Mars Telecom Orbiter reduxe

[Blackstar]

This headline and article are somewhat misleading. I doubt that there are many scientists who think that this is an either/or issue. The communications orbiter is going to be something on the order of a Discovery-class mission in cost. The Mars Ascent Vehicle is going to be a very expensive flagship mission. The question is whether the communications orbiter is needed, and what should it actually carry (for instance, should it primarily be a science orbiter with communications relay capability, or vice versa?). I doubt anybody thinks that it can be straight-up traded for the next step in sample return.



http://spacenews.com/nasa-mars-czar-defends-plan-to-follow-mars-2020-rover-with-orbiter/?utm_content=bufferfea14&utm_medium=social&utm_source=facebook.com&utm_campaign=buffer


NASA Mars Czar Defends Plan To Follow Mars 2020 Rover with Orbiter
by Dan Leone — April 7, 2015

WASHINGTON — NASA Mars czar Jim Watzin on March 30 defended the agency’s plans to follow up the Mars 2020 sample-collecting rover with a telecommunications orbiter that would launch in 2022 and possibly serve as a testbed for technologies applicable to future sample-return and even human spaceflight missions.

Watzin made his case for the orbiter to the NASA Advisory Council’s (NAC) planetary science subcommittee at NASA Headquarters here. Some NAC members wondered why, in Watzin’s words, an orbiter is the “next logical step” in the Mars sample-return campaign anointed as the top U.S. planetary science priority in a 10-year science roadmap, or decadal survey, published by the National Research Council in 2011.

The White House has been reluctant to commit to a multimission sample-return program because of the substantial investment required. However, it did allow NASA to start work in 2013 on a Mars 2020 sample-digging rover leveraging designs and hardware recycled from the Mars Science Laboratory mission, which landed the nuclear-powered Curiosity rover on the red planet in 2012.

[redliox]

I think it's essential, regardless of human flights or Mars sample return.

The most straightforward point the 'Mars Czar' made was that the currently com linchpin, Odyssey, is over a decade old and bound to fail sooner or later.  Everything else isn't apparently up to the job, most likely because their own orbital missions have more science than spare time.  Something dedicated ought to be sent.

Outside of Congress, I think the biggest roadblock may be the Mars community itself.  They may acknowledge the need, but likewise there's a constant drive for new missions while simultaneously saving old ones like Opportunity; from a communication stand-point it's like they're intentionally bottle-necking themselves!

[GuessWho]

I think it's essential, regardless of human flights or Mars sample return.

The most straightforward point the 'Mars Czar' made was that the currently com linchpin, Odyssey, is over a decade old and bound to fail sooner or later.  Everything else isn't apparently up to the job, most likely because their own orbital missions have more science than spare time.  Something dedicated ought to be sent.

What's wrong with MRO and MAVEN?  I know JPL doesn't like MAVEN because it is not "one of theirs" but it can certainly provide relay capability.  NASA has required that of all orbiters sent to Mars.

[hop]

What's wrong with MRO and MAVEN?

In 2022, MRO will be ~16 years old. MAVEN is expected to have fuel for ~3.5 years of science and ~6 years  in it's "retirement" orbit. That doesn't necessarily mean a new dedicated orbiter is the best solution, but there is real reason to be concerned about relay beyond the early 2020s.

[Blackstar]

I talked to him last week. He said that they're looking at a combination of comm, science, and tech demo (like laser comm), with multiple sponsors within NASA.

As I noted, the Space News article is somewhat misleading, so take what it says with a grain of salt. I don't think the science community is opposed to adding a new orbital relay, they just haven't really been consulted on it. I think that NASA would get opposition if SMD is supposed to foot 100% of the bill for something that is primarily data relay. But if the cost is split and they like the science package, they'll probably support it.

But everybody should remember that NASA proposed a telecom orbiter once before and it drew some complaints and then got killed. This is a balancing act.

[Space Ghost 1962]

MAVEN's orbit post science will be circularized.

[vjkane]

In addition to high resolution imaging for landing sites and science, atmospheric monitoring to fine tune entry of landers would be another goal for a future obiter.

