitoring and Response Functions (see Section 3). The Monitoring Function is 

implemented via a daily Summary Report emailed to interested parties. The Response Function is invoked

when there is a red event reported in the Summary Report. In these cases, a JPL MDNAV MADCAP 

Representative will work with the navigation team(s) involved to determine a course of action. In some 

cases, collision avoidance maneuvers are negotiated between the affected flight project teams. In the event 

a response plan cannot be agreed upon by the affected flight projects, the Manager of the Mars Program

Office (MPO) will determine the final response via a Conflict Resolution Process.

This document formalizes the conjunction assessment process in use for missions currently in orbit at Mars. 

As spacecraft (including non-NASA missions) are added to the existing fleet in orbit at Mars, every effort 

will be made to include them in this process.

A virtually identical process is also in use for Lunar orbiters and objects at Sun/Earth Lagrange Points.
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2 Driving Requirements

1. The MADCAP shall perform conjunction assessment analyses routinely for all maneuverable Mars

orbiting spacecraft and natural satellites. (MADCAP Requirements A.015, M.067, A.030)

2. The MADCAP shall identify potentially high risk Mars orbiter close approaches and communicate any 

to key stakeholders sufficiently in advance to enable an avoidance response. (MADCAP 

Requirements G.017, R.005)

3. The MADCAP shall maintain (on best efforts basis) estimated locations of non-functioning Marsorbiting spacecraft. (MADCAP Requirement G.020)
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3 Procedure

MONITORING FUNCTION

Step Who Action

1

JPL MDNAV (Mission 

Design and Navigation)

MADCAP Rep

Ensure routine daily execution of monitoring software to identify 

predicted close approaches (orbit crossing distances and orbit crossing 

timings). Provide daily summary to “Monitoring” group. (See Section 4.)

2 MDNAV MADCAP Rep

Invoke "Response Function" when the daily summary report shows that 

any close approach (orbit crossing distance AND orbit crossing timing)

within 14 days from run time falls below pre-defined thresholds 

(hereafter called a "red event"). 

RESPONSE FUNCTION

3 MDNAV MADCAP Rep Communicate with affected NAV Team Chiefs within 24 hours to 

confirm that they are aware of the reported red event. 

4

MDNAV MADCAP Rep 

and Flight Project 

Navigation (NAV) Reps

Discuss options and agree to recommended response actions to red 

event, which may include actions by at least one and possibly both 

flight projects. Obtain approvals as necessary. Depending on the timeto-go until the red event, "watch" may be the initial action.

5 MDNAV MADCAP Rep

Within 24 hours of discussing with NAV Team Chiefs, communicate 

reported red event and proposed action outcome to the identified 

“Response” group. (See Section 5.) Invoke "Conflict Resolution 

Function" in the event that agreement on action cannot be obtained.

6 Flight Project(s) Nav Prepare to implement agreed response action(s), e.g., design, build, 

and test of avoidance maneuver (if applicable).

7 All Continue Monitoring Function while response action is prepared

8 MDNAV MADCAP Rep

If response involves a maneuver, and if requested by flight project(s), 

execute a MADCAP test run (on a best effort basis) to confirm planned 

avoidance maneuver (a) mitigates red event risk and (b) no new 

threshold violations result.

9 Flight Project(s) Implement agreed response action(s) if/when desirable or necessary.

Confirm proper execution.

10 All Continue Monitoring Function (end of process).

CONFLICT RESOLUTION FUNCTION

N/A N/A

Next steps are conditional and only exercised if the normal process fails

(e.g., high criticality event, flight projects cannot agree on response 

actions, there is disagreement with proposed response actions, lack of 

response by a flight project involved in red event, etc.)

11 MDNAV MADCAP Rep

Convene a meeting with decision makers of affected flight project 

teams. Discuss issues with candidate response actions. Negotiate and 

iterate until agreement is reached. This may involve concurrence with

the NAV recommendation or an alternate response. This process may 

have to be modified for red events that do not involve NASA satellites.

