Send It Somewhere Special

By Michael Benson
Sunday, July 13, 2008

Consider the International Space Station, that marvel of incremental engineering. It has close to 15,000 cubic feet of livable space; 10 modules, or living and working areas; a Canadian robot arm that can repair the station from outside; and the capacity to keep five astronauts (including the occasional wealthy rubbernecking space tourist) in good health for long periods. It has gleaming, underused laboratories; its bathroom is fully repaired; and its exercycle is ready for vigorous mandatory workouts.

The only problem with this $156 billion manifestation of human genius -- a project as large as a football field that has been called the single most expensive thing ever built -- is that it's still going nowhere at a very high rate of speed. And as a scientific research platform, it still has virtually no purpose and is accomplishing nothing.

I try not to write this cavalierly. But if the station's goal is to conduct yet more research into the effects of zero gravity on human beings, well, there's more than enough of that already salted away in Russian archives, based on the many years of weightlessness that cosmonauts heroically logged in a series of space stations throughout the 1970s, '80s and '90s. By now, ISS crews have also spent serious time in zero gravity. We know exactly what weightlessness does and how to counter some of its atrophying effects. (Cue shot of exercycle.)

And if the station's purpose is to act as a "stepping stone" to places beyond -- well, that metaphor, most recently used by NASA Administrator Michael Griffin is pure propaganda. As any student of celestial mechanics can tell you, if you want to go somewhere in space, the best policy is to go directly there and not stop along the way, because stopping is a waste of precious fuel, time and treasure. Which is a pretty good description of the ISS, parked as it is in constant low Earth orbit.

This is no doubt why, after the horrifying disintegration of the space shuttle Columbia in 2003, the Bush administration belatedly recognized that, if we're going to spend all that money on manned spaceflight, we should justify the risks by actually sending our astronauts somewhere. So NASA is now developing a new generation of rockets and manned spacecraft. By 2020, the Constellation program is supposed to take astronauts beyond low Earth orbit for the first time since Apollo 17 returned from the moon in 1972. Yes, that'll be almost 50 years. Where will they go? To the moon -- the only place humans have already visited.

Which leads us right back to the expensively orbiting ISS. It hasn't a fig-leaf's role left. The moon is the new "stepping stone," with Mars bruited as a next destination. Although NASA officials will never quite say so, their current attitude seems to be that the station is essentially a high-maintenance distraction, even a mistake. Their plan is to finish assembling the thing ASAP and hand the keys over to the Russians, Canadians, Europeans and Japanese, with minimal continuing U.S. involvement. This should happen by the shuttle's mandatory retirement in 2010. Meanwhile, we're still writing a lot of high-denomination checks and preparing the two remaining shuttles for risky flights to finish something we then plan to be largely rid of. This seems absurd. I have an alternative proposal:

Send the ISS somewhere.

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. Although it's ungainly in appearance, it's designed to be boosted periodically to a higher altitude by a shuttle, a Russian Soyuz or one of the upcoming new Constellation program Orion spacecraft. It could fairly easily be retrofitted for operations beyond low-Earth orbit. In principle, we could fly it almost anywhere within the inner solar system -- to any place where it could still receive enough solar power to keep all its systems running.

It's easy to predict what skeptics both inside and outside NASA will say to this idea. They'll point out that the new Constellation program is already supposed to have at least the beginnings of interplanetary ability. They'll say that the ISS needs to be resupplied too frequently for long missions. They'll worry about the amount of propellant needed to push the ISS's 1,040,000 pounds anywhere -- not to mention bringing them all back.

There are good answers to all these objections. We'll still need the new Constellation Ares boosters and Orion capsules -- fortuitously, they can easily be adapted to a scenario in which the ISS becomes the living- area and lab core of an interplanetary spacecraft. The Ares V heavy-lift booster could easily send aloft the additional supplies and storage and drive modules necessary to make the ISS truly deep-space-worthy.

The Orion crew exploration module is designed to be ISS-compatible. It could serve as a guidance system and also use its own rocket engine to help boost and orient the interplanetary ISS. After remaining dormant for much of the one-year journey to, say, Mars, it could then be available to conduct independent operations while the ISS core orbited the Red Planet, or to investigate an asteroid near Earth, for instance.

But, the skeptics will say, the new Orion capsule's engines wouldn't be nearly enough; a spacecraft as large as the ISS would need its own drive system. Here, too, we're in surprisingly good shape. The ISS is already in space; the amount of thrust it needs to go farther is a lot less than you might think. Moreover, a drive system doesn't have to be based on chemical rockets. Over the past two decades, both the U.S. and Japanese programs have conducted highly successful tests in space of ion-drive systems. Unlike the necessarily impatient rockets we use to escape Earth's gravity and reach orbit, these long-duration, low-thrust engines produce the kind of methodical acceleration (and deceleration) appropriate for travel once a spacecraft is already floating in zero gravity. They would be a perfect way to send the ISS on its way and bring it back to Earth again.

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