NASA - MAVEN - updates and discussion

[ccdengr]

Last year I talked to one of the people who was still attached to Odyssey. I think she told me that 2023 is about the edge of its lifetime.

Documents linked upthread say ODY has 5 kg of fuel left as of late 2021, and uses 1 kg per year.  So 2023 seems pessimistic and the mission was extended through 2025 so there is money if it continues to work (unless they lose a reaction wheel, which I haven't heard about but can't rule out.)

[Kiwi53]

The Earth Return Orbiter should provide a good relay capability until it departs it 2032. The 2032 Decadal Survey will presumably put together a new Mars architecture, including a new relay. The earliest that relay will arrive will be 2037.

Surely there's a non-zero chance that by 2032 there will be at least a few Starships and maybe some crew / settlers on Mars surface. If they haven't set up their own Mars data relay satellite system by then, they'd surely have plans well advanced

So there will be at least a five year period where the relay capability will be very fragile. They will need at least a 24 year lifetime out of MAVEN to avoid a gap in US capabilities. Perseverance will be 17 years old at that time, or 6 years older than Curiosity is now.
NASA might get away with this, but any new landed mission like Mars Life Explorer will be out of the question until a new relay is in place. Maybe the Europeans will fly something if they find a way to save Exomars.

I'd guess there's a significant chance of this all being overtaken by events

[Zed_Noir]

The Earth Return Orbiter should provide a good relay capability until it departs it 2032. The 2032 Decadal Survey will presumably put together a new Mars architecture, including a new relay. The earliest that relay will arrive will be 2037.

Surely there's a non-zero chance that by 2032 there will be at least a few Starships and maybe some crew / settlers on Mars surface. If they haven't set up their own Mars data relay satellite system by then, they'd surely have plans well advanced

NASA does not take that as a possibility until a Starship have gotten to Mars. Which have implications for the various government robotic Mars programs. Since it is almost impossible to decontaminated a Starship or a crewed Starship to the current US planetary protection requirements.

So there will be at least a five year period where the relay capability will be very fragile. They will need at least a 24 year lifetime out of MAVEN to avoid a gap in US capabilities. Perseverance will be 17 years old at that time, or 6 years older than Curiosity is now.
NASA might get away with this, but any new landed mission like Mars Life Explorer will be out of the question until a new relay is in place. Maybe the Europeans will fly something if they find a way to save Exomars.

I'd guess there's a significant chance of this all being overtaken by events

We shall see. The future will be clearer after 2023 for explorations in the Mars locale.

[Lee Jay]

The Earth Return Orbiter should provide a good relay capability until it departs it 2032. The 2032 Decadal Survey will presumably put together a new Mars architecture, including a new relay. The earliest that relay will arrive will be 2037.

Surely there's a non-zero chance that by 2032 there will be at least a few Starships and maybe some crew / settlers on Mars surface. If they haven't set up their own Mars data relay satellite system by then, they'd surely have plans well advanced

Most things that can happen have a non-zero chance of happening.  However, "non-zero" could mean arbitrarily close to zero, which doesn't seem like something that should be counted on.  There's also a non-zero chance that Starship will fail and that SpaceX will be out of business by 2032.

[deadman1204]

So is the plan to do nothing until events force something to happen?

[Blackstar]

So is the plan to do nothing until events force something to happen?

Usually they act before then--the pressure builds, the commentary gets loud, then they take action. That's what their advisory groups are for.

[ccdengr]

So is the plan to do nothing until events force something to happen?

My take FWIW is that ODY and MEX failing will cause no change, MRO failing would cause a lot of concern but probably little action, and TGO or MAVEN failing would result in some action (maybe actual effective action, maybe just a lot of talk.)

As mentioned upthread, the MSR ERO can provide relay for MSR ops, but it's only doing that for an Earth year in the present baseline.

The rovers could be operated with no relay, but the data return would be highly curtailed; I doubt that mode of operation is really viable for anything but survival.  But I'm sure they would try.

[edzieba]

With the success of the MarCOs during Insight EDL, one or more could be included as a piggyback payload with a future mission (like the ERO) as a potentially faster option than integrating a relay payload into a science mission, albeit with the cost of likely a shorter relay mission lifetime (due to lack of propellant for orbit raising, and lack of systems redundancy). This adds some additional propellant burden to the host mission for MOI and an extra deployment sequence item for separating the relay cubesat, but also has the benefit that the science mission does not need to expend propellant carting the relay hardware around after that point.
Whilst the MarCO design as-is is not an 'ideal' relay (they orient to the sun the charge the internal batteries using the small onboard panels, then orient for relay and operate off of battery power for a limited period) it may be better than no relay at all, and may be an acceptable operations mode if relay operations are conducted in bursts rather than continuously.

[ccdengr]

With the success of the MarCOs during Insight EDL

The data rate from MarCO was only 8 kbps at most.  The rover can do that well direct to earth.

There may be something to this concept, but it would take a larger spacecraft than MarCO.

[vjkane]

The Earth Return Orbiter should provide a good relay capability until it departs it 2032. The 2032 Decadal Survey will presumably put together a new Mars architecture, including a new relay. The earliest that relay will arrive will be 2037.

Surely there's a non-zero chance that by 2032 there will be at least a few Starships and maybe some crew / settlers on Mars surface. If they haven't set up their own Mars data relay satellite system by then, they'd surely have plans well advanced

Most things that can happen have a non-zero chance of happening.  However, "non-zero" could mean arbitrarily close to zero, which doesn't seem like something that should be counted on.  There's also a non-zero chance that Starship will fail and that SpaceX will be out of business by 2032.

