Deep-space exploration remains challenging and infrequent due to a number of factors, including the high cost and limited number of launch opportunities capable of reaching earth-escape conditions.…

The National Aeronautics and Space Administration (NASA) awarded a $400,000.00 cooperative agreement to the Massachusetts Institute of Technology (MIT) to develop a strategy for using CubeSats equipped with electrospray thrusters to achieve the delta-V required for deep-space missions, particularly to near-Earth asteroids. The goal is to enable more frequent and lower-cost deep-space exploration using small satellite platforms. MIT will design, manufacture, and test the propulsion system, while the Jet Propulsion Laboratory (JPL) will integrate it into a small spacecraft bus and develop the necessary attitude control and simulation capabilities. This contract does not have a set-aside designation.

Deep-space exploration remains challenging and infrequent due to a number of factors, including the high cost and limited number of launch opportunities capable of reaching earth-escape conditions. A solution to improve this situation would be to use self-propelled small satellites, such as cubesats. Their low mass and volume would in principle allow flotillas of them to be deployed into deep-space to a variety of destinations and accomplish science and exploration return at a rate much higher than today. However, a number of technological challenges need to be resolved before small spacecraft can be used for this purpose. High delta-v propulsion equivalent to ION thrusters used in larger missions (such as dawn), and compact GNC, ACS and comm are still not demonstrated in beyond- LEO small satellites. We propose to develop a strategy that would allow cubesats (3U, 6U) and perhaps other form factors, to include electrospray thrusters with the objective of demonstrating that such vehicles, when deployed into relatively more accessible GTO or GEO orbits, could achieve enough delta-v to reach deep-space destinations. Electrospray thrusters use zero-vapor pressure, nontoxic ionic liquids as propellants. A strong electric field is applied to sharp emitting structures wetted with these liquids to extract and accelerate ions producing thrust at high specific impulse. In particular, we are interested in near earth asteroids (NEO's) due to their abundance and potential for scientific return. Existing electrospray propulsion systems (power electronics, control, reservoirs and thrusters) are small enough to fit in less than 0.5U of a cubesat and have demonstrated lifetimes of about 500 hours. We propose to use of existing devices in a configuration where thrusters are ejected (or staged) before they show degradation signs, such that the propulsion system makes use of "fresh" thrusters during the mission and therefore extend the lifetime of state-of-the-art devices to the required ~3000 hours needed to accomplish a typical GEO-NEO transfer. This approach leverages the characteristic that electrospray thrusters are micro-machined devices having less than 3% of the mass and less than 0.05% of the volume of the rest of the propulsion system. We propose to explore the strategy to eject (depleted) reservoirs and fired thrusters as required to maintain the spacecraft in its intended trajectory. The ejected mass would also allow the spacecraft to increase its acceleration, thus shortening thruster runs and improving mission performance. This approach would also add redundancy and robustness, by always having more thrusters on board than those required to achieve the mission, without penalizing the overall mass and volume budgets. Our team proposes to develop this capability and demonstrate its integration in a small satellite. MIT will perform the design, manufacturing and testing of the propulsion system, while JPL will work on its integration into a small spacecraft bus, develop the required ACS and perform simulations at JPL's ssdt facility.