[redliox]

I'm more curious about what kind of orbit they'd put a dedicated com stat into.  If this is going to really offer heavy communication something better than just low orbit should be used.

[TrevorMonty]

Instead of loading the relay orbiter up with expensive science payloads, use cubesats with dedicated science payloads. The plus side is that somebody else (eg Universities, ESA, JAXA) can pay for and build the cubesats, NASA only needs to provide a ride and communications backbone.

[AegeanBlue]

There is an interest comment by Keith Cowing on NASAwatch:

http://nasawatch.com/archives/2015/04/going-in-circle-1.html

He is harsh though possibly right.

[Comga]

(snip)
But everybody should remember that NASA proposed a telecom orbiter once before and it drew some complaints and then got killed. This is a balancing act.

To which "telecom orbiter" are you referring?
The "Mars Micro-Mission" of the late 1990's?
Surely a mission structured like that would cost less than a Discovery mission.
Now if they want to throw in Lasercom and a "few litttle" instruments.....

[Blackstar]

The plus side is that somebody else (eg Universities, ESA, JAXA) can pay for and build the cubesats, NASA only needs to provide a ride and communications backbone.

Universities that do space research usually get their money from the government (i.e. NASA).

[Blackstar]

To which "telecom orbiter" are you referring?
The "Mars Micro-Mission" of the late 1990's?
Surely a mission structured like that would cost less than a Discovery mission.
Now if they want to throw in Lasercom and a "few litttle" instruments.....

http://spacenews.com/nasa-mars-telecom-orbiter-axed-space-agency-priorities-shift/

NASA Mars Telecom Orbiter Axed As Space Agency Priorities Shift
by Brian Berger — July 25, 2005

NASA is scrapping plans to place a dedicated telecommunications relay satellite in orbit around Mars in 2009.

With fewer robotic explorers bound for the red planet early next decade than previously anticipated, NASA has decided it can get by without the Mars Telecommunications Orbiter, a satellite conceived to handle a now-forestalled avalanche of science data.

Doug McCuistion, Mars program director at NASA Headquarters here, said the decision to cancel the Mars Telecommunications Orbiter was driven by both a diminished need for a dedicated relay at Mars and the funding requirements for other missions in astronomy, Earth science and to other planets. In addition, NASA must begin preparing for the first human lunar expeditions since the Apollo program three decades ago.




The Mars Telecommunications Orbiter was to be built by Lockheed Martin Space Systems of Denver, the only company to bid on the project. Lockheed Martin entered into negotiations this spring with NASA and the Jet Propulsion Laboratory, Pasadena, Calif., to build the $500 million satellite, but the talks had not yielded a contract before NASA decided to pull the plug on the project.

The relay craft was meant to be the first piece of a permanent communications infrastructure intended to provide a link with Earth for all future Mars missions. The satellite also was to be equipped with a science package NASA had not yet selected and a laser optical communications experiment designed to point the way to a highly reliable method for transmitting large amounts of data back to Earth.

[JasonAW3]

Question; Would it be more efficent to send one big comsat to Mars or a cluster of smaller "mini-comsats"?  Sats that are larger than cube sats, but smaller than regular comsats.

By doing something like this, assuming that the total mass of the mini-comsats and fuel do not exceed the total mass of the regular Comsat, you would wind up with a more redundant network of sats, able to relay transmittions from anywhere on Mars, whether it's day or night.  Recent advances in communications electronics should allow the sats to network together and / or transmit the data gathered from ground and airbon sources either together or as independant units, for data straem redundancy.

[dchill]

The MTO vehicle that was cancelled in 2005 even had requirements to release and rendezvous with a practice orbital sample canister:

11.1.3   Orbital Sample canister detection and rendezvous
1)   The S/C shall support WAC and NAC imaging of the OSC immediately after it is jettisoned.
2)   The S/C shall be able to provide motion compensation during NAC imaging of the OSC, while meeting the requirements in paragraph 1) of section 7.3.
3)   The S/C shall support reception of the UHF beacon from the OSC, including time tagging of both acquisition and loss of signal.
4)   The S/C shall support 1 NAC image of the OSC every 15 minutes during the initial rendezvous phase.
5)   The S/C shall support WAC imaging of the OSC during the terminal rendezvous phase for 10 seconds every 30 seconds.
6)   The S/C shall maintain the HGA toward earth and have no constraints on roll attitude during the terminal rendezvous phase.

