Space Stations Phobos and Deimos

alpha_taur1 · Mar 6, 2005

Here's a crazy idea to think about. It depends largely on confirmation that Phobos has a high volatile content, but here goes: First establish a base on Phobos, anchoring it to the satellite itself. Establish a factory to process the volatiles into useable commodities for the station. Preliminary indications are that both Phobos and Deimos contain ice, organic substances, including nitrogen rich amino acids. Next comes the crazy half baked part. Using solar energy (Both direct and indirect, we manufacture large quantities of propellant which we store in liquefied tanks. We then build a large engine into Deimos, being the smaller of the two and the easier to move, and gradually nudge it out of Mars orbit and into an elliptical orbit around the sun that intercepts both the orbit of Mars and the orbit of Earth. When Deimos passes by Earth, synchronise so that an Earth orbiting satellite matches the approximate speed of Phobos. Use the orbital velocity of the Earth and the satellite to get optimal velocity match. Hop on to Deimos. Wait until Deimos gets to Mars then 'hop' on to Phobos. Ok, you don't get something for nothing, and orbital perturbation as a result of both the Earth and Mars would need substantial correction. Please feel free to knock this idea as is customary <img src="/images/icons/smile.gif" />

Aetius · Mar 6, 2005

Maybe it might be easier to move an Apollo-group asteroid whose orbit doesn't need to be jinked nearly so much to become an Earth-Mars cycler.

vogon13 · Mar 6, 2005

A handy rule of thumb to keep in mind when contemplating moving celestial objects is to recall that a ~10 megaton hydrogen bomb yields enough energy to accelerate US aircraft carrier Nimitz to escape velocity from earth (roughly). Deimos is massively more massive than Nimitz. Just keeping Deimos trajectory stable against perturbations of other solar system objects is a staggeringly big job (and this must be done after it's in the earth/Mars cycler orbit). Space shuttle burns swimming pool volumes of fuel to reach orbit, moving Deimos will take cubic miles of propellant if done chemically, and still enormous quantities of U and Pu and D and T if done with nuke power. Doesn't hurt to imagine neat things, put sadly, reality has to come in to play at some point. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

Aetius · Mar 6, 2005

A nuclear powered Mini-Magnetospheric Plasma Propulsion unit (M2P2) might also be a more efficient use of an asteroid's available reaction mass, also. A space-rated M2P2 drive still doesn't exist, however.

thalion · Mar 6, 2005

Ditto, Vogon. Let's not forget the additional energy needed to get Deimos out of Mars's gravity well. To roughly agree with an earlier poster, it would be easier to get a much smaller near-Earth asteroid, probably one in an orbit very close to Earth's (there are a few) to use as a ferry, should that technology ever come online.

yevaud · Mar 6, 2005

Here's another idea that would materially help us (kudos to Heinlein, who thought of it): We build several (say 6) self-sustaining deep-space stations, and place them into position exactly 1/2 way between Mars and Earth. This gives us a nice way-station 1/2 way to Mars. At 60 degree seperation, there'd be one in the right path every 60 days. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

alpha_taur1 · Mar 6, 2005

I realise that it would require enormous amounts of energy over a considerable period of time. However the energy is available on Phobos and Deimos(subject to confirmation). Perhaps a smaller near Earth asteroid would be a better proposition, especially if we could get one of similar composition. One advantage that Phobos and Deimos have (subject to confirmation) is a ready supply of water and organics. Getting fuel out of Earth's gravitational well is a major exercise in itself, and setting up a factory to produce propellant on one of the Martian satellites must provide a long-term solution to this problem, even if we never get around to trying to shift its orbit. There must be other ways to minimise the effects of perturbation, perhaps by using the position of the moon to provide an orbital correction. I don't think it does any harm in thinking out these crazy schemes.

paleo · Mar 6, 2005

"I don't think it does any harm in thinking out these crazy schemes." True. As long as one stays grounded in science. Vogon is correct. A 'small' Martian moon is still super enormous on human engineering scales.

alpha_taur1 · Mar 6, 2005

I still think that they could provide a very useful resource for propellant. The shifting orbit part was where we got into flights of fantasy, and I was thinking well ahead. Even just as a propellant manufacturing factory and staging base for Mars, both moons look very interesting.

