Author Topic: Station On Phobos  (Read 14495 times)

Offline sanman

  • Senior Member
  • *****
  • Posts: 3383
  • Liked: 376
  • Likes Given: 1
Station On Phobos
« on: 04/29/2016 09:13 AM »
Is there a case for establishing a manned station on Phobos before seeking a significant permanent manned presence on Mars? What would be required to establish such a station?

The idea would be to have personnel at this Phobos Station tele-operating robotic equipment on the Martian surface to construct the permanent base on Mars. People would aIso be able to shuttle between Phobos and the Martian surface to carry out exploration. The Phobos Station would initially be completely re-supplied from Earth, while trying to transition to Mars ISRU. Perhaps it could also serve as a springboard for missions to the asteroid belt, including asteroid ISRU.

This might permit more extensive tele-robotic exploration of the Martian surface for resources before deciding where to situate a permanent Mars base/colony.

So perhaps this station would be like an ISS farther away from home, but afforded protection by Phobos regolith.

What are the pro's, cons, and challenges for this approach?
« Last Edit: 04/29/2016 09:16 AM by sanman »

Offline The Amazing Catstronaut

  • Full Member
  • ****
  • Posts: 1066
  • Arsia Mons, Mars, Sol IV, Inner Solar Solar System, Sol system.
  • Liked: 753
  • Likes Given: 624
Re: Station On Phobos
« Reply #1 on: 04/29/2016 09:25 AM »

What are the pro's, cons, and challenges for this approach?

Assuming you don't have an LV large enough to launch most of your ship at once, it lets missions sized for SLS conduct manned missions to Martian space for less launches. Your landers can be less sophisticated, indeed, landing most of the components required for a Phobos base would be significantly easier.

The cons include minimal gravity, and a lack of true simulation of the Martian environment. A Phobos base would be more similar to a large asteroid base than Mars itself.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Online guckyfan

  • Senior Member
  • *****
  • Posts: 5955
  • Germany
  • Liked: 1461
  • Likes Given: 1178
Re: Station On Phobos
« Reply #2 on: 04/29/2016 10:01 AM »
With SLS type capabilities it may make sense, it would make things easier. Biggest problem would be very long microgravity trips. But these are part of NASA mission plans anyway. Alsowithout local water more supplies need to be shipped, but not too bad assuming closed loop ECLSS.

With MCT type capabilities direct to Mars would be easier, assuming fuel ISRU is prepositioned. If water and CO2 can be sourcedon Phobos fuel ISRU would be possible there too.  With fuel from Phobos less fuel is needed over all because the fuel for TEI would not need to be lifted up from Mars. It would enable larger payloads back to earth too.

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1492
  • Germany
  • Liked: 40
  • Likes Given: 24
Re: Station On Phobos
« Reply #3 on: 04/29/2016 10:12 AM »
Absolutely yes, but I've been saying that for years.

Some threads:
http://forum.nasaspaceflight.com/index.php?topic=18339.0 is one of the earlier ones.
http://forum.nasaspaceflight.com/index.php?topic=38158.0
http://forum.nasaspaceflight.com/index.php?topic=19308.msg498003#msg498003 where I outlined a route-map in 2009. This basically involves having a permanent base on Phobos, with ISRU fuel and food production, and manufacturing. This base later colonises Mars.
http://forum.nasaspaceflight.com/index.php?topic=18759.msg477151#msg477151 This is about big habitats on Phobos, which is one of the things that makes it so attractive.

Ideally, we'd like to know a bit more about Phobos:
- Is there water
- Are there organic materials we can use to make plastics and hydrocarbons?
- How can we deal with the regolith - is Phobos a loose rubble pile?

Hence we need an exploration vehicle there as soon as possible.

Online guckyfan

  • Senior Member
  • *****
  • Posts: 5955
  • Germany
  • Liked: 1461
  • Likes Given: 1178
Re: Station On Phobos
« Reply #4 on: 04/29/2016 10:46 AM »
Ideally, we'd like to know a bit more about Phobos:
- Is there water
- Are there organic materials we can use to make plastics and hydrocarbons?
- How can we deal with the regolith - is Phobos a loose rubble pile?

Hence we need an exploration vehicle there as soon as possible.

Absolutely, yes.

Though, assuming MCT, I would do this not as a first step. But I would appreciate, if NASA did this ASAP.

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 361
  • Likes Given: 0
Re: Station On Phobos
« Reply #5 on: 04/30/2016 12:31 AM »
The primary long term advantage to a Station on Phobos is as a logistical hub where interplanetary craft doing the long haul between Earth and Mars (probably with SEP) can exchange cargo, passengers and propellants with surface-2-orbit shuttle powered by conventional chemical propellants.

This would make it similar to McMurdo Station in Antarctica which serves as the American logistical hub.

Online savuporo

  • Senior Member
  • *****
  • Posts: 4753
  • Liked: 789
  • Likes Given: 273
Re: Station On Phobos
« Reply #6 on: 04/30/2016 12:34 AM »
Is there a case for establishing a manned station on Phobos before seeking a significant permanent manned presence on Mars? What would be required to establish such a station?

This will not end well ..


Orion - the first and only manned not-too-deep-space craft

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #7 on: 04/30/2016 08:17 AM »
I love the Martian moons, and certainly would support visiting them.  Personally, I favor Deimos over Phobos because it is closer to synchronous orbit as well as the gravity well edge; both of which would be a boon to orbiting craft; Phobos of course is more scientifically interesting and easier to reach Mars.  The odds of visiting them after seeing Mars are good, but setting up a permanent habitat is more difficult to figure.

The Flexible Plan NASA's currently following favors orbital vehicles.  Because of weak gravity, the same vehicles can double as asteroid/Martian moon landers with minimal tinkering.  Currently the NASA idea to orbit Mars include a Phobos habitat to stay at.  However, that could easily change with politics, and if Red Dragon proves equipment (not crews, but definitely habs) can be directly landed on Mars, NASA might switch funds for a Mars camp instead of a Phobos station.

If a Phobos station is cobbled together, I'd assume it'd be built first in orbit and then fixed to the moon; dust in micro-gravity would be a titanic pain.  Taking the Bigelow ideas for a Lunar station, which likewise would be assembled in orbit before landing it in once piece, could easily be implemented for Phobos (and Deimos).  There could be surface science for the moon, remote observations on Mars with perhaps telerobotics, and even the return vehicles could dock to the station.

Pros: Easily compatible with orbital missions;unique 'asteroid' science with some Mars science (including telerobotics); potentially useful staging point (at either moon)

Cons: Less desirable than Mars camp; micro-gravity and radiation effects; redundant rather than essential v.s. Mars

I believe in any case all that's genuinely needed is an orbital vehicle to visit Phobos.  A habitat is basically the same thing pinned to the moon; you only really need it if the visit lasts more than 30 days (and, especially if the crew are otw home, shorter visits are more likely).  IMO a dedicated habitat is unnecessary, but ultimately it will depend on how NASA's plans get revised in the near future, especially in light of a Red Dragon landing bypassing the orbital route.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline sanman

  • Senior Member
  • *****
  • Posts: 3383
  • Liked: 376
  • Likes Given: 1
Re: Station On Phobos
« Reply #8 on: 05/01/2016 10:10 AM »
If a manned presence were established on Phobos for the purpose of tele-operating equipment on the Martian surface in lieue of having people down on the planet, what kind of savings would that provide?

I'm also then wondering how to quantify a meaningful comparison: 
$/kg-to-Phobos vs $/kg-to-Mars?
MJ/kg-to-Phobos vs MJ/kg-to-Mars?
« Last Edit: 05/01/2016 10:14 AM by sanman »

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1492
  • Germany
  • Liked: 40
  • Likes Given: 24
Re: Station On Phobos
« Reply #9 on: 05/02/2016 10:17 AM »
If a manned presence were established on Phobos for the purpose of tele-operating equipment on the Martian surface in lieue of having people down on the planet, what kind of savings would that provide?

I'm also then wondering how to quantify a meaningful comparison: 
$/kg-to-Phobos vs $/kg-to-Mars?
MJ/kg-to-Phobos vs MJ/kg-to-Mars?

It's about 500m/s more delta V to reach Phobos than Mars, but the Mars entry system tends to weigh more than its payload - so at least doubles the cost and increases risk.

Then there's the issue of Mars to Earth, versus Phobos to Earth. The latter is easy. The former needs some level of ISRU. It is probably not feasible to do Mars to Earth direct without hydrogen. Whereas Mars to Phobos can be done with Carbon monoxide fuel, and at Phobos the crew could rendez-vous before heading home.

In fact, with Phobos ISRU, you could have a reusable lander making several trips to different points on the Mars surface. This would effectively allow multiple exploration trips before deciding on a first surface base.

Online A_M_Swallow

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8011
  • South coast of England
  • Liked: 236
  • Likes Given: 86
Re: Station On Phobos
« Reply #10 on: 05/02/2016 01:49 PM »
If the Phobos ISRU is reusable when the mass of fuel produced is about twice the mass of the ISRU equipment then it probably becomes worthwhile using the ISRU for Mars landings. Bringing things from Earth is very expensive.

Offline HotFyre

  • Member
  • Posts: 9
  • US
  • Liked: 1
  • Likes Given: 3
Re: Station On Phobos
« Reply #11 on: 05/19/2016 04:16 PM »
I think this is a good idea. We can, for instance, have 2 stations: one on Phobos, and one on Mars. This might be helpful in many ways.
:D

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 30379
  • Cape Canaveral Spaceport
  • Liked: 8679
  • Likes Given: 283
Re: Station On Phobos
« Reply #12 on: 05/19/2016 05:20 PM »
If a manned presence were established on Phobos for the purpose of tele-operating equipment on the Martian surface in lieue of having people down on the planet, what kind of savings would that provide?


Why?  Can teleoperate from earth.

Offline sanman

  • Senior Member
  • *****
  • Posts: 3383
  • Liked: 376
  • Likes Given: 1
Re: Station On Phobos
« Reply #13 on: 05/19/2016 05:24 PM »
If a manned presence were established on Phobos for the purpose of tele-operating equipment on the Martian surface in lieue of having people down on the planet, what kind of savings would that provide?


Why?  Can teleoperate from earth.

Well, I guess I meant realtime tele-operation -- or do you feel that's unnecessary?

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 30379
  • Cape Canaveral Spaceport
  • Liked: 8679
  • Likes Given: 283
Re: Station On Phobos
« Reply #14 on: 05/19/2016 05:26 PM »
 Or just land on Mars.

Offline Phil Stooke

  • Full Member
  • **
  • Posts: 286
  • Canada
  • Liked: 174
  • Likes Given: 0
Re: Station On Phobos
« Reply #15 on: 05/19/2016 05:46 PM »
Phobos operations are the Apollos 8 and 10 to landing on Mars's Apollo 11.  A full dress rehearsal mission - with useful science content including Phobos and Deimos exploration (much simpler lander required) and operation of assets on Mars, especially sample collection.  Imagine for instance sample collection of polar volatiles, with maybe a 48 hour travel time to the Phobos and/or orbital base for quick analysis rather than trying to keep a cryogenic sample in good shape for an 8 month trip to Earth.  That would be a really good precursor to the first Mars landing.  Probably essential, I would suggest, just like Apollos 8 and 10.

Offline docmordrid

  • Senior Member
  • *****
  • Posts: 4086
  • Michigan
  • Liked: 1287
  • Likes Given: 1
Re: Station On Phobos
« Reply #16 on: 05/20/2016 07:12 AM »
AIUI Phobos may be a dust coated rubble pile with tidal issues. Not sure that's a stable platform for a base.
DM

Offline K-P

  • Full Member
  • *
  • Posts: 145
  • Liked: 61
  • Likes Given: 0
Re: Station On Phobos
« Reply #17 on: 05/20/2016 07:45 AM »
AIUI Phobos may be a dust coated rubble pile with tidal issues. Not sure that's a stable platform for a base.

And because of this uncertainty I find it un-be-lie-vab-le that we still have not found time, money & interest to send even a modest lander / orbiter to Phobos or Deimos...! Those moons are near Mars, are two interesting targets on their own, are also asteroids, give possibility to do Mars observations at the same time, give knowledge for future manned mission... Looking at all this, it seems so weird NASA has no interest at all for those Martian moons.

OK, Russians have tried, but...

Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 3497
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 593
  • Likes Given: 981
Re: Station On Phobos
« Reply #18 on: 05/20/2016 07:49 AM »
Phobos is geologically interesting in it's own right - probably more so than most free-range asteroids. And any rumours of it's instability I feel would be greatly exaggerated. And some feel Deimos would be a better location for a base because of it's lower delta-v requirements. But I'd prefer the view from Phobos! :) Putting a station down in Stickney crater would be a good shield from a lot of cosmic radiation. Also; unless Space X cracks the problem of landing vehicles heavier than 10 tons on Mars for a reasonable cost, most any large scale manned lander is going to be an expensive, unfunded fantasy at this point :(

NOTE: There are some other threads here on this and very similar subjects - have a look around...

http://forum.nasaspaceflight.com/index.php?topic=38487.0;all

http://forum.nasaspaceflight.com/index.php?topic=36977.0;all
« Last Edit: 05/20/2016 10:22 AM by MATTBLAK »
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 30379
  • Cape Canaveral Spaceport
  • Liked: 8679
  • Likes Given: 283
Re: Station On Phobos
« Reply #19 on: 05/20/2016 01:26 PM »
Phobos operations are the Apollos 8 and 10 to landing on Mars's Apollo 11.  A full dress rehearsal mission - with useful science content including Phobos and Deimos exploration (much simpler lander required) and operation of assets on Mars, especially sample collection.  Imagine for instance sample collection of polar volatiles, with maybe a 48 hour travel time to the Phobos and/or orbital base for quick analysis rather than trying to keep a cryogenic sample in good shape for an 8 month trip to Earth.  That would be a really good precursor to the first Mars landing.  Probably essential, I would suggest, just like Apollos 8 and 10.

Such missions are not needed and would be a waste of resources.  Actually, they would not be like Apollo 8 & 10 because MOR (the Martian equivalent of LOR) is not likely going to be the conop (example, Mars Direct doesn't use MOR) and hence the missions would be dead ends. 
« Last Edit: 05/20/2016 01:29 PM by Jim »

Offline Bynaus

  • Full Member
  • ***
  • Posts: 316
  • Planetary Scientist
  • Switzerland
  • Liked: 211
  • Likes Given: 119
Re: Station On Phobos
« Reply #20 on: 05/20/2016 02:15 PM »
There are two approaches to Mars landings by humans: "do it right" from the beginning and "do it in incremental steps".