11.1.4   Mars Sample Return Orbital Sample Canister Detection
1)   The S/C shall be able to point either NAC toward any point in a low Mars orbit and provide motion compensation during imaging of the Mars Sample Return orbital sample canister (MSR OSC), while meeting the requirements in paragraph 1) of section 7.3.
2)   The S/C shall be capable of 2 MSR OSC imaging sessions per orbit that are each up to 45 minutes in duration.
3)   The S/C shall support reception of the UHF beacon from the MSR OSC, including time tagging of both acquisition and loss of signal.

[Blackstar]

Question; Would it be more efficent to send one big comsat to Mars or a cluster of smaller "mini-comsats"?  Sats that are larger than cube sats, but smaller than regular comsats.

By doing something like this, assuming that the total mass of the mini-comsats and fuel do not exceed the total mass of the regular Comsat, you would wind up with a more redundant network of sats, able to relay transmittions from anywhere on Mars, whether it's day or night.  Recent advances in communications electronics should allow the sats to network together and / or transmit the data gathered from ground and airbon sources either together or as independant units, for data straem redundancy.

How many rovers are operating (or will be operating) all over Mars requiring such comprehensive coverage? (Answer: at most, two.)

They need comprehensive global coverage far less than they need coverage that lasts a long time. And the goal is to keep this thing relatively inexpensive, and the more capabilities that are added to it the more expensive it becomes.

[Blackstar]

The MTO vehicle that was cancelled in 2005 even had requirements to release and rendezvous with a practice orbital sample canister:

You know, considering that this telecom orbiter might have ion propulsion, there's no reason that it could not be designed to carry an Earth reentry vehicle with it and bring that back to Earth. Thus, you'd get telecom at Mars for a long period of time and then you could use that asset to bring back a sample that was launched up from Mars with an ascent vehicle.

Now that would require somebody approving the telecom orbiter for such a purpose, and you probably would not want to have to rely upon it working 10 years after it was launched in order to bring back a precious sample, but there's no inherent reason why it could not be integrated into the overall Mars sample return plans.

[Graham]

MAVEN's orbit post science will be circularized.

Do you happen to know if this will be done via aero braking or with burns?

[Space Ghost 1962]

MAVEN's orbit post science will be circularized.

Do you happen to know if this will be done via aero braking or with burns?

Only burns. Currently, occassional deep "dips" lowering then raising perapsis.

Relay is raising periapsis even more.

[Burninate]

Question; Would it be more efficent to send one big comsat to Mars or a cluster of smaller "mini-comsats"?  Sats that are larger than cube sats, but smaller than regular comsats.

By doing something like this, assuming that the total mass of the mini-comsats and fuel do not exceed the total mass of the regular Comsat, you would wind up with a more redundant network of sats, able to relay transmittions from anywhere on Mars, whether it's day or night.  Recent advances in communications electronics should allow the sats to network together and / or transmit the data gathered from ground and airbon sources either together or as independant units, for data straem redundancy.

How many rovers are operating (or will be operating) all over Mars requiring such comprehensive coverage? (Answer: at most, two.)

They need comprehensive global coverage far less than they need coverage that lasts a long time. And the goal is to keep this thing relatively inexpensive, and the more capabilities that are added to it the more expensive it becomes.

The answer is that a lot more than two will need to be in operation before a human surface mission is attempted, and this capacity needs to be forward-looking if we want permission to do that human surface mission this century.

[vjkane]

Question; Would it be more efficent to send one big comsat to Mars or a cluster of smaller "mini-comsats"?  Sats that are larger than cube sats, but smaller than regular comsats.

