April 29, 2013
Credit: KECK INSTITUTE
Capturing a tiny asteroid and nudging it into the Earth-Moon system for study by spacewalking astronauts is at the outer edge of U.S. capabilities right now, and will pull NASA's deep-space exploration technologies along even if it does not catch a space rock.
The idea has drawn a mixed reaction on Capitol Hill and elsewhere in the U.S. space establishment. But NASA managers consider it a unifying goal to bring focus to the various deep-space exploration development activities underway. In general, that work is going very well, considering NASA's mismatch of programs and money to pay for them.
The agency reports good progress on the heavy-lift Space Launch System (SLS) and Orion crew capsule that is central to its deep-space goals, including the asteroid mission. So far, NASA-oversight committees on Capitol Hill appear ready to keep money flowing to those two programs.
Meanwhile, astronomers already are looking for threatening near-Earth asteroids only a little larger than the one that would be captured, and International Space Station planners are preparing the life-science and engineering research necessary to keep an Orion crew alive on the 22-day asteroid mission. The long-duration solar-electric propulsion (SEP) technology necessary to reach and “redirect” the asteroid is on the horizon, and the capture mission could advance it enough to propel human crews down the invisible “gravity rivers” they are likely to follow deeper into the Solar System.
William Gerstenmaier, NASA's associate administrator for human exploration and operations, coined that term when NASA intensified its study of cislunar space as a jumping-off point for human exploration (AW&ST Oct. 15, 2012, p. 24). He has been briefing the asteroid-capture mission to Washington space stakeholders since it was presented in NASA's fiscal 2014 budget request April 10, stressing the effect it will have on capabilities over the scientific value of the asteroid itself.
“I believe there are other compelling aspects of this mission that are very worthwhile,” Gerstenmaier says. “To be able to understand the risk posture to take astronauts to this deep retrograde orbit; to understand the abort options out of those orbits; to look at the lunar gravity [factors], those are all tremendously important to us. I'm going to do those independent of whether we've got this asteroid or not.”
Astronomer Steve Squyres, the principal investigator on the twin Mars Exploration Rovers Spirit and Opportunity who chairs the NASA Advisory Council, finds that argument compelling, as well as the idea of broadening the study of near-Earth asteroids to include those in the 7-10-meter (22.9-32.8-ft.) class that conceivably could be captured. But in presenting his views to the National Academy of Sciences Committee on Human Spaceflight, Squyres said he believes it is too soon to say if the capture mission itself would be worthwhile.