Technology for a robotic Asteroid Redirect Mission and its extensibility to future human and robotic missions

Three aspects of the proposed Asteroid Redirect Mission (ARM) could be extended to provide greater capability for future NASA missions: higher-power versions of the baseline asteroid redirect vehicle, in-space resource utilization, and planetary defense. The baseline ARM vehicle assumes the use of a 50 kW beginning-of-life solar array which provides a maximum of 40 kW to the electric propulsion system. Launch dates in mid to late 2020 could provide the opportunity for the development and implementation of higher-power solar arrays and electric propulsion systems that are farther along the path to the 100-kW-class systems that could be used to support human missions to Mars. The ARM robotic vehicle conceptual design provides a straightforward approach to increasing the solar array power to ~100 kW for the first asteroid redirect mission. Transportation is also a major challenge for harvesting asteroids for the use of their material resources in space. ARM addresses this issue by selecting an asteroid that naturally returns close to Earth and then redirecting it into lunar orbit. Deriving propellants from asteroids is essential to a robust utilization of asteroid material resources. Two elements, magnesium and sulfur, abundantly available in common chondrite asteroids could be used as propellants in Hall thrusters and may be the key to asteroid mining. Finally, ARM has the potential to demonstrate two different planetary defense techniques: an enhanced gravity tractor, or an ion beam deflector. High-power solar electric propulsion (SEP) is needed for both techniques. Simple analyses highlight a clear choice between these options. To obtain the same force and total impulse applied to a potentially hazardous asteroid you can either develop higher power SEP systems for ion beam deflection or you can develop the capability to acquire hundreds of tons of mass from the asteroid for use with a lower power SEP system in an enhanced gravity tractor approach.