JonClarke · Mar 6, 2005

Hi A-T I agree. Energetically, Diemos is one of the easiest places to do a round trip to - easier than than the moon or Mars. I suspect that these might be where asteroid minign techniques are developed. The only issue might be the debris might impact on other missions to Mars. They are of course very interesting objects in their own right, and may be useful precursor human missions prior to actual Mars landings. They might also provide useful radiation shielding for missions that study mars via teleoperated robots rather than actual landing. The Russians are still working slowly on a Phobos sanple return mission (Phobos-GRUNT), so we may see some material back on earth in the next 10 years. Cheers Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

mental_avenger · Mar 10, 2005

Alpha Tauri says: First establish a base on Phobos, anchoring it to the satellite itself. Keep in mind that on Phobos, an average man would weight about 2 grams. Operations would be (essentially) zero G. Alpha Tauri says: When Deimos passes by Earth, synchronise[sic] so that an Earth orbiting satellite matches the approximate speed of Phobos. Use the orbital velocity of the Earth and the satellite to get optimal velocity match. It would not be possible to get orbital matches you indicate. Since the orbit of Earth is eccentric, and the orbit of Mars is over 5 times more eccentric than that, and those eccentricities are not synchronized, the orbit of a “cycler” would have to constantly and significantly adjusted. Alpha Tauri says: Hop on to Deimos. Wait until Deimos gets to Mars then 'hop' on to Phobos. Since the amount of delta-V required to move from Earth orbit to a “cycler” orbit would be the same as accelerating to that orbit, there is no “hopping” on and off. In most cases, that delta-V would be greater than that required for a ideal transfer orbit to Mars. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 10, 2005

Yevaud says: We build several (say 6) self-sustaining deep-space stations, and place them into position exactly 1/2 way between Mars and Earth. This gives us a nice way-station 1/2 way to Mars. At 60 degree seperation[sic], there'd be one in the right path every 60 days. Only a few problems with that idea. First, it would be rare if one of the standard transfer orbits between Earth and Mars ever intersected the position of one of those stations. Second, and most importantly, it would require nearly as much fuel to stop at the “way station” as it did to accelerate to interplanetary velocity. Then, the vessel would have to be accelerated back up to it’s original velocity. Third, the vessel would no longer be on the proper path to Mars. Other than that…………………….. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 10, 2005

aetius says: A nuclear powered Mini-Magnetospheric Plasma Propulsion unit (M2P2) might also be a more efficient use of an asteroid's available reaction mass, also. Possibly, IF the M2P2 can actually be made to work in space and IF you have several hundred years for the maneuver. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 10, 2005

Stevehw33 says: timing the orbits so they intersect Earth & Mars, or any other planet, on a regular basis. Just hope on board, work to keep the system going, follow the rules and hop off at your destination. As indicated above, it doesn’t work that way. Stevehw33 says: But once in motion, a highly efficient, moderate power ion drive would suffice to keep it on course. Unlikely. The amount of energy required would probably be significant due to the eccentricity of the orbits. In addition, keep in mind that by the very nature of the requirements for the Mars-Earth coinciding orbit of the “cycler”, very few of the cycles are likely to be viable due to the extremely long cycle times. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

alpha_taur1 · Mar 10, 2005

Perhaps a better concept would be to cut a chunk off Phobos or Deimos to act as a radiation shield. Then use this as a cycler. We could still have enough raw material to manufacture propellant. The cycler concept could work, regardless of the eccentricity of the Martian orbit. One ellipse can have four intercepts with the Martian orbit and four intercepts with the orbit of Earth. If we had a series of such 'cyclers', they would cover a large number of scenarios. If we used an interceptor with a highly elliptical orbit around the Earth, corrections to its orbit could be used to optimise the rendezvous. When I said 'anchor', I was aware of the extremely low gravity, and implied some kind of mechanical connection. We have already landed on an asteroid, so we know that's possible at least. It was just intended to initiate discussion.