Determine appropriate escalation if agreement cannot be reached.

12 MDNAV MADCAP Rep Communicate agreed action outcome to the identified “Response” 

group. (See Section 5.)

13 All Go to Step 5 of Response Function.
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4 Monitoring Function (Daily*)

*Frequency of execution used for current Mars orbiters. Frequency can be increased/decreased if 

conditions render it necessary or desirable. Red event threshold values are based on each Project's threesigma trajectory uncertainty estimates and are provided by the Project to the MADCAP Team.

The MADCAP Summary Report is emailed to interested parties maintained in an email list 

(mars_madcap_monitor@list.jpl.nasa.gov) maintained by the MDNAV MADCAP Representative. It is 

essentially open to subscription by parties interested in the Mars orbital environment. It provides information 

about pairwise orbit crossing distances, orbit crossing timing, and closest approaches based on flight 

project determined thresholds. Lander and flyby missions are included in MADCAP analyses during final 

approach. The organizations and personnel represented in this list (as of publication date) include at least:

• Mars Program Office Representatives

• Mars Orbiter Flight Projects (modified as missions are added/retired): 

• NASA Mars Odyssey (ODY)

• ESA Mars Express (MEX)

• NASA Mars Reconnaissance Orbiter (MRO)

• NASA Mars Atmosphere and Volatile Evolution (MAVEN)

• ISRO Mars Orbiter Mission (MOM)

• ESA ExoMars Trace Gas Orbiter (TGO)

• UAESA/Hope

• CNSA/Tianwen-1 (Note: Special distribution mechanism for this report recipient)

• JPL MDNAV Section Management Team

• MGSS Program Office

• NASA CARA Representative

• MADCAP Representatives
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5 Response Notifications

The Response Report is sent to designated leadership with respect to the missions involved in a MADCAP 

"red event" (i.e., orbit crossing distance AND orbit crossing timing both below mission defined thresholds

within 14 days from run time). A list of designated recipients for each interest group is maintained by the 

MDNAV MADCAP representative. Missions indicate who they would like to receive the red event messages. 

"Response" notifications are tailored for the missions involved in the red event and include a preliminary 

recommendation for addressing the situation (see Section 9). The organizations that are represented in this 

list (as of publication date) include:

• Mars Orbiter Flight Projects (generally two of the following):

• NASA Mars Odyssey (ODY)

• ESA Mars Express (MEX)

• NASA Mars Reconnaissance Orbiter (MRO)

• NASA Mars Atmosphere and Volatile Evolution (MAVEN)

• ISRO Mars Orbiter Mission (MOM)

• ESA ExoMars Trace Gas Orbiter (TGO)

• UAESA/Hope

• CNSA/Tianwen-1 (Note: Special distribution mechanism for this report recipient... recipients also 

include NASA/Office of International and Interagency Relations) 

• Mars Exploration Program Office Representatives

• JPL MDNAV Section Management Team

• MGSS Program Office

• NASA CARA Representative

• MADCAP Representatives

6 Non-NASA Vehicles Considerations

Non-NASA Mars spacecraft (e.g., ESA/Mars Express, ISRO/MOM, ESA/TGO, etc.) will be included in the 

MADCAP process to the extent that accurate trajectory prediction information is available. Use of the DSN 

for tracking and communication services by those missions facilitates but is not required for the Monitoring

and Response functions.

7 Inactive Vehicles Considerations

Conjunction events for inactive Mars orbiters are not included in the summary reporting messages. 

However, for MGS (Mars Global Surveyor) and Viking 1/2, end-of-mission orbital states are used to produce 

long-term future predictions of orbit crossings and close approach estimates and are available upon 

request. Given the large orbital uncertainties the orbit crossing and close approach data are of marginal 

value. Bands of inclination may be the only useful information.

