Space Stations Phobos and Deimos

JonClarke · Mar 13, 2005

Jim I can't quite see it. I am sorry. If the cycler is travelling with an excess of 7 top 8 km/s relative to the planet it can never go into orbit unless something slows it down. Similarly you can't go from earth orbit (less than 11.2 km/s to a cycler orbit without boosting it those extra km/s. 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>

najab · Mar 13, 2005

>... if in space more than 4-5 mos. at best, they never get back to normal on earth...Tell that to the ISS Expedition crews who have walked off the Shuttle after 6 months on Station. The effects of zero-gee for periods less than a year can largely be moderated by strict adherence to an exercise regimen that includes a sizable portion of resistance training for the lower body (the upper body tends to get a workout through general moving around).That said, some of the Mir cosmonauts have suffered serious long-term problems, but the Mir missions were sometimes as long as 400+ days.

JonClarke · Mar 14, 2005

"That said, some of the Mir cosmonauts have suffered serious long-term problems" Which ones? 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 14, 2005

Steve Inside or outside the box, the dV penalty of a cycler means that you either use more propellant for the same payload or less payload for the same mass. The difference is not trivial, in the worst case you have 43% less payload when you leave earth and and 42% when you leave Mars. These are not trivial numbers. A saturn 5 class booster can put 140 tonnes into LEO. This can send 40 tonnes to Mars or 23 tonnes to a cycler. Which is better? Plus you need much tougher heat shielding when you enter the atmosphere. Again, worst case numbers is that entry velocities are 38% higher for earth and 69% higher for Mars. That means more mass and less actual payload for the cycler. Which is better? These are not once-off costs - you are going to pay this penalty every time. It is always going to be more costly in energy terms per kg of payloads to use a cycler than not. Then there is the infrastructural overhead of cyclers. You are not going to build a cycler once. The minimum number needed is two, you may need as many as five. They won't be trivial spacecraft, mass estimates range from 50 to several 100 tonnes. This mass need to be put in place before you get your missions going. Plus they have to be resupplied and maintained as well. Up to 5 ISS equivalents. You also have to add in the shuttles. You might be able to get away with one that does everything, but you may need three or even four, one each for earth to orbit, LEO to the cycler and back, cycler to mars orbit and back, mars orbit to the surface. So up to four new manned spacecraft will have to be developed, plus the unmanned cargo carriers which will always fly separately because it is more cost effective, so six in all. Other mission architectures with greater payload capabilities on the surface of Mars need only 4-5. Are these shuttles going to be reusable? If so how many times will they be reused? You can't overhaul and inspect them the <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 14, 2005

I'll leave the question of the orbits of cyclers. I think we'll have to agree to disagree. The propellant issue is one of the reasons that I wanted to use bits of Phobos or Deimos in the first place. Have a propellant plant on a cycler containing a large proportion of ice. Of course I'm thinking way out in the future, and bulk transfer. I agree with most of the points that you both make. The advantage is in the security of a larger ship with more reserve of propellant, and possibly the ability to rotate the cycler to provide artificial gravity. With a propellant supply already in orbit and visiting Earth every so many years, this improves the economics of having to launch propellant into orbit. It only improves economics if we have many transfers, so it's in the far future. The Russians have vastly more experience in the effects of long-term space flight. The main effect is the reduction of calcium from the bones and the loss of muscle strength. Alexandir Serebrov used to talk about his daily exercise regime, and how important it was to his well-being. (I used to contact the old MIR station on a regular basis via amateur radio.) I don't know of any non-reversable long-term effects, but that isn't to say that there aren't any.

najab · Mar 14, 2005

The word 'serious' ended up in that sentence as an orphan after an edit. While the health effects have been long-term, they have rarely been serious. It's my understanding that some of them now have to walk with canes, but that's about the worst of it.

claywoman · Mar 14, 2005

NajaB, Does this mean that if we send men to Mars or probably any of the planets in our solar system, since a time of 400 days gives visible problems to the astronauts health wise, does this mean, we cannot send men to the planets?

najab · Mar 14, 2005

No, definitely not. The Russians learned a lot about countering the ill-effects of zero-gee. In fact, they were getting very good at it during the latter days of the Mir program. It's no coincidence that the last long-term Mir resident spent 438 days aboard the Station but was able to walk from the Soyuz to the recovery area. He said that the doctors actually slowed his recovery by constantly insisting that he rest!