Doing it right is something like the scenario layed out by Andy Weir in "The Martian", where you have a large interplanetary transfer habitat/ship and massive, prepositioned landers. A lot of margin to all sides. Or like the MCT system.

From watching NASA plans wax and wane over the last two-three decades or so, I fear that there will never be enough funding or political will to fully finance the "do it right" approach. If one accepts this as true, we can still hope for a private enterprise to succeed (like, obviously, SpaceX), but if we want a long-term plan for sending humans to Mars that can survive the possibility of, say, a SpaceX collapse, I think there is no other way than the "incremental" one. This way will not bring humans to the surface of Mars in the 2030ies, but has a decent chance of doing so later. In the incremental approach, a cislunar habitat might be the next step. Then, eventually, a Mars flyby mission. Then a Mars orbital station, quickly followed (or evolving into) a Phobos station.

And therefore, while I agree that it is not "needed" in the "do it right" approach, I think that a station on Phobos would be a good step in the context of the incremental approach. It provides shielding from much of the cosmic radiation (Stickney has been mentioned, where the shielding of GCR should actually be better than on the martian surface: you have the body of Phobos including the crater walls, and Mars on the other end of the sky for shielding).

- It provides great opportunities for science (collecting Mars rocks ejected by impacts on the martian surface and deposited on Phobos and investigating the formation of the satellites).

- There might be ISRU opportunities, but I wouldn't hold my breath that Phobos and Deimos are actually captured asteroids with high water contents. It looks more and more like they are the last Mohicans from series of satellites formed by an early Giant Impact on Mars. As such, they would likely be very dry apart from what has been implanted by micrometeorites and the solar wind (like the Moon).

- Teleoperation has been mentioned, this could go to the point of "Varging" / "Avataring" :) into humanoid robots on the surface of Mars to carry out most of the tasks which would otherwise be accomplished by astronauts on the surface. A station could also assist with the repair/uprating of sophisticated science and telecommunication satellites in orbit around Mars.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 30379
  • Cape Canaveral Spaceport
  • Liked: 8679
  • Likes Given: 283
Re: Station On Phobos
« Reply #21 on: 05/20/2016 02:39 PM »
A station could also assist with the repair/uprating of sophisticated science and telecommunication satellites in orbit around Mars.

No, that is false, much like how "useful" the ISS would be in performing the same tasks in Earth orbit.   Space stations are only useful for servicing spacecraft in similar orbits, which is the exception and not the rule. (ISS or an LEO station is terrible for servicing GSO, GPS, sun synch and other cluster orbits).

Offline Eric Hedman

  • Full Member
  • ****
  • Posts: 723
  • Liked: 162
  • Likes Given: 143
Re: Station On Phobos
« Reply #22 on: 05/20/2016 02:58 PM »
There are two approaches to Mars landings by humans: "do it right" from the beginning and "do it in incremental steps".

Doing it right is something like the scenario layed out by Andy Weir in "The Martian", where you have a large interplanetary transfer habitat/ship and massive, prepositioned landers. A lot of margin to all sides. Or like the MCT system.
Then there are those who think doing it in incremental steps is doing it right because it is more likely to leave an infrastructure in place for permanently staying where ever we go next.  It also doesn't force you into mission architecture choices too early before the latest breakthroughs can be evaluated and incorporated.  If NASA had settled on an architecture ten years ago for going to Mars and had somehow finagled funding for it, all the major choices would have been made without the valuable knowledge gained from the last decade.  All I could imagine from that is a horribly expensive, way over budget, significantly delayed one time flags and footprints mission.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 25908
  • Minnesota
  • Liked: 5951
  • Likes Given: 4414
Re: Station On Phobos
« Reply #23 on: 05/20/2016 07:39 PM »
Phobos operations are the Apollos 8 and 10 to landing on Mars's Apollo 11.  A full dress rehearsal mission - with useful science content including Phobos and Deimos exploration (much simpler lander required) and operation of assets on Mars, especially sample collection.  Imagine for instance sample collection of polar volatiles, with maybe a 48 hour travel time to the Phobos and/or orbital base for quick analysis rather than trying to keep a cryogenic sample in good shape for an 8 month trip to Earth.  That would be a really good precursor to the first Mars landing.  Probably essential, I would suggest, just like Apollos 8 and 10.

Such missions are not needed and would be a waste of resources.  Actually, they would not be like Apollo 8 & 10 because MOR (the Martian equivalent of LOR) is not likely going to be the conop (example, Mars Direct doesn't use MOR) and hence the missions would be dead ends.
Jim is a semi-closeted SpaceX fan, as we can see.

The NASA PoR (or the closest we have to one) uses Mars-Orbit-Rendezvous. Of all the different NASA paths to Mars, basically all assume MOR. SpaceX intends to go the Mars Direct route by skipping a separate transit vehicle.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Bynaus

  • Full Member
  • ***
  • Posts: 316
  • Planetary Scientist
  • Switzerland
  • Liked: 211
  • Likes Given: 119
Re: Station On Phobos
« Reply #24 on: 05/20/2016 09:26 PM »
A station could also assist with the repair/uprating of sophisticated science and telecommunication satellites in orbit around Mars.

No, that is false, much like how "useful" the ISS would be in performing the same tasks in Earth orbit.   Space stations are only useful for servicing spacecraft in similar orbits, which is the exception and not the rule. (ISS or an LEO station is terrible for servicing GSO, GPS, sun synch and other cluster orbits).

You are right, but thats not what I meant. Of course, astronauts based at this station would have to do sorties with a vehicle to reach the hardware in its orbit (or have some robots teleoperated from the station do so), and either repair it on-spot (more likely) or haul it back to the station for longer repair jobs (less likely). This has been done in Earth orbit, with a one-piece-maneuverable-reusable-space-station (called the Space Shuttle) repairing a telescope a couple of times. By the time we have a space station on Phobos, (unmanned) satellite repairing and refueling might even be a thing around Earth, so it would be natural to use a Phobos base (or a Mars orbital base) to that end. One could e.g. think of using an ARM-derived vehicle to do this job.

One could also say that a Phobos station may be terrible to service a satellite in a polar orbit around Mars, but in many situations this is actually less terrible than losing the satellite completely or servicing it from Earth.
« Last Edit: 05/20/2016 09:31 PM by Bynaus »

Offline Phil Stooke

  • Full Member
  • **
  • Posts: 286
  • Canada
  • Liked: 174
  • Likes Given: 0
Re: Station On Phobos
« Reply #25 on: 05/20/2016 10:14 PM »
"Such missions are not needed and would be a waste of resources."

Not a waste if they return a lot of good science and allow a full-up test of everything except the big Mars lander. 

For teleoperation of assets on Mars, Deimos has several advantages.  It can see more of the planet (line of sight to higher latitudes), offers longer direct communication sessions with a lander (but with longer gaps between them), is eclipsed less often by Mars, and offers longer periods of continuous summer sunlight (AKA peaks of nearly eternal light) (since P and D have seasons just like Mars).

Refs:

Hopkins, J. B. and Pratt, W. D., 2011a.  Comparison of Deimos and Phobos for human exploration and identification of preferred landing sites on Deimos.  Presented at the Second International Conference on the Exploration of Phobos and Deimos, NASA Ames Research Center, 14-16 March 2011.

Hopkins, J. and Pratt, W., 2011b.  Comparison of Deimos and Phobos as destinations for human exploration, and identification of preferred landing sites.  Presented at the AIAA Space 2011 Conference, Long Beach, California, 27-29 September 2011.



Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 3497
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 593
  • Likes Given: 981
Re: Station On Phobos
« Reply #26 on: 05/21/2016 12:50 AM »
The more I read about the subject, the more I'm seeing that Deimos is a better place for a Space Station and tele-robotics operation center and Phobos is 'merely' a place to visit as a scientific destination. You could place a tele/vidcomm relay station on Phobos for future missions as well, once it's been visited a couple times by people. Though a program of exploration by probes would execute most if not all of what Astronauts could do. I wish Russia/ESA would make another attempt at the Phobos/Grunt mission!

As for Space X on Mars: there are several threads about such things and no particular need to rubbish manned Phobos expeditions at this point. If Red Dragon succeeds spectacularly, then we will have a (partially) working 'scale model' of a Mars Direct style architecture - at least the first stage. As a closer for this thread-diversion, for a potential splinter thread, I'd say to Bob Zubrin - revise and redraw your Space X-based Mars Direct version from a few years back and have at it. Also, I've posted a link to this video before, but here's a manned Phobos mission video, using some Space X hardware...

"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 361
  • Likes Given: 0
Re: Station On Phobos
« Reply #27 on: 05/21/2016 02:15 AM »
Phobos operations are the Apollos 8 and 10 to landing on Mars's Apollo 11.  A full dress rehearsal mission - with useful science content including Phobos and Deimos exploration (much simpler lander required) and operation of assets on Mars, especially sample collection.  Imagine for instance sample collection of polar volatiles, with maybe a 48 hour travel time to the Phobos and/or orbital base for quick analysis rather than trying to keep a cryogenic sample in good shape for an 8 month trip to Earth.  That would be a really good precursor to the first Mars landing.  Probably essential, I would suggest, just like Apollos 8 and 10.

Such missions are not needed and would be a waste of resources.  Actually, they would not be like Apollo 8 & 10 because MOR (the Martian equivalent of LOR) is not likely going to be the conop (example, Mars Direct doesn't use MOR) and hence the missions would be dead ends.
Jim is a semi-closeted SpaceX fan, as we can see.

The NASA PoR (or the closest we have to one) uses Mars-Orbit-Rendezvous. Of all the different NASA paths to Mars, basically all assume MOR. SpaceX intends to go the Mars Direct route by skipping a separate transit vehicle.

Long term MOR between transit vehicles and landers is the only way to get any kind of colonization going.  A direct flight is simply untenable due to vehicle amortization, for a first mission I could see it being done but it would only be a stepping stone.

Online guckyfan

  • Senior Member
  • *****
  • Posts: 5955
  • Germany
  • Liked: 1461
  • Likes Given: 1178
Re: Station On Phobos
« Reply #28 on: 05/21/2016 04:03 AM »
"Such missions are not needed and would be a waste of resources."

Not a waste if they return a lot of good science and allow a full-up test of everything except the big Mars lander. 

For teleoperation of assets on Mars, Deimos has several advantages.  It can see more of the planet (line of sight to higher latitudes), offers longer direct communication sessions with a lander (but with longer gaps between them), is eclipsed less often by Mars, and offers longer periods of continuous summer sunlight (AKA peaks of nearly eternal light) (since P and D have seasons just like Mars).

I would love to see Phobos and/or Deimos thoroughly researched and am wondering why it has not happened yet. It looks like a low hanging fruit compared to Mars landers.

I see why any NASA mission concept would do that before Mars landing. Low hanging fruit again, very tasty and nutritious fruits though. But I do wonder why NASA is that confident to do very long missions in microgravity. Are the data collected on the ISS that positive?

The SpaceX MCT concept requires going to Mars directly. Phobos, Deimos missions can be done from there, initially automated, with low latency control from the ground.

I don't see an advantage from better line of sight options from Deimos. By then there will be a network of com sats that ensure permanent connections between Mars, Phobos, Deimos, Earth.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #29 on: 05/21/2016 11:02 AM »
For teleoperation of assets on Mars, Deimos has several advantages.  It can see more of the planet (line of sight to higher latitudes), offers longer direct communication sessions with a lander (but with longer gaps between them), is eclipsed less often by Mars, and offers longer periods of continuous summer sunlight (AKA peaks of nearly eternal light) (since P and D have seasons just like Mars).
The more I read about the subject, the more I'm seeing that Deimos is a better place for a Space Station and tele-robotics operation center and Phobos is 'merely' a place to visit as a scientific destination. You could place a tele/vidcomm relay station on Phobos for future missions as well, once it's been visited a couple times by people. Though a program of exploration by probes would execute most if not all of what Astronauts could do. I wish Russia/ESA would make another attempt at the Phobos/Grunt mission!

That's why I like Deimos more as well.  It's not as intriguing as Phobos, but it's nicely positioned between the synchronous orbit and the edge of the Martian gravity well.

I would love to see Phobos and/or Deimos thoroughly researched and am wondering why it has not happened yet. It looks like a low hanging fruit compared to Mars landers.

Well in terms of fruit you're comparing two grapes to a watermelon, both in literal size and scientific interest.  Phobos and Deimos have the misfortune of being perpetually overshadowed by their parent planet.  Their formation is mysterious, but comparing that to the prospects of Mars having been a living planet blows things out of the water.

I don't see an advantage from better line of sight options from Deimos. By then there will be a network of com sats that ensure permanent connections between Mars, Phobos, Deimos, Earth.

Considering the threads dedicated to Martian com networks that's far from guaranteed, and we'll probably have just the next NASA orbiter; a network of one (sans any international contributions) isn't much.

If things persist in NASA desiring staging in Mars orbit first, I'd assume the parking orbit of the crew vehicles might designate the com network orbit; this could be virtually any equatorial orbit although something coordinated with Deimos, Phobos, or the synchronous orbit are prime candidates.


As for Space X on Mars: there are several threads about such things and no particular need to rubbish manned Phobos expeditions at this point. If Red Dragon succeeds spectacularly, then we will have a (partially) working 'scale model' of a Mars Direct style architecture - at least the first stage. As a closer for this thread-diversion, for a potential splinter thread, I'd say to Bob Zubrin - revise and redraw your Space X-based Mars Direct version from a few years back and have at it. Also, I've posted a link to this video before, but here's a manned Phobos mission video, using some Space X hardware...