8 Natural Body Considerations

Ephemerides for the Mars natural satellites Phobos and Deimos are used in the daily analyses; these are 

prepared by the Solar System Dynamics group in the MDN Section and used in Mars orbiter operations.

Conjunctions of a spacecraft and one of the satellites are included in the summary reporting messages.

Special considerations in threshold settings are necessary for the natural satellites given that (a) the 

ephemeris position is predicted with respect to the center of gravity of the body, and (b) the body has 

significant size compared to a spacecraft, and unlike a spacecraft cannot be treated as essentially a point 

mass.
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9 Sample Response Message (Associated w/Next Section)

From: David Berry <david.s.berry@jpl.nasa.gov>

Date: Thursday, July 9, 2020 at 3:18 PM

To: <<list of recipients based on conjunction>>

Subject: FW: MADCAP -- Mars -- Summary -- 1 Red

All,

In today's MADCAP Summary report (shown below) one Red event was 

triggered for Odyssey/MAVEN on 2020-07-23.

The recommendation at this time is:

• COLLISION AVOIDANCE ACTION is watch this predicted close approach. 

Justification for Recommendation

================================

This event is at the 14-day red event boundary, and in that span of time 

conditions often change between the analysis and the predicted event. 

According to the MAVEN Navigation Team Chief, the MAVEN team will have 

maneuver opportunities for this over a week in the future, at which time 

they will look at this in detail and plan to take action if the red 

event persists.

Background

========== 

Per the Conjunction Assessment Process for Mars Orbiters (JPL D-93790, 

Revision 2, 2018-01-08), a recommended response by the

MDNAV MADCAP representative and the navigation teams involved is 

required when a close approach is predicted in less than 14 days to be 

within pre-defined threshold values. These events are flagged as "Red" 

events in the daily monitor email sent to the Mars MADCAP monitor mail 

list.

Regards,

David Berry

MDNAV MADCAP Representative
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10 Sample Monitor Message: Red Event with 2 Spacecraft

Analysis Time: 2020-07-09 21:30:20 UTC

RED Threshold Updates: 0

ALL Threshold Updates: 0

Ephemeris Updates: 2

Conjunction Assessment Bodies and Types

Body Name Type

1 Odyssey Active

1r Odyssey Active/Reference

2 Mars_Express Active

3 MRO Active

4 MAVEN Active

5 MOM Active

6 TGO Active

7 Phobos Natural

8 Deimos Natural

9 Viking1 Inactive

10 MGS Inactive

Red (Conjunction Data < 'Red' Thresholds and Event < 14 days from Analysis Time)

Bodies OXD value/limit 

(km)

OXT value/limit 

(sec)

CAD value/limit 

(km)

CA Epoch (UTCSCET)

1-4 1.5 4.1 4P 168.6 257.4 4P 292.1 ----- -- 2020-07-23 

00:25:39

All (Conjunction Data < 'All' Thresholds for <= 100 days)

Bodies OXD (km) OXT (sec) CAD (km) CA Epoch (UTC-SCET)

1-4 -4.3 -1105.7 1893.4 2020-07-22 20:39:41

1-4 -2.1 6004.6 2787.9 2020-07-22 21:37:12

1-4 1.5 168.6 292.1 2020-07-23 00:25:39

1-4 1.3 7284.4 2703.0 2020-07-23 01:28:10

1-4 2.8 1450.5 2301.4 2020-07-23 04:10:44

3-4 -8.2 -897.2 2289.3 2020-08-06 13:12:00

3-4 -4.2 -393.9 1024.0 2020-08-06 16:51:43

3-4 -2.9 122.1 318.5 2020-08-06 20:31:11

3-4 -1.5 635.4 1631.3 2020-08-07 00:10:32

3-4 -0.8 1138.0 2827.4 2020-08-07 03:49:48

1r-6 8.6 31.4 95.6 2020-08-08 16:35:27

Notes
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OXD means "Orbit Crossing Distance". OXT means "Orbit Crossing Timing". CAD means 

"Close Approach Distance".

