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Send the ISS To the Moon
Posted by
kdawson
on Tue Jul 15, 2008 03:45 PM
from the one-of-these-days-alice dept.
from the one-of-these-days-alice dept.
jmichaelg writes "Michael Benson is proposing that NASA send the ISS to the moon instead of leaving it in low earth orbit. (While we're at it, we should re-brand it as the 'International Space Ship.') He points out that it's already designed to be moved periodically to higher orbits so instead of just boosting it a few miles, strap on some ion engines and put it in orbit around the moon instead of the earth. That would provide an initial base for the astronauts going to the moon and give the ISS a purpose other than performing yet more studies on the effect of micro gravity on humans. Benson concludes: 'Let's begin the process of turning the ISS from an Earth-orbiting caterpillar into an interplanetary butterfly.'"
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Problems... (Score:5, Interesting)
I like this idea on he face of it, but we are talking about a lot of work. The ISS, as presently configured, is in no way designed to stand on its own without regular re-supply... and we are a very long way from the moon in the sense of the energy it takes to keep punting supplies out to a lunar orbit.
Right now, in LEO, getting a new toilet up there is still an effort that can take quite a bit of time and co-ordination. Food and other sundries depend upon lifting resources that cannot be generalized into getting a lot further out of our gravity well; we'd need a new generation of lifters to get that done (and, I suspect, more efficient and hopefully at least somewhat less polluting and poisonous propulsion methods.)
Think over the ISS-related news of the last few years. The oxygen generator failure. The toilet failure. The bad elbow joint on the arm. The computer failures. Solar panel problems. All of these, and more, would have been that much more serious at lunar distances and energy requirements.
Honestly, I get the very strong impression that the ISS is a piecemeal effort, not up to the quality required to exist at a significant distance from resupply and service; more than once there has been talk of having to abandon it. And that doesn't even factor in the dithering support at the political level — at lunar distances, we're talking huge increases in costs, and that will tend to amplify the politician's waffling in support, if indeed one could gain it in the first place.
I would much rather see a serious effort put into a large enough work that it would have some chance at self-sustaining operation; a large hollow globe with cultivation, running water, and a manufacturing base. It'd be hugely expensive, but the vast majority of that would come up front, thus reducing the vulnerability to failed re-supply or loss of political support to kill it outright.
Sadly, I don't see us doing that. We're a lot more likely to commit a trillion dollars or two (of our descendant;s money and interest) to reducing Iran to rubble than we are to seriously attempt to create a viable lunar space station.
Don't get me wrong, I would love to see us actually get the heck off this planet and start populating the solar system, but the realities aren't just daunting, they're outright Godzilla-like.
Re:Problems... (Score:5, Interesting)
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Re:Problems... (Score:5, Insightful)
Instead of putting it in to standard orbit around ether the Earth or the moon can we put it into a orbit where it orbits both? That way it could be used as a spaceship traveling between the earth and the moon. It could be refueled and resupplied as it pass around earth. It could then carry passengers to a moonbase or whatever is up there.
Try standing on the side of the highway and handing a hamburger to someone who's driving past at 70 miles per hour.
If the ISS was orbiting the moon+earth, it would always be going fast enough to get all the way to the moon. Any resupply ship would have to be going the same speed to make contact, which would mean that the resupply ship would also have to be capable of making it all the way to the moon. Which means that things wouldn't be any cheaper.
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Lagrange Points? (Score:5, Insightful)
(according to Wikipedia, several missions are planned there already)
http://en.wikipedia.org/wiki/Lagrangian_point [wikipedia.org]
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Re:Problems... (Score:5, Informative)
You are correct, it would only need to go as fast as the ISS for a moment. However, this is space we're talking about, and there's nothing to slow you down out there. Going that fast for a microsecond takes as much energy as going that fast for a century.
And, unfortunately, the ISS would be going its fastest when it was close to Earth, and its slowest somewhere near the moon.
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Re:Problems... (Score:5, Funny)
Think outside the box!
Take a wire rope that gets hooked when the ISS flies by. On the end of the wire is a supply container. The ISS pulls the container in, docks it and transfers goods out and trash into it.
Then it can throw the container back at earth again at the most appropriate time (e.g. when it can gain the speed back).
The container would "land" at sea, for a ship to pick it up.
New containers would be launched like satellites, and to propel the wire out, a small cap would be blasted off, extending the wire
I think this would work nicely, with a maximum amount of re-usage and a minimum energy loss, to get a "moon express ferry".
Okay, for humans you'd have to make the "satellite containers" start and land softer, but this got solved a long time ago. :)
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Re:Problems... (Score:5, Insightful)
Remember inertia. The cheapest thing you can do is simply move inertially. Moving to high speeds, then slowing back down, is twice as hard as moving to high speeds and staying there. There's absolutely no equivalent of "speed bursts" in space. (Heck, it's not even a very good intuition for things moving around on Earth, either.)