Sweet video, although the prospects of a Venus flyby and nuclear thermal propulsion are a bit unfeasible.  However, it does wonderfully illustrate the 3 core elements for specifically exploring the moons, sans a space suit with rocket backpack: 1) Habitat Module 2) Propulsion Module 3) Earth Return Vehicle.  The ERV probably could be left behind in Earth orbit to save weight, but if brought along for a Deimos/Phobos trip it would enhance the visit.  The largest disadvantage of orbiting Mars first alongside Martian moon visits is you definitely have to carry or preposition the fuel without Mars for fuel production; Deimos has a slight advantage in requiring slightly less fuel, but you may as well splurge and see both moons in the same trip.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 3497
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 593
  • Likes Given: 981
Re: Station On Phobos
« Reply #30 on: 05/21/2016 12:05 PM »
Totally agree. There would be no nuclear propulsion - you'd basically be using two chemical stages for every 1x  portrayed nuclear one. Meaning an extra couple Falcon Heavy launches per mission - still cheaper than the billions needed to develop nuclear thermal propulsion though. Hab module could be either a triple-length Cygnus or perhaps a Falcon upper stage propellant tank as a 'Skylab' type. I'd suggest keeping the crew to only two Astronauts for keeping the consumables manageable..
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline RonM

  • Full Member
  • ****
  • Posts: 1950
  • Atlanta, Georgia USA
  • Liked: 862
  • Likes Given: 678
Re: Station On Phobos
« Reply #31 on: 05/21/2016 12:17 PM »
Totally agree. There would be no nuclear propulsion - you'd basically be using two chemical stages for every 1x  portrayed nuclear one. Meaning an extra couple Falcon Heavy launches per mission - still cheaper than the billions needed to develop nuclear thermal propulsion though. Hab module could be either a triple-length Cygnus or perhaps a Falcon upper stage propellant tank as a 'Skylab' type. I'd suggest keeping the crew to only two Astronauts for keeping the consumables manageable..

Nuclear thermal sounded good with Ares V and SLS, but with cheaper launchers chemical makes sense.

A crew of two keeps the mission smaller and more affordable, but you lose crew redundancy. What happens if one of the crew becomes incapacitated or worse? Crew of four would be better.

Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 3497
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 593
  • Likes Given: 981
Re: Station On Phobos
« Reply #32 on: 05/21/2016 12:23 PM »
Then split the difference and use 3 Astros - but your consumables then rise by more than 33% percent.
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Online Kaputnik

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 2687
  • Liked: 367
  • Likes Given: 303
Re: Station On Phobos
« Reply #33 on: 05/22/2016 12:12 PM »
I think it is human nature to want to visit 'stuff' in space, but I can't help thinking that the benefits may be outweighed by the disadvantages in this case.
The only two reasons I am aware of that a base on (in reality, flying in formation with) a Martian moon are 1) possibility of ISRU; 2) Partial radiation shielding

On 1) I believe that too many people underestimate the big leap in technology between atmospheric ISRU and ISRU that involves regolith processing. The former is essentially 'non contact' and uses a uniform, known substance which does not present challenges with wear, jamming, etc. Mining and processing regolith will require a much greater volume of material to be processed, all of which comprises potentially hazardous dusty and rocky material. Parts will need replaced, bits of rock and dust will jam in machinery and seals. A totally different prospect for long term maintenance.

On 2) the radiation shielding provided is 50% at best (well a Mars-facing location on Phobos would be pretty good) but radiation needs to be addressed for the transit portions of the mission anyway, so it's not as though this solves anything that doesn't need to be addressed in another way as well.

The main downsides I see are: dust environment; difficulty in providing AG (although I acknowledge that many missions do not baseline AG anyway).
Waiting for joy and raptor

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 361
  • Likes Given: 0
Re: Station On Phobos
« Reply #34 on: 05/23/2016 06:04 AM »
If your trying to shield yourself from radiation in a Crater on Phobos the most important thing is the slope of the crater walls and the degree to which that rim reduces the visible horizon to less then that of a full hemisphere.

Mars being in the sky and acting to shield you is almost irreverent as Mars though it is the huge in the sky at an angular size of ~43 degrees (imagine a dinner plate held at arms length) only blocks about 7% of a hemisphere.  But it would certainly be nice to have it in view as it would aid communications and observation.

If you were in a bottom of a cone shaped crater in which the rim was 30 degrees above the horizon (not very steep for a crater) then you will have cut out half the hemisphere and half the Cosmic radiation with it. 

That would be half the dosage of a flat open plane on Mars surface but you would need to worry about solar-flare exposure when on EVA as their is no atmosphere, a vehicle should easily protect you from this so get inside during bad space weather.

So from a radiation perspective Phobos is highly attractive, a spacecraft would just need to make a soft landing (almost more of a docking when escape velocity is 11 m/s) to get the best radiation shielding in the Mars system short of going full underground.  Plus such a vehicle could be re-positioned to multiple locations for easy visitation of many sites.

A habitat designed for zero-g would continue to function normally under such low gravity irregardless of orientation as the crew members inside can jump/bounce off walls/floors under what is basically micro-gravity.  Solar power would be the trickiest detail as the less sky view you have the less power you have, polar craters would be no go likely due to this but their are still many equatorial craters to choose from that get light each revolution.

Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 3497
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 593
  • Likes Given: 981
Re: Station On Phobos
« Reply #35 on: 05/23/2016 06:55 AM »
Checkout the secondary crater within Stickney ;)
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline Bynaus

  • Full Member
  • ***
  • Posts: 316
  • Planetary Scientist
  • Switzerland
  • Liked: 211
  • Likes Given: 119
Re: Station On Phobos
« Reply #36 on: 05/23/2016 07:31 AM »
Checkout the secondary crater within Stickney ;)

Jup, the bottom of that secondary crater (called Limtoc, by the way) would be a good site for a station, not least due to the steep crater walls (which provide shielding from not only GCRs, but also micrometeorite impacts). Communications with other assets in the Mars system (except the planets surface) would likely be hindered a bit, but this is a question of setting up a couple of relais at a few exposed points on the surface. Same for solar power, just position your arrays outside the crater. The high tilt of the Mars system means there are no peaks of perpetual light, so batteries will have to do, similar as on the ISS, so this should be doable.

I am not sure about gravity being fully negligible: surface gravity is about 600 micro-gee (average, I would expect this to vary considerably, likely a bit higher at the crater floor), so when floating, you would accelerate by 6 mm/s per second. An object falling from 1 m height would reach the floor in 18 seconds, at which point it would have a speed of ~0.1 m/s. If you were to push off at one wall at 1 m/s in horizontal direction and 1 m above the floor, you could carry on for a distance of 18 m before touching the floor again. I imagine that would be quite cool. A bit like flying in dreams.

EDIT: Another interesting thing about a station within Stickney is that the Mars-Phobos L1 is just about 2.5 km above Stickney. It could be reached by a super-short "space elevator" of only a few km length. A small docking module at the Phobos-Mars L1 could then be used by incoming resupply vehicles, so they wouldn't even need to land and deal with surface dust issues.
« Last Edit: 05/23/2016 07:40 AM by Bynaus »

Online Kaputnik

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 2687
  • Liked: 367
  • Likes Given: 303
Re: Station On Phobos
« Reply #37 on: 05/23/2016 01:27 PM »
So it's a win for radiation, a loss for insolation and dust, and ISRU could be called 'inconclusive'.

I just think that any spacecraft capable of acting as a Phobos base would have to be pretty much capable of acting as a free flying craft anyway. Surely it would be easier to sit in the sunlight in Mars orbit and maybe visit Phobos for scientific sorties using a specialised excursion vehicle.

Of course in the distant future Phobos and a L2 elevator sounds very cool, but let's not talk about running before we can crawl.
Waiting for joy and raptor

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 30379
  • Cape Canaveral Spaceport
  • Liked: 8679
  • Likes Given: 283
Re: Station On Phobos
« Reply #38 on: 05/23/2016 02:07 PM »
"Such missions are not needed and would be a waste of resources."

Not a waste if they return a lot of good science and allow a full-up test of everything except the big Mars lander. 


Huge waste to go to Mars to perform "full-up test of everything".  There is nothing unique about a Mars orbit that needs specific testing.  All can be done in LEO or cislunar space.  Apollo 8 and 10 happened because we were still learning rocket science.  Don't need to shake down a spacecraft in Mars orbit, don't need to test comm from Mars distances, don't need to shake down a launch vehicle for Mars trajectories.    In summary, there is no benefit for a manned Mars orbital mission.  Additionally, there is no science from a manned Mars orbital mission that can't be obtain more cheaply and easier by other means.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 30379
  • Cape Canaveral Spaceport
  • Liked: 8679
  • Likes Given: 283
Re: Station On Phobos
« Reply #39 on: 05/23/2016 02:15 PM »

You are right, but thats not what I meant. Of course, astronauts based at this station would have to do sorties with a vehicle to reach the hardware in its orbit (or have some robots teleoperated from the station do so)

With what propellant?  That is the whole issue.

1.  This has been done in Earth orbit, with a one-piece-maneuverable-reusable-space-station (called the Space Shuttle) repairing a telescope a couple of times.

2.   By the time we have a space station on Phobos, (unmanned) satellite repairing and refueling might even be a thing around Earth,

3.  One could also say that a Phobos station may be terrible to service a satellite in a polar orbit around Mars, but in many situations this is actually less terrible than losing the satellite completely or servicing it from Earth.


1.  That is plain wrong.  It is not even close to an analogy.  The shuttle was launched into the specific orbits to perform its servicing.   A station is in a fix orbit and doesn't have the luxury of the the propellant that the shuttle used.

2.  My point is still valid about earth satellites.  GSO is the only place that makes sense for servicing. 

3.  Not terrible but next to impossible with current propulsion techniques.
« Last Edit: 05/23/2016 02:16 PM by Jim »

Offline Bynaus

  • Full Member
  • ***
  • Posts: 316
  • Planetary Scientist
  • Switzerland
  • Liked: 211
  • Likes Given: 119
Re: Station On Phobos
« Reply #40 on: 05/23/2016 07:05 PM »
@Jim: you are right that propellant might indeed be a problem. So yes, rather a long-term thing, if anything. Perhaps the propellant could eventually be baked out of the Phobos regolith, solar wind implanted H, Ar (for ion propulsion) and O from silicates or oxides should be available. Alternatively, a solar/laser sail? I am not saying this is something that can/will be done from day one when the station is built. Its just a possible further application down the road (granted, if a source of propellant can be found). But perhaps I am indeed underestimating the fuel needs.

I also wasn't suggesting to move the entire station to the target orbit. Servicing would need a small "sortie" vehicle with a reasonable delta-V budget. This.could be smaller than in Earth orbit due to the slower orbital velocities.

Offline the_other_Doug

  • Senior Member
  • *****
  • Posts: 2396
  • Minneapolis, MN
  • Liked: 1452
  • Likes Given: 2481
Re: Station On Phobos
« Reply #41 on: 05/23/2016 07:28 PM »
@Jim: you are right that propellant might indeed be a problem. So yes, rather a long-term thing, if anything. Perhaps the propellant could eventually be baked out of the Phobos regolith, solar wind implanted H, Ar (for ion propulsion) and O from silicates or oxides should be available. Alternatively, a solar/laser sail? I am not saying this is something that can/will be done from day one when the station is built. Its just a possible further application down the road (granted, if a source of propellant can be found). But perhaps I am indeed underestimating the fuel needs.

I also wasn't suggesting to move the entire station to the target orbit. Servicing would need a small "sortie" vehicle with a reasonable delta-V budget. This.could be smaller than in Earth orbit due to the slower orbital velocities.

Yeah, but -- are you aware of the amount of energy you need to change orbital inclination?  Just as an example, after the Columbia tragedy, a lot of less-well-informed people demanded to know why, if there was even a hint that Columbia's tiles were damaged, they didn't just fly her to the ISS and let the crew shelter there until another orbiter could come and pick them up.  The reason was that the Shuttle orbital inclination was something like 32 degrees from equatorial, and the ISS inclination is something like 53 degrees.  (These numbers are from the top of my head and aren't exact, for the nitpickers out there.  They are very much in the right ballpark.)

They would have needed another fully fueled external tank and a full 12 minute burn of the SSMEs to change the orbital inclination that much.  It would have taken as much energy to change the orbital inclination that much as it took to get into orbit in the first place.

Changing inclination is an extremely delta-V costly thing to do.  I don't care that Mars is only 38% as massive as the Earth -- you would still need more propulsion to go from Phobos' roughly equatorial inclination to a polar orbit than it would take to launch the same repair mission from the surface of Mars.  Really.  So, from any point of view, it would actually be more useful to maintain a quick SSTO repair ship on the surface of Mars for this kind of satellite repair than to try and base such a repair service out of Phobos.

So, please -- Jim is right.  It's not that it wouldn't be nice to have such a repair facility on Phobos, it's just that physics lays certain limits, and this is one of those that you just can't sidestep.  Unless you have a multiple-orders-of-magnitude breakthrough in propulsion technology, the idea is dead, just from the rules of orbital mechanics.

Sorry...
-Doug  (With my shield, not yet upon it)

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 361
  • Likes Given: 0
Re: Station On Phobos
« Reply #42 on: 05/23/2016 09:33 PM »
People seem to be thinking in terms of ISS-on-Phobos, the thread title certainly suggests that.

But their are only two reason to go to Phobos, either as stop-over radiation sheltering point for a manned in-space transit vehicle during a dry-run mission prior to landing on Mars (any science is just to kill time).

Or as a logistical hub where in-space transit vehicle transfer cargo to landing craft that shuttle between Phobos and the surface, analogous to McMurdo station in Antarctica.

ISRU on Phobos (or any asteroid) is not something I think will ever happen, I don't even think Martian regolith will be collected for anything other then burying structures for radiation protection for a lot longer then any one imagines.  Rocks and rubble are a truly horrible horrible source material for any resource extraction, we only do it on Earth because it's the only way to get metal and metal is kinda important.

A dry-run is absolutely going to happen in any mission as complex as Mars landing, NASA is planning to send Orion on a dry-run mission around to moon first unmanned then manned before trying anything, and that is a just the moon a body 3 days away that's already been landed on.  It is not a matter of going to Phobos because we want to study it so specifically, we can get to NEA much more easily, it's just something to do when on a dry-run mission that would be happening if Mars had no moons at all.

Offline CuddlyRocket

Re: Station On Phobos
« Reply #43 on: 05/24/2016 12:18 AM »
A dry-run is absolutely going to happen in any mission as complex as Mars landing, NASA is planning to send Orion on a dry-run mission around to moon first unmanned then manned before trying anything, and that is a just the moon a body 3 days away that's already been landed on.  It is not a matter of going to Phobos because we want to study it so specifically, we can get to NEA much more easily, it's just something to do when on a dry-run mission that would be happening if Mars had no moons at all.