Data for active spacecraft and natural bodies are displayed in the tables above. Data 

for inactive spacecraft are not displayed, but they are available in the conjunction 

metric tables and plots, which have been stored in the output directory listed below. 

Data for reference trajectories are not considered for Red events, but are considered 

in the All section for events not covered by the predicts file. Reference trajectories 

use the same thresholds as the nominal trajectories.

For more information, please see the point of contact listed below.

Analysis time: 2020-07-09 21:30:20 UTC

Active spacecraft: Odyssey, Mars Express, MRO, MAVEN, MOM, TGO

Natural bodies: Phobos, Deimos

Inactive spacecraft: Viking1, MGS

Output directory: /nav/home/jplmdnav/MADCAP/Mars/archive

Point of contact: MADCAP_Mars@jpl.nasa.gov

MADCAP build: 3.0

Red Thresholds -- Polynomial Coefficients

Body Name OXD0 

(km)

OXD1 

(km/t)

OXD2 

(km/t^2)

OXT0 

(sec)

OXT1 

(sec/t)

OXT2 

(sec/t^2)

1 Odyssey 0.0050 0.0013 0.0000 0.0705 -0.0411 0.0096

2 Mars_Express 1.0000 0.0000 0.0000 10.0000 0.0000 0.0000

3 MRO 0.0877 -0.0315 0.0040 0.0100 0.4939 0.0765

4 MAVEN 0.5000 0.2300 0.0030 2.1000 2.8000 1.2300

5 MOM 0.2498 0.0014 0.0012 0.0100 33.0089 0.3246

6 TGO 1.0000 0.0000 0.0000 10.0000 0.0000 0.0000

7 Phobos 30.0000 0.0000 0.0000 15.0000 0.0000 0.0000

8 Deimos 40.0000 0.0000 0.0000 20.0000 0.0000 0.0000

Red OX Distance Threshold = OXD0 + (OXD1 * t) + (OXD2 * t^2) [km]

Red OX Timing Threshold = OXT0 + (OXT1 * t) + (OXT2 * t^2) [sec]

where t = CA Epoch - Ephemeris File Submit Time (in days)

Red thresholds are based on 3-sigma values. Thresholds listed as "P" are based on a 

quadratic fit of the 3-sigma values as a function of time to the event. The polynomial 

coefficients used are listed in the table above. Lines for coefficients which have 

been updated since the last run are colored blue, and each line's body is marked with 

an "*". Thresholds listed as "C" are based on 3-sigma covariance data provided by the 

mission.

All Thresholds -- Constants

Body Name OXD (km) CAD (km)

1 Odyssey 10 100

2 Mars_Express 10 100

3 MRO 10 300

4 MAVEN 10 3000

5 MOM 20 100

6 TGO 10 100
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7 Phobos 45 100

8 Deimos 60 200

All OX Distance Threshold = OXD

All CA Distance Threshold = CAD

All thresholds are always constants. The constants used are listed in the table above. 

Lines for constants which have been updated since the last run are colored blue, and 

each line's body is marked with an "*".

