Matt McIrvin's Freaky Alternate Reality

As I've said elsewhere, I'm no great fan of George W. Bush's big space exploration roadmap. It seems to me that he's trying to bask in the aura of enormous dreams that he has no intention or ability to even begin to fund, and I'm suspicious that there's some damage to science hidden in there. But one accusation I've been hearing a lot over the past few days—that Bush's moonbase/Mars plan has killed the Hubble Space Telescope—is actually unfair, and I'll explain why (elaborating on some stuff bram said).

The HST is, as everyone knows, one of the most productive and publicly spectacular scientific instruments in history, ever since its initially embarrassing mirror flaw was corrected with compensating optics in an on-orbit servicing mission. But it's also an aging instrument, and it's dependent on the Space Shuttle for periodic refurbishing by astronauts; furthermore, no replacement manned transportation system will be ready in time to save it. If another Hubble servicing mission can't happen, it will stop working and have to be scuttled several years from now, leaving a significant gap before the new Webb telescope at Earth-Sun L2 comes on-line sometime around 2011. This would be a pity.

The Space Shuttle is, as everyone knows, not the great space-transportation panacea it was made out to be early on; the economy supposedly associated with a reusable spacecraft has not materialized, two out of five orbiters have crashed with all hands lost, and the system is probably more dangerous than it ought to be. The remaining Shuttles are also getting on in years, and ending the program as soon as possible is probably a good idea, regardless of the context in which it's done. If it were up to me, I'd probably scrap the whole program now. But Bush is committed to bringing the remaining Shuttles back to flight for the single purpose of finishing (for some value of the word "finishing") the International Space Station.

Now, I'm no great fan of the ISS either; while it's kind of cool to have people in space on a semi-permanent basis, and it's undoubtedly an admirable technical achievement, I think it's an expensive pork project of little scientific or other utility. And the question has come up of why, if there are going to be more Shuttle flights at all, they'll be devoted to the ISS rather than the far more scientifically valuable Hubble telescope.

The answer is probably partly political, but it's also a matter of safety. The ISS actually is good for one thing. After a decade and a half of worrying primarily about launch because of Challenger, what finally destroyed Columbia was the big thing that was on everyone's minds the first time Columbia flew in 1981: failure of the heat shield on reentry. When the Shuttle goes to the ISS, it's easy for it to do an inspection fly-around, and, if it's determined that a safe trip home isn't likely, the crew could even stay there and come down in a series of Soyuz capsules; this would be considerably easier and safer than mounting a Shuttle rescue mission on the spur of the moment.

So going to the Space Station actually makes a Shuttle flight a little bit safer, in that it allows an option to not bring the orbiter back (an option that is particularly thinkable with the Shuttle program winding down anyway). Notice that the fatal flight of Columbia wasn't actually to the ISS, nor would a Hubble servicing mission be. So there actually is a reason to prioritize the Space Station over Hubble if there's going to be any future Shuttle activity at all.

Also, I tend to think that the ISS isn't that integral a part of Bush's grand Moon-Mars fantasy; it was, on the other hand, a prominent feature of the space program that preceded it. So it's a bit unfair to blame Bush for the desire to keep it going.

So, while the eventual loss of the Hubble will be a tremendous shame and I'd love the opportunity to score a partisan point here, I can't.