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Found a site that list all thought of, implimented ISS modules and space vehicles.
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That is why a free Soyuz and a free Progress is such a good idea, IMHO. Heck the incremental cost of flying such a tandem for tethered flight practice could be covered by the Discovery Channel special run about the missions.
If by "Covered by the Discovery Channel" means One Hundred Million Dollars, then yeah. It costs about $40-50M for a Soyuz and a bit less for Progress, plus modifications to the control systems, balencing vehicle weights(they have to weight about the same), and engineering involved (will the solar pannels snap off when spun up? safety cable-cutting system?) will easily make this a nine-digit project. And it will only last a few days, not months.
Use a Soyuz and a Progress that are already up at ISS.
Delay the incineration of a Progress by a few months and spin up the Soyuz for a few weeks before it completes a crew transfer mission.
No new spacecraft required.
IIRC - - at this very moment there is a Progress and a Soyuz docked at ISS. In October a new Soyuz (TMA-5) will launch and TMA-4 will come home.
In December the next Progress will launch and the current Progress will be filled with refuse and incinerated.
Time the garbage dump and the Soyuz return flight to allow a few weeks of tether practice.
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Those spacecraft have already been written down to ZERO by the bean-counters. We just use them one more time before re-entry.
Agreed, its only a week or two or three first time out but its essentially free.
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Start slow - - maybe 1/16th gee - - and see what happens.
Spin on a plane parallel with the surface of the Earth, so altitude cannot be gained or lost.
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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The key question is not whether humans can survive in periods of reduced gravity, because they can (albeit with some health problems.) From a Mars exploration perspective, we need to determine if humans are adaptable enough to transition from going from zero-g (in space) to 0.38g on Mars. Will the astronauts quickly get used to it? Will they be totally incapacitated after landing on the surface of Mars? That's why we need much more detailed and varied research into all aspects of long-duration spaceflight.
Who needs Michael Griffin when you can have Peter Griffin? Catch "Family Guy" Sunday nights on FOX.
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The key question is not whether humans can survive in periods of reduced gravity, because they can (albeit with some health problems.) From a Mars exploration perspective, we need to determine if humans are adaptable enough to transition from going from zero-g (in space) to 0.38g on Mars. Will the astronauts quickly get used to it? Will they be totally incapacitated after landing on the surface of Mars? That's why we need much more detailed and varied research into all aspects of long-duration spaceflight.
If they fly to Mars in 3/8ths gee, then there is no problem, right?
Will tethers work? I don't know.
But until we try we won't know and that just gives the "warp drive" advocates more arguments why we need another 50 - 75 years and a few dozen billion in basic research.
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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Use a Soyuz and a Progress that are already up at ISS.
Delay the incineration of a Progress by a few months and spin up the Soyuz for a few weeks before it completes a crew transfer mission.
No new spacecraft required.
Thats an awful risk to take, considering neither vehicle is designed to function under heavy loads after deploying from the booster. The solar pannels, radar dish, etc may quite literally snap clean off. The RCS thrusters on both vehicles must also be synchronized pretty carefully, which probobly means physical electronic linkages, which will require control avionics changes to both vehicles.
Also being that the nose of the Soyuz-TMA and Progress-M spacecraft are hatches, its going to take reworking of the Soyuz orbital module and the Progress nose to accomodate a cable/winch system, which you can't do while they are docked. At the very least, it would take a new Progress with the the cable, winch, and a Soyuz docking collar and probobly wouldn't be able to carry any cargo, so thats about $50M right there... Oh and both vehicles ought to have similar masses, do they?
Soyuz only has an "active" life span, on its own, of about one week. Thats it. Seven days of experiments to predict years of physiological change... Even for only a few million, and being that it appears to be a small engineering challenge for a purpose-built craft, and that it isn't worth much for the next 25 years of spaceflight, it sounds like a bad investment to me.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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If they fly to Mars in 3/8ths gee, then there is no problem, right?
Therein lies the problem. If we design our Mars ship assuming that we need to simulate Martian gravity, we will get a heavier ship. We will also need to test it extensively. At this point I do not trust tethers to last for the ~180 day journey to Mars, and only rigorous testing will dispel this belief.
