NASA - MAVEN - updates and discussion

[Targeteer]

Can some of the experts provide some factual information like comm out modes/timelines the spacecraft SHOULD go into after a failed contact?

[StraumliBlight]

Can some of the experts provide some factual information like comm out modes/timelines the spacecraft SHOULD go into after a failed contact?

Navigation challenges in the MAVEN science phase [Nov 2, 2012]

3.1. Deep Space Network Support: Radiometric Tracking Data

Since the MAVEN spacecraft does not have an ultra-stable oscillator (USO), navigation will rely on 2-way Doppler data during the science phase. The MAVEN DSN coverage is 8 hours per day, yielding 7+ hours of 2-way Doppler per pass. Two additional 8 hour DSN passes have been added on Sunday and Wednesday to decrease navigation’s sensitivity to lost tracking data, and to allow more flexibility in navigation and other team scheduling. The 8 hour DSN pass is a recent increase over the previous minimal 6 hour pass (5+ hours of Doppler). This also reduces navigation’s sensitivity to possible DSN related problems, including weather.

Since MAVEN does not have a gimbaled high-gain antenna (HGA) like the previous Mars orbiters, the entire spacecraft must turn when it wants to communicate with Earth. Since this results in the loss of science data, the HGA Earth pointed modes only occur twice per week, on Tuesday and Friday. Furthermore, the spacecraft only points towards the Earth for approximately 5 of the 8 hours during these “HGA” passes. All other DSN contact will be on the low-gain antenna (LGA). In general, navigation will perform its analyses on the LGA pass before the HGA pass. Navigation will deliver its products in time for them to be processed into sequence products and uplinked during the HGA pass.

Previous times MAVEN entered safe mode:
 • Feb 22 - May 28, 2022
 • Feb 16 - 17, 2023

[ccdengr]

Can some of the experts provide some factual information like comm out modes/timelines the spacecraft SHOULD go into after a failed contact?

There are multiple reasons why the spacecraft might go into safe mode: low power, loss of attitude reference, processor watchdog resets, etc.  In most of those the spacecraft will switch to low rate telemetry on the low-gain antenna.  If there is also a transmitter failure, then this might take a while to notice; the spacecraft has a command-loss timer that triggers if it hasn't heard from Earth in a while, but these are usually set to a few days at least.

To complicate things, Mars is approaching solar conjunction and there will be limited command and telemetry through that.

If it goes power-negative because it can't find the sun or can't figure out how its solar panels are oriented, then the spacecraft will die pretty quickly after its batteries discharge.

Reviewing https://lasp.colorado.edu/maven/files/2015/05/The-Mars-Atmosphere-and-Volatile-Evolution-MAVEN-Mission.pdf reminds me that unlike MRO, Ody, etc, MAVEN's solar panels are not articulated, so it would take a massive failure of the attitude control system to get to the point where it couldn't get sun on the panels.

[LouScheffer]

[...] The MAVEN DSN coverage is 8 hours per day, yielding 7+ hours of 2-way Doppler per pass. [...]

Since MAVEN does not have a gimbaled high-gain antenna (HGA) like the previous Mars orbiters, the entire spacecraft must turn when it wants to communicate with Earth. Since this results in the loss of science data, the HGA Earth pointed modes only occur twice per week, on Tuesday and Friday. Furthermore, the spacecraft only points towards the Earth for approximately 5 of the 8 hours during these “HGA” passes. All other DSN contact will be on the low-gain antenna (LGA).

In my entirely amateur opinion, this approach to communication implies that loss of all contact is a very bad omen.  Communication through the LGA is not dependent on pointing, and is the default configuration in safe mode.  So expecting a daily LGA contact, and not finding it, is much worse than missing an HGA contact - it's not a simple pointing problem or the spacecraft going into safe mode - these would still allow LGA contact.

Presumably, MAVEN can monitor the output of its RF power stages, and would switch to a redundant amplifier if needed.  So a simple failure of the power amp should also not result in loss of contact.  Nor should loss of charging due to bad pointing or other fault - the batteries should have been enough that at least some contact would have been possible coming out of earth eclipse.  That leaves (again in my non-professional opinion) a much higher chance of some catastrophic fault.

[Targeteer]

DSN is trying to contact MAVEN

[Blackstar]

A decent overview. Suggests that Odyssey has enough fuel for another 2 years or so. I am puzzled by Odyssey, because I remember back around 2020 asking somebody who was on the team saying that they figured it would go until 2023 at most. It's 2025 and it's still going. All I can guess is that even though they predicted a low rate of fuel usage, they somehow got it even lower. Maybe luck? Maybe they figured out an additional trick?

https://arstechnica.com/space/2025/12/nasa-just-lost-contact-with-a-mars-orbiter-and-will-soon-lose-another-one/

[jimvela]

DSN is trying to contact MAVEN

They’ve been trying all along.  Watching this from outside, it looks to me like they may be just listening and stopped blind commanding to let CLT time out.