alpha_taur1 · Mar 10, 2005

"The savings would come in not having to put the relatively massive cycler into Mars orbit at the end of the trip. " You wouldn't have to. Just leave it in Solar orbit, and use a satellite to intercept. (perhaps even Deimos itself at 22,000 km, would be a useful interceptor)

mental_avenger · Mar 11, 2005

Cyclers offer only one advanage. On long trips, they would provide space for more comfortable travel. That's it. There is no savings in fuel and no savings in time. In fact, a cycler would usually make the trip longer than a Hohmann tranfer. It would take the same amount of acceleration to catch up to the cycler on each end as it would to make the entire journey. There would have to be a great deal of traffic, and I mean hundreds of passenger trips each year, to make a cycler practical, and even then it would usually mean a longer voyage. We migtht equate it to a passenger liner on an Earth ocean, without the ability to stop at any ports along the way. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

alpha_taur1 · Mar 11, 2005

" It would take the same amount of acceleration to catch up to the cycler on each end as it would to make the entire journey. There would have to be a great deal of traffic, and I mean hundreds of passenger trips each year, to make a cycler practical, and even then it would usually mean a longer voyage. We might equate it to a passenger liner on an Earth ocean, without the ability to stop at any ports along the way." The orbital velocity of the Earth around the sun is around 29km/s. Mars is around 24 km/s. The cycler might orbit at a comparable orbital velocity of say 21km/s. If our cycler intercepts the orbit of a satellite in Geostationary orbit around the Earth, the maximum possible intercept speed will be approximately 21+29 + 2.5 = 52.5km/s! The minimum intercept velocity would be 29-21-2.5 = 5.5 km/s. The benefit would be the difference between accelerating a probe to 21km/s each time and accelerating to 5.5km/s. On the Martian side, the benefits could be greater. I didn't realise when I cooked up this idea that people had been experimenting with the concept for years: http://www.spaceref.com/news/viewpr.html?pid=7311

JonClarke · Mar 11, 2005

The idea for travelling to Mars via cyclers is very elegant from a celestial mechanics perspective. But the practical logistics and safety problems are huge. 1. To make and break the cycler orbit is always going to cost more in terms of dV than going to Mars directly. When you arrive it may require propulsive breaking as well as aerocapture, a severe mass penalty. This alone kills cyvlers for cargo. 2. A round trip using cyucleris is at best as long as using a conjunction class trajectory (2.5 years), and can be a lot longer (3.5 years). This alone kills cyclers for crew. 3. The launch constraints are extreme. Whether leaving from earth or Mars you are trying to rendevzous with something flying past in deep space at hyperbolic velocities relative to the planet you are launching from. I have never seen it calculated but the launch wind must be very small - minutes at best. If you miss it that is it until the next cycler, several years down the track. 5. The standard cycler scenario requires a high dV-cycler shuttle with minimal life support to rendevzous with the cycler in deep space. This is just nuts, this is the ultimate rendezvous or die scenario. If the shuttle under burns by even trivial margin your crew are stranded. therefore the shuttle must be able to sustain the crew all the way to the planet of destination. This defeats the whole point of having a cycler. The resources that would be intested in cyclers would be better invested in advanced propulsion systems. IMHO of course! Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

alpha_taur1 · Mar 11, 2005

"I have never seen it calculated but the launch wind must be very small - minutes at best. If you miss it that is it until the next cycler, several years down the track." That's if you're launching from Earth. If you're in a Space Station orbiting Earth, that's a different matter. You undock the shuttle and lauch in the direction of the cycler before it arrives. Once the velocity and trajectory is matched roughly, you just need minor course corrections on the part of the shuttle to rendezvous with the cycler. If we have a supply of fuel on board the cycler, the shuttle could refuel there. That's where my idea of using a chunk of (dirty) ice as raw material came in. The cycler would have to be reasonably self-sufficient and habitable because of the time factor. There is still a relatively narrow 'launch' window of course. The ideal minimum dV for rendezvous is a 'collision course' with the cycler coming up behind the shuttle from an Earth orbit perspective, and from behind the Earth from a solar orbital perspective. The Earth's orbital velocity partially cancels out the cycler's orbital velocity, and the shuttle's orbital velocity around the Earth 'fills the gap' in dV. The shuttle engine would burn prior to the arrival of the cycler, so that the cycler is gradually catching up with the shuttle. Then it's a question of gradually adjusting the orbital trajectory with small burns until they dock. A lump of ice could be mined from within - hollow out the centre and build living quarters inside the 'asteroid', or chunk of Martian satellite. Then rotate the asteroid to provide an artificial gravity environment. The docking area would be at the 'poles'. The floors would be the inside walls. I'm not suggesting we just rely on ice for integrity of course. Think about how superconductor technology could be used in such an environment.