JonClarke · Mar 14, 2005

Jim Certainly the ability to make propellant on Diemos will be most useful. I agree that it is something quite some way off as I suspect there are a few practical issues (like waste rock disposal) that have not been worked through. I am sure cycler orbits have their uses, I just can't see ferries as being among them. 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>

JonClarke · Mar 14, 2005

NajaB Do you have a source for "walking with canes"? I was speaking with someone who works with Polyakov and he is fine. Mind you, the guys who flew the first duration missions />6 months in the late 70's are now in their 60's, so we would expect some effects of old age to creep up on them (as it does on all of us). 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>

najab · Mar 15, 2005

Jon, I tried looking for quotable sources online, but haven't found any yet. However I have heard anecdotally that the bone loss on the early long duration missions (the early Salyut stations) was bad enough that the some of the cosmonauts had to walk with canes for months or years after they returned to Earth.

JonClarke · Mar 15, 2005

Hmm, that makes it difficult, and nebulous. The early Salyut? I would take that to mean Salyut 1-5. Six missions flew for longer than 2 weeks (other that Soyuz 11 where the crew died because of depressurisation). One of these was pre Salyut (Soyuz 9, Nikolayev/Sevastyano/ for 18 days). The others were Soyuz 14 (Popovich/Artyukhin) for 15 days, Soyuz 17 (Gubarev/Grechko) for 30 days, Soyuz 18 (Klimuk/Sevastyanov) for 64 days, Soyuz 21 (Volynov/Zholobov) for 49 days, and Soyuz 24 (Gorbakto/Glazkov) for 17 days. Of these Gubarev, Gorbakto, and Klimuk flew one mission after their long flight. Grechko flew another long mission and a short one, and Sevastyanov flew two long mission in all. So these can be eliminated as candidates. Nikolayev, Popovich, Artyukhin, Volynov, Zholobov, and Glazkov did not fly again. Nikolayev and Popovich were veterans due for retirement, so can be discounted, I think. Glazkov only flew once and left the space service only 5 years after his flight. Nothing much is available on him. He may be a candidate. That leaves Volynov, Zholobov and Artyukhin. Artyukhin flew only once in a 19 year career and died in 1998 aged 68 following a long illness, 24 years after his flight and 16 years after leaving the space service. However his flight was only 15 days, the illness may not of been related to space service, and 68 is close to the average age of death for a Russian male. If there is any truth in the story, and it is unsubstantiated, I would have to say that the most likely candidates are Volynov and Zholobov of Soyuz 21 to Salyut 5. They had a most unpleasant flight. Neither of them exercised, Zholobov suffered from severe space sickness and some mental issues, plus there is supposed to have been a chemical leak. The mission was scheduled to last 60 days but was truncated. I am not sure I believe the chemical leak story, it may have been minor, as Soyuz 24 also spent two weeks docked <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 15, 2005

Alpha Tauri says: 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. and The minimum intercept velocity would be 29-21-2.5 = 5.5 km/s. Using that logic, we could leave Earth, slow down 5km/s, and be on our way to Mars. It doesn’t work that way. In any case, you are overlooking several very important factors. Let’s adopt your assumption of goesynchronous orbit as the departure/arrival point. All the mass that is going to be transferred to the “cycler” will have to be boosted from Earth. That includes fuel, food, water, and people. In other words, the takeoff point for the trip is still Earth, not GSO. Breaking up the transport into stages does not reduce the overall fuel required. In fact, the procedure will increase fuel required due to the extra maneuvering for the transfer. Until and unless food can actually be produced on a “cycler”, ALL the food required for the trip will have to be boosted up from Earth. Therefore, there is no savings there. In fact, the extra personnel will make the requirement for food boosted up from Earth even greater than a direct trip. End result is a loss, not a gain. Unless the necessary elements could be found on the “cycler” for growing food, then all those raw materials will have to be boosted to the “cycler” anyhow. Water can be recycled, so there will be a savings in water, though not a lot, since water can also be recycled on a direct ship. The savings in water would probably about equal the debt in food. Net gain so far = 0. The fuel required to boost people from Earth to Mars direct would be the same as that required from Earth to GSO to Mars via a “cycler”. Net gain still = 0. Now for the benefit. The difference in fuel requirements will show up only in the vessel <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 15, 2005

stevehw33 says: The cycler idea will work. "Mining the Sky" was pretty obvious and clear about the concept. Oh, it will “work” allright, it just won’t be feasible as outlined above. stevehw33 says: You must understand MA, who often makes lots of statements without ANY references or explanations of why he believes them. What is your point? Everyone does that ALL time. If everyone included all their reasons and all their explanations into their first post, there would be no discussion. Additionally, those few posts which do include ALL the explanations and information in a single post are often left unread as being too long and too cumbersome to read. If you are insinuating that I don’t provide explanations when questioned, then that would be a false accusation. stevehw33 says: There are no real objections to cyclers. Read my above explanations. There are many valid objections. stevehw33 says: They would be large, steadily orbiting craft whose orbits would be pretty well and easily synchronized with earth and Mars. They would be basically, solar orbiting[sic] artificial asteroids, with stable orbits intersecting synchronized rendezvous near to Mars and the earth. Easily synchronized? You need to check out the difference between an orbit that intersects the orbits of both Earth and Mars, and an orbit that intersects the orbits of both Earth and Mars at a time when each is present at that point in the orbit. stevehw33 says: There are many hundreds of asteroids in such orbits Wrong, there are NONE in such orbit. See the above statement. stevehw33 says: A similar system using an long elliptical orbit around the Earth could easily shuttle materials and peop <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 15, 2005