Fingers still crossed they can save it.

[jimvela]

All I can guess is that even though they predicted a low rate of fuel usage, they somehow got it even lower. Maybe luck? Maybe they figured out an additional trick?

It’s difficult to model prop usage through RCS and difficult to measure small amounts of remaining prop in the tanks and lines.

Deep Impact / EPOXI was using a bunch of novel tricks that are probably fairly well known by those in the practice these days.

Maneuvering with prop savings has also gotten better.

You can also start playing games with contacts and observations to avoid the ones that accumulate momentum the worst, saving on desats

[djellison]

Suggests that Odyssey has enough fuel for another 2 years or so. I am puzzled by Odyssey, because I remember back around 2020 asking somebody who was on the team saying that they figured it would go until 2023 at most. It's 2025 and it's still going.

Take it from the horses mouth.....

https://assets.science.nasa.gov/content/dam/science/psd/resources/senior-review/2025/PMSR25_Final_Report_Package_June9_2025_Tagged.pdf

" The low mass of usable propellant (3.2 kg) with its high uncertainty (±2.0 kg [3σ] or ±1.33 kg [2σ]) represents a risk to the duration and success of the extended mission. This risk could be realized early in the event of a safe-mode event or loss of a reaction wheel, either of which would increase propellant usage. [Note: E10 requires 1.3 kg of propellant for successful completion of all objectives in the absence of any safe mode events or other such realized risks.] "

It's VERY hard to get an accurate measurement of a propellant tank when it's that empty.    This paper - https://star.spaceops.org/2025/user_manudownload.php?doc=398__1llfyrji.pdf - discusses it.

[Blackstar]

I share this only to add a bit of amusement to a depressing subject.

[djellison]

I share this only to add a bit of amusement to a depressing subject.

Just because it's worth clarifying.....'scamVonDoom' is quite obviously wrong.

https://science.nasa.gov/solar-system/comets/3i-atlas/comet-3i-atlas-image-gallery/

MAVEN data on 3I/ATLAS was acquired Sept 28th and Oct 9th and was released weeks ago.

[Blackstar]

https://science.nasa.gov/blogs/maven/2025/12/15/nasa-continues-maven-spacecraft-recontact-efforts/


Recontact Efforts

NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) mission team, in partnership with the agency’s Deep Space Network, continues recovery activities after losing contact with the spacecraft on Dec. 6. To date, attempts to reestablish contact with the spacecraft have not been successful.

Although no spacecraft telemetry has been received since Dec. 4, the team recovered a brief fragment of tracking data from Dec. 6 as part of an ongoing radio science campaign. Analysis of that signal suggests that the MAVEN spacecraft was rotating in an unexpected manner when it emerged from behind Mars. Further, the frequency of the tracking signal suggests MAVEN’s orbit trajectory may have changed. The team continues to analyze tracking data to understand the most likely scenarios leading to the loss of signal. Efforts to reestablish contact with MAVEN also continue.

NASA is also working to mitigate the effect of the MAVEN anomaly on surface operations for NASA’s Perseverance and Curiosity rovers. Four orbiters at Mars, including MAVEN, relay communications to and from the surface to support rover operations. NASA’s Mars Reconnaissance Orbiter, Mars Odyssey, and ESA’s (European Space Agency’s) ExoMars Trace Gas Orbiter all remain operational. For the next two weeks of scheduled surface operations, NASA is arranging additional passes from the remaining orbiters, and the Perseverance and Curiosity teams have adjusted their daily planning activities to continue their science missions.

[s_wood]

https://assets.science.nasa.gov/content/dam/science/psd/resources/senior-review/2025/PMSR25_Final_Report_Package_June9_2025_Tagged.pdf

" The low mass of usable propellant (3.2 kg) with its high uncertainty (±2.0 kg [3σ] or ±1.33 kg [2σ]) represents a risk to the duration and success of the extended mission. This risk could be realized early in the event of a safe-mode event or loss of a reaction wheel, either of which would increase propellant usage. [Note: E10 requires 1.3 kg of propellant for successful completion of all objectives in the absence of any safe mode events or other such realized risks.] "

It's VERY hard to get an accurate measurement of a propellant tank when it's that empty.    This paper - https://star.spaceops.org/2025/user_manudownload.php?doc=398__1llfyrji.pdf - discusses it.

yes. especially after a long period of time.

you have an MOI burn that uses orders of magnitude more fuel than anything else, so small % uncertainties here end up coming into play 10-20 years down the line.

then usually after that its mass bookkeeping using mathematical models of the thrusters, but the results you get out of the thruster models have an error bar on the consumption figures. At the start its ok, but eventually, you end up in the situation where if you add up the error margin its larger than the amount of fuel the models predict are left. 

so you end up with a drop dead value that says you have 10 years of fuel left, but by then the error margin is so big if you take the worst case of the models, then they say you ran out 10 years ago.

it gets even trickier the longer you push it, then you get into how much fuel was really in the tank to start with. if you're using a few hundred grams per year then 1% under or over fill then suddenly becomes significant.