Orion is going to the Moon because why not? It's got to be tested in space anyway so it may as well be on the way to the Moon and back; it wouldn't cost much if anything more and is much better PR! Whereas a dry-run mission to Mars is a lot more expensive and doesn't test anything that can't be tested in cislunar space.

Online A_M_Swallow

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8011
  • South coast of England
  • Liked: 236
  • Likes Given: 86
Re: Station On Phobos
« Reply #44 on: 05/24/2016 12:53 AM »
With their large and easily damaged solar panels it is unlikely that SEP tugs and SEP transfer vehicles will land on Mars. They will stay in orbit. Will they be left by themselves? Or docked to an orbiting spacestation?

Any spacestation and associated propellant depot would need setting up.

Offline the_other_Doug

  • Senior Member
  • *****
  • Posts: 2396
  • Minneapolis, MN
  • Liked: 1452
  • Likes Given: 2481
Re: Station On Phobos
« Reply #45 on: 05/24/2016 01:06 AM »
With their large and easily damaged solar panels it is unlikely that SEP tugs and SEP transfer vehicles will land on Mars. They will stay in orbit. Will they be left by themselves? Or docked to an orbiting spacestation?

Any spacestation and associated propellant depot would need setting up.

And even microgravity helps keep things stay where they're put, especially relatively massive things.

I think a manned presence on Phobos will happen eventually, and IMHO it does make a good destination for a check-out flight of the Earth-Mars transit system, without needing to add the complexity of a landing mission into the mix.  But I'll agree, it doesn't add a lot to Mars surface operations, though it's quite interesting in its own right.

I still like my idea of using a Phobos station as part of a stand-in for the current Mission Control paradigm, using some of a Phobos station crew to serve something of the same function flight controllers serve in crewed LEO operations.  But since no one else seems to like it, I'll admit that, this aside, there's really no crying need to have a Phobos base in place before you start manned landings...
-Doug  (With my shield, not yet upon it)

Offline The Amazing Catstronaut

  • Full Member
  • ****
  • Posts: 1066
  • Arsia Mons, Mars, Sol IV, Inner Solar Solar System, Sol system.
  • Liked: 753
  • Likes Given: 624
Re: Station On Phobos
« Reply #46 on: 05/24/2016 01:13 AM »
I feel that the moons (and any station on them) should come after the parent planet. As noted upthread, they are of less direct scientific interest. Any preliminary robotic test runs for, say, Deimos/Phobos ISRU (I'm in the Deimos camp), could hypothetically be secondary payloads on a manned mars surface mission.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #47 on: 05/24/2016 10:29 AM »
I feel that the moons (and any station on them) should come after the parent planet. As noted upthread, they are of less direct scientific interest. Any preliminary robotic test runs for, say, Deimos/Phobos ISRU (I'm in the Deimos camp), could hypothetically be secondary payloads on a manned mars surface mission.

I could agree although it's obviously more in the hands of NASA bureaucracy.  A direct path to Mars would definitely get you to where things truly need to be.  If a mission to the Martian moons is advocated, it's ultimately more an excuse to test fly the orbital equipment and a cheaper way to impress while the Mars gear is under wraps/works.  Whether first or second, I think a visit to Phobos/Deimos should be on the itinerary, whereas a station/base on them not so much.
"Let the trails lead where they may, I will follow."
-Tigatron

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 25908
  • Minnesota
  • Liked: 5951
  • Likes Given: 4414
Re: Station On Phobos
« Reply #48 on: 05/27/2016 03:03 AM »
Phobos operations are the Apollos 8 and 10 to landing on Mars's Apollo 11.  A full dress rehearsal mission - with useful science content including Phobos and Deimos exploration (much simpler lander required) and operation of assets on Mars, especially sample collection.  Imagine for instance sample collection of polar volatiles, with maybe a 48 hour travel time to the Phobos and/or orbital base for quick analysis rather than trying to keep a cryogenic sample in good shape for an 8 month trip to Earth.  That would be a really good precursor to the first Mars landing.  Probably essential, I would suggest, just like Apollos 8 and 10.

Such missions are not needed and would be a waste of resources.  Actually, they would not be like Apollo 8 & 10 because MOR (the Martian equivalent of LOR) is not likely going to be the conop (example, Mars Direct doesn't use MOR) and hence the missions would be dead ends.
Jim is a semi-closeted SpaceX fan, as we can see.

The NASA PoR (or the closest we have to one) uses Mars-Orbit-Rendezvous. Of all the different NASA paths to Mars, basically all assume MOR. SpaceX intends to go the Mars Direct route by skipping a separate transit vehicle.

Long term MOR between transit vehicles and landers is the only way to get any kind of colonization going.  A direct flight is simply untenable due to vehicle amortization, for a first mission I could see it being done but it would only be a stepping stone.
I don't see how separating them improves vehicle amortization to any significant degree, and it may make things worse. You'll still need amortization of the in-space element in addition to the large lander.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline KelvinZero

  • Senior Member
  • *****
  • Posts: 3223
  • Liked: 375
  • Likes Given: 82
Re: Station On Phobos
« Reply #49 on: 05/27/2016 11:09 AM »
We really should send some probes to those moons, just as we should investigate the lunar poles.

Precursor missions (that answer basic questions that could allow us to make informed decisions about destinations before committing to absurdly expensive HSF architectures) just fall through the gap between planetary science and HSF. It is depressing.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #50 on: 05/27/2016 08:11 PM »
We really should send some probes to those moons, just as we should investigate the lunar poles.

Precursor missions (that answer basic questions that could allow us to make informed decisions about destinations before committing to absurdly expensive HSF architectures) just fall through the gap between planetary science and HSF. It is depressing.

I couldn't agree more.  Problem is, as I'm sure you've noticed, is that Mars itself overshadows Phobos and Deimos.  The last Discovery mission announcement included at least 3 proposals but none were selected (Venus and the asteroids became the current candidates).  At this rate, I suspect human footprints will be on them before any landing pads. 

The best candidate for a decent visit between now and the 2030s, albeit in the form of a 'passing glance' of sorts, will be from NeMo, the next generation Mars orbiter.  As a benefit, its spiral entry via solar electric propulsion will allow multiple flybys of Deimos and Phobos as it descends through high to low Mars orbits.  It is supposed to include radar and infrared instruments so on the good news it will be the best flybys the moons will ever see.

However this is supposed to be about putting stations on Phobos, so talking about probes is slightly distracting from topic.  My opinion on actual Mars moon stations is that they're unnecessary as opposed to either probes or an orbital vehicle visiting them and putting permanent equipment on Mars itself.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 361
  • Likes Given: 0
Re: Station On Phobos
« Reply #51 on: 05/28/2016 02:15 AM »
I don't see how separating them improves vehicle amortization to any significant degree, and it may make things worse. You'll still need amortization of the in-space element in addition to the large lander.

It's rather obvious, you use the lander multiple times per synod taking cargo down to Mars surface, the exact same way the BFR booster is used multiple times per Synod to launch and fuel a fleet of vehicles before they depart en-mass during the window.  This is just applying the same logic at the Mars end of the transit that we employ at the Earth end.

Offline Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 10584
  • Liked: 2164
  • Likes Given: 1
Re: Station On Phobos
« Reply #52 on: 05/28/2016 01:31 PM »
We really should send some probes to those moons, just as we should investigate the lunar poles.

Precursor missions (that answer basic questions that could allow us to make informed decisions about destinations before committing to absurdly expensive HSF architectures) just fall through the gap between planetary science and HSF. It is depressing.

I couldn't agree more.  Problem is, as I'm sure you've noticed, is that Mars itself overshadows Phobos and Deimos.  The last Discovery mission announcement included at least 3 proposals but none were selected (Venus and the asteroids became the current candidates).  At this rate, I suspect human footprints will be on them before any landing pads. 

The best candidate for a decent visit between now and the 2030s, albeit in the form of a 'passing glance' of sorts, will be from NeMo, the next generation Mars orbiter.  As a benefit, its spiral entry via solar electric propulsion will allow multiple flybys of Deimos and Phobos as it descends through high to low Mars orbits.  It is supposed to include radar and infrared instruments so on the good news it will be the best flybys the moons will ever see.

However this is supposed to be about putting stations on Phobos, so talking about probes is slightly distracting from topic.  My opinion on actual Mars moon stations is that they're unnecessary as opposed to either probes or an orbital vehicle visiting them and putting permanent equipment on Mars itself.

Japan is going to do a Phobos sample return mission and NASA will hop on board that. So you'll get data that way.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #53 on: 05/28/2016 07:03 PM »
Japan is going to do a Phobos sample return mission and NASA will hop on board that. So you'll get data that way.

That's promising.  Any news on that or NeMo?
"Let the trails lead where they may, I will follow."
-Tigatron

Online oldAtlas_Eguy

  • Senior Member
  • *****
  • Posts: 2635
  • Florida
  • Liked: 1056
  • Likes Given: 61
Re: Station On Phobos
« Reply #54 on: 05/29/2016 04:11 AM »
From the standpoint of using Phobos as an Interplanetary transshipment transfer point, it is to deep into the Mars gravity well. The heavier elements being the interplanetary craft vs the SSTO craft would more logically place such a station at Deimos not Phobos. A lot like EML2 would be a similar transfer point. Characteristics: high orbit less delta V required of interplanetary craft. Phobos would only be useful in the scenario of a Mars SSTO that is DV challenged. The SpaceX BFS(MCT) would easily reach Deimos without having to refuel since it is supposedly being designed to reach Mars escape from Mars surface. Plus the sophistication of large cycler interplanetary craft, transshipment points, etc is fairly later in the Mars colonization/exploration timelines like 20 years after first man landing.

On another point in a three body system like the two moon Mars system doing a 90 degree inclination change is rather easy by heading out from Phobos to Deimos using a gravity turn to change the inclination then circularizing at the desired orbit height or performing a direct return entry. The problem is that the maneuver still does not come cheap (DV wise) but significantly less than the alternative with also a bigger problem of a narrow window spaced at large intervals of time. Such a maneuver would not be a unplanned event but one planned literally months/years in advance suitable for planned deployments but not rescue or ad-hoc missions. A BTW you can use the Moon the same way but it sort of defeats the purpose since the DV needed to get to it and back may be larger than just landing back on earth and launching again into the inclination you want.

Orbital Mechanics: Gravity assist is your friend.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #55 on: 05/29/2016 04:57 AM »
From the standpoint of using Phobos as an Interplanetary transshipment transfer point, it is to deep into the Mars gravity well. The heavier elements being the interplanetary craft vs the SSTO craft would more logically place such a station at Deimos not Phobos. A lot like EML2 would be a similar transfer point. Characteristics: high orbit less delta V required of interplanetary craft. Phobos would only be useful in the scenario of a Mars SSTO that is DV challenged. The SpaceX BFS(MCT) would easily reach Deimos without having to refuel since it is supposedly being designed to reach Mars escape from Mars surface. Plus the sophistication of large cycler interplanetary craft, transshipment points, etc is fairly later in the Mars colonization/exploration timelines like 20 years after first man landing.

This is why I favor Deimos more, coupled with its proximity to synchronous orbit.

Cycler craft, frankly, are stupid ideas.  You still have to waste launch fuel and rendezvous in open, interplanetary space which means, if you're misaligned in your little capsule, you're lost in space without a robot to yell "Danger Will Robinson, danger!"

On another point in a three body system like the two moon Mars system doing a 90 degree inclination change is rather easy by heading out from Phobos to Deimos using a gravity turn to change the inclination then circularizing at the desired orbit height or performing a direct return entry. The problem is that the maneuver still does not come cheap (DV wise) but significantly less than the alternative with also a bigger problem of a narrow window spaced at large intervals of time. Such a maneuver would not be a unplanned event but one planned literally months/years in advance suitable for planned deployments but not rescue or ad-hoc missions. A BTW you can use the Moon the same way but it sort of defeats the purpose since the DV needed to get to it and back may be larger than just landing back on earth and launching again into the inclination you want.

Orbital Mechanics: Gravity assist is your friend.

Earth's moon could provide gravity assist; Mars' moons...not in the least.  When I asked about the usefulness of gravity assists from a few members knowledgeable about it and electric propulsion, they pointed out how trajectory is a huge factor.  Basically, much as you have to hit a correct launch window, you have to hit a specific angle to get any use from a celestial body's gravity.

I'm not familiar with 'gravity turns,' but in general if you're trying to change orbits or escape Mars, simpler just to use fuel.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 361
  • Likes Given: 0
Re: Station On Phobos
« Reply #56 on: 06/01/2016 04:58 AM »
Atlas & redliox:  You have it backwards you want to have your point for transfer between in-space vehicles and landers right at the atmospheric interface so each craft type spends essentially all of it's time and energy in the flight regime for which it is optimized, that will result in overall system optimization.  That would mean low orbit is ideal and Phobos is preferable to Demos. 

Phobos is only about 1400 m/s from LMO and has some features we already discussed which could compensate for this increased distance from the Martian surface.  A Mars shuttle lander would need 5.5 km/s to make the transit up and likely another 1 km/s to come down again.

While your right that being high in the gravity well such as EML-1&2 is advantageous it would be the place to transfer cargo between cis-planetary in-space vehicles and helocentric transfer in-space vehicles.  I think we will have this distinction at the Earth end of the logistical chain because Earth Lagrange points are at roughly the halfway point of the entire DeltaV span between LEO and LMO. 

But the Martian gravity well is sufficiently small relative to the velocity needed to transfer to Mars that it makes little sense to make another transfer point their.  The two break points at or near atmospheric interfaces and one in gravitational 'divide' should suffice.


Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #57 on: 06/01/2016 09:03 AM »
Atlas & redliox:  You have it backwards you want to have your point for transfer between in-space vehicles and landers right at the atmospheric interface so each craft type spends essentially all of it's time and energy in the flight regime for which it is optimized, that will result in overall system optimization.  That would mean low orbit is ideal and Phobos is preferable to Demos. 

By chance is this related to how perigee burns tend to work best when you're at closest approach to the target planet?  Whenever I see an elliptical orbit I can't help but think "sloppy" but, if you're trying to be fuel conservative, I can understand the merit is sticking to a simplified orbit without necessarily insisting on it being perfectly synchronized.

In the sense of orbital mechanics, I believe I understand the favoritism of Phobos now, although I still see equal if not better merit in Deimos' near-synchronous position higher up.