Ephemerides

Body Ephemeris Submitted Begin End

1 p_m_od82331-82333_82666_v1.bsp 2020-07-07 

00:35:45 UTC

06-JUL-2020 

11:21:50 UTC

02-AUG-2020 

23:58:50 UTC

1r p_m_od82071-82076_83382_v1.bsp_V0.1 Analysis Time 15-JUN-2020 

01:45:50 UTC

30-SEP-2020 

23:58:50 UTC

2 MOEM_200706OAS_PREDICT__0001.CR.bsp 2020-07-06 

10:16:27 UTC

25-JUN-2020 

21:48:17 UTC

05-AUG-2020 

07:59:17 UTC

3* pf_psp_rec65401_65399_66364_p-v1.bsp 2020-07-09 

16:34:21 UTC

09-JUL-2020 

08:55:50 UTC

22-SEP-2020 

13:45:50 UTC

4* trj_orb_11897-11900_12147_v1_mvn.bsp 2020-07-09 

16:55:01 UTC

09-JUL-2020 

01:04:29 UTC

15-AUG-2020 

10:21:11 UTC

5 ISRO-MOM-2020-06-30-OD2436-189-

v1.bsp

2020-07-07 

17:28:36 UTC

30-JUN-2020 

00:00:00 UTC

05-AUG-2020 

00:10:00 UTC

6 TOEM_200706OAS_PREDICT__0001.CR.bsp 2020-07-06 

09:53:57 UTC

05-JUL-2020 

23:50:54 UTC

15-AUG-2020 

16:41:20 UTC

7 mar097.2010-2029.bsp Analysis Time 29-DEC-2009 

23:58:53 UTC

01-JAN-2030 

23:58:50 UTC

8 mar097.2010-2029.bsp Analysis Time 29-DEC-2009 

23:58:53 UTC

01-JAN-2030 

23:58:50 UTC

9 Viking1_200101_210101.boa Analysis Time 31-DEC-2019 

23:58:50 UTC

31-DEC-2020 

23:58:50 UTC

10 p_191030-201029-

061215_10yr_nominal.nio Analysis Time 30-OCT-2019 05:28:50 UTC

29-OCT-2020 

06:28:50 UTC

Ephemeris files for the bodies analyzed are listed in the table above. Lines for files 

which have been updated since the last run are colored blue, and each line's body is 

marked with an "*".
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11 Sample Monitor Message: Red Event with 1 Spacecraft, 

1 Natural Object

Analysis Time: 2020-05-28 21:30:20 UTC

RED Threshold Updates: 0

ALL Threshold Updates: 0

Ephemeris Updates: 2

Conjunction Assessment Bodies and Types

Body Name Type

1 Odyssey Active

1r Odyssey Active/Reference

2 Mars_Express Active

3 MRO Active

4 MAVEN Active

5 MOM Active

6 TGO Active

7 Phobos Natural

8 Deimos Natural

9 Viking1 Inactive

10 MGS Inactive

Red (Conjunction Data < 'Red' Thresholds and Event < 14 days from Analysis Time)

Bodies OXD value/limit 

(km)

OXT value/limit 

(sec)

CAD value/limit 

(km)

CA Epoch (UTCSCET)

5-7 3.9 30.0 7P 67.4 817.2 5P 73.3 ----- -- 2020-06-11 

10:57:28

All (Conjunction Data < 'All' Thresholds for <= 100 days)

Bodies OXD (km) OXT (sec) CAD (km) CA Epoch (UTC-SCET)

4-5 4.6 101.3 256.9 2020-05-31 09:26:22

3-4 -5.0 5677.2 543.5 2020-05-31 20:10:37

3-4 1.4 -574.3 281.8 2020-05-31 23:50:47

3-4 2.0 6154.8 2530.9 2020-06-01 00:50:34

3-4 7.3 -98.2 45.5 2020-06-01 03:30:50

3-4 7.4 6631.0 2828.6 2020-06-01 04:32:44

3-4 7.0 -6360.7 2680.5 2020-06-07 17:10:47

3-4 5.9 370.3 192.5 2020-06-07 18:11:19

4-6 9.0 1906.5 2118.8 2020-06-08 19:10:22

4-6 7.9 702.1 885.1 2020-06-08 22:55:04

1-6 9.4 7050.2 25.3 2020-06-09 01:24:23

4-6 10.0 6585.5 2500.9 2020-06-09 01:40:15

4-6 7.8 -492.8 640.8 2020-06-09 02:40:05

4-6 7.8 5390.8 2501.0 2020-06-09 05:29:03
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1-6 9.7 41.7 43.9 2020-06-09 06:19:52

