October 08, 2012
Credit: Credit: Boeing/Energia
Frank Morring, Jr. Naples, Italy, and Amy Svitak Berlin
International space partners are starting to feel their way beyond their orbiting station for mankind's next step into the Solar System. Some of them at the 63rd International Astronautical Congress (IAC) in Naples are finding a lot more to like about the Earth-Moon Lagrangian points, and particularly the L-2 site beyond the far side of the Moon.
While cash-strapped governments scramble to squeeze as much value as they can out of the International Space Station (ISS), scientists and market-hungry space companies around the world are leading the way toward the curious regions in space where gravity is largely nulled by pairs of celestial bodies. As a result, spacecraft can essentially hover there without using much energy. The infrared James Webb Space Telescope (JWST) is being developed for the supercold temperatures at the Sun-Earth L-2 point.
Space-exploration architects have long eyed the Earth-Moon L-2 as a way point where spacecraft carrying humans bound deeper into the Solar System can be assembled. More recently, it has drawn attention as a possible hand-off point where astronauts could rendezvous with vehicles transporting samples collected robotically on Mars (AW&ST Oct. 1, p. 36). Spacecraft circling in “halo orbits” around the far-side L-2 point can move on with relatively little change in velocity, compared to taking off or landing in the “gravity wells” of the Earth, Moon or Mars.
“We're trying to learn how to use these gravity lanes to maneuver around space with humans,” says William Gerstenmaier, NASA's associate administrator for human exploration and operations, who likens the routes between Lagrangian points to the rivers that took explorers into uncharted continents in the days of sail. He is also quick to stress that the idea has not even reached the “pre-study phase” at NASA.
But it is not being ignored at the U.S. space agency, which is spending $3 billion a year to develop the deep-space crew vehicle and heavy-lift rocket needed for exploration beyond low Earth orbit. “Crude” simulations have given way to more sophisticated computer models as engineers delve into the issue, Gerstenmaier says. And NASA contractor Lockheed Martin has generated enticing architectures using the L-2 point as an early target for the Orion multipurpose crew vehicle it is developing for NASA (AW&ST July 2, p. 22).
Boeing, too, is working in the area, as are large aerospace companies in Europe, Japan and Russia. “Space infrastructure should be international,” says Alexander Derechin, the deputy chief designer at Russia's RSC Energia, who co-authored an IAC technical paper on the subject with Michael Raftery of Boeing Defense, Space & Security in Houston. “It's too big for any country.”
The very uncertainty about the next stop in human space exploration—the Moon, an asteroid, Mars or one of its moons—argues for development of a human-tended facility at the cislunar L-2 point, Derechin says.