What are the pro's, cons, and challenges for this approach?
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.
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?
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?
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?
Quote from: sanman on 05/01/2016 10:10 amIf 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.
AIUI Phobos may be a dust coated rubble pile with tidal issues. Not sure that's a stable platform for a base.
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.
A station could also assist with the repair/uprating of sophisticated science and telecommunication satellites in orbit around Mars.
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.
Quote from: Phil Stooke on 05/19/2016 05:46 pmPhobos 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.
Quote from: Bynaus on 05/20/2016 02:15 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).
Quote from: Jim on 05/20/2016 01:26 pmQuote from: Phil Stooke on 05/19/2016 05:46 pmPhobos 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.
"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).
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!
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 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.
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...
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..
Checkout the secondary crater within Stickney
"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.
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)
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.
@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.
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.
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.
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.
Quote from: Robotbeat on 05/20/2016 07:39 pmQuote from: Jim on 05/20/2016 01:26 pmQuote from: Phil Stooke on 05/19/2016 05:46 pmPhobos 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.
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 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.
Quote from: KelvinZero on 05/27/2016 11:09 amWe 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.
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.
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.
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.
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.
Mars moons are probably bone-dry. This is a significant downside.
Quote from: gospacex on 06/02/2016 11:11 amMars 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.
Even if a station is put on Phobos, how often will it be occupied, especially after a Mars landing?
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.
Quote from: alexterrell on 06/05/2016 07:15 pmQuote from: gospacex on 06/02/2016 11:11 amMars 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!
Quote from: Bob Shaw on 06/11/2016 02:01 amThe 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.
Quote from: Bynaus on 06/09/2016 05:00 pmQuote from: alexterrell on 06/05/2016 07:15 pmQuote from: gospacex on 06/02/2016 11:11 amMars 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.
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?
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.
Quote from: Dalhousie on 03/05/2017 05:01 amPhobos 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.
Quote from: TakeOff on 03/13/2017 07:56 pmAstronauts 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.
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.
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. MarsI 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.
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.
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.
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.
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, formedas 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.
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 spectraFeatures 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 μmThe 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.
QuoteOf 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.
Of course, any offworld "mining" process at all has serious TRL issues to overcome. Even just water production.
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.
http://www.sciencedirect.com/science/article/pii/S0019103513004934Quote 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 spectraFeatures 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 μmThe 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.
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 spectraFeatures 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 μmThe 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.
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 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.
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.
Quote from: Rei on 03/16/2017 10:12 amThere 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.
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.
Quote from: mikelepage on 03/05/2017 04:26 amSo 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.
Quote from: Hop_David on 03/24/2017 08:24 pmQuote from: mikelepage on 03/05/2017 04:26 amSo 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.
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?
Quote from: mikelepage on 03/25/2017 11:41 amThanks 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.
Quote from: docmordrid on 05/20/2016 07:12 amAIUI 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?
Quote from: JasonAW3 on 03/27/2017 05:02 pmStrange 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
Quote from: redliox on 03/27/2017 05:20 pmQuote from: JasonAW3 on 03/27/2017 05:02 pmStrange 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.pdfOk, I stand corrected. So, why hasn't anyone done anything with this idea?
I've attached a rough pic indicating different hyperbolic orbits entering the SOI at different latitudes.
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."
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.
Reviving this thread because of discussion here:https://forum.nasaspaceflight.com/index.php?topic=50157.300The discussion was about my post #100 upthread about whether it's possible to get to Phobos or Deimos as a "way-station" more than twice a year. Quote from: Hop_David on 03/26/2017 04:49 pmComing 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.
Anywhere on the surface of Phobos will reduce radiation simply because the body of Phobos blocks about 50% of the sources. The bottom of Stickney will not be very much different (it's not really very steep and deep), and from the bottom of the crater that stunning view will be somewhat reduced as well.