Sunday, July 13, 2008

Tie A Rocket To Its Tail

Michael Benson has an odd article in today's Washington Post about the International Space Station. Even with a working toilet, Benson says the ISS, literally, is useless:
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.
I have no trouble believing this. But, rather than allowing it to become more "space junk," Benson has an audacious suggestion for the station:
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.

This leaves a lander. A lunar lander substantially larger than the spidery Apollo-era LEMs is currently on the drawing board. It's not nearly as far along in development as the Ares booster and Orion spacecraft components of the Constellation program -- which is a good thing. While I question the need to return to the moon in the first place, I wouldn't exclude it as a possible destination, so I think we should modify the lander's design to make it capable of touching down on either the moon or Mars and then returning to the ISS with samples for study in its laboratories.
I've no idea whether turning the ISS into an inter-planetary space ship is possible. But--especially since our two remaining shuttles will be retired in two years--anything would be better than the present orbiting roach motel that requires Americans to hitchhike just to check in.

1 comment:

OBloodyHell said...

This whole proposition is based on a faulty understanding of both orbital mechanics and what we SHOULD be doing up there.

1) If you're in orbit, you're already halfway there.

2) There is a HUGE mass of stuff we don't have the slightest real clue about in space, including and especially in material sciences -- making stuff in zero G is something we know nothing about at all.

In order to have a useful presence in space we need to have a small processing and collection station on the moon, and a mass driver to put stuff up where we can do something with it in space. That way we don't have to haul material up out of our own rather hefty gravity well.

In other words, the only intelligent movement you might do with the ISS, if anything, is in a fixed orbit around the earth-moon system so that we have regular trips and it is easy to use the moon for whatever.

We aren't using the moon sufficiently at all -- there is only limited use we can get from an interplanetary craft, and the money, if it were going to be spent, should be spent on making space useful not showpiece activities like mars or whatever.

We already did that sort of thing going to the moon back when, and look what it got us -- a lot of whiny idiots ready to chop the budget for it because it did not appear to serve a useful purpose.

We should be aiming to make space a place where wealth comes from, so that people will WANT to stay there.