Or that we will find little green women inhabiting Mars who have terrabyte/nanosecond internet and they'll give us a terminal.

[deadman1204]

The Earth Return Orbiter should provide a good relay capability until it departs it 2032. The 2032 Decadal Survey will presumably put together a new Mars architecture, including a new relay. The earliest that relay will arrive will be 2037.

Surely there's a non-zero chance that by 2032 there will be at least a few Starships and maybe some crew / settlers on Mars surface. If they haven't set up their own Mars data relay satellite system by then, they'd surely have plans well advanced

Most things that can happen have a non-zero chance of happening.  However, "non-zero" could mean arbitrarily close to zero, which doesn't seem like something that should be counted on.  There's also a non-zero chance that Starship will fail and that SpaceX will be out of business by 2032.

Or that we will find little green women inhabiting Mars who have terrabyte/nanosecond internet and they'll give us a terminal.

Are you sure you want to be signing Martian service agreements? I'm reminded of the South Park about Apple's terms of service 

[ccdengr]

With the success of the MarCOs during Insight EDL...

FWIW, "MarCO: Flight Review and Lessons Learned" https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=4575&context=smallsat has a lot of interesting info about the MarCO spacecraft, including the fact that both spacecraft were lost after the Mars flyby possibly due to a sun sensor/software issue.  Also one had a leaky prop system and wouldn't have lasted much longer anyway.

And this design had nowhere near enough delta V to get into Mars orbit.

I'm aware of one 12U cubesat design that could serve as an orbital relay, some discussion at https://forum.nasaspaceflight.com/index.php?topic=45678.0

[deadman1204]

For the MarCos, we're forgetting the point that they were never in orbit. They just flew by.

If something is big enough to enter orbit (large enough engine and fuel) can it even be considered a cubesat? I'm assuming ion engines won't ever be powerful enough to do this job.

[edzieba]

With the success of the MarCOs during Insight EDL...

FWIW, "MarCO: Flight Review and Lessons Learned" https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=4575&context=smallsat has a lot of interesting info about the MarCO spacecraft, including the fact that both spacecraft were lost after the Mars flyby possibly due to a sun sensor/software issue.  Also one had a leaky prop system and wouldn't have lasted much longer anyway.

And this design had nowhere near enough delta V to get into Mars orbit.

I'm aware of one 12U cubesat design that could serve as an orbital relay, some discussion at https://forum.nasaspaceflight.com/index.php?topic=45678.0

Thanks, that's a great document!
The idea was for any relay craft to piggyback on a host mission through orbit capture, and only detach afterwards (unlike the MarCOs, that detached shortly after Earth departure and free-flew their way to Mars).

MMO looks like it was trying to be a shrunk-down science mission (with an array of instruments and its own communications link) rather than a dedicated relay-only mission. And hit the problem that if it's ride to Mars didn't inject it into the correct orbit it was stuck in the wrong orbit to perform its mission. A relay has a bit more flexibility in that as long as its ground-track can cross the missions it is relaying, it can do its job to some extend (asynchronous transmit/receive separates local bandwidth from return-to-Earth bandwidth). 

[ccdengr]

The idea was for any relay craft to piggyback on a host mission through orbit capture, and only detach afterwards...

Sorry, I missed that.  But I really don't think the numbers work out on the concept.  You want your relay to have high data rate, which means more power, more mass, etc.  Seems like the current strategy of piggybacking just the UHF relay system on larger spacecraft and using them as infrastructure makes more sense.

Somebody will suggest laser comm, to which I'd say I'd like to see the mass, power, link margin, pointing budget, and ground infrastructure analyses.

[Blackstar]

If something is big enough to enter orbit (large enough engine and fuel) can it even be considered a cubesat?

"Cubesat" is not a useful term. Think "smallsat," for various definitions of "small."

I'm not sure that a smallsat would make sense for relay purposes, but it might. The problem with small satellites is that they don't scale well--you spend a lot of money on launch and operations and radiation hardening and stuff like that just to get to a planetary distance, and so it doesn't make a lot of sense to spend all that money on a small payload as opposed to a larger payload. But who knows? Maybe there's a good solution out there waiting to be proposed.

[JayWee]

The value of a smallsat relay might not be the bandwitdth, but ground pass availability - especially useful during EDL.

[ccdengr]

The value of a smallsat relay might not be the bandwitdth, but ground pass availability - especially useful during EDL.

Agreed (and hence MarCO), but a couple of points: 1) relay comm during EDL is a nice-to-have, not an absolute requirement.  I get why after the MPL failure that people have insisted on it, but it doesn't keep you from crashing, you might just get more insight into why you crashed if you do.  2) what your relay network would look like for some specific future use case depends a lot on that use case.  Right now, the only missions on the books are continuing ops for MSL and M2020, and MSR.  Nobody is likely to spend money on infrastructure unless there are customers for it.

[deadman1204]

The value of a smallsat relay might not be the bandwitdth, but ground pass availability - especially useful during EDL.

MSR is about WAY more than just landing. There will be a rover and a lander to communicate with.

[JayWee]

The value of a smallsat relay might not be the bandwitdth, but ground pass availability - especially useful during EDL.

MSR is about WAY more than just landing. There will be a rover and a lander to communicate with.

See what ccdengr said.

What is meant - if you want to listen to EDL progress you have to time (and place) it to either:
a) line-of-sight between the Lander and DSN Antenna on Earth
b) line-of-sight between the Lander and some orbital asset.

b) is where the cheap smallsats come in.

For ordinary comm with rover/lander you can just wait.

See for example landing tones generated by the MSL:
https://spaceflight101.com/msl/msl-edl-communications/