Author Topic: Station On Phobos  (Read 15789 times)

Offline Bynaus

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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

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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).

Online Eric Hedman

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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.

Offline Robotbeat

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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.
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Offline Bynaus

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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 »

Online Phil Stooke

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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

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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...

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Offline Impaler

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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.

Offline guckyfan

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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

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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.
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Offline MATTBLAK

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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..
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Offline RonM

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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

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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.
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Online Kaputnik

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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).
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Offline Impaler

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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

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Re: Station On Phobos
« Reply #35 on: 05/23/2016 06:55 AM »
Checkout the secondary crater within Stickney ;)
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Offline Bynaus

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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

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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.
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Offline Jim

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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

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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 »

Tags: Mars Phobos Deimos cubesats