SAN FRANCISCO – ExoTerra Resources LLC, a Littleton, Colorado, startup obtained a $1.5 million investment to further its campaign to develop solar electric propulsion systems for microsatellites.

The investment is significant because “it allows us to fund our flight qualification effort and it shows investor confidence in our business plan and in the growth of the microsatellite market,” Michael VanWoerkom, ExoTerra president and founder, told SpaceNews.

Since VanWoerkom founded ExoTerra in 2011, the company has developed its Halo Hall-Effect Thruster, flexible solar arrays and radiation-resistant power distribution systems with funding from NASA and Air Force Small Business Innovative Research programs. ExoTerra plans to complete environmental testing of its solar electric propulsion systems by May, VanWoerkom said.

In 2017, NASA’s Space Technology Mission Directorate awarded ExoTerra a contract through its Tipping Point initiative, which supports development of promising commercial technologies that also could benefit the space agency. NASA said it selected ExoTerra’s thruster due in part to safety concerns.

“Opportunities to launch as secondary payloads offer an affordable way to get small spacecraft into orbit, but safety restrictions on launching with energetic and pressurized materials often prevent those spacecraft from carrying significant propulsion capabilities,” NASA said in a Feb. 22, 2017 news release. “ExoTerra will flight test a 300-watt solar electric propulsion system that uses iodine in place of xenon gas. Iodine can be launched as an inert solid and then vaporized into an ionized gas once in orbit, which removes the risk to the launch vehicle. Launching as a dense solid instead of a gas also increases the amount of propellant that can be stored in the same volume on the spacecraft.”

In March, ExoTerra won a NASA Innovative Advanced Concepts award for its Nano Icy Moons Propellant Harvester mission to develop a miniature in-situ resource utilization (ISRU) system for liquid oxygen and liquid hydrogen propellant.

“The system takes advantage of developments in the cubesat arena to reduce the dry mass of the ISRU system by 90 percent compared to current systems,” according to ExoTerra. “This will allow missions to refuel at their destinations, such as Europa, Mars and the Lunar poles, drastically reducing the size and cost of the mission.”

ExoTerra is growing rapidly. The firm employs 20 people, including six who joined this summer, VanWoerkom said.

At the investor’s request, ExoTerra is not disclosing the source of its $1.5 million investment, VanWoerkom said.