Good points, Jon. Add those to the points I have already made and the “cycler” concept seems rather pointless, doesn’t it? Jon says: . This is just nuts, this is the ultimate rendezvous or die scenario. Well said, a most astute observation. That alone would be a project killer. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 15, 2005

Alpha Tauri says: 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 chosen asteroid would have to be carefully surveyed to make certain it won’t fly apart under the rotation. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 15, 2005

stevehw33 says: Again, the details are in "Mining the Sky' and it's a good concept. There are NO real theoretical objections to it. So you say. Show us how you overcome the many objections I posted earlier. stevehw33 says: It's based on good facts and science No it is not. It ignores many vital factors as I have pointed out. stevehw33 says: I agree that it would probably take longer to get to Mars & back, instead of using a direct space craft, "express flight", but the energy, mass and technologies transfer savings would be huge. Once more, there are few savings, and a lot of debits. Since some of the orbits a “cycler” would take would be several years long, the personnel and food issue alone would be unacceptable. Also, we aren’t talking about an “express flight”, but rather an ordinary Hohmann Transfer orbit. stevehw33 says: You do NOT have to build a massive, expensive space ship ($100-200 B cost at least!) every time you want to travel to Mars, or elsewhere. That very Important fact is left out, of course. Actually it is not. In a practical colonization of Mars, about 2/3 of the spacecraft will be unmanned cargo vessels, especially at first. A “cycler” would be of no value there. Also, as pointed out above, the mass difference between a minimum space (cramped) space craft, and a comfortable spacecraft would probably be only about 20%. stevehw33 says: I'd ask the doubters what would be done with the massive "express' rocket ship at the Mars end, then? Junk it? First of all, it need not be “massive” in the sense that you insinuate, but only massive enough to be comfortable. Some of them would be refueled to return people to Earth, though that number should be small. Other <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

najab · Mar 15, 2005

Jon, as I said, this is something I've heard several times, but only in passing. For example, Valeri Polyakov is quoted by Robert Zimmerman as having said that the exercise program he had followed during his Mir mission had solved the problems that the earlier cosmonauts had suffered. *EDIT* The important point is, however, that even though the early long-duration astro/cosmonauts may have suffered ill-effects, the health of the current expedition crews to ISS has been closely studied, and no long-term disabilities seem to have resulted from flights of 6+ months.

najab · Mar 15, 2005

>It's very well known that people returning from longer than 4 month zero gee trips in space are not able to walk very far, if at all.Actually, with the improved exercise programs that have been developed, most astronauts are able to stand and walk within a few minutes of returning to Earth. Several of them - Bill Sheppard stands out in my mind - have actually expressed their frustration with the doctors who insist that they have to rest, when the astronauts themselves actually feel perfectly fine.>And spending 3 hours a day exercising is not an efficient use of astronaut time. On a station, with experiments to be conducted, I guess I would agree with you. But during a cruise to Mars, what else are they supposed to do?

mental_avenger · Mar 15, 2005

Stevehw33 says: As I've written before, you have to think somewhat outside of the box……… What an incredibly useless phrase. Since everything takes place within the “box” that encloses the event, thinking “outside the box” is futile and a waste of time. Stevehw33 says: Sure it would not be cheap, but it's way cheaper than building a Completely New space ship, which must travel all the way to Mars and then what? What do you do with it? Accelerate it all the way back to the earth again, Junk it? A multiple $100's of billions space craft? As pointed out earlier, there are many different scenarios, depending on the situation. Some would be sent back for the few people (and probably samples) returning to Earth. Some would be landed on Mars and used for parts and materials. Some might be used as habitats or labs, depending on how they were prefitted. Almost certainly, some would remain in orbit, interconnected to form a space platform, layover station, re-fueling platform, or emergency habitation. We certainly won’t be able to build such things from local materials for a long time, so they have to come from somewhere. Reusing the transit spacecraft at Mars will give them dual duty, saving money all around. If we were truly colonizing Mars, mass production would reduce the cost by several orders of magnitude. The ISS is a poor example, since it was ill conceived to start with, and nearly every system and component was a new design. In addition, because it was let as government contracts, the costs were often literally many many times what they should have been. Once spacecraft are being produced in quantity, by civilian companies at realistic prices, the cost will go way down. Stevehw33 says: Ir's a red herring. Total cost of the propellant of a huge new ship to Mars vs. cost of a small, re-usable shuttle? Weighing 10% <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 15, 2005