I've seen thermal gauging tests tried to give better estimates but never seen them really work. Partly because no one tests their tanks empty before launch, and its hard to get the tanks up to the temperatures needed to see any difference that gives an answer that's more accurate than the bookkeeping. The heaters aren't designed for it

on top you've got residuals, even if you had an accurate measure of the kg left in the tank, it depends where it is in the tank as its unlikely every drop of fuel in the tank is going make it into lines.

basically, once you get 15+ years, all you can really do is use as little fuel as you possible can

[Kaputnik]

https://science.nasa.gov/blogs/maven/2025/12/15/nasa-continues-maven-spacecraft-recontact-efforts/


Recontact Efforts

NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) mission team, in partnership with the agency’s Deep Space Network, continues recovery activities after losing contact with the spacecraft on Dec. 6. To date, attempts to reestablish contact with the spacecraft have not been successful.

Although no spacecraft telemetry has been received since Dec. 4, the team recovered a brief fragment of tracking data from Dec. 6 as part of an ongoing radio science campaign. Analysis of that signal suggests that the MAVEN spacecraft was rotating in an unexpected manner when it emerged from behind Mars. Further, the frequency of the tracking signal suggests MAVEN’s orbit trajectory may have changed. The team continues to analyze tracking data to understand the most likely scenarios leading to the loss of signal. Efforts to reestablish contact with MAVEN also continue.

Change in orbit presumably means either propellant leak, uncommanded thruster firing, or debris event?

NASA is also working to mitigate the effect of the MAVEN anomaly on surface operations for NASA’s Perseverance and Curiosity rovers. Four orbiters at Mars, including MAVEN, relay communications to and from the surface to support rover operations. NASA’s Mars Reconnaissance Orbiter, Mars Odyssey, and ESA’s (European Space Agency’s) ExoMars Trace Gas Orbiter all remain operational. For the next two weeks of scheduled surface operations, NASA is arranging additional passes from the remaining orbiters, and the Perseverance and Curiosity teams have adjusted their daily planning activities to continue their science missions.

Is Mars Express not available as a relay?

[djellison]

Is Mars Express not available as a relay?

Its orbit is not especially conducive to regular relay.    It has been checked out from time to time by various surface assets but not regularly used.    MRO and TGO can return a lot more data in a single pass - reliably.       I would suspect that the backfill in terms of downlink for surface assets will be picked up by using more overflights from MRO and TGO.

There's a few papers out there discussing the MEX MELACOM performance.

https://arc.aiaa.org/doi/pdf/10.2514/6.2012-1295328

https://pdfs.semanticscholar.org/a277/f981c56f44ce1e25e4151e5fd08f54396965.pdf

It details getting a few megabits on some demo passes on MER and up to about ~100 megabits for MSL.  That compares to ~300 megabits for an average MRO pass, ~600 megabits for an average TGO pass ( these values have massive ranges based on overflight geometry - but those numbers are fairly average ).

[s_wood]

MEX currently conducts regular demo overflights to confirm it's able to provide emergency relay support if needed.

But the data rates on MELACOM are lower than the those on ELECTRA as it's an older radio.

Its orbits not too dismilar to MAVENs, meaning it can have longer view periods to compensate a bit for the lower data rates but the higher apocenter means the link budget takes a hit. Also like MAVEN, it's a pointed spacecraft, so you have orientate the uhf antennas at the rover, which it's science mission means isn't always the case.

TGO already relays almost 2 thirds of all the data coming from the rovers, if MAVEN is unavailable I would expect more TGO and MRO once solar conjunction is over.

[Star One]

Scott Manley - NASA’s MAVEN Spacecraft - Spinning Out Of Control?

[catdlr]

https://twitter.com/amsatdl/status/2001310683032367323

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#MAVEN @NASA is still alive and transmitting on the low gain antenna! 📡〰️🛰️  Signal is weak on our 20m dish
@SternwarteBO , but Maven is currently in command lock with DSN in Madrid. Here a screenshot when it came out from periareion (periapsis) behind Mars. Also visible is the doppler on the carrier frequency, which will allow NASA engineers withing a couple of orbits to determine the orbit.    Fingers crossed, that they will be able to fully recover the spacecraft.

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Our own preliminary doppler profile shows that Maven's orbit period is now 1h52m instead of 3h30m.  That would be a huge discrepancy.  112 minutes period gives SMA of 3659km.

[DaveS]

The orbital period has shrunk by nearly 50%? This is more than an IMU failure. Either something hit MAVEN in a really bad place (thinking propellant tank) or something blew on its own.

Either scenario means End of Mission even if they manage to restore comms.

[Blackstar]

That seems like a huge delta-v change. Maybe they made an error in their calculations and it is not that big.