While your right that being high in the gravity well such as EML-1&2 is advantageous it would be the place to transfer cargo between cis-planetary in-space vehicles and helocentric transfer in-space vehicles.  I think we will have this distinction at the Earth end of the logistical chain because Earth Lagrange points are at roughly the halfway point of the entire DeltaV span between LEO and LMO. 

But the Martian gravity well is sufficiently small relative to the velocity needed to transfer to Mars that it makes little sense to make another transfer point their.  The two break points at or near atmospheric interfaces and one in gravitational 'divide' should suffice.

I believe you make a good point after all.  You're trying to explain how, in some ways, many of us are still thinking in an Earth-centric pov.  As far as breaking points, I doubt NASA would agree on a perigee near the atmospheric interface, but if you're employing a lander that would use aerobraking to slow down from high to low Mars orbit this would be advantageous...but again I'd expect the orbiter would keep its distance.  On the topic, where would the two 'break points' be located roughly from the Mars surface, which I presume you define as the Martian upper atmosphere at one end and the Hill sphere as the other?
"Let the trails lead where they may, I will follow."
-Tigatron

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #58 on: 06/01/2016 09:07 AM »
While on the topic of stations, Phobos, and Deimos, the International Conference on the Exploration of Phobos and Deimos is coming up fairly soon: http://phobos-deimos.arc.nasa.gov/
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 361
  • Likes Given: 0
Re: Station On Phobos
« Reply #59 on: 06/02/2016 01:31 AM »
If your using high thrust rocket propulsion the deeper gravity well plung is definitly preferable for Oberth effect, regardless of the final orbit you want to take at a planet if your coming in at above escape velocity you want a burn at just above the atmosphere to brake.

I had not really considered elliptical orbits at Mars, I had assumed that while initial orbital insertion (either propulsive or via airo-capture) would be elliptical and then airo-braking would bring it down to either LMO or to intersection with Phobos from which the landing on Phobos would be made.

Ultimatly a lot depends on what kind of propulsion the in-space vehicle has, I'm assuming SEP (without SEP their is not much point in stopping in Mars orbit anywhere) which is more likely to just spiral down from capture down to Phobos or LMO.  Then cargo/passengers can shuttle between the transit vehicle and the surface.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #60 on: 06/02/2016 09:50 AM »
Assuming a Phobos station is established, how useful of a communication relay could it be for Mars surface missions, be they telerobotic or crewed missions?  I presume one issue would be the need for the Phobos station to be Mars-facing, and the second issue being how much of Phobos itself would obscure Earth.  Even if the Phobos station is only used once for a one-off precursor mission, it does represent a substantial orbiting asset more robust than any probe or com satellite will ever be; it ought to have a long-term use even if effectively abandoned.  Considering Phobos is in a ~8 hour orbit near the equator, a Martian base, up to the mid-latitudes, would have 3 decent daily passes with the Phobos station on this note, which is better than what a low-orbiting probe could offer and on a more regular basis.
« Last Edit: 06/02/2016 09:51 AM by redliox »
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Bob Shaw

  • Full Member
  • ****
  • Posts: 941
  • Liked: 329
  • Likes Given: 325
Re: Station On Phobos
« Reply #61 on: 06/02/2016 10:14 AM »
A Molniya-like constellation of orbiters, combined with a manned base, would do the trick. Phobos is invisible from even moderately high Mars latitudes - as Tennyson didn't put it, 'The moonless poles of snowy Mars' don't see either moon.

Remember, though, that the speed of light begins to be an issue as you bounce your signal around. This doesn't have to be a problem - human consciousness copes well with the physical reality of our fleshy bodies, where our perceptions often don't match up with our intended movements (and vice versa). In other words, the humans would guide, rather than control, with the 'arms and legs' on Mars doing their stuff at a lower operating level.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #62 on: 06/02/2016 10:40 AM »
A Molniya-like constellation of orbiters, combined with a manned base, would do the trick. Phobos is invisible from even moderately high Mars latitudes - as Tennyson didn't put it, 'The moonless poles of snowy Mars' don't see either moon.

That's useful, and I would presume at least 1 satellite or probe would be utilized, but I was referring to the station itself as a relay.  As I said, it is a large asset and, even if abandoned after the Phobos mission, could still be of use.
"Let the trails lead where they may, I will follow."
-Tigatron

Online gospacex

  • Senior Member
  • *****
  • Posts: 2885
  • Liked: 440
  • Likes Given: 490
Re: Station On Phobos
« Reply #63 on: 06/02/2016 11:11 AM »
Mars moons are probably bone-dry. This is a significant downside.

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1492
  • Germany
  • Liked: 40
  • Likes Given: 24
Re: Station On Phobos
« Reply #64 on: 06/05/2016 07:15 PM »
Mars moons are probably bone-dry. This is a significant downside.

We don't know that. It could be they're dry to a few metres.

Kerogen would also be a nice material to find - as well as water.   

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2031
  • Liked: 245
  • Likes Given: 288
Re: Station On Phobos
« Reply #65 on: 06/08/2016 11:00 PM »
Mars moons are probably bone-dry. This is a significant downside.

We don't know that. It could be they're dry to a few metres.

Kerogen would also be a nice material to find - as well as water.

I think we should avoid the term "kerogen" in asteroids and satellites, as it has clear implications of biogenesis. Even "kerogen-like" is misleading.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #66 on: 06/09/2016 09:38 AM »
Even if a station is put on Phobos, how often will it be occupied, especially after a Mars landing?
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 10584
  • Liked: 2164
  • Likes Given: 1
Re: Station On Phobos
« Reply #67 on: 06/09/2016 04:45 PM »
Even if a station is put on Phobos, how often will it be occupied, especially after a Mars landing?

The answer is four. Which, coincidentally, is the same number of angels that can fit on the head of a pin.

Really, this is all speculating on top of speculating.

Offline Bynaus

  • Full Member
  • ***
  • Posts: 316
  • Planetary Scientist
  • Switzerland
  • Liked: 211
  • Likes Given: 119
Re: Station On Phobos
« Reply #68 on: 06/09/2016 05:00 PM »
Mars moons are probably bone-dry. This is a significant downside.

We don't know that. It could be they're dry to a few metres.

Kerogen would also be a nice material to find - as well as water.

The question whether they are dry or volatile-rich is a function of their mode of formation. If they are captured asteroids with a composition similar of carbonaceous chondrites, they might have a significant volatile content. If, on the other hand, they were formed from a debris disk after a Giant Impact on Mars, they will likely be dry. So if they are dry, they are dry all the way through (same if they are rich in volatiles).

But then, nature has that tendency to be different from what we imagine. Lets go and see. :)

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 7573
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 4481
  • Likes Given: 3004
Re: Station On Phobos
« Reply #69 on: 06/10/2016 12:33 AM »
if we built an outpost on either, or both, I'd expect it was there to stay. I think that's just how Musk rolls.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Online guckyfan

  • Senior Member
  • *****
  • Posts: 5955
  • Germany
  • Liked: 1461
  • Likes Given: 1178
Re: Station On Phobos
« Reply #70 on: 06/10/2016 06:27 AM »
if we built an outpost on either, or both, I'd expect it was there to stay. I think that's just how Musk rolls.

I don't see such a station by Elon Musk any time soon. NASA may want to go there. That would likely be temporary. For SpaceX something would have to be in it. Like water and CO2 to produce fuel for earth return, which would mean permanent presence. With people or remote controlled robotic.

Assuming that MCT can do more than one launch and landing before earth return, a visit with MCT on phobos could be a mission with a lot of ressources and not that expensive.

Offline Bob Shaw

  • Full Member
  • ****
  • Posts: 941
  • Liked: 329
  • Likes Given: 325
Re: Station On Phobos
« Reply #71 on: 06/11/2016 02:01 AM »
Mars moons are probably bone-dry. This is a significant downside.

We don't know that. It could be they're dry to a few metres.

Kerogen would also be a nice material to find - as well as water.

The question whether they are dry or volatile-rich is a function of their mode of formation. If they are captured asteroids with a composition similar of carbonaceous chondrites, they might have a significant volatile content. If, on the other hand, they were formed from a debris disk after a Giant Impact on Mars, they will likely be dry. So if they are dry, they are dry all the way through (same if they are rich in volatiles).

But then, nature has that tendency to be different from what we imagine. Lets go and see. :)

The biggest value of the Martian moons might be - literally - nothing at all. There is real reason to believe that they may be rock piles, with significant voids. Such voids (if stable) would be perfect places to put habitats and storage areas. Leave the dusty surface for visitors, and PV farms, burrow in, and Port Phobos is in business!

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1492
  • Germany
  • Liked: 40
  • Likes Given: 24
Re: Station On Phobos
« Reply #72 on: 06/12/2016 04:05 PM »
Mars moons are probably bone-dry. This is a significant downside.

We don't know that. It could be they're dry to a few metres.

Kerogen would also be a nice material to find - as well as water.

The question whether they are dry or volatile-rich is a function of their mode of formation. If they are captured asteroids with a composition similar of carbonaceous chondrites, they might have a significant volatile content. If, on the other hand, they were formed from a debris disk after a Giant Impact on Mars, they will likely be dry. So if they are dry, they are dry all the way through (same if they are rich in volatiles).

But then, nature has that tendency to be different from what we imagine. Lets go and see. :)

Surely if formed from a giant impact, they would have been unstable over the course of billions of years. Phobos has a short life ahead of it.

This probably means they are captured asteroids. Whether originally dry asteroids, or whether they've had moisture baked out of them, we don't know.

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1492
  • Germany
  • Liked: 40
  • Likes Given: 24
Re: Station On Phobos
« Reply #73 on: 06/12/2016 04:07 PM »

The biggest value of the Martian moons might be - literally - nothing at all. There is real reason to believe that they may be rock piles, with significant voids. Such voids (if stable) would be perfect places to put habitats and storage areas. Leave the dusty surface for visitors, and PV farms, burrow in, and Port Phobos is in business!

If the moon is soft - e.g. a rubble pile, voids won't be stable.

However, stable voids can be made with a balloon and a supply of compressed air.  Somewhere between 0.4 and 1.0 bar Oxygen / Nitrogen mix would do the job.

Offline Bob Shaw

  • Full Member
  • ****
  • Posts: 941
  • Liked: 329
  • Likes Given: 325
Re: Station On Phobos
« Reply #74 on: 06/12/2016 04:23 PM »

The biggest value of the Martian moons might be - literally - nothing at all. There is real reason to believe that they may be rock piles, with significant voids. Such voids (if stable) would be perfect places to put habitats and storage areas. Leave the dusty surface for visitors, and PV farms, burrow in, and Port Phobos is in business!

If the moon is soft - e.g. a rubble pile, voids won't be stable.

However, stable voids can be made with a balloon and a supply of compressed air.  Somewhere between 0.4 and 1.0 bar Oxygen / Nitrogen mix would do the job.

I was thinking of cutting down to voids and backfilling a la Camp Century. A lot will depend on tides - I believe the jury is still out on the origin of the grooves, but if they indicate tidal effects then the interior might not be very trustworthy.

Has the density of Phobos been nailed down yet? Mathilde is certainly blessed with a lot of empty space.

Good article on Wikipedia: https://en.wikipedia.org/wiki/Rubble_pile

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1492
  • Germany
  • Liked: 40
  • Likes Given: 24
Re: Station On Phobos
« Reply #75 on: 06/13/2016 06:11 PM »
I'd rather expect a rubble pile to be like a shingle beach with a few boulders thrown in - except under microgravity. The voids won't be much use, but you can always make your own big voids.

Any digging will be difficult and limited to fairly shallow slope angles.
« Last Edit: 06/13/2016 06:12 PM by alexterrell »

Offline Bynaus

  • Full Member
  • ***
  • Posts: 316
  • Planetary Scientist
  • Switzerland
  • Liked: 211
  • Likes Given: 119
Re: Station On Phobos
« Reply #76 on: 06/17/2016 06:39 AM »
Mars moons are probably bone-dry. This is a significant downside.

We don't know that. It could be they're dry to a few metres.

Kerogen would also be a nice material to find - as well as water.

The question whether they are dry or volatile-rich is a function of their mode of formation. If they are captured asteroids with a composition similar of carbonaceous chondrites, they might have a significant volatile content. If, on the other hand, they were formed from a debris disk after a Giant Impact on Mars, they will likely be dry. So if they are dry, they are dry all the way through (same if they are rich in volatiles).

But then, nature has that tendency to be different from what we imagine. Lets go and see. :)

Surely if formed from a giant impact, they would have been unstable over the course of billions of years. Phobos has a short life ahead of it.

This probably means they are captured asteroids. Whether originally dry asteroids, or whether they've had moisture baked out of them, we don't know.

If you mean "unstable" in the sense of having tidally migrating orbits (like the Moon has), then yes, they are "unstable". Their orbits have been migrating over the last billions of years. Deimos is beyond the co-rotation orbit, so it has been migrating slowly outward (like our Moon). Phobos is below the co-rotation orbit and must have been so since its formation (because that orbit cannot be crossed by tidal migration).

There was an interesting talk at this year's LPSC about a Giant Impact formation scenario where Mars once had a larger, interior satellite which has since crashed back onto the planet: http://www.hou.usra.edu/meetings/lpsc2016/pdf/1943.pdf (PDF). After this happened (billions of years ago), the two remaining satellites were left to migrate away from the co-rotation radius. We just happen to live at a time just before Phobos' demise.

The idea of them being captured asteroids is problematic because their orbits are circular and co-planar. No easy way to explain this if they are captured. But perhaps we are just not clever enough (yet) how to figure that one out. :)

Offline JasonAW3

  • Senior Member
  • *****
  • Posts: 2324
  • Claremore, Ok.
  • Liked: 359
  • Likes Given: 9
Re: Station On Phobos
« Reply #77 on: 06/21/2016 06:15 PM »

The biggest value of the Martian moons might be - literally - nothing at all. There is real reason to believe that they may be rock piles, with significant voids. Such voids (if stable) would be perfect places to put habitats and storage areas. Leave the dusty surface for visitors, and PV farms, burrow in, and Port Phobos is in business!

If the moon is soft - e.g. a rubble pile, voids won't be stable.

However, stable voids can be made with a balloon and a supply of compressed air.  Somewhere between 0.4 and 1.0 bar Oxygen / Nitrogen mix would do the job.