Stevehw33 says: What one does with the shuttle, again, is a typical red herring meant to avoid the issue of total propellant cost of a new huge, custom built craft to Mars, vs. the far lesser propellant needs of shuttles at either end.. And time. And time. Don’t forget that one. It is absolutely certain that a “cycler” would take longer to get to Mars on most if not all cycles, than a Mars Direct Spacecraft on a Hohmann Transfer orbit. What do we do with the passengers that must ride for 1 ½ - 2 years on a long “cycler” orbit instead of 6 months on Mars Direct? Stevehw33 says: What costs more in mass/propellant, a little shuttle or a hugely more massive interplanetary space craft? HMMMM? You just can’t get past that invalid exaggeration, can you? The only difference between a “cycler shuttle” and a Mars Direct Spacecraft would be the living space. Extra volume for living space costs very little in mass. Compared to the mass of the main hull, the engines, the fuel, the supplies, and the passengers, the mass of the actual furniture for living would be very small. Keep in mind, this furniture will serve double duty as habitat furniture when the ships are grounded and used as habitats. Stevehw33 says: Your objections are general, but not specific about this 'human time' cost. Which means it's not a real problem. Because he didn’t spell it out it’s not a problem? Get real. Sending colonists on a 1-2 year journey instead of a 6 month journey is not just a problem, but a significant problem. In addition to the lost man hours, there is the additional expense (and mass) of all that extra food. It is a REAL problem. <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

mental_avenger · Mar 15, 2005

Let's see..............typically people are expected to work 8 hours of a 24 hour day. Even with 8 hours of sleep, that would give them 8 hours to spend at other activities, such as eating, reading, watching tv, and ........oh, I dunno............... uh............... maybe................. exercise? (On Earth, exercise is not considered a waste of time, in fact it is encouraged.) <div class="Discussion_UserSignature"> Our Solar System must be passing through a Non Sequitur area of space. </div>

alpha_taur1 · Mar 16, 2005

" '....minimum intercept velocity would be 29-21-2.5 = 5.5 km/s.' Using that logic, we could leave Earth, slow down 5km/s, and be on our way to Mars. It doesn’t work that way. In any case, you are overlooking several very important factors. " 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. "Unless the necessary elements could be found on the “cycler” for growing food, then all those raw materials will have to be boosted to the “cycler” anyhow. " 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. If we could confirm that we could grow food on the cycler, then the whole idea would start to become feasible. Will it be stable when hollowed out ? Who knows? Is there a way to improve its stability?- It's certainly worth investigating. In the meantime, we have a potential source of propellant in a much lower gravity well than that of the Earth or Moon, and we have a potential source of oxygen at least for respiration. There are a lot of 'ifs' in the argument, I agree. If the cycler could 'drop-off' supplies of propellent into Earth orbit on each pass, the idea becomes more and more attractive. We could possibly justify it on those terms alone, and perhaps as a more self-sufficient manufacturing base which would provide added security in case of any problems. This is obviously not a trivial ideal to be dismissed as impossible when even NASA has looked into the concept in a great deal of depth as recently as 2002. There are obstacles to be overc

alpha_taur1 · Mar 16, 2005

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? How much human effort is it worth to open up Space to exploration? It takes effort to do anything. Who should impose limits us as to how much effort we should spend?

JonClarke · Mar 16, 2005

I agree. A 6-month voyage equivalent to a trip to mars is quite acceptable and there are quite a few missions of this length that have been flown. A number of people, of whom Michael Foale is but one, have flown at least two such missions. Longer ones up to 14 months are also feasible, although the data base is much smaller. However according to a contact in IBMP there seems to be no obstracle for missions of several years other than human stamina (a big issue for LEO missions). 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>

Space Stations Phobos and Deimos

JonClarke

Guest

najab

Guest

JonClarke

Guest

JonClarke

Guest

alpha_taur1

Guest

najab

Guest

claywoman

Guest

najab

Guest

JonClarke

Guest

JonClarke

Guest

najab

Guest

JonClarke

Guest

mental_avenger

Guest

mental_avenger

Guest

mental_avenger

Guest

mental_avenger

Guest

mental_avenger

Guest

najab

Guest

najab

Guest

mental_avenger

Guest

mental_avenger

Guest

mental_avenger

Guest

alpha_taur1

Guest

alpha_taur1

Guest

JonClarke

Guest

Similar threads

TRENDING THREADS

Latest posts

Share this page