4-6 3.2 -1695.1 2110.1 2020-06-09 06:26:17

1-6 9.3 -7040.0 89.4 2020-06-09 07:19:04

1-6 9.3 77.5 80.8 2020-06-09 08:18:08

4-6 3.7 4187.6 2718.0 2020-06-09 09:16:12

4-6 0.7 1791.4 1972.8 2020-06-09 16:46:48

4-6 0.1 7672.8 2900.6 2020-06-09 19:26:42

4-6 -2.4 585.4 725.9 2020-06-09 20:31:30

5-7 3.9 67.4 73.3 2020-06-11 10:57:28

Notes

OXD means "Orbit Crossing Distance". OXT means "Orbit Crossing Timing". CAD means 

"Close Approach Distance".

Data for active spacecraft and natural bodies are displayed in the tables above. Data 

for inactive spacecraft are not displayed, but they are available in the conjunction 

metric tables and plots, which have been stored in the output directory listed below. 

Data for reference trajectories are not considered for Red events, but are considered 

in the All section for events not covered by the predicts file. Reference trajectories 

use the same thresholds as the nominal trajectories.

For more information, please see the point of contact listed below.

Analysis time: 2020-05-28 21:30:20 UTC

Active spacecraft: Odyssey, Mars Express, MRO, MAVEN, MOM, TGO

Natural bodies: Phobos, Deimos

Inactive spacecraft: Viking1, MGS

Output directory: /nav/home/jplmdnav/MADCAP/Mars/archive

Point of contact: MADCAP_Mars@jpl.nasa.gov

MADCAP build: 3.0

Red Thresholds -- Polynomial Coefficients

Body Name OXD0 

(km)

OXD1 

(km/t)

OXD2 

(km/t^2)

OXT0 

(sec)

OXT1 

(sec/t)

OXT2 

(sec/t^2)

1 Odyssey 0.0009 0.0013 0.0000 0.0705 -0.0411 0.0096

2 Mars_Express 1.0000 0.0000 0.0000 10.0000 0.0000 0.0000

3 MRO 0.0877 -0.0315 0.0040 0.0100 0.4939 0.0765

4 MAVEN 0.5000 0.2300 0.0030 2.1000 2.8000 1.2300

5 MOM 0.2498 0.0014 0.0012 0.0100 33.0089 0.3246

6 TGO 1.0000 0.0000 0.0000 10.0000 0.0000 0.0000

7 Phobos 30.0000 0.0000 0.0000 15.0000 0.0000 0.0000

8 Deimos 40.0000 0.0000 0.0000 20.0000 0.0000 0.0000

Red OX Distance Threshold = OXD0 + (OXD1 * t) + (OXD2 * t^2) [km]

Red OX Timing Threshold = OXT0 + (OXT1 * t) + (OXT2 * t^2) [sec]

where t = CA Epoch - Ephemeris File Submit Time (in days)

Red thresholds are based on 3-sigma values. Thresholds listed as "P" are based on a 

quadratic fit of the 3-sigma values as a function of time to the event. The polynomial 

coefficients used are listed in the table above. Lines for coefficients which have 
This document has been reviewed and determined not to contain export controlled technical data. URS309986 CL#22-3991 12

been updated since the last run are colored blue, and each line's body is marked with 

an "*". Thresholds listed as "C" are based on 3-sigma covariance data provided by the 

mission.

All Thresholds -- Constants

Body Name OXD (km) CAD (km)

1 Odyssey 10 100

2 Mars_Express 10 100

3 MRO 10 300

4 MAVEN 10 3000

5 MOM 20 100

6 TGO 10 100

7 Phobos 45 100

8 Deimos 60 200

All OX Distance Threshold = OXD

All CA Distance Threshold = CAD

All thresholds are always constants. The constants used are listed in the table above. 

Lines for constants which have been updated since the last run are colored blue, and 

each line's body is marked with an "*".