JonClarke · Mar 11, 2005

Jim, you are just transfering the launch window from the earth's surface to to LEO. While LEO is relative benign - you don't have to worry about weather for instance - and you can loiter at a space station for quite a while, none the less the size of the window won't change. If you miss it that is it until next time round. You can't loiter indefinitely though, assuming you will be using a H2-O2 earth escape stage you will want to minimise boil off. All the other objections still apply also if you launch from LEO Best Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

alpha_taur1 · Mar 11, 2005

Yes, the weather is probably the main reason I would 'lauch' from orbit. If you know the orbital trajectory for the cycler, you can get into a highly elliptical intercept orbit perhaps 2 days before the cycler arrives and gradually modify this with a series of burns to meet the cycler. It is quite a narrow window, but it should be easily achievable. You don't need to reach anything like Earth escape velocity with the shuttle if you factor in the Earth's orbital velocity. The earth orbits the sun faster than the cycler. If we carefully select the angle at which the the cycler intercepts Earth's orbital path, then we can match the tangential velocity component relative to that of the Earth. The approach velocity of the cycler relative to the Earth is much lower than Earth's escape velocity, because they are moving in a similar direction at the time of rendezvous.

JonClarke · Mar 13, 2005

Hi Jim I am a refined geologist, not a hairy-knuckled celestial mechanic, but my reading of this paper: http://web.ics.purdue.edu/~mcconagh/AIAA_2002_4423.pdf is that to rendevous with the cycler near earth the shuttle will need and additional 4 to 7.5 km/s over and above the 11.2 km/s needed to escape earth (3 km/s from LEO). At Mars the difference is 3 to 8 km/s additional to the 7.7 km/s needed to escape Mars (2.7 from LMO). Making this velocity change over several burns rather than one makes it even more inefficient. These numbers bites you at both ends, requiring extra propellant when you leave the planet and imposing much more severe braking when you arrive at your destination. Additional propellant is also needed to move from the flyby cycler orbit to one that intersects the planet's atmosphere, although this will be modest if done early enough. Also worth noting The 19 km/s areobrake on return to earth and 15.7 km/s on arrival at Mars may be too much for aerobraking alone, at least for crews, thus requiring a propulsive component. All in all, using a cycler on the round trip means that your total propulsive velocity change (assuming you can use aerobraking for all de-acceleration on arrival at earth and Mars rises from 21.8 km/s to 28.8-37.5 km/s. This does evil things to mass ratios. Of course, I could be wrong. Cheers Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

alpha_taur1 · Mar 13, 2005

I agree that the object would have to leave Earth at about the velocity you suggest, but if the rendezvous is at the right angle, the cycler can effectively use the orbital speed of the Earth to accomplish this. This may be horribly simplistic to a celestial mechanics specialist, but it seems intuitively correct. Perhaps there is a danger that the cycler will actually go into Earth orbit as a result of this approach, but I guess that will depend on the separation.

JonClarke · Mar 13, 2005

Steve, You have to rendevzous with something that passes close by by with a relative velcoity of between 4 and 8 km/s. Please explain how you cannot have a narrow lanuch window. The issue is not minimum time but minimum propellant. every tonne of textra prolleant you need to renezvous with the cycler is a tonne you don't land on Mars. No real objections to the cycler? Then I suggest you read the arguments more carefully and think through the mass and velocity implications. These alone kill it. Not to mention the mission times, mass overhead. However, there is no bias against the cycler, there is a huge literature on them. What is noticeable from most of the literature is a detailed analysis of the impact on overal mission mass. People are like cycler orbits because they are so elegant. But elegance is not the point, it is efficiency. Send your shuttle back to NEO automatically after the rendezvous? Just how much propellant you you think you have? Far better to keep it on the cycler (if you must have one) and send in back once the cycler returns to earth. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

Space Stations Phobos and Deimos

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