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#1 2012-07-26 21:58:36

RobS
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Phobos and Deimos

Check out this powerpoint:

http://spirit.as.utexas.edu/~fiso/telec … -19-11.pdf

It has 16 slides showing what parts of Phobos and Deimos have seasonally continuous sunlight, gives all sorts of delta-vs for going from either moon to the Earth or from the Martian surface to either moon (as a function of latitude, too), and argues that a manned mission to Deimos has advantages over one to Phobos because continuous solar power is available. Very interesting.

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#2 2012-07-27 20:11:52

TwinBeam
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Re: Phobos and Deimos

I keep seeing quotes (E.g. Wikipedia, but other sources also) that Phobos' L1 point is 2.5km over Stickney crater. 
But shouldn't L1 be directly between the moon and Mars?
And Stickney is on the "Western" limb of Phobos as seen from Mars, right?
Could it be that they are actually thinking about L4 ? 
Or am I missing some aspect of the orbital mechanics involved?

Given how small Phobos is, seems like staying in orbit at L1 would make sense, where you could spin for gravity while still getting most of the radiation shielding of Phobos and Mars.  Or maybe a solar synchronous orbit, since that seems to be the major concern in the UT proposal.  Can't take advantage of piled up regolith for more shielding that way, of course.  But the crew will want to get out and explore Phobos' surface anyhow, and getting to the surface is extremely easy - so perhaps the crew could split their time between surface and orbital bases, with most of the high power-consuming equipment staying in orbit?

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#3 2012-07-27 21:05:58

RobS
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Re: Phobos and Deimos

Yes L1 should be between Phobos and Mars. It's only a semi-stable point; it requires station keeping.

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#4 2012-07-27 21:08:37

TwinBeam
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Posts: 144

Re: Phobos and Deimos

I didn't find their argument conclusive. 

The extra dV to Phobos is significant, I agree - though they could go do Deimos first, study it a bit, then go on to Phobos - much increased value for not much extra dV.

The slight increase in Mars surface coverage isn't terribly significant - and if it were, putting up a small relay sat could give you fuller surface coverage.

Near continuous solar power is nice - but losing only about 3 hours of sunlight a day on Phobos doesn't seem like that big a deal - charge some batteries when everyone is sleeping - you'll need them anyhow to handle varying loads.

The increased lag to Deimos won't be a big deal for the level of robots we'll have by their proposed mission date.  But it does make remote telepresence far less convincing,  I suspect a humanoid telepresence robot wandering around on Mars giving crew members much of the feeling of "being there" would make a near-Mars mission far more popular on Earth.  And being in a lower orbit also makes a telescope aimed at Mars that much more useful - e.g. for weather and season studies.

The longer duration exposure to one Mars site doesn't seem like a big deal - two 3 hour shifts working two sites on opposite sides of Mars is probably about right before turning over to the next crew shift.

And of course, the big bonus would lie in exploring Phobos itself - far more interesting than Deimos.  You're going all that way and landing on one of two moons - and you pick Deimos mainly because "the light is better there"?  Sounds like the punchline of an old joke...

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#5 2012-07-28 10:15:34

SpaceNut
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Re: Phobos and Deimos

RobS wrote:

Yes L1 should be between Phobos and Mars. It's only a semi-stable point; it requires station keeping.

Here is a couple of quick references for what are the lagrange points of the Earth moon system and mars would be no different with regards to locations around mars only the distances will change.

http://www.freemars.org/l5/aboutl5.html

http://hyperphysics.phy-astr.gsu.edu/hb … lagpt.html

lagpot2.gif

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#6 2012-10-17 15:43:55

falkor
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From: Surrey
Registered: 2004-08-21
Posts: 112

Re: Phobos and Deimos

RobS wrote:

it's a 6MB download but as Rob says is very interesting

so NASA would pay for this rather than a Mars landing?

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#7 2012-11-03 03:35:39

dunwich
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Re: Phobos and Deimos

falkor wrote:

so NASA would pay for this rather than a Mars landing?


Does NASA have a official position on this?

http://spirit.as.utexas.edu/~fiso/telec … -19-11.pdf makes a interesting read but it is completly focussed on how to get there and how you could observe Mars from it.

Not much is known about the make up of these moons but they are either c-type or d-type asteroids (meaning carbon and ice or carbon silicates and [a little] ice). Here are in any cases the building blocks to make fuel for later martian descend and return flights back to earth.

Either way both Phobos and deimos would be interesting candidates to visit but are so similar in comparison to getting there and observing mars that the final candidate should be considerd on easy access to water ice, radiation protection and and interesting geology. This I believe favors phobos over deimos altough a new mission would be required to select a candidate. I hope one where they can detect water ice in it's interior without the need of sending people first


People think dreams aren't real just because they aren't made of matter, of particles. Dreams are real. But they are made of viewpoints, of images, of memories and puns and lost hopes.