If we absolutely must build a heavier, artificial-g spacecraft, we should make sure that it is necessary. That's why I advocate parallel demonstrations of humans in zero-g for long periods of time, alongside demonstrations of living organisms in a simulated-g environment. Test both methods and may the best one be used.
Who needs Michael Griffin when you can have Peter Griffin? Catch "Family Guy" Sunday nights on FOX.
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The best part of planning for the mars mission is that you can do it while going back and forth to the moon, vary the duration that the crew stay in the ships and do the experiments incrementaly to gain the needed knowledge while in close proximity to Earth.
What ever happened to rather than two ships rotating about the center where they are joined doing just a linear spin of a single ship instead.
Also maybe the cancelled or shelved module for demonstrating that this principle works be built and sent to the ISS so that we can work with varing the rotation to gravity load effect.
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If they fly to Mars in 3/8ths gee, then there is no problem, right?
Therein lies the problem. If we design our Mars ship assuming that we need to simulate Martian gravity, we will get a heavier ship. We will also need to test it extensively. At this point I do not trust tethers to last for the ~180 day journey to Mars, and only rigorous testing will dispel this belief.
If we absolutely must build a heavier, artificial-g spacecraft, we should make sure that it is necessary. That's why I advocate parallel demonstrations of humans in zero-g for long periods of time, alongside demonstrations of living organisms in a simulated-g environment. Test both methods and may the best one be used.
Okay, instead of using a Soyuz and a Progress, park a refuse dump Progress for a few months. Tether it to another refuse dump Progress and then spin the thing uncrewed for 3 months, 6 months, 12 months, 18 months whatever.
I can't argue that we need to test tethers before using them on a Mars mission but testing tethers with leftover Progress and/or Soyuz is so easy, and cheap.
Why not?
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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Bill, but they are NOT "easy and so cheap:"
Both Progress vehicles would have to have the solar pannels re-engineered, the RCS engines would have to have linkages between both vehicles to properly synchronize, and one vehicle will have to have its pressurized cargo hold replaced to accomodate the cable and docking hardware, which means you can't use it for an ISS cargo mission... so, the minimum cost for such an experiment is on the order of $50M.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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*There's another article ("Astronotes") at space.com, relative to stress from lack of "elbow room"-- and of course crewmates continually working so closely together. That would wear on the ol' nerves after a while...no matter how polite, considerate, etc. your pals may be.
How to free up some extra space within such close quarters? Everyone needs a bit of privacy, and I mean beyond the "oh...that's my coffin-sized personal space" situation.
Sure, could build bigger craft...which is just that much more $ and etc. Can't help wondering how making a bit more personal space (and privacy) available might not increase health (stress reduction and psychological factors) somewhat.
--Cindy
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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That lessons learned info could be gotten from the Mars desert research facility operated by the Mars society for how tight the personel space issue is.
On the note of spinning or rotating on a central axis only the ends would feel the gravity and at the center it would probably unuseable space.
First problem would be how to get it spinning since rockets tend to be designed in a linear fashion and then stopping it would be just as hard to do.
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GCNR,
uh...$50 million is cheap for a space mission.
Notice how the use of italics is irrefutable evidence to prove my claim. :;):
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$50-60 million dollars is fairly inexpensive compared to a "regular" NASA robotic mission, yes, but you usually get quite a bit of results and science out of it... with this, all you are really doing is testing how strong the cable is, since Progress can't operate for months powerd up without extreme modification (how are the solar pannels going to track the sun when your spinning? batteries? metal fatigue of zero-G engineerd parts?) to test biological or other experiments, and we can do the simple mechanical testing down here in a vacuum chaimber with UV/Proton radiation sources. On an absolute scale, yeah, it is pretty cheap... on a bennefits-per-dollar scale, its a lousy investment.
I felt that the italics were warrented because Bill was making it sound like it would cost like only a few hundred thousand by recycling old spacecraft without much modification or reengineering, which I say you cannot and will require at least one modified Progress that can only be used for this mission.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Bill, but they are NOT "easy and so cheap:"
Both Progress vehicles would have to have the solar pannels re-engineered, the RCS engines would have to have linkages between both vehicles to properly synchronize, and one vehicle will have to have its pressurized cargo hold replaced to accomodate the cable and docking hardware, which means you can't use it for an ISS cargo mission... so, the minimum cost for such an experiment is on the order of $50M.