It depends on whether you want temporal coverage or higher data rates.  If you want more comm sessions, then more satellites are better.  If you want higher data rates, then bigger comsats with larger solar panels and higher power comm systems are better.

If you have just one landed asset (or multiple that are relatively close together), you can have both: a large spacecraft with lots of power in geosynchronous orbit.

[nadreck]

The answer is that a lot more than two will need to be in operation before a human surface mission is attempted, and this capacity needs to be forward-looking if we want permission to do that human surface mission this century.

While I totally agree that we need more surface examination before manned landings, and that multiple rovers and other probes are needed, and that a communications GPS constellation around Mars is needed and I imagine already 100% in the cards in the Musk universe of Mars exploitation. I have to ask what authority did you have in mind that can grant permission for manned Mars landings?

[kevin-rf]

GPS? It is not currently needed, and should not be needed for the initial manned landings at specific site(s). It has not been needed by the rovers and was not needed during Apollo.

[vjkane]

GPS? It is not currently needed, and should not be needed for the initial manned landings at specific site(s). It has not been needed by the rovers and was not needed during Apollo.

Rovers, no.  But would be useful for planes (several have been proposed; I doubt that any will fly).

[nadreck]

GPS? It is not currently needed, and should not be needed for the initial manned landings at specific site(s). It has not been needed by the rovers and was not needed during Apollo.

It hasn't been available which means that missions have never been designed around it's use. Lets put it this way, if you put a communications/GPS/monitoring/surveying constellation around Mars so that all the information available from the satellites including positioning could be received and processed in a 100gm/100mW device. What capabilities and missions could you dream up for the subsequent generation of probes? GPS would be used if it was available, especially if rendezvous with a sample return craft was necessary by a sample collecting rover. However in performing better site surveys, geology, mapping, etc the GPS will certainly improve the work as will all the other features of such a constellation.

[Burninate]

The answer is that a lot more than two will need to be in operation before a human surface mission is attempted, and this capacity needs to be forward-looking if we want permission to do that human surface mission this century.

While I totally agree that we need more surface examination before manned landings, and that multiple rovers and other probes are needed, and that a communications GPS constellation around Mars is needed and I imagine already 100% in the cards in the Musk universe of Mars exploitation. I have to ask what authority did you have in mind that can grant permission for manned Mars landings?

Crossposted to a separate thread to prevent this from going offtopic: http://forum.nasaspaceflight.com/index.php?topic=37244.msg1355699#msg1355699

[zubenelgenubi]

For a single, communications-relay satellite, whose prime function is relaying from multiple surface assets:
What is the optimal orbit?

Polar Low Mars Orbit ? (PLMO, to coin an acronym)
Molniya orbit?

I deduce that an areosynchronous orbit would not be useful, as a surface asset or assets could permanently be at a Martian longitude over the planet's limb from the satellite's perspective.

Zubenelgenubi

[hop]

For a single, communications-relay satellite, whose prime function is relaying from multiple surface assets:
What is the optimal orbit?

FWIW, the original Mars telecom orbiter was targeted at a 5000km orbit: http://web.archive.org/web/20050924232548/http://mars.jpl.nasa.gov/missions/future/mto.html

The spacecraft will be in contact with Earth almost around the clock, because its orbit will place it 20 times farther from the planet's surface than other spacecraft, meaning it will nearly always have a direct line of sight to Earth. The Mars Telecommunications Orbiter will fly above the surface of Mars at a distance of 5,000 kilometers (3,000 miles).

[vjkane]

For a single, communications-relay satellite, whose prime function is relaying from multiple surface assets:
What is the optimal orbit?

If communications is your only goal, and your landed assets are going to be in the equatorial zone, then you'd want to have an orbiter with an orbit that goes no further north or south.  That will result in more communication passes than with a polar orbiter.  Of course, if you are only going to have polar landers, than a polar orbit would provide a number of passes.

[zubenelgenubi]

For a single, communications-relay satellite, whose prime function is relaying from multiple surface assets:
What is the optimal orbit?

If communications is your only goal, and your landed assets are going to be in the equatorial zone, then you'd want to have an orbiter with an orbit that goes no further north or south.  That will result in more communication passes than with a polar orbiter.  Of course, if you are only going to have polar landers, than a polar orbit would provide a number of passes.