Or you could use a spray on epoxy resin.  Might actually be a good idea, to reinforce the void space prior to inflating a balloon in the void.  Kind of like shotcrete is used to reinforce many tunnels and cliff faces that stand a good chance of collapse.
My God!  It's full of universes!

Offline TakeOff

  • Full Member
  • ***
  • Posts: 317
  • Liked: 64
  • Likes Given: 91
Re: Station On Phobos
« Reply #78 on: 07/08/2016 11:40 AM »
It wouldn't need permanent crew, but Phobos and Deimos (both at the first trip) is a pretty obvious first target. The expedition there could leave a habitat in the well shielded Stickney crater as a survivable emergency backup, or an outpost for further exploration, for the next expedition which goes to Mars's surface.

Teleoperation of rovers on Mars from orbit is nonsense. It is very much cheaper and safer to teleoperate them from Earth. The time delay is only 10 to 40 minutes. Curiosity is given a set of commands only once every 25 hours, and some days not at all. Spending $100B on a risky human mission to teleoperate a $3B slow moving rover is not rational. For a few minutes per orbit when it is in line of sight. By a tiny 4 or 6 man crew who should be busy with other things, like escavations on Deimos. This stupid idea out there needs to go away. You either teleoperate rovers from Earth, even if delayed and slow, operating Martian rovers 24/7 using large groups of specialists would massively multiply the productivity, or you send humans to the surface who move themselves quickly. Sending people to Mars' orbit to remotely control rovers on Mars is just wrong. Like launching people to Earth's orbit to teleoperate rovers on Earth. Makes no sense.

Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 3497
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 593
  • Likes Given: 981
Re: Station On Phobos
« Reply #79 on: 07/08/2016 11:56 AM »
Tele-operating Science rovers might be a marginal activity - but not rovers that might be undertaking future base-building activities. Also, having the manned vehicle collect an array of Sample Return Ascent vehicles from several Martian hemispheres could be good. The whole point of even sending humans to Phobos & Deimos in the first place in a manned craft is to 'shake out' the whole interplanetary transportation infrastructure ahead of a manned landing, if the landing has to be delayed because of low funding levels for the manned lander or if further development of it is deemed necessary.

I'd like to think that the very first manned Mars landing would be an 'all up test' on the very first mission all the way out there - but we have no way of knowing at this point if NASA (or Space X) will be brave enough to dive right into that attempt. Somehow, I don't think so.
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline TakeOff

  • Full Member
  • ***
  • Posts: 317
  • Liked: 64
  • Likes Given: 91
Re: Station On Phobos
« Reply #80 on: 07/08/2016 01:27 PM »
I think that Deimos and Phobos are important targets for scientific reasons, not just as a stepping stone to Mars' surface. How were they formed or captured? What are low density objects like? We could learn more from them than from Mars itself. We have to go there sooner or later anyway, it is unstoppable, so why not start out with them since it is easier and actually demonstrate how we can get out there during two years. They are the perfect combination of lunar, martian and asteroid exploration, and kind of microgravity space station too. It should unify everyone regardless of favorite target to visit. Phobos and Deimos have something for everyone, and certainly surprises.

Offline mikelepage

Re: Station On Phobos
« Reply #81 on: 03/05/2017 04:26 AM »
I think that like everyone else, I have always assumed that any manned station in orbit around Mars will be at/around Phobos or Deimos, but I just remembered that Mars' equator (and Phobos and Deimos orbits) is at ~25 degrees to the ecliptic.

So any craft going to Phobos or Deimos is coming in on a hyperbolic trajectory at 1.85 degrees to the ecliptic (Mars' inclination), and has to aerobrake into an orbit 25 degrees to the ecliptic.

I presume that this is possible if your approach to the limb of Mars occurs during the time point when the Mars equator is co-planar with your trajectory.  BUT (someone please correct me if I'm wrong), doesn't this mean this can only occur twice per Martian year?  Even if you assume you can do some plane-change adjustment burns of (5?) degrees, that puts some serious time constraints on launching to Phobos and Deimos, doesn't it?

It would probably be far easier to have manned stations in orbit around Mars at 1.85 degrees to the ecliptic? Or is this the main reason that people prefer direct-to-Mars-surface missions?

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2031
  • Liked: 245
  • Likes Given: 288
Re: Station On Phobos
« Reply #82 on: 03/05/2017 05:01 AM »
Phobos has it's points of interest. However it has a surface area of only 1500 km2.  For comparison the 100 km radius exploration zone for the first crewed missions has a surface area of over 30,000 km2, more than 20 times that of Phobos. Plus Phobos by it's nature will be a much simpler and less diverse body than the surface of Mars.  It's won't take long for it to be fairly exhaustively explored.  A month at most.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline TakeOff

  • Full Member
  • ***
  • Posts: 317
  • Liked: 64
  • Likes Given: 91
Re: Station On Phobos
« Reply #83 on: 03/13/2017 07:51 PM »
I think that like everyone else, I have always assumed that any manned station in orbit around Mars will be at/around Phobos or Deimos, but I just remembered that Mars' equator (and Phobos and Deimos orbits) is at ~25 degrees to the ecliptic.

So any craft going to Phobos or Deimos is coming in on a hyperbolic trajectory at 1.85 degrees to the ecliptic (Mars' inclination), and has to aerobrake into an orbit 25 degrees to the ecliptic.

I presume that this is possible if your approach to the limb of Mars occurs during the time point when the Mars equator is co-planar with your trajectory.  BUT (someone please correct me if I'm wrong), doesn't this mean this can only occur twice per Martian year?  Even if you assume you can do some plane-change adjustment burns of (5?) degrees, that puts some serious time constraints on launching to Phobos and Deimos, doesn't it?

It would probably be far easier to have manned stations in orbit around Mars at 1.85 degrees to the ecliptic? Or is this the main reason that people prefer direct-to-Mars-surface missions?
I don't think there's any problem with using gravity assist at Mars in order to achieve 25 degrees inclination for an orbital insertion. 25 degrees is still small relative to 45 (half) or 90 (zero) gravity assist in the direction of Mars' orbit. And with aerobraking you have a much greater freedom to choose inclination. And add the Oberth effect to that. One doesn't need to match Phobos plane around Mars with the ecliptic in order to enter orbit around it. Mars' gravity and atmosphere is well enough to take care of that adjustment.
« Last Edit: 03/13/2017 07:52 PM by TakeOff »

Offline TakeOff

  • Full Member
  • ***
  • Posts: 317
  • Liked: 64
  • Likes Given: 91
Re: Station On Phobos
« Reply #84 on: 03/13/2017 07:56 PM »
Phobos has it's points of interest. However it has a surface area of only 1500 km2.  For comparison the 100 km radius exploration zone for the first crewed missions has a surface area of over 30,000 km2, more than 20 times that of Phobos. Plus Phobos by it's nature will be a much simpler and less diverse body than the surface of Mars.  It's won't take long for it to be fairly exhaustively explored.  A month at most.
Astronauts would spend half a year going to, and another half a year coming home from, Mars' moons. So there remains one year to 14 months or so of a conjuncture period to spend there. 1,500 km^2 for 4 astronauts to explore in milligravity EVA's at a world of a kind thus far completely unknown, is plenty of work, plenty, trust me! And two moons at that.
« Last Edit: 03/13/2017 07:57 PM by TakeOff »

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2031
  • Liked: 245
  • Likes Given: 288
Re: Station On Phobos
« Reply #85 on: 03/13/2017 10:13 PM »
Phobos has it's points of interest. However it has a surface area of only 1500 km2.  For comparison the 100 km radius exploration zone for the first crewed missions has a surface area of over 30,000 km2, more than 20 times that of Phobos. Plus Phobos by it's nature will be a much simpler and less diverse body than the surface of Mars.  It's won't take long for it to be fairly exhaustively explored.  A month at most.
Astronauts would spend half a year going to, and another half a year coming home from, Mars' moons. So there remains one year to 14 months or so of a conjuncture period to spend there. 1,500 km^2 for 4 astronauts to explore in milligravity EVA's at a world of a kind thus far completely unknown, is plenty of work, plenty, trust me! And two moons at that.

Phobos is worth a visit, but is hardly worth spending an entire long stay mission there.  There is far more of interest on the surface.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #86 on: 03/14/2017 06:19 AM »
Astronauts would spend half a year going to, and another half a year coming home from, Mars' moons. So there remains one year to 14 months or so of a conjuncture period to spend there. 1,500 km^2 for 4 astronauts to explore in milligravity EVA's at a world of a kind thus far completely unknown, is plenty of work, plenty, trust me! And two moons at that.

Phobos is worth a visit, but is hardly worth spending an entire long stay mission there.  There is far more of interest on the surface.

Ahem...I spoke of this a while ago:

I love the Martian moons, and certainly would support visiting them.  Personally, I favor Deimos over Phobos because it is closer to synchronous orbit as well as the gravity well edge; both of which would be a boon to orbiting craft; Phobos of course is more scientifically interesting and easier to reach Mars.  The odds of visiting them after seeing Mars are good, but setting up a permanent habitat is more difficult to figure.

The Flexible Plan NASA's currently following favors orbital vehicles.  Because of weak gravity, the same vehicles can double as asteroid/Martian moon landers with minimal tinkering.  Currently the NASA idea to orbit Mars include a Phobos habitat to stay at.  However, that could easily change with politics, and if Red Dragon proves equipment (not crews, but definitely habs) can be directly landed on Mars, NASA might switch funds for a Mars camp instead of a Phobos station.

If a Phobos station is cobbled together, I'd assume it'd be built first in orbit and then fixed to the moon; dust in micro-gravity would be a titanic pain.  Taking the Bigelow ideas for a Lunar station, which likewise would be assembled in orbit before landing it in once piece, could easily be implemented for Phobos (and Deimos).  There could be surface science for the moon, remote observations on Mars with perhaps telerobotics, and even the return vehicles could dock to the station.

Pros: Easily compatible with orbital missions;unique 'asteroid' science with some Mars science (including telerobotics); potentially useful staging point (at either moon)

Cons: Less desirable than Mars camp; micro-gravity and radiation effects; redundant rather than essential v.s. Mars

I believe in any case all that's genuinely needed is an orbital vehicle to visit Phobos.  A habitat is basically the same thing pinned to the moon; you only really need it if the visit lasts more than 30 days (and, especially if the crew are otw home, shorter visits are more likely).  IMO a dedicated habitat is unnecessary, but ultimately it will depend on how NASA's plans get revised in the near future, especially in light of a Red Dragon landing bypassing the orbital route.

I agree with Dal in that we should check out (hopefully both) moons, especially so we can find out if they're useful.

I wouldn't go so far as to suggest establishing stations though.  On top of that, odds are there's going to be an agenda shift for NASA again once Trump puts his full attention on its for a fleeting moment.
« Last Edit: 03/14/2017 06:23 AM by redliox »
"Let the trails lead where they may, I will follow."
-Tigatron

Offline mikelepage

Re: Station On Phobos
« Reply #87 on: 03/15/2017 07:05 AM »
Phobos is worth a visit, but is hardly worth spending an entire long stay mission there.  There is far more of interest on the surface.

Not meaning to be too facetious, but replace the word "Phobos" with the word "Space", and you have the opinion of the majority of Earth's population.

We don't know what we don't know.  I suggest we make that call ("long stay missions") after we visit there the first time.  As to making planning decisions based on what we do know, at least from a logistical perspective, it could turn out to be the easiest "asteroid" to study up close in a HSF mission.

Offline Rei

  • Full Member
  • ****
  • Posts: 467
  • Iceland
  • Liked: 179
  • Likes Given: 58
Re: Station On Phobos
« Reply #88 on: 03/15/2017 11:15 AM »
Phobos is worth a visit, but is hardly worth spending an entire long stay mission there.  There is far more of interest on the surface.

Surface access dramatically increases the mission cost.

I agree that the surface is far more interesting.  But if the choice was between a simple LMO mission, or a mission that involved a stay on Phobos or Deimos, which would you choose?

And I don't think the local propellant options should be played down. Both Phobos and Deimos have absorption spectra indicative of unmodified volatile-rich carbonaceous bodies, similar to carbonaceous chondrites (regardless of how they actually formed / ended up as moons of Mars). I've seen estimates suggesting that they're up to 20% water.  And IMHO, if they do actually have carbon similar to carbonaceous chondrites, that's really fascinating and potentially more useful for industry than Mars's plain, low pressure CO2. Carbonaceous chondrites contain a wide range of organics, including aliphatic and aromatic hydrocarbons, polycyclics like naphthalene and PAHs, carboxylic acids, alcohols, aldehydes, and tons of other things, including nitrogen-bearing compounds like ammonia, amino acids, urea, etc. I guess the closest earth analogy to the mixture would be something like bitumen, but with more nitrogen.  Sounds like a great feedstock for varying combinations of hydrocracking and distillation, you could get a full petrochemical industry going based on just that without having to take the sabatier + partial oxidation, or alternatively, SOFC -> syngas ->  liquids -> combinations of cyclization and pyrolysis route.

Of course, any offworld "mining" process at all has serious TRL issues to overcome. Even just water production.
« Last Edit: 03/15/2017 11:39 AM by Rei »

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2031
  • Liked: 245
  • Likes Given: 288
Re: Station On Phobos
« Reply #89 on: 03/15/2017 08:23 PM »

I agree that the surface is far more interesting.  But if the choice was between a simple LMO mission, or a mission that involved a stay on Phobos or Deimos, which would you choose?

If you are going to go to Mars orbit then you should visit at least one of the moons.  But neither probably justify the cost, except as a stepping stone to surface missions.  You could also visit one of the moons as a part of a surface mission as well.

Quote
And I don't think the local propellant options should be played down. Both Phobos and Deimos have absorption spectra indicative of unmodified volatile-rich carbonaceous bodies, similar to carbonaceous chondrites (regardless of how they actually formed / ended up as moons of Mars). I've seen estimates suggesting that they're up to 20% water.  And IMHO, if they do actually have carbon similar to carbonaceous chondrites, that's really fascinating and potentially more useful for industry than Mars's plain, low pressure CO2. Carbonaceous chondrites contain a wide range of organics, including aliphatic and aromatic hydrocarbons, polycyclics like naphthalene and PAHs, carboxylic acids, alcohols, aldehydes, and tons of other things, including nitrogen-bearing compounds like ammonia, amino acids, urea, etc. I guess the closest earth analogy to the mixture would be something like bitumen, but with more nitrogen.  Sounds like a great feedstock for varying combinations of hydrocracking and distillation, you could get a full petrochemical industry going based on just that without having to take the sabatier + partial oxidation, or alternatively, SOFC -> syngas ->  liquids -> combinations of cyclization and pyrolysis route.

