K, so President Bush wants to send us back to the moon, and on to Mars .. someday. Critics of the recent space announcements have pointed out that Bush's crewed missions to the moon and Mars are scheduled far beyond the end of his term. In effect, the president is promising future money he doesn't actually control. Still, the speech has had a galvanizing effect on NASA's political, scientific and budgetary planning: henceforth, most of the agency's effort will be building toward these specific goals. Science not for its own sake, but in support of human exploration. In response, though, NASA leader Sean O'Keefe promptly announced he was abandoning the Hubble Space Telescope—a move that prompted immediate outrage from nearly every quarter. But like many issues bound up in space and money and politics, there's more to this story than meets the eye. What exactly does Hubble—and its cancellation—do for us?
First of all, in a world of limited budgets, you do have to pick your battles. NASA can do only so many things at once, and unless its budget expands faster than inflation, something has to be cut in order for anything else to grow. That's life, baby. Second, there are some pretty good scientific arguments for targeting the Hubble over other programs. The original purpose behind Hubble was to get an ordinary visible-light telescope above the atmosphere. Why? Because the air's mirage-like heat shimmers cause stars to twinkle and jump, which sharply limits the ability of telescopes to focus on distant objects. But a new generation of ground-based telescopes, led by the Keck on Mauna Kea in Honolulu, use laser beams and deformable mirrors to cancel out this twinkle. They haven't got quite the resolution of Hubble, but they do have more light-gathering ability, and are superior instruments in other ways as well (see "Super Scopes," June 2000).
Ground-based scopes will never completely replace space telescopes, but these days they come pretty close—in visible light. Unfortunately, other parts of the spectrum—infrared, ultraviolet, X-rays and gamma rays—never reach the ground, because they're strongly absorbed by the atmosphere in the same way that visible light is absorbed by a sheet of black glass. Thus, NASA's lesser-known space telescopes—the infrared Spitzer, the Far Ultraviolet Spectroscopic Explorer, the Chandra X-Ray Observatory and the Compton Gamma Ray Observatory—are more important, since they give us something we could never hope to match on the ground. If you have to kill one of these, Hubble really is the logical choice.
Putting the Hubble into focus
Unfortunately, this scientific reasoning played no part in O'Keefe's decision. Nor was it fundamentally a budget issue, since O'Keefe has called for a $100 to $200 million unmanned mission to Hubble, to attach a special rocket motor to bring the thing down safely from orbit. And if we can afford that, we can afford to send a shuttle, right? "The problem," O'Keefe insists, "is purely one of safety."
Ah, safety. It's an even better excuse than money, for avoiding the work you don't want to do. According to new safety rules laid down in the wake of last year's Columbia accident, no space shuttle is allowed to fly into an orbit from which the international space station is unreachable. Safe harbor, yeah: From there you can inspect and repair any damaged heat shielding, so the shuttle comes back to Earth in one piece. It's a nice idea, which nevertheless fails to cure the 50 percent of space accidents that occur during launch. And anyway, there are no safe harbors on the way to the moon and Mars, and if NASA is too chicken to fly in its own backyard, we might as well hang up our space-cowboy spurs and give the Hubble to China.
Since the very dawn of the space age, there've been political struggles not only between pro-space and anti-space lobbies, but within the space program itself, between the advocates of human exploration and those of pure, robotic science. Interestingly, though, Hubble has always managed to satisfy both camps. It is a robotic space probe with no humans on board, which gathers excellent data for scientists waiting on the ground. But most machines need a visit from the repairman every now and then, and Hubble would have died a long time ago if not for our nation's gallant shuttle astronauts. In this sense, Hubble is the perfect marriage between science and adventure, industry and government. And it doesn't hurt that the images it captures have ignited imaginations around the world. You never hear anyone complaining about Hubble anymore, or promising to feed the homeless if it's canceled. In a public-interest kind of way, Hubble is possibly the most successful space project ever. And really, for a government-funded space program, serving the public interest is the only ethical goal.
Hobbling the home of the brave
What does this tell us about O'Keefe? He seems to be playing a game of bureaucratic chicken, answering the president's initiative by threatening NASA's most popular program. It's a PR disaster that will likely end his career. But what if it doesn't? What if—heaven forbid!—we actually take him at his word? "Safety" is a bogeyman with bottomless appetites, and when people slap gigantic $500 billion price stickers on a manned Mars mission, this is exactly what they mean: "Making it completely safe will cost all the money in the world." Well, yeah. And on the other end of the spectrum, we could send a man to Mars for $200 million if we didn't mind killing him in the process. Just strap him to a rover with a Snickers and a bottle of Gatorade and let nature take its course. In the real world, you find a happy medium between these extremes, weighing the risks against the costs and doing the best you can.
So, just how risky would a Hubble repair mission be? Exactly two shuttle flights out of 113 have ended in tragedy. That's a 98.2 percent success rate—odds any gambler should love. In fact, I suspect there'd be no shortage of volunteer astronauts even if the odds were as bad as 50/50. And let's just say, for the sake of argument, that shuttle disasters could be predicted with 100 percent accuracy. Say we know, for an absolute fact, that the shuttle will break up during re-entry after the Hubble servicing mission. Shall we fret about the loss of yet another vehicle? Aren't we going to retire the whole shuttle fleet in 2010? And is a monument in the Air and Space Museum more important than a working telescope everyone loves?
I think not. If we're worried about anything, it should be the human cost of an accident. But ask a daredevil, or a smoker: Safety is an individual choice, and the last time I checked, this was still the home of the brave. In the face of certain doom, how many elderly pilots, scientists and ordinary tradesmen out there will give up their last few years of life for the glory and adventure of that trip? A thousand? A million? Can we have a show of hands? Because let's face it: Whether you're on the ground or in outer space, life is 100 percent fatal in the end. The only question is whether you do anything cool before you exit.
Wil McCarthy is a rocket guidance engineer, robot designer, science-fiction author and occasional aquanaut. He has contributed to three interplanetary spacecraft, five communication and weather satellites, a line of landmine-clearing robots and some other "really cool stuff" he can't tell us about. His short writings have graced the pages of Analog, Asimov's, Wired, Nature and other major publications, and his book-length works include the New York Times notable Bloom, The Collapsium and most recently The Wellstone and a related nonfiction book, Hacking Matter.