Orbital mechanics can absolutely not be approached intuitively, until you've completely retrained your intuition. It's right up there with QM, in that regard, though IMHO easier to learn the basics of.
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Re:Problems... (Score:5, Informative)
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Re:Problems... (Score:5, Insightful)
If the ISS was orbiting the moon+earth, it would always be going fast enough to get all the way to the moon. Any resupply ship would have to be going the same speed to make contact, which would mean that the resupply ship would also have to be capable of making it all the way to the moon. Which means that things wouldn't be any cheaper.
Just curious, wouldn't it only need to be able to go as fast as the ISS for a much shorter period of time? It seems like that would be cheaper than a vehicle that needed to go that fast all the way to the moon.
Are you joking? Am I gonna get a well-deserved "whoosh" for this reply?
If you're going the same direction and the same speed as something that's orbiting in such a way that it'll get to the moon, then you could climb inside and ride with it to the moon - or you could just chill out and get there on your own. Your speed would continue to match that of the orbiting station, because you would, in fact, be in the same orbit...
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Re:Problems... (Score:5, Funny)
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Awesome response posted on Washingtonpost.com (Score:5, Informative)
astrobill wrote:
As a space physicist and engineer, I praise Mr. Benson's enthusiasm for space exploration. However, I feel compelled to explain to him and the millions of Post readers he was allowed to mislead why his idea to send the International Space Station (ISS) on interplanetary jaunts is wholly unrealistic, and frankly, impossible.
For one thing, the shielding, wall thicknesses, and many other design aspects of the ISS were chosen to protect crews from the worst-case radiation environment known to exist throughout its present orbital environment. The ISS spends its entire time wholly within the protective cocoon of the Earth's magnetosphere, a complex electromagnetic structure generated within the Earth which also happens to protect the Earth from most forms of high energy cosmic rays and other ionizing particles. The ISS design is wholly unsuitable for long-duration jaunts outside this region and could not easily or practically be changed at this point to accommodate a different environment.
Secondly, Mr. Benson's proposal to simply connect engines to the ISS and launch it away from Earth and onto interplanetary trajectories completely ignores the fact that every source of propulsion he cites would impart accelerations, even small ones for certain scenarios, that the ISS structure, joints, and arrays simply cannot accommodate -- the structure would simply exceed design tolerances under any source of thrust sufficient to launch it out of Earth orbit and on a transfer trajectory around the Sun to another Solar System body. Moreover, even the low-thrust ion engines Mr. Benson cites (actually, low "specific impulse," but that's another lesson...) would be unable to launch the ISS onto a transfer orbit to another solar system body, and certainly not on any reasonable timescale. It would be, perhaps, years before Mr. Benson's hypothetically-suitable ion engines could impart enough added velocity ("delta-V" to engineers) to move the ISS into an appreciably higher orbit, much less on a suitable trajectory to another planet in our Solar System. The ISS would require thousands of miles per hour of additional velocity to be placed onto such an orbit, regardless of the engine type used.
Thirdly, Mr. Benson's essay completely ignores the fundamental fact that even the most efficient transfer orbit between Earth and, say, Mars, requires at least 8-9 months each way, not to mention the time spent actually DOING anything once there. The ISS is simply unable to hold enough food, water, air, and other "consumables" for any sized crew for the duration of any mission of the type Mr. Benson has in mind. And "direct" trajectory missions that ignore the more efficient transfer trajectories require so much acceleration that the ISS would simply flex and buckle were an attempt made.
Forth, the amount of power the ISS solar arrays can generate is fundamentally tied to the solar energy received on their surfaces. Some of the interplanetary bodies Mr. Benson proposes visiting are at locations too far from the Sun for the arrays to generate enough power to operate systems on board. For example, the ISS solar arrays at Mars would receive only about half as much solar energy per square meter as they do at Earth. The ISS simply cannot accommodate hanging enough "extra" solar panels on its structure to make up for the difference, and wiring in new, additional power sources would require wholesale redesign of the ISS.
There are about a dozen other significant reasons why sending the ISS on interplanetary missions is completely unfeasible from a technical perspective, and which time an space prohibit me from addressing here.
Mr. Benson's claim that "...there are good answers to all these objections..." and his attempt at preemptive criticism of "skeptics" -- as well his claim that NASA is not "particularly welcoming to outside ideas" -- does not obviate the laws of physics, engineering limitations, much less the laws of astrodynamics and the hostile environment of our solar system.
And contrary
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Translation (Score:5, Funny)
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Re:Problems... (Score:5, Insightful)
Oooh, what a great use for MIR, or SpaceLab. Oh wait, WE THREW THEM AWAY.
Eventually someone is going to say.. Hey, this stuff costs a bajazillion dollars to build and $14,000 an ounce to get into orbit, maybe we should keep it in orbit and see if it can be reused?*
-ellie
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Time to moon: 9.2 years (Score:5, Informative)
My quick Wikipedia-based calculations are that the ISS could match orbits with the moon in 9.2 years if its solar panels were entirely devoted to powering ion engines.
