To Mars, by Tortoise
In November, engineers at NASA’s Dryden Flight Research Center in Edwards, CA, conducted their third and final test of the X-43A scramjet – an unpiloted “supersonic combustion ramjet” that reached speeds of nearly Mach 10. The beauty of a scramjet is that it has none of the moving parts that compress air for combustion in a conventional jet; instead, the air is compressed by the vehicle’s own forward motion. This also gives scramjets a big advantage over rockets, which must carry their own oxygen aloft in heavy tanks.
The X-43A’s purpose was merely to prove the concept of hypersonic flight. But NASA believes future scramjets could be part of a next-generation system for launching piloted vehicles into space – and that makes the Dryden tests one hopeful sign that NASA’s program of human space exploration is rousing itself from its 30-year slumber. Not since February 8, 1974, when Skylab was abandoned by its third crew, has the United States had a continuous, purposeful human presence in space. The International Space Station hardly counts: thanks to the grounding of the remaining space shuttles, it’s halted in mid-construction and has a crew of two whose main job is to keep it from falling apart. Crew members come and go in Soviet-era Soyuz capsules. The shuttles themselves are a post-Apollo joke – $2 billion behemoths that, until the space station, had nowhere to go and nothing much to carry. They have also proved unacceptably dangerous, killing 14 astronauts since their initial flight in 1981.
It is time for a fresh start. If there is a post-Cold War rationale for sending humans into space – and Mark Williams argues in our new “Reviews” section that there is (see “Toward a New Vision of Manned Spaceflight”) – then Apollo-style crash projects and bloated, bureaucratized, cart-before-the-horse boondoggles like the shuttle program are not the way to put them there. Creating a permanent foundation for human exploration of the solar system will require a patient, incremental effort with tangible, science-driven goals – say, returning to the moon by 2020 and sending humans to Mars by 2050. In fact, this is the plan proposed by NASA and endorsed by President Bush last year. The first step will be the construction of a safer, simpler, Crew Exploration Vehicle (CEV) that can ascend to the space station, finally allowing NASA to send Discovery, Atlantis, and Endeavour off to the Smithsonian, where they belong. A second-generation lunar CEV would be built in orbit, whence rocketing on to the moon requires much less energy. The moon would then be the staging area for a third-generation CEV designed for the much longer trip to Mars.
There are, of course, enormous problems to be solved before this plan can proceed, such as how to shield interplanetary explorers from deadly solar and cosmic radiation and how to counter the debilitating effects of long-term weightlessness. But if NASA and international partners were to undertake a measured effort, with realistic milestones that spread the costs over a period of decades, then people under 40 – few of whom have any memory of Apollo – may yet live to see a Mars landing.