Description:

ExoTerra will build, test, and launch a twelve-unit (12U) CubeSat that combines a compact, high-impulse Hall effect thruster, a deployable fold-out solar array with >200 W power and radiation hardened electronics. They call the product a solar electric propulsion module “Courier”. Incorporated in a 12U spacecraft, the system can provide >1km/s delta-v.

This small electric propulsion system, consisting of a Micro Hall effect thruster, power system, and solar arrays could open up the inner solar system for targeted science exploration missions, using affordable spacecraft that range from 22 to 220 kg. Microsatellites and CubeSats represent a rapidly growing segment of the satellite industry. Because satellite mass has traditionally correlated directly to mission cost, their small size promises significant reduction in the cost of NASA missions. CubeSats have very limited propulsion options due to their small size and restrictions on using hazardous or toxic materials when launching on rideshare missions. Options that have flown in space, such as green propellant, warm gas, and pulsed plasma thrusters have very low total impulse due to low Isp or low propellant storage capability. Lack of propulsion has been a key factor in limiting CubeSat’s application in the commercial, military, and sustained science fields. Low impulse propulsion limits satellite lifetime, orbit optimization maneuvers and interplanetary orbit insertions. The small surface area of microsatellites has also limited the power available to the missions. This reduces the satellite’s instrument and telecommunications capabilities, and severely limits microsatellite missions at higher distances from the sun, where the sun’s flux drops rapidly. In addition, CubeSats commonly use COTS electronics with low radiation tolerance. This limits their use beyond the protection of Earth’s magnetic fields, reducing applications in GEO or at interplanetary destinations.

ExoTerra’s Courier enables high power, high impulse, compact, radiation tolerant propulsion for Microsatellites. Its propulsion module uses Hall Effects thruster utilizing non-toxic noble gases e.g. Krypton or Xenon. Fold-out solar arrays produce the necessary electrical power, and radiant tolerant electronics enable survivability outside the low earth orbit (LEO) environment. This Tipping Point activity aims to build, test and demonstrate Courier as part of a LEO mission, providing km/s class delta-v in a CubeSat package.

Benefits: Currently, many microsatellites are launched without propulsion systems. This limits their utility due to an inability to alter their orbit from where the rocket deposits them after the rideshare, or to even maintain their orbit once they get there. Modern microsatellites have typical lifetimes of less than 2 years and immediately start to lose altitude upon deployment due to the slight atmospheric drag in low Earth orbit (LEO). Growth predictions in the industry are predicated upon advances in microsatellite propulsion that will allow multiple satellites to work as a constellation in optimal orbits. Exoterra’s system aims to be significantly more cost effective that other systems. It is also substantially lighter and smaller than legacy systems. This opens up the ability to adjust and optimize CubeSat/MicroSat orbits and increase their lifetime. This begins to enable CubeSats and microsatellites to meet reliability and lifetime needs of commercial satellites. Besides increasing the affordability of CubeSat propulsion systems, it also opens up new classes of missions. The propulsion system is being looked at as a means of enabling satellite servicing or providing deorbit capability for failed satellites. It also enables microsatellites to reach GEO from LEO, reducing the cost of GEO missions.