Consider the International Space Station (ISS), that marvel of incremental engineering. It has close to 15,000 cubic feet of livable space, 10 living and working areas, a robot arm that can repair the station from outside, and the capacity to keep five astronauts in good health for long periods.
The only problem with this $156 billion manifestation of human genius – a project 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. As a scientific research platform, it has virtually no purpose and is accomplishing nothing.
Is its purpose to act as a “stepping stone” to places beyond? 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. Stopping is a waste of fuel, time and treasure. Which is a pretty good description of the ISS, parked in constant low Earth orbit.
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. Where will they go? To the moon – the only place humans have already visited.
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Which leads us right back to the expensively orbiting ISS. The moon is the new “stepping stone.” 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. Meanwhile, we're still writing a lot of big 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.
Retrofit station for a journey
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.
Skeptics will point out that the new Constellation program is already supposed to have at least the beginnings of interplanetary ability. They'll worry about the amount of propellant needed to push the ISS's 1,040,000 pounds anywhere.
There are good answers to these objections. We'll still need the new Constellation Ares boosters and Orion capsules – they can easily be adapted to a scenario in which the ISS becomes the living area and lab core of an interplanetary spacecraft.
The Orion crew exploration module 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.
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 appropriate for travel once a spacecraft is already floating in zero gravity.
Political vision can make it happen
How likely is any of this to happen? Not very. A lot depends on the flexibility of a NASA that hasn't always been particularly welcoming to outside ideas. But it's not impossible. The reason the ISS went from being a purely American project to one including the Russians and other nations was a political decision by the Clinton administration. A similar political vision will be necessary here.
All the billions already spent on the space station would pay off – spectacularly – if this product of human ingenuity went somewhere and did something. But it would also serve as a compelling demonstration that we're one species, living on one planet, and that we're as capable of cooperating peacefully as we are at competing militaristically. Let's begin the process of turning the ISS from an Earth-orbiting caterpillar into an interplanetary butterfly.