Good point differentiating requirements of "tropical" surface assets vs. polar assets.  My mental image was of several assets spread wide in latitude and longitude.

Do any "serious" agencies or organizations have serious upcoming plans for polar landers or rovers?

[vjkane]

Do any "serious" agencies or organizations have serious upcoming plans for polar landers or rovers?

Chris McKay and his team are proposing the IceBreaker mission that would return to the polar regions to follow up on the Phoenix mission for this coming Discovery competition.  The mission would launch in 2021.

The challenge is that the new orbiter, if it flies, needs to support missions of the mid- to late-2020s and early 2030s.  No one has a real idea of what they would be except the Mars community wants to send a mission to pick of the samples collected by the 2020 rover.  That latter mission is roughly constrained to the equatorial regions.

A comm orbiter with a serious ion engine and lots of time can shift from an equatorial to a polar and back to an equatorial orbit.

[baldusi]

I understand that the north pole of Mars is very shallow and thus has the most atmosphere, which makes EDL simpler. And it has a lot of water ice, thus, is the easiest place to land and a very interesting scientific place. I would hazard a guess that it is required coverage for a comm sat.

[notsorandom]

I understand that the north pole of Mars is very shallow and thus has the most atmosphere, which makes EDL simpler. And it has a lot of water ice, thus, is the easiest place to land and a very interesting scientific place. I would hazard a guess that it is required coverage for a comm sat.

If the comm sat is going to be carrying remote sensing instruments of some sort. Many of those will prefer a sun synchronous orbit which gives most site on the planets two fly overs a day. Odyssey for example is in a sun sync orbit. One is at night the other day. If the communications orbiter were in such an orbit it should be able to cover the polar regions pretty well.

[Blackstar]

Do any "serious" agencies or organizations have serious upcoming plans for polar landers or rovers?

Chris McKay and his team are proposing the IceBreaker mission that would return to the polar regions to follow up on the Phoenix mission for this coming Discovery competition.  The mission would launch in 2021.

The challenge is that the new orbiter, if it flies, needs to support missions of the mid- to late-2020s and early 2030s.  No one has a real idea of what they would be except the Mars community wants to send a mission to pick of the samples collected by the 2020 rover.  That latter mission is roughly constrained to the equatorial regions.

A comm orbiter with a serious ion engine and lots of time can shift from an equatorial to a polar and back to an equatorial orbit.

The ion engine adds an interesting dimension, including optimizing the orbit based upon what is on the ground on Mars.

But I suspect that a mission like IceBreaker, which is Discovery class and would have a limited lifetime, would have relatively little impact on deciding the comm-relay needs. They're going to design the comm relay solution to cover the most important and broadest range. A single mission to the poles that would only operate for a relatively short time would not justify major changes to the relay architecture.

[redliox]

Do any "serious" agencies or organizations have serious upcoming plans for polar landers or rovers?

A comm orbiter with a serious ion engine and lots of time can shift from an equatorial to a polar and back to an equatorial orbit.

The ion engine adds an interesting dimension, including optimizing the orbit based upon what is on the ground on Mars.

But I suspect that a mission like IceBreaker, which is Discovery class and would have a limited lifetime, would have relatively little impact on deciding the comm-relay needs. They're going to design the comm relay solution to cover the most important and broadest range. A single mission to the poles that would only operate for a relatively short time would not justify major changes to the relay architecture.

Considering we're starting to get ion engines with Earthly communication satellites it makes sense to put them aboard a Martian one, not so much for orbit insertion but so it can remain stable in orbit for not just 5 or 10 but perhaps even 20 years.

I have a feeling the first manned landing will be equatorial; heck if you look at the current operating rovers you'll notice even they are pretty much equatorial.  So a synchronous (or otherwise in a high orbit) satellite won't be a disadvantage.  If we have to settle for a single comsat, I'd suggest putting it in a 12 hour equatorial orbit so I can get coverage over the majority of Mars at least twice a day.