Yup.
And by doing so we can also test solar panel configurations for use during tethered flight.
On a tethered flight to Mars you would probably want the place of rotation established so the solar panels lie "flat" in reference to the incoming insolation.
And the Progress can practice tethered flight manuevers - - spin up, spin down, alter the plane of rotation. Stuff like that.
$50 million for proof of concept is chump change.
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P.S. - - If NASA won't do it, a private company should do it and claim proprietary rights to the data streams generated by the tests. Maybe file for patent rights on new supports designed for the solar panels.
Then sell the stuff to NASA, the same way Bigelow will sell back to NASA the TransHab stuff NASA paid to design.
:;):
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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The proof of concept of what? That the cable won't break after being pulled on that long? And putting beefier solar pannels work? Practice flight maneuvers with the vehicle you won't be using? This is provided you can even use a Progress up there already in ISS cargo configuration as the counterweight with essentially zero modifications, which is questionable, otherwise you double the price.
Its not worth the cash, $50M could about buy you a launcher for a Lunar rover payload... there are better uses for the money.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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The proof of concept of what? That the cable won't break after being pulled on that long? And putting beefier solar pannels work? Practice flight maneuvers with the vehicle you won't be using? This is provided you can even use a Progress up there already in ISS cargo configuration as the counterweight with essentially zero modifications, which is questionable, otherwise you double the price.
Its not worth the cash, $50M could about buy you a launcher for a Lunar rover payload... there are better uses for the money.
No tethered flight means we NEED warp drive for Mars.
Tethered flight means we don't.
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Its circular - -we can't use tethered flight for a Mars mission because its not tested.
But we can't test it because, why?
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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What? No it doesn't Bill, humans can manage okay in zero-G for a 5-6 month trip to Mars if humans can manage okay for a solid year in LEO. Next-gen superengines nor artifical gravity are required for humans to travel as far as Mars.
Edit: In fact, if Elon does pull off his Falcon-V rocket and NASA switches to it from Delta-II, then $50M would buy you two small missions.
Edit #2: We should not invest in artifical gravity research because A) we don't need it for about 30 years from now B) we need money, $50M is a small but nontrivial sum which would be wasted.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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What? No it doesn't Bill, humans can manage okay in zero-G for a 5-6 month trip to Mars if humans can manage okay for a solid year in LEO. Next-gen superengines nor artifical gravity are required for humans to travel as far as Mars.
I take it you disagree with Ad Astra on this?
The key question is not whether humans can survive in periods of reduced gravity, because they can (albeit with some health problems.) From a Mars exploration perspective, we need to determine if humans are adaptable enough to transition from going from zero-g (in space) to 0.38g on Mars. Will the astronauts quickly get used to it? Will they be totally incapacitated after landing on the surface of Mars? That's why we need much more detailed and varied research into all aspects of long-duration spaceflight.
Quote from above.
Me? I just don't know and want to cover as many bases as possible.
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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I think that we really don't need loads of experimentation no, 40% gravity ought to be enough combined with mild excercise on Mars to keep you in shape enough to return to Earth. The two real problems are bone density and muscle loss, and both of these can be mitigated for extended and nearly arbitrary periods if you push your muscles and load your bones to Earth levels regularly. This is why bed rest is used to simulate zero-G, and it works fairly well.
In any event, if research needs to be done, then using Progress to just test the cable and stiffer solar pannels is a waste of money.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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GCNRevenger, you keep bringing up the point that not only do both modules used in Bill's proposed experiment have to be modified, but they both have to be functional. I don't believe that's necessarily true.
What about a dead module on one end of the string, and only one module having a live RCS?
If practical, it would eliminate the need for both modules to talk to each other because only one would control the maneuvers. It could also eliminate the need for modifying the dead module. Since it might as well be a ton of bricks, it can be suspended in a sling brought up by the single modified module.
Also, there is no need for the two modules to be of equal mass. The center of mass of the bound modules just has to fall far enough away from the test module, and only the test module has to have its center of mass aligned with the tether. As long as the dead module doesn't flop back and forth chaotically at the end of the tether, it can lay how it falls. This arrangement would have pendular motion anyway, even with two live, perfectly balanced modules. What's a little more as long as it stays within limits?
