Space Stations Phobos and Deimos

JonClarke · Mar 16, 2005

Steve Development costs are indeed imponderables, even the professionals find it hard. However, all things being equal, the larger and more complex the mission, the more expensive. So let's look at what actually leaves LEO for 4-person missions. Mars Direct architecture Hab, cargo/logistics module, earth return vehicle - three in all. About 100-120 tonnes (Zubrin says 80, but I think his ERV masses are optomistic). 40 tonnes stays on Mars. Mars semi-direct architecture Hab, Mars transfer vehicle, cargo/logistcs module, Mars ascent vehicle. Four in all. You will also need an earth return module, but this will be a CRV type craft and therefore have its development costs written off on other programs. A colleague and I have submitted a paper and are working on a second about this and come to 200 tonnes gross mass. Of this 80 tonnes stays on Mars. Cycler (average) Cycler (2), LEO-cycler shuttle, MEO-cycler shuttle, Mars-MEO shuttle, Mars cargo/logistics module. You mays also need a LEO-cycler logistics module. Five-six in all. I assume the development of the earth-LEO ferry will be written off on other programs. Mass is really hard to estimate. The cyclers are probably 50 tonnes apiece, the Mars cargo modules 40. Mars-MEO shuttles maybe 20 tonnes (dry). The LMO-cycler and LEO cycler and logistics shuttle perhaps 23 tonnes each. Total of 229 tonnes. Mass permanantly delivered to Mars 25 tonnes. This is, as you suggest speculative, back of the envelope stuff. But it is based on basic orbital mechanics and generally used assumptions about spacecraft masses, plus an extensive reading of the relevant literature on both cycler and non-cycler missions proposed over the last 50 years. So, while the economics are indeed speculative, all other features being equal, the fact is that larger more complex missions with less efficient fuel usage per kg will co <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 16, 2005

"there are a few practical issues (like waste rock disposal) that have not been worked through." Phobos and Deimos have enough gravity that waste rock could be gently transported to another sector say a kilometre away if necessary, either way steam extraction via a pressurised drill stem would probably be the best way of extracting water.

JonClarke · Mar 16, 2005

It usually does <img src="/images/icons/smile.gif" /> 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>

JonClarke · Mar 16, 2005

Not much though. Phobos 860-190 µg (variation due to shape and strong tidal forces, Diemos 400 µg. The escape velocity is very low, 11 and 6.9 m/s respectively. The last thing you want is to create a cloud of debris round both moons. Some sort of in situ extraction would be best - make heating the rock in bore holes and then collecting the steam. But you would not want to have a permeable surface, otherwise you would loose steam through vents and perhaps some entrained material with it. This is why we need a lot of data on the interior structure and chemistry, that is for sure. 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 19, 2005

Alpha Tauri says: When did I say that you had to slow down? You are actually speeding up with respect to the Earth, but travelling in the opposite direction to the Earth's orbit. The exact trajectory is a little bit more complex than that. [laughs] Well, no offense intended. I didn’t mean to insinuate that you intended we “slow down”. It IS more complex than that. But, if it was as simple as you say, then we would put our Mar probes in GSO, and then give them a very small boost to send them on their way to Mars. However, I feel I should correct you on one point. Proceeding in a Hohmann transfer orbit from Earth to Mars, we never travel in the opposite direction to Earth’s orbit. Really, we don’t. What we do is to accelerate the spacecraft, in the same direction as the Earth’s orbit (and the orbit of Mars). Acceleration causes the spacecraft to spiral outward from the Sun. Although it sound contradictory, that actually puts the spacecraft into (if we don’t overdo the acceleration) a stable orbit that is further[/u] from the sun, but orbiting at a slower velocity. Alpha Tauri says: Exactly. I put a lot of 'subject to confirmations' in there. The first indications are that Phobos and Deimos contain Ice and organics, including (nitrogenous) amino acids. For food production, you still need P and K. That is dependent on what other classes of meteorites might have impacted on the satellites, eg phosphides, etc. One of the most overlooked elements is energy. Most people don’t know it, but producing food for a single human requires a LOT of garden area and a LOT of sunlight. I don’t recall the figures (someone here may have them), but IIRC, producing food for one human requires about half an acre of ground and a corresponding square footage of solar energy, minimum. Remember that a “cycler” would be heading away from the Sun, w <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 19, 2005

Alpha Tauri says: In the end, everything comes down to money. The accountants rule supreme. Reduced to its basic terms, what is 'money' other than a means of measuring human effort? Actually, wealth (money) is a reflection of the cost of energy. Cheap energy (oil, gas, whatever) can be sold for the same price as expensive energy. The difference is wealth. Notice that the wealth of a country is directly proportional to the cost of the energy to that country. A prime example is Kuwait, where the people expend very little effort, but are extremely wealthy. The value of “wealth” changes constantly, and so does the value of “human effort”. In fact, the value of human effort changes from country to country, and from state to state, sometimes from town to town. In the end, the cost (in human effort, resources, or whatever) of energy is the basis of all transactional wealth on Earth. That will be true in space as well. As pointed out above, the (cost of the) energy to drive the spacecraft, grow the food, and power the machines, will be the determining factor in all our endeavors. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

alpha_taur1 · Mar 19, 2005

It's a little bit more complex than energy, and a lot depends on the basis of the accounting system. For example, ecological accounting is a buzzword of the day. If we look at a tree, it is a chemical processing plant which converts carbon dioxide into oxygen, which is required by mankind. If we could build a machine to do the job of a tree, the value of that machine would be environmentally equivalent to that of a tree. Perhaps resources, or 'exploitation of resources', is a better term. Some resources can be material, some energy. Most of the world's Tantalum is mined in the Congo. Most of the world's Nickel is in the Southern Pacific rim etc. 40% of the world's Uranium is in Australia. However, it all comes down to whether a resource is beneficial to man (at the time). Everything is changeable. A resource of methane hydrates on the edge of the continental shelf is worth nothing today, whereas 60 years hence, it may be extremely valuable. A source of ice and hydrocarbons in a low gravitational environment has little value to us today, but if we ever get to the stage of colonising space, such a resource could be of enormous potential. Another way of looking at money is in terms of benefit to mankind. Will it benefit mankind to open up the solar system to colonisation? There must be a tangible benefit to mankind. Once we start accounting in non fiscal or non trading based terms, the whole picture changes. The definition of money changes in terms of what is needed to survive and grow as a species. If can find a potentially cheaper form of energy, then the cost per unit will obviously drop. Will mankind survive and grow if confined to Earth for millennia?

vogon13 · Mar 20, 2005

Good point about debris release/containment. The pristine vacuum around Phobos and Deimos should also be considered a valuble commodity. 'Knocking' material loose will leave it in a very similar orbit, and even though if and when the stuff comes back it won't be traveling very fast, it will still be at least a nuisance and most likely a serious hazard. Material from either moon that encounters the other will have a significant closing velocity and could be a potentially bigger problem. <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>

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Space Stations Phobos and Deimos

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