Ephemerides

Body Ephemeris Submitted Begin End

1 p_m_od81833-81835_82168_v1.bsp 2020-05-26 

23:11:20 UTC

26-MAY-2020 

09:55:35 UTC

22-JUN-2020 

23:58:50 UTC

1r p_m_od81732-81738_82848_v1.bsp_V0.1 Analysis Time 18-MAY-2020 

03:38:50 UTC

17-AUG-2020 

23:58:50 UTC

2 MOEM_200525OAS_PREDICT__0001.CR.bsp 2020-05-25 

14:06:21 UTC

07-MAY-2020 

23:42:29 UTC

25-JUN-2020 

14:21:45 UTC

3* pf_psp_rec64862_64857_65825_p-v1.bsp 2020-05-28 

16:34:47 UTC

28-MAY-2020 

03:28:50 UTC

11-AUG-2020 

13:53:50 UTC

4* trj_orb_11613-11617_11863_v1_mvn.bsp 2020-05-28 

17:29:42 UTC

27-MAY-2020 

10:30:50 UTC

03-JUL-2020 

23:26:50 UTC

5 mom_spk_200512-241210_isroOD200518_dsn.bsp

2020-05-21 

20:48:44 UTC

12-MAY-2020 

00:00:00 UTC

09-DEC-2024 

23:58:50 UTC

6 TOEM_200525OAS_PREDICT__0001.CR.bsp 2020-05-25 

14:06:15 UTC

24-MAY-2020 

23:58:47 UTC

04-JUL-2020 

16:35:22 UTC

7 mar097.2010-2029.bsp Analysis Time 29-DEC-2009 

23:58:53 UTC

01-JAN-2030 

23:58:50 UTC

8 mar097.2010-2029.bsp Analysis Time 29-DEC-2009 

23:58:53 UTC

01-JAN-2030 

23:58:50 UTC

9 Viking1_200101_210101.boa Analysis Time 31-DEC-2019 

23:58:50 UTC

31-DEC-2020 

23:58:50 UTC

10 p_191030-201029-

061215_10yr_nominal.nio Analysis Time 30-OCT-2019 05:28:50 UTC

29-OCT-2020 

06:28:50 UTC

Ephemeris files for the bodies analyzed are listed in the table above. Lines for files 

which have been updated since the last run are colored blue, and each line's body is 

marked with an "*".
This document has been reviewed and determined not to contain export controlled technical data. URS309986 CL#22-3991 13

12 References

1. Demcak, S., “MAVEN Navigation Response to MOR RFA-003: Collision Avoidance Process,” JPL 

Internal Document IOM-343A-13-001.

2. Berry, D. et al., "Automated Spacecraft Conjunction Assessment at Mars and the Moon", Paper 

1262983, 12th International Conference on Space Operations, Stockholm, Sweden, 11 June 2012.

3. Tarzi, Z., Berry, D., Roncoli, R., “An Updated Process for Automated Deepspace Conjunction 

Assessment” Paper AAS 14-373, 25th International Symposium on Space Flight Dynamics, Munich, 

Germany, October 2015.

4. Berry, D., Tarzi, Z., Roncoli, R., Wilson, R., “Automated Spacecraft Conjunction Assessment at Mars 

and the Moon-A Five Year Update”, Paper 2810036, 14th International Conference on Space 

Operations, Marseille, France, May 2018

5. Berry, D., Tarzi, Z., "Multimission Automated Deepspace Conjunction Assessment Process 

(MADCAP) Requirements", MGSS DOC-001813, Revision E, February 8, 2022.

6. Tarzi, Z., “Multimission Automated Deepspace Conjunction Assessment Process (MADCAP) 

Software Description and User's Guide,” MGSS DOC-000664, Revision H, 09 May 2022. 

13 Acknowledgment

This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a 

contract with the National Aeronautics and Space Administration (80NM0018D0004). 

© 2022 California Institute of Technology. Government sponsorship acknowledged.