"Dead" may be too strong a word, of course. You'd want both modules to have their own RCS in the event of a tether failure. However, they would already have that if we just re-used Progress and Soyuz modules. Only one needs the sling, ordinance (to cut loose), crew and/or test package, etc. The other one can be the ISS's usual garbage scow.
"We go big, or we don't go." - GCNRevenger
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Tethered flight is either easy, hard or in the middle.
If its easy then lets stop whining that micro-gravity is a problem for Mars mission. Not necessarily you GCNRevenger, but the folks who wrote the article about immunity loss that started this thread.
If tethered flight is easy, extended zero-gee human life science experiements at ISS border on the unethical.
If tethered flight is hard, then lets practice and solve the tough bits.
Thats all I am saying.
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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BOTH modules have to have working RCS thrusters, if you don't then the "dead" module will be jerked around like the end of a whip being cracked when the cable tightens, not a good situation.
Even better, the thrusters need to have both their timing and direction carefully synchronized, or the rotation will be out of the desired plain (bad of itself) and the solar pannels would not align with the Sun properly. You can't do this safely if you don't have physical wire linkages between vehicles and modified RCS control hardware, so neither vehicle can be a "stock" Progress.
To make a bad even worse, the solar pannels themselves on the current day Progress vehicle may not be strong enough to withstand signifigant force when deployed, so without heavy structural modifications that will essentially kill the payload of the Progress, there is a good chance the pannels will just snap off. Same with the radar dish.
And how is the cable going to attach? One vehicle could be outfitted with the cable, winch drive, and a docking collar clamp and the two could simply mate, but the ship with the cable would have to have this collar/winch adapter in the front, where it would block the docking hatch, so combined with the winch & cable weight you would basicly not be able to use that Progress for anything else.
So, you have to make at least some RCS modifications to both vehicles, the "slave" vehicle needs to have power and will lose signifigant payload mass to SPS structure modifications, and the "master" will need a "winch orbital module," extra control circutry too, and not be able to carry any cargo.
$50M might have been a little low.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I'd have to agree with Edwards on this one. Let's take a common, down to earth example, shall we.
If I tie a rock to the end of a string and start to spin it, my hand is the only part of the system that has control. I can easily change planes, attitude, speed, etc. The hand exerts total control over the entire system. Why should space tethers work any differently?
To avoid bullwhip action I simply have to keep the system in constant tension. A solution to avoid the initial jerk as the system initiates the spin is to start the spinning first and then slowly let the line out. This keeps tension on the line through the entire process as opposed to the bullwhip action of letting the line out then firing the thrusters. Take your rock and string and pinch the string close to the rock. Start spinning the rock, then slowly let the string slide through your fingers until you get to the end. No bullwhip effect.
GCNR,
Have you ever played with a rock and a string? Not even a Yo-yo? :laugh:
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Its not that way in space though, the center of rotation is not on one of the two vehicles (your hand) but rather between them, as neither vehicle has the bennefit of being held steady in space; you can't control the motion if you are of similar mass and have nothing to hold onto... Imagine the two vehicles, the cable deployed and taught. The way it is supposed to work, is that both vehicles will thrust in opposit directions perpandicularly to the cable and the direction of motion will change uniformly versus the other vehicle. Now, if only one vehicle thrusts, then the other vehicle will still be pointing the original direction, so there is going to be a big tug at an angle instead of directly again the cable, which could cause damage and loss of control.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I don't think that the Soyuz/Progress tether experiment will be a sufficient test of Zubrin's artificial-g tether. When I said that I wanted a test of the tether system, I mean a full-up, manned test flight. That would mean observing how humans adapt to long periods of spinning in space and whether Coriolis forces are detrimental.
What I imagine instead is that NASA or a private entity should build a bio-sat that will test the 0.38g equivalent on small mammals (sound familiar? Is the Translife project still active?) If that is successful, we can build a prototype of our Mars spacecraft. It will be launched into earth orbit, and its human crew would test the life support and artificial g systems for an extended period.
Who needs Michael Griffin when you can have Peter Griffin? Catch "Family Guy" Sunday nights on FOX.
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