But there's the rub.  Early studies suggested they were carbonaceous chondrite-like in composition, either C or D-type.  More recent work has questioned it,  suggesting that are represent material related directly to Mars, formed
as left over co-accretion debris (which means they are possibly more silicate rich than carbonaceous) or re-accretion of Mars impact debris (in which case they are probably largely anhydrous, like our moon).  The problem is the spectra of Phobos and Deimos are quite nondescript.
 
Of course, any offworld "mining" process at all has serious TRL issues to overcome. Even just water production.
[/quote]

Indeed it does.  It's going to be a lot easier to manufacture propellant on the martian surface.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Rei

  • Full Member
  • ****
  • Posts: 467
  • Iceland
  • Liked: 179
  • Likes Given: 58
Re: Station On Phobos
« Reply #90 on: 03/16/2017 10:12 AM »
If you are going to go to Mars orbit then you should visit at least one of the moons.  But neither probably justify the cost, except as a stepping stone to surface missions.  You could also visit one of the moons as a part of a surface mission as well.

Except that NASA (and other agencies) have repeatedly done studies Mars orbital missions with no surface landing to save cost. So it's worth considering, since that's a type of mission that's gotten significant consideration - whether you like that kind of mission or not.

Quote
But there's the rub.  Early studies suggested they were carbonaceous chondrite-like in composition, either C or D-type.  More recent work has questioned it,  suggesting that are represent material related directly to Mars, formed
as left over co-accretion debris (which means they are possibly more silicate rich than carbonaceous) or re-accretion of Mars impact debris (in which case they are probably largely anhydrous, like our moon).  The problem is the spectra of Phobos and Deimos are quite nondescript.

http://www.sciencedirect.com/science/article/pii/S0019103513004934

Quote
Studies using visible to near infrared spectroscopy show that the moons’ surfaces resemble D- or T-type asteroids or carbonaceous chondrite meteorites (e.g. Murchie and Erard, 1996, Rivkin et al., 2002 and Fraeman et al., 2012), although their specific mineralogy is difficult to determine because they lack strong diagnostic absorption features.

...

Comparison to asteroid spectra

Features similar to both the 0.65 μm and 2.8 μm absorptions are observed on dark asteroids interpreted to have primitive compositions (C-, G-, P-, and D-class asteroids). A search through the Vilas asteroid spectral catalog (Vilas et al., 1998) revealed several asteroids with 0.65 μm absorptions that are similar in shape and wavelength to the corresponding features observed on Phobos and Deimos (Fig. 6). Asteroids that exhibit these features sometimes have an additional absorption near 0.43 μm or 0.9 μm, but all of them are dark and red sloped. Absorptions near 0.7 μm on low albedo asteroids have been ascribed to Fe-bearing phyllosilicates, and almost always are accompanied by additional absorptions associated with hydration or hydroxylation near 3 μm (Vilas and Gaffey, 1989, Vilas et al., 1993, Vilas, 1994 and Rivkin et al., 2002).

...

5.2. Spectral feature at 2.8 μm

The position and asymmetric shape of the 2.8 μm feature is uniquely diagnostic of a fundamental vibration caused by a M–O–H (hydroxyl) stretch (Clark et al., 1990). The specific position of this absorption can vary depending on the cation attached to the hydroxyl, although the lack of reliable CRISM data around 2.7 μm makes it difficult to assign a band center with enough precision to provide a constraint for phase identification. Because this feature is generally stronger in pixels with stronger 0.65 μm bands and the 0.65 μm band is consistent with desiccated clays, the 2.8 μm band could result from an M–OH in a desiccated clay. Alternatively, this feature be caused by solar-wind induced hydroxylation because of the exposure of Phobos’ and Deimos’ surfaces to the space environment.

There is no water visible on their surfaces, which is expected because the surface will quickly lose water to space at those distances. However, even if their is no water beneath the surface - something that is suggested - there are at a bare minimum significant levels of surface minerals with hydroxyl groups, aka, hydrogen-bearing. As for carbon, regardless of how Phobos and Deimos formed, their spectra are similar to that of carbonaceous chondrites.

No, we certainly can't say at this point that Phobos and Deimos are good places for ISRU. But the data is suggestive that they might be.

Of course, microgravity mining suffers from significant challenges concerning anchoring.  On the other hand, removing overburden is much simpler (surfaces are generally only loosely bound, and you can throw large amounts of material significant distances with little energy). Given that we have no experience with either microgravity mining or offworld surface mining, it's quite a bit of speculation as to which would be "easier" overall.
 
Quote
Quote
Of course, any offworld "mining" process at all has serious TRL issues to overcome. Even just water production.

Indeed it does.  It's going to be a lot easier to manufacture propellant on the martian surface.

I don't follow.

1) Mars, too, is offworld.

2) I had just argued in my previous post that there are factors that argue for Phobos/Deimos propellant production vs. on the surface.

So I'm not getting how your comment follows from what I had written.
« Last Edit: 03/16/2017 10:14 AM by Rei »

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2031
  • Liked: 245
  • Likes Given: 288
Re: Station On Phobos
« Reply #91 on: 03/16/2017 09:23 PM »
Except that NASA (and other agencies) have repeatedly done studies Mars orbital missions with no surface landing to save cost. So it's worth considering, since that's a type of mission that's gotten significant consideration - whether you like that kind of mission or not.

I have read most of them.  What those studies show is that they don't offer a lot of return given the cost and risk.  They might have a place as a precursor mission.  Going to Mars and only landing on Phobos makes as much sense as crossing an ocean to a new continent and then only landing on a small offshore rock.

Quote
http://www.sciencedirect.com/science/article/pii/S0019103513004934

Quote
Studies using visible to near infrared spectroscopy show that the moons’ surfaces resemble D- or T-type asteroids or carbonaceous chondrite meteorites (e.g. Murchie and Erard, 1996, Rivkin et al., 2002 and Fraeman et al., 2012), although their specific mineralogy is difficult to determine because they lack strong diagnostic absorption features.

Comparison to asteroid spectra

Features similar to both the 0.65 μm and 2.8 μm absorptions are observed on dark asteroids interpreted to have primitive compositions (C-, G-, P-, and D-class asteroids). A search through the Vilas asteroid spectral catalog (Vilas et al., 1998) revealed several asteroids with 0.65 μm absorptions that are similar in shape and wavelength to the corresponding features observed on Phobos and Deimos (Fig. 6). Asteroids that exhibit these features sometimes have an additional absorption near 0.43 μm or 0.9 μm, but all of them are dark and red sloped. Absorptions near 0.7 μm on low albedo asteroids have been ascribed to Fe-bearing phyllosilicates, and almost always are accompanied by additional absorptions associated with hydration or hydroxylation near 3 μm (Vilas and Gaffey, 1989, Vilas et al., 1993, Vilas, 1994 and Rivkin et al., 2002).

5.2. Spectral feature at 2.8 μm

The position and asymmetric shape of the 2.8 μm feature is uniquely diagnostic of a fundamental vibration caused by a M–O–H (hydroxyl) stretch (Clark et al., 1990). The specific position of this absorption can vary depending on the cation attached to the hydroxyl, although the lack of reliable CRISM data around 2.7 μm makes it difficult to assign a band center with enough precision to provide a constraint for phase identification. Because this feature is generally stronger in pixels with stronger 0.65 μm bands and the 0.65 μm band is consistent with desiccated clays, the 2.8 μm band could result from an M–OH in a desiccated clay. Alternatively, this feature be caused by solar-wind induced hydroxylation because of the exposure of Phobos’ and Deimos’ surfaces to the space environment.

There is no water visible on their surfaces, which is expected because the surface will quickly lose water to space at those distances. However, even if their is no water beneath the surface - something that is suggested - there are at a bare minimum significant levels of surface minerals with hydroxyl groups, aka, hydrogen-bearing. As for carbon, regardless of how Phobos and Deimos formed, their spectra are similar to that of carbonaceous chondrites.

No, we certainly can't say at this point that Phobos and Deimos are good places for ISRU. But the data is suggestive that they might be.

Given the tenuousness of the evidence, it would be unwise to make this a priority of destination.  Here's another paper of the same vintage.

http://www.planetary.brown.edu/pdfs/5030.pdf

The cumulative data available for compositional analyses across the surface of Phobos and Deimos, however, remain incomplete in scope and character and ambiguous in interpretation. Consequently the composition of the moons of Mars remains uncertain


No conclusive meteorite analogues for either of the two units were identified, and two quite different models for
the composition of Phobos (and Deimos) were formulated and continue to be discussed. (see review by Rosenblatt, 2011 and references therein). (1) The most common concept involves some form of primitive material comparable to that thought to compose low-albedo asteroids currently found in the outer portion of the main belt (e.g., asteroid type D). Such a composition would require a mechanism to capture this material into Mars orbit. (2) The alternate concept involves material related directly to Mars, formed by co-accretion with Mars or re-accretion of Mars impact debris. Such scenarios would require that the surface of the moons have been extensively processed in orbit and/or in the space environment so that the original composition is beyond recognition.


Quote
Of course, microgravity mining suffers from significant challenges concerning anchoring.  On the other hand, removing overburden is much simpler (surfaces are generally only loosely bound, and you can throw large amounts of material significant distances with little energy). Given that we have no experience with either microgravity mining or offworld surface mining, it's quite a bit of speculation as to which would be "easier" overall.

I think we can be very confident that mining on the surface of Mars is going to be a lot easier.  Gravity is an asset in mining.  Techniques can be adapted from terrestrial methods rather than invented from scratch.  Plus we know a lot more about the physical properties, chemistry, and mineralogy of the martian surface and shallow subsurface.  And we know there are multiple possible water resources. by contrast even the possibility of resources on Phobos is speculative at best.

What you see as advantages of mining on Phobos are actually problems.  The low gravity means that material will be easy remobilised to cause hazards.   Gravity cannot be used to aid processing and stockpiling. Conventional mining technologies with won't work or will have severe limits. 

Quote
I don't follow.

1) Mars, too, is offworld.

2) I had just argued in my previous post that there are factors that argue for Phobos/Deimos propellant production vs. on the surface.

So I'm not getting how your comment follows from what I had written.

1) Don't focus so much on the off world character, but the context, conditions under which you are mining, what you are mining and what is known.  Mars is where the interest is, where the action will be, where the demand will be. Phobos is at best a stepping stone, at worst a digression.  We understand martian conditions much better than those of Phobos, we have experience of excavation, drilling, and abrading the surface (on a small scale).  We know the physical, chemical, and mineral properties of the surface. We know the possible resources with some degree of accuracy, we know that terrestrial experience can be readly applied, and can be readily simulated on Earth.  We have no such knowledge for Phobos.

2) However the counter arguments I think are much stronger. ;)  Phobos is worth a visit, certainly.  Spending a lot of time there, based on what we know now?  No.

3) Hopefully you understand better now.

"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1492
  • Germany
  • Liked: 40
  • Likes Given: 24
Re: Station On Phobos
« Reply #92 on: 03/21/2017 02:54 PM »

There is no water visible on their surfaces, which is expected because the surface will quickly lose water to space at those distances. However, even if their is no water beneath the surface - something that is suggested - there are at a bare minimum significant levels of surface minerals with hydroxyl groups, aka, hydrogen-bearing. As for carbon, regardless of how Phobos and Deimos formed, their spectra are similar to that of carbonaceous chondrites.

No, we certainly can't say at this point that Phobos and Deimos are good places for ISRU. But the data is suggestive that they might be.

The logical course of action is to send a probe, complete with drilling mechanism to evaluate some 10s of metres below the surface.

If there is indeed 20% water or Kerogen bearing materials, then from an exploration point of view, Phobos (or Deimos) becomes the most interesting place in the solar system.

If there isn't, then it's not particularly interesting - unless we want to build space habitats with mega-tonnage of radiation shielding.

Offline Rei

  • Full Member
  • ****
  • Posts: 467
  • Iceland
  • Liked: 179
  • Likes Given: 58
Re: Station On Phobos
« Reply #93 on: 03/21/2017 05:51 PM »
My sentiments exactly. Mars's moons have great potential (or not) for ISRU, and there's some significant questions about them that need answering (which have implications for Mars as well). At least a Discovery class mission seems warranted.
« Last Edit: 03/21/2017 05:55 PM by Rei »

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2031
  • Liked: 245
  • Likes Given: 288
Re: Station On Phobos
« Reply #94 on: 03/22/2017 09:57 PM »

There is no water visible on their surfaces, which is expected because the surface will quickly lose water to space at those distances. However, even if their is no water beneath the surface - something that is suggested - there are at a bare minimum significant levels of surface minerals with hydroxyl groups, aka, hydrogen-bearing. As for carbon, regardless of how Phobos and Deimos formed, their spectra are similar to that of carbonaceous chondrites.

No, we certainly can't say at this point that Phobos and Deimos are good places for ISRU. But the data is suggestive that they might be.

The logical course of action is to send a probe, complete with drilling mechanism to evaluate some 10s of metres below the surface.

If there is indeed 20% water or Kerogen bearing materials, then from an exploration point of view, Phobos (or Deimos) becomes the most interesting place in the solar system.

If there isn't, then it's not particularly interesting - unless we want to build space habitats with mega-tonnage of radiation shielding.

Drilling autonomously is hard, drilling tens of m in microgravity is even harder.

There is no need for it.  Impact gardening on Phobos will have exposed free material for analysis.  Neutron instruments should detect any shallow ice of hydrated minerals, radar would tell us about any a depth, as will as inform us on the structure (are these moons rubble piles for example).

This can all be done with an orbiter mission plus or minus a surface hopper.  Let's do things the easy way.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Hop_David

  • Full Member
  • ****
  • Posts: 1620
  • Ajo, Arizona
    • Hop's Gallery
  • Liked: 107
  • Likes Given: 39
Re: Station On Phobos
« Reply #95 on: 03/24/2017 08:24 PM »
So any craft going to Phobos or Deimos is coming in on a hyperbolic trajectory at 1.85 degrees to the ecliptic (Mars' inclination), and has to aerobrake into an orbit 25 degrees to the ecliptic.

for an incoming craft, the velocity vector when it enters Mars' sphere of influence is pretty much co-linear with the hyperbola's asymptote. And the hyperbola's focus is the center of mars. This asymptote and focal point set the plane of the hyperbolic orbit.