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#8 2012-11-03 07:47:44

RobS
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Re: Phobos and Deimos

We'd need to send several probes to the moons, and ideally land a few seismometers, so we can determing the interior structure. You don't need landers for that; you can design small sensor packages to hit the moon at several hundred kilometers per hour and survive. Each impact would set off seismic waves that the previously impacted seismometers could detect. The moons may be rubble piles and impact heating may have depleted their water content. I think it would be a shame to send astronauts to within 5,000 kilometers of Mars and stop, but maybe it would be wise, especially if they could set up a water extraction facility. That would provide orbital refueling and make a Mars landing and a return to Earth much easier. I think the delta-v from Phobos to an elliptical orbit around Mars is 700 meters per second (about 1,500 mph). An elliptical 24.6-hour orbit with the periapsis at several hundred kilometers and the apoapsis at 20,000 kilometers or so is an ideal parking orbit; the periapsis always occurs over the landing spot every day and the delta-v from that orbit to Earth is not too high (I don't remember how much; maybe 2 km/sec).

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#9 2012-11-03 10:47:41

dunwich
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Re: Phobos and Deimos

well we need a way to determine their (phobos and deimos) composition hopefully with not to many probes as it would increase the price. I wonder if a impactor mission would do considering it gould get a gravity slingshot from mars before hitting one of the moons.

And on stopping 5000 km before reaching your destination (mars) remember that christopher columbus didn't reach the mainland of america until his third voyage (before that he yust visisted the caraiben islands). You also have to consider what the ultimate goal is getting to mars or settling mars. If you're content with getting there then it's a shame to stop but if the goal is settlement then your probably better of at the moons.

The prospect seems to be that a martian moon mission would be cheaper simpler but more then that the moons have been over the course of their history received many impacts of mars that reached orbit afther a other impact these rocks could be collected (the most a apollo mission returned was yust over a 100 kg it is not unlikely that a 100 kg of mars rocks and dust could be collected from phobos and these rocks would come from all over mars. Then the official teleoperating mission could start following by searching for water ice. And if water ice is found and is easy to extract a next phase could follow that will benefit the settlement of mars more then a actual mars base (I believe).


People think dreams aren't real just because they aren't made of matter, of particles. Dreams are real. But they are made of viewpoints, of images, of memories and puns and lost hopes.

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#10 2012-11-03 11:45:50

RobS
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Re: Phobos and Deimos

Regarding a series of impactors, they don't need to cost too much. If you're manufacturing six of them, they'd all be identical. The probe that includes them would be put into an orbit very close to that of Phobos or Deimos and would release them one at a time over several weeks. The release times would be planned so that each one came down at a different spot on the moon. You might even be able to drop one or two at the poles where there's less light and therefore more ice. Neither moon's poles, however, are in constant darkness, like the poles of our moon, so we won't find permanent ice on the surface at either one.

Regarding Martian rocks on the moons, yes, the estimate is that there are a lot of them there. But they are in no geological context; you don't know where on Mars they came from. So their use is somewhat limited.

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#11 2012-11-03 13:06:52

dunwich
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Re: Phobos and Deimos

It's true that there is little geological context but, they speak to the imagination and can still be useful. http://en.wikipedia.org/wiki/Martian_meteorite
Dating them and analysing trapped gas pockets to study the history of the martian atmosphere could be interesting in terms if mars was ones habitable and if it could be terraformed.

I also think certain meteorites like the allan hills 84001 became relativly famous if not by name then by the supposed worm like fossils found in it. And then their is offcourse the moon itself digging inside it could probably tell us something abouth the early solar system the origin of phobos and deimos and give some how they ended up in their orbits and what you could expect if you would mine a asteroid.

The impactor idea to study the moon would probably work but couldn't the tides (caused by mars) also tell us something abouth the chemical makeup off these moons?


People think dreams aren't real just because they aren't made of matter, of particles. Dreams are real. But they are made of viewpoints, of images, of memories and puns and lost hopes.

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#12 2012-11-03 14:21:51

RobS
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Re: Phobos and Deimos

I am not aware of ways the tides caused by Mars would tell us much. Possibly a rubble body would flex in a different way than a solid body, though.

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#13 2012-11-03 16:34:07

dunwich
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Re: Phobos and Deimos

it might cause vibrations inside the moon different parts might move at ever so slightly different speeds  hard rock might flex differently then ice (smashing vs splatting) a better gravity map combinend with the know size and volume might also give a better idea on the composition, a thermal camera could measure the thermal conductivity altough I suspect this in combination with a spectroscopic map have allready been done.


People think dreams aren't real just because they aren't made of matter, of particles. Dreams are real. But they are made of viewpoints, of images, of memories and puns and lost hopes.

