NASA - MAVEN - updates and discussion

[StraumliBlight]

https://twitter.com/jeff_foust/status/2011089344602202471

It's "very unlikely" NASA will be able to recover the MAVEN Mars orbiter, NASA planetary science division director Louise Prockter says at the Small Bodies Assessment Group meeting this morning. Efforts to restore contact will resume Friday, after solar conjunction ends.

[redliox]

A major pity we've lost MAVEN.  I am glad it at least completed its primary mission; we've been lucky with Odyssey and MRO up to this point.  By comparison, didn't the Mariner 9 and Viking orbiters last maybe a year for the former and small handful for the later?

[Kaputnik]

A major pity we've lost MAVEN.  I am glad it at least completed its primary mission; we've been lucky with Odyssey and MRO up to this point.  By comparison, didn't the Mariner 9 and Viking orbiters last maybe a year for the former and small handful for the later?

Nearly one earth year in Mars orbit for Mariner 9, and 4 years for the Viking 2 orbiter (the lander lasted a couple more years).

Very impressive at the time (both designed for 90d orbital missions), but not a patch on what we can do with modern spacecraft.

[StraumliBlight]

NASA Resumes Efforts to Reestablish Contact With MAVEN [Jan 26]

As spacecraft and rovers at Mars emerge from solar conjunction – a period when the Red Planet and Earth are on opposite sides of the Sun and contact with Mars missions isn’t possible – NASA has resumed efforts to recontact its MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft using NASA’s Deep Space Network and the U.S. National Science Foundation’s Green Bank Observatory. The spacecraft was last heard from on Dec. 6.

In addition, the MAVEN team continues to analyze snippets of data recovered from a Dec. 6 radio science campaign. This analysis is being used to create a timeline of possible events and identify likely root causes of the issue. NASA is assembling a formal anomaly review board to investigate the available data.

[LouScheffer]

NASA establishing a review board:

NASA begins formal anomaly review after MAVEN probe lost in space

[jimvela]

Alright- since the review board is spinning up, I'll throw in my outsider speculation.

Maven had trouble with IMUs, eventually re-configuring the vehicle to use all-stellar navigation.
My speculation is that during the activity where DSN watched them be occulted by Mars, they took some kind of fault that rendered the all-stellar mode to lose its solution.
I further speculate that the onboard safe mode wasn't properly reconfigured for this edge case problem, and it picked a faulty solution from whichever IMU it picked as the vehicle went safe, and then spun itself to death.

Such a pity to lose MAVEN, I hope I'm wrong and there's some other recoverable failure mode.

[ccdengr]

I further speculate that the onboard safe mode wasn't properly reconfigured for this edge case problem, and it picked a faulty solution from whichever IMU it picked as the vehicle went safe, and then spun itself to death.

Maybe, but FWIW it seems unlikely to me.  MAVEN had no articulation for its solar panels (unlike MRO and Odyssey) and spacecraft usually use redundant sun sensors to keep power on the panels, so a complete loss of attitude knowledge should have been easily recoverable.  Once power is low, spacecraft ignore most data sources.

But I guess we'll see what the review board comes up with.

[jimvela]

a complete loss of attitude knowledge

Not all attitude, rates. 
Seeing a bad [wrong] source of rate data and believing it is really bad.
If their safe mode just tries to sun point on sun sensors then my theory is bunk.
If it only does that when power is low, then it's already too late. 
Most CSS sun solutions cannot cope with a high body rate when spun up, because the sun vector is changing so rapidly.

[ccdengr]

Not all attitude, rates. 
Seeing a bad [wrong] source of rate data and believing it is really bad.

Fair enough, could be.  All-stellar mode has a long heritage at LM, though, and I'd like to believe that they've made it pretty bullet-proof.  See "Verification of Mars Odyssey all-stellar attitude determination ten years after launch" https://www.researchgate.net/publication/301432626_Verification_of_Mars_Odyssey_all-stellar_attitude_determination_ten_years_after_launch

[djellison]

All-stellar mode has a long heritage at LM,

Yup - even for MVN itself

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

Page 15, on MVN.

"For instance, attitude control has been accomplished since 2022 primarily with the spacecraft’s star trackers, in an All-Stellar Mode, to preserve the lifetime of the probe’s remaining operational Inertial Measurement Unit"

The same senior review out-brief also mentions all-stellar mode for MRO as well.

[LouScheffer]

a complete loss of attitude knowledge

[...]
If their safe mode just tries to sun point on sun sensors then my theory is bunk.
[...]
 Most CSS sun solutions cannot cope with a high body rate when spun up, because the sun vector is changing so rapidly

Not necessarily bunk.  The Earth and Sun would be close together in the Mars sky (as evidenced by the recent interruption of radio contact by the Sun).   So Maven was likely in the shadow of Mars when the anomaly happened, and sun pointing would not work either.  Then by the time it comes out of Mars shadow it's already spinning too fast for the Sun sensors to cope.

[DaveS]

I don't want jump the gun here, in case it is a mis-identification, but DSS-35 at Canberra currently has a lock on an X-band downlink that shows as MAVEN with a data rate of 46.43 b/s.

[djellison]

I don't want jump the gun here......

I'd refer you to the info section of DSN Now which states

"Idiosyncrasies
In off-nominal scenarios when a project may be attempting to recover a spacecraft that is in safe mode or experiencing other operational challenges, an antenna may wrongly report that is receiving data from the spacecraft in question. While the ground station is searching for a signal, it may ‘lock on’ to a signal from a different spacecraft and wrongly identify it as the spacecraft being searched for. This is particularly common with spacecraft at Mars as multiple spacecraft are within the field of view of a single DSN antenna. For example, attempts to recover the Opportunity Rover (MERB) may appear successful when the antenna has actually locked on to a signal from one of the orbiters around Mars such as MAVEN or MRO. When this occurs, engineers ask the antenna to ‘drop lock’ and the hunt for the spacecraft continues."

[ccdengr]

I don't want jump the gun here, in case it is a mis-identification, but DSS-35 at Canberra currently has a lock on an X-band downlink that shows as MAVEN with a data rate of 46.43 b/s.

I'd love to believe this, but in multiple spacecraft per aperture mode DSN Now is known to get confused easily; this happened many times after Opportunity went silent and led to a lot of false alarms.  But I hope I'm wrong in this case. [exactly what Doug said.]

[Sam Ho]

Here is a table of average Mars relay data volume, from https://science.nasa.gov/mars/mars-relay-network/

Spacecraft	Average Data Volume
Odyssey	170.4 Mb/day
Mars Express	N/A (backup)
MRO	447.5 Mb/day
MAVEN	897.5 Mb/day
ExoMars TGO	1562.7 Mb/day

MAVEN was providing about 30% of the Mars Relay Network bandwidth.

And here is a table comparing Tianwen-1's relay capabilities against other spacecraft, from "Research on Tianwen-1 Mars Probe Relay Communication Technology," https://rdcu.be/e2aNo (These numbers are lower than the corresponding NASA numbers for some reason.)

Spacecraft	Average Data Volume
Tianwen-1 UHF	150 Mb/sol
Tianwen-1 X-band	500 Mb/sol
Odyssey	111 Mb/sol
Mars Express	83 Mb/sol
MRO	327 Mb/sol