Any craft incoming from an earth to Mars Hohmann will have a velocity vector pointing the same direction as Mars wrt sun. So no matter what latitude the ship enters the sphere of influence, the velocity vectors would still be parallel to Mars velocity vector.

The inclination is set by what latitude of the Sphere of Influence the ship enters. No big periapsis burn is needed to match inclination with Phobos or Deimos. It is more a question of timing and how precisely we can set the approach path.

I've attached a rough pic indicating different hyperbolic orbits entering the SOI at different latitudes.

Offline mikelepage

Re: Station On Phobos
« Reply #96 on: 03/25/2017 11:41 AM »
So any craft going to Phobos or Deimos is coming in on a hyperbolic trajectory at 1.85 degrees to the ecliptic (Mars' inclination), and has to aerobrake into an orbit 25 degrees to the ecliptic.

for an incoming craft, the velocity vector when it enters Mars' sphere of influence is pretty much co-linear with the hyperbola's asymptote. And the hyperbola's focus is the center of mars. This asymptote and focal point set the plane of the hyperbolic orbit.

Any craft incoming from an earth to Mars Hohmann will have a velocity vector pointing the same direction as Mars wrt sun. So no matter what latitude the ship enters the sphere of influence, the velocity vectors would still be parallel to Mars velocity vector.

The inclination is set by what latitude of the Sphere of Influence the ship enters. No big periapsis burn is needed to match inclination with Phobos or Deimos. It is more a question of timing and how precisely we can set the approach path.

I've attached a rough pic indicating different hyperbolic orbits entering the SOI at different latitudes.

Thanks for responding David, but my question was not just about matching inclination (which I now see can be done easily), but also matching argument of Phobos' ascending node.  As you say, the vector of any approaching ship is parallel with Mars', so does that not mean that a direct approach to Phobos would only be possible twice per year?

Presumably there are other transfer orbits that can be used to precess your starting orbit around quickly, but I'm not sure what the best way to do that is.

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #97 on: 03/25/2017 02:48 PM »
So any craft going to Phobos or Deimos is coming in on a hyperbolic trajectory at 1.85 degrees to the ecliptic (Mars' inclination), and has to aerobrake into an orbit 25 degrees to the ecliptic.

for an incoming craft, the velocity vector when it enters Mars' sphere of influence is pretty much co-linear with the hyperbola's asymptote. And the hyperbola's focus is the center of mars. This asymptote and focal point set the plane of the hyperbolic orbit.

Any craft incoming from an earth to Mars Hohmann will have a velocity vector pointing the same direction as Mars wrt sun. So no matter what latitude the ship enters the sphere of influence, the velocity vectors would still be parallel to Mars velocity vector.

The inclination is set by what latitude of the Sphere of Influence the ship enters. No big periapsis burn is needed to match inclination with Phobos or Deimos. It is more a question of timing and how precisely we can set the approach path.

I've attached a rough pic indicating different hyperbolic orbits entering the SOI at different latitudes.

Thanks for responding David, but my question was not just about matching inclination (which I now see can be done easily), but also matching argument of Phobos' ascending node.  As you say, the vector of any approaching ship is parallel with Mars', so does that not mean that a direct approach to Phobos would only be possible twice per year?

Presumably there are other transfer orbits that can be used to precess your starting orbit around quickly, but I'm not sure what the best way to do that is.

What about the opposite?  A spacecraft coming from Mars to visit these moons before finally leaving for Earth.  The main disadvantage I know lies with circularizing the orbit to match the moon's.  If this route is chosen, which moon would also be more efficient to visit...more so if the priority is to head to Earth immediately afterwards?
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Rei

  • Full Member
  • ****
  • Posts: 467
  • Iceland
  • Liked: 179
  • Likes Given: 58
Re: Station On Phobos
« Reply #98 on: 03/25/2017 04:22 PM »
It depends - are you trying to save energy for the ascent stage or the Earth transfer stage?  Also, I suspect (although I haven't run the math) that the optimal trajectories are going to be different for the two bodies. From Phobos the optimal is probably a direct transfer burn, while from Deimos it's probably a burn to lower the periapsis, followed by the transfer burn at periapsis, in order to maximize the Oberth effect. 

Let's at least do the basics... if  you go down to a 150km periapsis from Deimos then I calculate a velocity at periapsis of 4730m/s, versus 1351m/s at Deimos (and 2138 m/s at Phobos). Calculating the same periapsis orbit from Phobos I get... 4431m/s, hmm, not as much difference as I would have expected. But of course you have to spend a lot more delta-V to lower the periapsis from Phobos.

It makes a difference whether you're doing one burn or two for the transfer because inclination changes are easier at lower orbital velocities (aka Deimos)

Offline Hop_David

  • Full Member
  • ****
  • Posts: 1620
  • Ajo, Arizona
    • Hop's Gallery
  • Liked: 107
  • Likes Given: 39
Re: Station On Phobos
« Reply #99 on: 03/26/2017 04:49 PM »
Thanks for responding David, but my question was not just about matching inclination (which I now see can be done easily), but also matching argument of Phobos' ascending node.  As you say, the vector of any approaching ship is parallel with Mars', so does that not mean that a direct approach to Phobos would only be possible twice per year?

Am drawing some pictures to help me think about this.

Deimos and Phobos aren't exactly coplanar with Mars' equatorial plane but close. I'll call them equatorial because it makes it easier to visualize and I can use some well known words.

Coming in from a Hohmann transfer, the Vinf velocity vector is perpendicular to the heliocentric position vector.

This Vinf vector needs to lie in the equatorial plane to have the ship enter on a coplanar orbit. Over a complete circuit of the moon's orbit, the moon's velocity vectors will point in every direction in that plane. The ship's Vinf velocity vector must be parallel to one of the moon's velocity vectors.

The only time a moon's velocity vector is perpendicular to the heliocentric position vector is when the moon's high in the sky at Martian noon or midnight.

Also the moon's high noon or midnight velocity vectors must occur at a time when Mars equatorial plane forms a 23.5º angle with the sun's position vector. When does this happen? At Mars' summer and winter solstice.

You might be right. A vexing observation I can't ignore.

If you just do a small braking burn to park into a large capture orbit, plane change expense is minor in the neighborhood of apoapsis. But a large capture orbit can last month to two months. Less of an option when humans are aboard but possibly a way to get less time sensitive supplies and infrastructure on the Martian moons.
« Last Edit: 03/26/2017 05:42 PM by Hop_David »

Offline mikelepage

Re: Station On Phobos
« Reply #100 on: 03/27/2017 04:35 PM »
Thanks for responding David, but my question was not just about matching inclination (which I now see can be done easily), but also matching argument of Phobos' ascending node.  As you say, the vector of any approaching ship is parallel with Mars', so does that not mean that a direct approach to Phobos would only be possible twice per year?

Am drawing some pictures to help me think about this.

Deimos and Phobos aren't exactly coplanar with Mars' equatorial plane but close. I'll call them equatorial because it makes it easier to visualize and I can use some well known words.

Coming in from a Hohmann transfer, the Vinf velocity vector is perpendicular to the heliocentric position vector.

This Vinf vector needs to lie in the equatorial plane to have the ship enter on a coplanar orbit. Over a complete circuit of the moon's orbit, the moon's velocity vectors will point in every direction in that plane. The ship's Vinf velocity vector must be parallel to one of the moon's velocity vectors.

The only time a moon's velocity vector is perpendicular to the heliocentric position vector is when the moon's high in the sky at Martian noon or midnight.

Also the moon's high noon or midnight velocity vectors must occur at a time when Mars equatorial plane forms a 23.5º angle with the sun's position vector. When does this happen? At Mars' summer and winter solstice.

You might be right. A vexing observation I can't ignore.

If you just do a small braking burn to park into a large capture orbit, plane change expense is minor in the neighborhood of apoapsis. But a large capture orbit can last month to two months. Less of an option when humans are aboard but possibly a way to get less time sensitive supplies and infrastructure on the Martian moons.

Add to the cons: from Phobos/Deimos you also have to perform additional plane changes to land anywhere on Mars other than the martian equator.  Likewise any surface ascent craft from elsewhere than the equator would be detouring (more plane changes) to go to Phobos/Deimos on the way back to Earth.

Having said that, there are obviously huge advantages in being able to utilise the moons for resources, and surface colonies will likely be somewhat close to equatorial anyway.

Question: does the plane change maneuver have to occur after capture?  If approaching at a non-optimal time, you could surely shortcut the whole procedure by making a small burn some 30-60 days out from capture, so as to approach Mars from above or below the plane of Mars' orbit.  That way you can perform a simple capture maneuver into the equatorial plane no matter what time of year your approach is.

Offline JasonAW3

  • Senior Member
  • *****
  • Posts: 2324
  • Claremore, Ok.
  • Liked: 359
  • Likes Given: 9
Re: Station On Phobos
« Reply #101 on: 03/27/2017 05:02 PM »
AIUI Phobos may be a dust coated rubble pile with tidal issues. Not sure that's a stable platform for a base.

And because of this uncertainty I find it un-be-lie-vab-le that we still have not found time, money & interest to send even a modest lander / orbiter to Phobos or Deimos...! Those moons are near Mars, are two interesting targets on their own, are also asteroids, give possibility to do Mars observations at the same time, give knowledge for future manned mission... Looking at all this, it seems so weird NASA has no interest at all for those Martian moons.

OK, Russians have tried, but...

Strange thought here;

      Anybody ever thought to send a number of cube sats as probes to Phobos?  They wouldn't require near as much fuel to get there as a much larger probe, and, in theory, they could use the currently established network of orbital sats around Mars to piggyback a data signal back to Earth.  By using the available communications gear in orbit already, you reduce the power requirements for data transmissions significantly.

      Using cold gas propelled tethered penetrator probes, not only could you get an idea of the composition of Phobos, (In the dust ball/rubble pile/hollow rock realm) but you could anchor the probes, say around 5 or so, to the surface to gather more data.  (By using more than one probe, especially self tethering ones with the penetrating sensor probe, one would get a better idea of the actual approximate makeup of Phobos, than if only one location was utilized.  As low a gravity as Phobos has, it would be unlikely that it would have a consistent makeup throughout its structure, as evidenced by some of the cometary and asteroid encounters that have been made thus far).

      Large probes are great for long term exploration and observation, but for something like an initial probe of something like Phobos, "shotgunning" a number of smaller, cheaper and shorter duration probes at it, is likely to produce at least some results, rather than a major failure.  The same would, of course, apply to Deimos as well.

      Once we have a better idea of the ACTUAL makeup of Phobos, rather than what we speculate that it is, we could then make better and more accurate plans for building a station on Phobos, or even if it is practical in the first place.
My God!  It's full of universes!

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #102 on: 03/27/2017 05:20 PM »

Strange thought here;

      Anybody ever thought to send a number of cube sats as probes to Phobos?

Yes.  Look: http://www.lpi.usra.edu/meetings/lpsc2017/pdf/1707.pdf
"Let the trails lead where they may, I will follow."
-Tigatron

Offline JasonAW3

  • Senior Member
  • *****
  • Posts: 2324
  • Claremore, Ok.
  • Liked: 359
  • Likes Given: 9
Re: Station On Phobos
« Reply #103 on: 03/27/2017 05:33 PM »

Strange thought here;

      Anybody ever thought to send a number of cube sats as probes to Phobos?

Yes.  Look: http://www.lpi.usra.edu/meetings/lpsc2017/pdf/1707.pdf

Ok, I stand corrected.

      So, why hasn't anyone done anything with this idea?
My God!  It's full of universes!

Offline redliox

  • Full Member
  • ****
  • Posts: 1596
  • Arizona USA
  • Liked: 291
  • Likes Given: 53
Re: Station On Phobos
« Reply #104 on: 03/27/2017 06:32 PM »

Strange thought here;

      Anybody ever thought to send a number of cube sats as probes to Phobos?

Yes.  Look: http://www.lpi.usra.edu/meetings/lpsc2017/pdf/1707.pdf

Ok, I stand corrected.

      So, why hasn't anyone done anything with this idea?

Short answer: Mars is the overshadowing celebrity and NASA has limited funds.
Slightly longer answer: Cubesats are a relative new concept, haven't been employed beyond Earth orbit just yet, and you'll get scientists and engineers that'll favor more robust satellites to basically obtain "more-bang-for-the-buck" science.

You may wish to talk more about cubesats in the science section's thread about Deimos and Phobos spacecraft here: https://forum.nasaspaceflight.com/index.php?topic=36977.0
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Hop_David

  • Full Member
  • ****
  • Posts: 1620
  • Ajo, Arizona
    • Hop's Gallery
  • Liked: 107
  • Likes Given: 39
Re: Station On Phobos
« Reply #105 on: 03/28/2017 12:44 PM »
I've attached a rough pic indicating different hyperbolic orbits entering the SOI at different latitudes.

My earlier pic of incoming hyperbolic orbits was somewhat inaccurate.

I asked a astrogator friend of mine if we needed to come in at Mars winter or summer solstice if we wanted an easy slide into a near equatorial orbit.

He replied with the attached illustration from Bates Mueller and White. It's a pic of envelope of outgoing hyperbolas but it could just as well be incoming hyperbolas. In his words "You can pick any inclination available by rotating around the incoming asymptote."

Offline mikelepage

Re: Station On Phobos
« Reply #106 on: 03/29/2017 07:02 AM »
I asked a astrogator friend of mine if we needed to come in at Mars winter or summer solstice if we wanted an easy slide into a near equatorial orbit.

He replied with the attached illustration from Bates Mueller and White. It's a pic of envelope of outgoing hyperbolas but it could just as well be incoming hyperbolas. In his words "You can pick any inclination available by rotating around the incoming asymptote."

Great pic, although that doesn't actually answer the question, does it? Your friend appears to have latched onto the inclination part of the question as you did upthread.  We already know any inclination is possible.

One actually has to change the angle of the incoming motion vector relative to Mars motion vector if one wants to influence the final orbit's argument of ascending node, right? and I think you can achieve this with a small burn perpendicular to spacecraft direction of motion/Mars orbital plane some weeks before capture... thus skipping the need to enter large elliptical initial orbit, followed by plane change maneuver at apoapsis.

Tags: Mars Phobos Deimos cubesats