(They wouldn't be, of course, and my other major omission is the need to orbit the moon -- I have no idea how the moon's gravity would perturb the ISS as it approached, I suppose it would increase or decrease orbital transfer efficiency but I don't know which.)
Sources:
Low-thrust transfer [wikipedia.org] - "going from one circular orbit to another by gradually changing the radius costs a delta-v of simply the absolute value of the difference between the two speeds"
Ion engine comparisons [wikipedia.org] - 25 kW can produce 1 N thrust
ISS Solar Arrays [wikipedia.org] - 4 pairs of "wings" to be installed on ISS, totalling 262 kW (I think; might be half that [wikipedia.org] if I misunderstood "wing"); ISS weighs 1 million pounds
Moon's orbital velocity [wikipedia.org] = 1.0 km/sec, ISS's orbital velocity [wikipedia.org] = 7.7 km/sec
Google says: 9.2 years [google.com]
Not feasible (Score:5, Interesting)
Actually, I thought this was a cool proposal until I started thinking about it..., these are the ones that came into my head immediately:
* The ISS may be designed to be boosted into a higher orbit, but this is not the same as the stresses involved with a Trans-Lunar injection boost. It would have to have the entire structural integrity improved which would be VERY expensive.
* Yes, solar panels would work at the moon but the whole directional system would have to be redesigned and the number of panels probably increased.
* The resupply craft are not designed to go to the moon nor is there a booster (currently) available that could take them there. We'd need a whole new booster built to even get them close.
* Our current proposal is to put a base ON the moon. There's really not much to be gained by creating, or moving, a space station into lunar orbit. You certainly couldn't land the ISS on the moon (well you *could* I guess but it'd take some serious engineering!).
Lumpy Gravity (Score:5, Informative)
Re:Lumpy Gravity (Score:5, Informative)
Very interesting...and I did Google it...and ii turns out that there are actually four inclinations that allow one to orbit the moon indefinitely: 27Â, 50Â, 76Â, and 86Â
http://science.nasa.gov/headlines/y2006/06nov_loworbit.htm [nasa.gov]
Still though, it's an interesting point and a nice read...so thanks for the info.
Me? I am still going with the lack of radiation shielding as the nail in the coffin. That reason alone makes this guy's idea seem fairly poorly thought out.
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Technicalities? (Score:5, Funny)
FTFA:
"The ISS, you see, is already an interplanetary spacecraft -- at least potentially. It's missing a drive system and a steerage module, but those are technicalities."
On that basis my house, next-door's cat and G.W.Bush's arse are also "potentially" interplanetary spacecraft. It's only "technicalities" that prevent them from being so.
Cosmic Ray problem (Score:5, Insightful)
One major problem that the author ignores is cosmic rays. In Low Earth Orbit, the ISS is protected from cosmic rays and the solar wind by the Van Allen belts. If you move it out to the moon it won't have this protection any more and the occupants would be exposed to high energy particls much more so than in low earth orbit. I'm not sure of the level of shielding on the ISS but it's probably insufficient to protect the crew.
Yeah.. (Score:5, Funny)
And while we're at it, we can replace the space shuttle with ordinary airplanes by FLYING HIGHER. How come noone has ever thought of this before?
He makes one blatant error (Score:5, Interesting)
That is false.
It is a VERY different trip out of the deep gravity hole, filled with atmosphere that we call earth than it is within space.
The best reason to stop in space is to SWITCH crafts.
Specifically, you need a high G (3 or , aerodynamically sound, craft to get out of the atmosphere.
Once you get out there, you generally want a low G (actually, One G would be perfect), space ship, and you don't care that much about shape. (radiation becoems important however).
We generally deal with this now either two ways:
1. Put a smaller ship inside a throw-away one,
2. give a high initial thrust, and plan it out so that it goes where we want it to without any additional thrust.
These ideas are rather primitive, cheap, and silly. A better idea is to launch ship components up to the space station, build them there, then launch the second ship from there. This gets rid of the size constraint of the method 1, and allows powered flight for much quicker delivery, negating the huge disadvantage of method 2. Yes, this will be more expensive, but it lets us do things we could not at all using the current methods.
Re:Why stop at the moon? (Score:5, Funny)
Why don't we just rename the ISS 'Alice'. Then Jackie Gleason can send it there.
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Re:Why stop at the moon? (Score:5, Funny)
We've already been to the moon.
Careful... There might be a few around here that disagree with that :)
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Re:Why stop at the moon? (Score:5, Funny)
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Re:Leave it where it is. (Score:5, Informative)
The inclination of the ISS orbit is too great with respect to the plane of the solar system. If I remember right it's inclined by 56 degrees to allow the Russian rockets easier access.
With this orbit it's essentially useless for a "dry dock" since too much energy would have to be expended in changing the inclination to match the solar system.
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