The Space Station as an Interplanetary Transport Vehicle?

I thought that the readers of this blog (as well as the author) were more well-informed than to buy into this idea. Here is a post written to the washington post which basically debunks this entire idea. Please read the whole thing before making any more misinformed comments:

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 to Mr. Benson’s assertions, the cost of implementing his “good answers” to the objections (extra capsules, beefing up the ISS structure, adding new arrays or power sources, etc., etc…really WOULD cost far more than simply designing a purpose-built interplanetary spacecraft.

Needless to say, the Post and its readers would be well-served by having essays that make serious engineering proposals first vetted by someone with even a modicum of engineering knowledge before foisting them on an unsuspecting public.

Okay, I’ve said this here before but this is a good time to say it again. The ISS should stay where it is and be converted into an orbital ship yard. Any ship large enough to carry crew, supplies, and fuel enough for touring the solar system or beyond would have to be built in space. The ISS is ideal for that. Add some more robotic arms and some storage capsules for sensitive materials and there you go. There is enough space junk and dead satellites in orbit already to provide some raw materials to start with. I think that the space shuttles should go up to stay too. Why throw away and waste something so useful? Even if they are not actually used they could still be dismantled in orbit and be rebuilt into the ship we are looking for.

If the ISS can’t be made suitable for a journey to Mars, then how much will a purpose-built spaceship cost? My sense is all the problems raised by Jason should be addressed. I’d like to see the acceleration design limits for the space station, so we can calculate how long it would take to reach a velocity to transfer it to a lunar or Mars trajectory. Whether it’s do-able or not is calculation, not opinion. How much electrical power would be needed – if the solar panels aren’t sufficient, can more be added, or can nuclear batteries be added? As far as shielding, can some Bigelow-style inflatibles be filled with water and surround the key areas? It’s hard to imagine humanity building a larger space vehicle anytime in the next 50 years – the scarcity of oil will keep the pressure on all economies. This is it – although we are spoiled by money for space, the space station was the result of that generosity. Either help make it work, or get used to seeing Mars through telescopes or rovers.

Conflicts, corporate monopolies and mis-education / senseless entertainment are all far more profitable to stockholders than space exploration or human unity.

As it’s been said it all boils down to money and how you make more of it. We could pretty much go anywhere if we had even just a quarter of what we spend yearly to kill each other, reinforce corporation’s various strangleholds, sell useless junk on tv and generally act like retarded monkeys…

Hell even the Tobin Tax (0.1 -0.25% tax on speculative trade) would bring in at least 150 USD billions a year…That could be used to actually help people and draw them together using, for example, a global space exploration program…

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* World military expenditure in 2006 is estimated to have reached $1204 billion in current dollars;
* This represents a 3.5 per cent increase in real terms since 2005 and a 37 per cent increase over the 10-year period since 1997;
* The USA, responsible for about 80 per cent of the increase in 2005, is the principal determinant of the current world trend, and its military expenditure now accounts for almost half of the world total.

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World Ad Spending Growing Faster Than U.S. in 2008

According to a new study from GroupM, Advertising spending in US measured media is expected to increase almost 4% in 2008 compared with 2007, when spending was up about 3%. Worldwide spending is expected to go up 7% in 2008, after an anticipated 6% increase in 2007.

US advertising spending is expected increase 3.7%, to $168.6 billion, in 2008. Spending in 2007 is expected to come in at 2.8% higher than in 2006. Worldwide spending is expected to go up 6.8%, to some $479 billion

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* Currency speculators trade over $1.8 trillion dollars each day across borders. The market is huge, and volatile.
* Each trade would be taxed at 0.1 to 0.25 percent of volume (about 10 to 25 cents per hundred dollars)
* This would discourage short-term currency trades,about 90 percent speculative, but leave long-term productive investments intact.
* The currency market would thus shrink in volume, helping to restore national economic autonomy. Nations again could intervene effectively to protect their own currency from devaluation and financial crisis.
* Billions in revenue, estimated at $100 – $300 billion per year, would be generated.
* Revenue could go into earmarked trust funds to fund urgent international priorities.

IT’S ALL JUST A MATTER OF PEOPLE’S POWER + PRIORITIES. Technology was never the blocking factor for us humans…

Ion propulsion could send the ISS to Mars.

Even if it would take a decade, it would be worth it. Send the ISS to Mars with a module to withstand the Corornal Mass Ejections, (for both humans and computers), and send it fully stocked with food and water for the Mars exploration crews.

Technology will advance within the next decade to make the naysayers of this look silly.

Hmm, ok, so it’s a complex and thorny issue and we’re not going to resolve it here, but it is still fun to speculate.

I think having spent the time, effort and money in putting the ISS in orbit it seems very strange to allow her to burn up. Even if she can’t set sail amongst the stars she should be maintained at the very least in LEO for staging for other support missions.

Given the massive area that LEO covers and the fact that the Shuttle can’t reach Hubble AND ISS in the same mission I think we are in need of Multiple ISSs.

Each of the new ISSs should be built with the future in mind. Make it modular so each section can be mass produced on production lines like a car. Make them shielded so they can be put anywhere outside Mercury orbit and still work. Make them easy to bolt together so we can throw them up into orbit quickly. Make them strong so they can be shunted around the heavens without falling apart. And make them cheap so we can afford the odd loss on take-off.

Then Make lots of them. One Module and one solar array capable of sustaining two people for 6 months without re-supply. Put 6 stations in orbit around the globe, then start putting them at the 5 Earth Moon Lagrange points. L1 and L2 providing the perfect points from which to ferry missions to the lunar surface.

Then develop each station, expand it with more modules so that each one becomes a stellar ship-yard, building the ships that will take robots and humans out into the cosmos. Robotic missions are limited by the payload size of the launch vehicle, but if it was assembled in space at a station then you don’t have to worry about size. L3, L4 and L5 could be good places to assemble deep-space probes and manned vehicles for martian missions as they could be launched towards earth giving them a slingshot.

But what of the ISS? We could use it as a technology test-bed or fill it with emergency supplies that could quickly be transferred to another station when needed. Whatever we do we must not waste what we have. Find uses for it as a whole or in bits and keep it flying as long as physically possible.

We took a step backward we we allowed Concorde to be grounded, we must not do the same in space. If we crash the ISS before we have other permanantly manned stations in orbit then we are not making progress.

I believe we possess all the resources and talents necessary. But the facts of the matter are that we have never made the national decisions or marshaled the national resources required for such leadership. We have never specified long-range goals on an urgent time schedule, or managed our resources and our time so as to insure their fulfillment.

This gives promise of some day providing a means for even more exciting and ambitious exploration of space, perhaps beyond the moon, perhaps to the very end of the solar system itself.

If we are to go only half way, or reduce our sights in the face of difficulty, in my judgment it would be better not to go at all.

In case the last three paragraphs sounded familiar they were taken from President John F. Kennedy’s Special Message to the Congress on Urgent National Needs, May 25, 1961.

47 years later and we still find ourselves squabbling about what can be achieved and how much it will cost. We can achieve anything we put our mind too. Physical restraints, even the laws of physics, are overcome by technology and discovery. We re-write the rules as we go along and we must push ourselves to do these things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win. Kennedy said that too. Bright bloke!!!