by Michael Benson
Ljubljana — Earth, as we have known for only a small part of the trajectory of the human species, hangs in an inconceivably vast space. That void isn’t empty, however; it’s spangled with other planets, moons and stars. The planets of our solar system have all been visited by robot probes now – with the sole exception of tiny, distant Pluto. These preliminary explorations have revealed a diversity of spheres so dazzling that many can hold their own with the wildest science fictional imaginings. More than enough reason, one would think, for human beings to go.
In the mid-1990’s I asked the planetary scientist Gregg Hoppa, then involved in decrypting the mysteries of Jupiter’s bizarrely ice-enveloped moon Europa, what he thought about crewed space flight. Hoppa’s team at the University of Arizona had been beneficiaries of a torrent of information from NASA’s late, lamented Jupiter-orbiting Galileo spacecraft – data which, among other things, indicated that Europa most likely possesses a vast liquid-water ocean under its fissured ice shell – and I expected to hear that robots can do everything that astronauts can do, only better and more cheaply. Instead, Hoppa contemplated the question for a moment and finally said: “Well, I wish they’d go somewhere.”
This point of view would seem to be supported by both the new Bush space exploration proposal, unveiled Wednesday, and the recent wave of public interest in NASA’s successful placement of the first of two robot rovers on the Martian surface. Contrast that with the general public indifference to the presence of humans in low Earth orbit, be they on the space shuttle, when it’s up and running, or the International Space Station. The Spirit rover and its intriguingly crab-like, stereo-eyed twin are only the latest fruit of a determined effort over four decades, by a highly talented coterie of scientists and engineers, to make the best possible use of the small part of NASA’s budget allocated for true solar system exploration.
Unfortunately, Bush’s election-year vision of where to take America’s space program is muddled. It’s true that his plan proposes finally taking human beings out of low Earth orbit – as Hoppa and many others, including myself, would like. But when a single, decisive, dramatic goal would seem to be crucially necessary, Bush wants to have things various ways. Decades after the public’s declining interest in lunar exploration helped force NASA to cut the Apollo program short of its full complement of planned missions, Bush argues that we should return to the moon.
This time the purpose would be to establish a permanent base, intended to provide a kind of steppingstone to Mars – the same shaky argument used to justify the International Space Station. According to the plan, a trip by astronauts to Mars itself would be several decades away, and even the putative moon base would be 16 years in the future. The only truly sensible element of this vision is the replacement of the space shuttle by a vehicle capable of taking astronauts well beyond Earth orbit.
NASA has stood in dire need of political direction for decades. But if the human exploration of space is really the goal, as it should be, then the Bush proposal is not the right way to proceed. In fact it is virtually the same nonstarter scenario unveiled, with a similar fanfare but dearth of actual funding, by the first President Bush more than a decade ago. Much of the expense of space flight comes from the quantities of propellant required to get crews and payloads beyond the gravity of Earth or other planets. It therefore makes little sense to use the moon, which possesses its own considerable gravity field, as a way-station to Mars. Even purely on the level of public relations the bleak moon shouldn’t be our first destination this second time around. We’ve been there, done that.
Over the last decade an alternative, more focused and achievable vision of crewed deep space flight has been elaborated. Called Mars Direct, it wouldn’t even require much of an increase in NASA’s budget – if the shuttle program and the International Space Station were gradually cut back or eliminated, as the Bush plan envisages. The shuttle alone costs half a billion dollars per flight; Mars Direct is estimated to cost from $20 billion to $30 billion – about twice NASA’s annual budget, but for a program that would take a decade to complete.
Mars Direct envisions three launchings directly from the Earth to Mars, starting with two large auto-piloted Earth-return vehicles designed to precede human astronauts to the Martian surface and manufacture propellant for the return journey from that planet’s atmosphere. Thoroughly conceptualized and widely recognized as feasible, Mars Direct can be accomplished largely with proven, existing space shuttle engines and solid rocket boosters. And in contrast to the hit-and-run moon landings of three decades ago, Mars Direct is designed to place humans on Mars for a year – long enough to do some serious exploration.
It’s important, however, that neither of these visions of where to take crewed spaceflight drains more cash from NASA’s highly successful, but woefully under-funded, robotic program – the only part of NASA that has actually been exploring the solar system for the past three decades. But it’s hard to imagine the dogmatic Bush team re-examining the substance of its new initiative, particularly since, given its hazy timetable and lack of real funding, it runs the risk of appearing largely an election-year exercise. So it may take a change of administrations, and a more streamlined and realistic – and therefore truly ambitious – plan to respond to the siren song of deep space. On the face of it, that might sound like a challenge to the Democratic candidates to come up with a bit of the old “vision thing.”