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#14 2012-11-17 20:49:58

JoshNH4H
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From: Pullman, WA
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Re: Phobos and Deimos

While Phobos and Deimos are interesting and viable targets of their own right, the fact that they're closer to earth than Mars shouldn't obscure the fact that as targets for colonization and exploration they are just waypoints to Mars and other places, of minimal interest in their own right.  While full sunlight is an advantage, if a scheme where solar thermal power is the norm the storage of heat to be used later to generate energy is a pretty reasonable way to store heat.  Alternatively, in the long term Aerostationary solar power satellites are certainly possible.  In other situations, Nuclear power is not subject to a day-night cycle.

Something else worth considering is that, because Mars is a planet, it is nearly guaranteed to have any resource that you could want somewhere.  Phobos and Deimos, on the other hand, are on the other hand, don't necessarily.  In fact, the jury appears to still be out as to whether or not they even have significant amounts of water.  This makes them far less attractive targets for colonization in the long term.


-Josh

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#15 2012-11-18 09:42:38

RobS
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Re: Phobos and Deimos

The main value of Phobos and Deimos derives from their being satellites of Mars. We can reach chondritic asteroids (if that is what they are) that may have more water for less delta-v. I could see them become very important if Mars ever is settled by lots of people. Mars could provide them cheap raw materials (cheaper than anything low Earth orbit can get from Earth) and the moons would provide a large, stable, zero-gee manufacturing platform, complete with cheap volatiles (for fuel and making plastics) and regolith for radiation shielding. If transport from Mars orbit to Earth gets cheap, Phobos and Deimos might be able to compete with manufacturing in low earth orbit. They may be a cheaper source for materials for colonies on the moon than the Earth is.

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#16 2012-11-18 11:06:24

JoshNH4H
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Re: Phobos and Deimos

I definitely agree with that assessment, but IMO the fact that they will be economically dependent on a developed Mars means that they are secondary targets for colonization.  Because exploration is a natural precursor to colonization, I think it makes sense to go to Mars from the get-go.


-Josh

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#17 2012-11-18 15:32:40

RobS
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Re: Phobos and Deimos

I agree. I was glad to see that people were thinking very thoroughly about Phobos and Deimos, though, and making a case for them. I'd favor some automated exploration early on to determine whether they have volatiles, and an effort to obtain fuel from them in order to make the flight back to Earth cheaper. I'd love to see that done before we actually land people on Mars, but I wouldn't postpone the latter for the former, and in a real world with a shortage of resources, I doubt we can afford both.

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#18 2018-01-14 10:44:44

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,303

Re: Phobos and Deimos

Topic of discusion for a first mission using BFR alternative...We also were talking about megasphere re-enforcing via using the L1 point to which some measurements from the moons could prove to be useful.

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#19 2021-09-10 07:55:29

Mars_B4_Moon
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Registered: 2006-03-23
Posts: 9,774

Re: Phobos and Deimos

Japan’s Mission to deliver Mars’ Moon Sample
https://scitechdaily.com/japans-mission … e-by-2029/

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#20 2021-12-30 16:16:27

Mars_B4_Moon
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Registered: 2006-03-23
Posts: 9,774

Re: Phobos and Deimos

Mars Piloted Orbital Station (or Marspost) is a Russian concept for an orbital human mission to Mars, the mission never went ahead but had  several proposed configurations, including using a nuclear reactor to run an electric rocket engine

https://web.archive.org/web/20081108061 … s/obl.html

http://www.huffingtonpost.com/2009/10/2 … 38297.html

Martian Moons eXploration (MMX) the Japanese mission to Mars that would survey the two moons; Phobos and Deimos, and collect a sample to bring back to Earth.

https://twitter.com/mmx_jaxa_en/status/ … 3319937025

Jaxa budget discussion
https://twitter.com/sado_kouta/status/1 … 1618125830

Last edited by Mars_B4_Moon (2021-12-30 16:19:05)

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#21 2021-12-30 20:27:42

louis
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From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Phobos and Deimos

Why would anyone want to land on Mars when they can mess around on Mars's moons. I just don't get it.

Mars_B4_Moon wrote:

Mars Piloted Orbital Station (or Marspost) is a Russian concept for an orbital human mission to Mars, the mission never went ahead but had  several proposed configurations, including using a nuclear reactor to run an electric rocket engine

https://web.archive.org/web/20081108061 … s/obl.html

http://www.huffingtonpost.com/2009/10/2 … 38297.html

Martian Moons eXploration (MMX) the Japanese mission to Mars that would survey the two moons; Phobos and Deimos, and collect a sample to bring back to Earth.

https://twitter.com/mmx_jaxa_en/status/ … 3319937025

Jaxa budget discussion
https://twitter.com/sado_kouta/status/1 … 1618125830


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#22 2021-12-30 20:58:44

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,303

Re: Phobos and Deimos

https://en.wikipedia.org/wiki/Martian_M … tion_(MMX)

The robotic sample return is still set to Launch sometime around September 2024 at this point.

https://www.isas.jaxa.jp/en/missions/sp … g/mmx.html

https://www.mmx.jaxa.jp/en/

rover is still undergoing testing https://mmx-news.isas.jaxa.jp/?p=1271&lang=en

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