NASA has reportedly submitted its budget for the 2014 fiscal year and it will include a $100 million line item for a mission to capture an asteroid and reposition it near the moon. According to the submitted budget, once the asteroid is relocated, NASA scientists will study it before sending astronauts to visit its surface.
A report by the Keck Institute for Space Studies, which developed the proposal, sets forth plans for the robotic mission to find and nab a Near Earth Asteroid (NEA) that is approximately 25 feet (7 meters) in diameter with a mass of approximately 500,000 kg (551 tons). The sought after asteroid would be a C-type or carbonaceous asteroid with the consistency of a “dried mudball.”
A robotic probe would grab the asteroid and position it in orbit near the second Earth-Moon Lagrange Point (EML2) above the far side of the Moon. Gravity and inertia would act to keep the asteroid in place so that, at least theoretically, astronauts could reach its surface.
The report recommends using a probe weighing about 18,000 kg (19.8 tons) to capture the asteroid and then positioning it in space with an existing launch vehicle, like an Atlas V. Instead of relying on conventional rockets — which would need to carry enormous amounts of propellant — the probe would be equipped with an ion thruster.
The report describes an ion thruster as a “~40-kW solar electric propulsion system with a specific impulse of 3,000 s.” Instead of burning propellant in a thrust chamber, ion thruster technology uses electricity generated by solar panels to accelerate charged particles away from the spacecraft. Although the thrust from this kind of engine is comparatively low, its efficiency at extracting energy from a specific amount of fuel– known as the specific impulse–is very high.
NASA scientists could use various gravity assist methods to capture the targeted asteroid, depending on its location. These methods include a slingshot around the Moon to catapult the probe outside the Earth-Moon gravitational system. Once the probe reached the asteroid, it would cover it in a large bag and stabilize its rotation with xenon-powered maneuvering thrusters. Once the asteroid was stablized, it would be positioned near the Moon using a braking maneuver to place it into orbit.
Critics will likely denounce the plan as somewhat far-fetched. In January, NASA spokesman Bob Jacobs told Space.com that the idea was one of several being explored in an effort to fulfill the goals of NASA’s manned asteroid mission in the current climate of budget constraints. The space agency sees the asteroid capture mission as a potential path to manned Mars exploration.
NASA officials declined to comment on details of the 2104 budget request until April 10, when the Obama administration reveals its budget. The entire asteroid retrieval mission is expected to cost approximately $2.6 billion.