In 2010, President Obama set a sky-high goal for NASA: to send a team of astronauts to visit a near-Earth asteroid (NEO) by 2025.
But rather then propelling humans on a dangerously long journey into interplanetary space, why not bring the asteroid here? This is the ultimate rock collector's dream - plop a 500-ton space rock into orbit about the moon.
Bruce Willis couldn't go walking around the on target asteroid, however. It would be only 20-feet across, small enough to fit in a backyard. NASA would not require something as exotic as a Star Trek tractor beam to tow the space rock back here. A robotic spacecraft would, literally, put the asteroid in a giant shopping bag and tote it home.
This far-out proposal comes from a workshop sponsored by the Keck Institute for Space Studies to investigate the feasibility of identifying, autonomously capturing, and returning a NEO to Earth. They say that this could be done before then end of the next decade. They estimate that the cost would be less than the price tag of sending another Mars Science Lab class rover to the Red Planet.
This is not a new idea. In 1903 the great Russian space visionary, Konstantin Tsiolkovsky, described snagging asteroids in a publication with the understated title: "The Exploration of the Cosmos by Means of Reaction Motors."
That dream has now become technologically feasible by three key developments: 1) We now have the ability to discover and characterize a number of sufficiently small NEOs for capture and return; 2) We know how to build sufficiently powerful solar electric propulsion systems to transport the asteroid; 3) NASA's timetable of sending humans beyond low Earth orbit the 2020s will enable astronauts' exploration of the asteroid.
The report describes the asteroid mission as a stepping-stone between human presence on the International Space Station in low Earth orbit and deep space exploration. The report emphasizes: "Placing an asteroid in high lunar orbit would provide a unique, meaningful, and affordable destination for astronaut crews in the next decade. This disruptive capability would have a positive impact on a wide range of the nation's human space exploration interests."
The house-sized sample would be dissected and provide valuable information for planetary defense strategies that may someday have to be used deflect a much larger NEO headed on a collision course with Earth. Capturing an asteroid would also mark mankind's first attempt at modifying the solar system to enable the permanent settlement of humans in space.
A long shopping list of space supplies could be extracted from a 20-foot asteroid: 200 tons of silicates, 100 tons of water, 100 tons of carbon compounds, 90 tons of metals: mostly iron, nickel and cobalt.
The material could ultimately be used to build, supply, and radiation-shield a manned outpost at the Earth-moon Langrage point 2, a sort of space "trucker's stop" on the way to the moon.
What's enabling about this approach is that the mission would make available 28 times as much mass for building space habitats as the mass required to launch the initial "space tug" for retrieving the asteroid.