Asteroid Redirect Mission
[1] If funded, the mission would have launched in December 2021,[2] with the additional objectives to test a number of new capabilities needed for future human expeditions to deep space, including advanced ion thrusters.
[5] Key technologies being developed for ARM have continued, especially the ion thruster propulsion system that would have been flown on the robotic mission.
[6][11][8][14][15][16] Not only would the solar electric propulsion (SEP) technologies and designs be applied to future missions, but the ARRM spacecraft would be left in a stable orbit for reuse.
[20] Lunar Distant Retrograde Orbit (DRO), encompassing Earth-Moon L1 and L2, is essentially a node for Earth system escape and capture.
[2][24][25] Additional mission aims included demonstrating planetary defense techniques able to protect the Earth in the future – such as using robotic spacecraft to deflect potentially hazardous asteroids.
[27] The mission would also test the performance of advanced solar electric propulsion (ion engines)[13] and broad-band laser communication in space.
[13][47] The advanced ion engine uses 10% of the propellant required by equivalent chemical rockets, it can process three times the power of previous designs, and increase efficiency by 50%.
[48] It would use the Hall-effect, which provides low acceleration but can fire continuously for many years to thrust a large mass to high speed.
By early 2017 NASA had yet to select a target for ARM, but for planning and simulation purposes, the near-Earth asteroid (341843) 2008 EV5 was used as an example for the spacecraft to pick up a single 4 m (13 ft) boulder from it.
[53] The carbonaceous boulder that would have been captured by the mission (maximum 6 meter diameter, 20 tons)[45] is too small to harm the Earth because it would burn up in the atmosphere.
[28] Option B, which was selected in March 2015, would have the vehicle land on a large asteroid and deploy robotic arms to lift up a boulder up to 4 m (13 ft) in diameter from the surface, transport it and place it into lunar orbit.
[24][29] This option was identified as more relevant to future rendezvous, autonomous docking, lander, sampler, planetary defense, mining, and spacecraft servicing technologies.
[62] In January 2016 contracts were awarded by NASA's Jet Propulsion Laboratory (JPL) for design studies for a solar electric propulsion-based spacecraft.
