Smallsats driving innovation in propulsion technologies

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PASADENA, Calif. — Technological advances have opened up a wide range of propulsion options for satellites, but companies developing those systems don’t expect a single approach to become dominant.

During a panel session at the Space Tech Expo conference here May 23, executives with several propulsion startups said that the demands for propulsion that can meet mass, volume and power constraints of small satellites were helping drive innovation in this field.

“What we are seeing right now is a reasonably large disruption in the propulsion community,” said Alexander Reissner, founder and chief executive of Enpulsion, an Ausrian company with offices in Silicon Valley. “To be honest, it’s more than we thought it would be in the beginning.”

Enpulsion has developed an electric propulsion system called the IFM Nano Thruster that can fit within a one-unit cubesat form factor. The propulsion system can be used as building blocks for a larger propulsion system, which he said can alter satellite design.

“Basically, up to now we were building our spacecraft around the propulsion system,” he said, which usually involved a large tank and associated plumbing. With Enpulsion systems, thrusters can be easily added or removed as needed without needing to alter the overall spacecraft design.

That system is currently being tested on a cubesat in orbit, and Reissner said that the thruster’s performance was closely matching pre-launch expectations.

Neumann Space, an Australian company, is developing a different electric propulsion system that can use solid materials, like metal, for fuel in an arc thruster that can operate at low voltages.

In the right conditions, that thruster can operate at efficiencies as high as 10,000 seconds of specific impulse. “We’re in the process of moving through the [technology readiness level] stages from laboratory prototype to engineering models through to something we can test in space,” said Patrick Neumann, director and chief scientist of Neumann Space. That flight test, he said, is planned for 2020.

Additive Rocket Corporation is focused on chemical propulsion rather than electric propulsion, but using new technologies to manufacture engines. That includes the use of additive manufacturing as well as “generative design” tools that can result in systems for moving propellants that can look more biological in nature, like tree roots or blood vessels, that are more efficient than standard approaches.

“We can squeeze out more thrust and eliminate weight from cold-gas thrusters and monopropellant thrusters to such an extent that we can make them viable for cubesats and small satellites,” said Andy Kieatiwong, founder and chief executive of the California-based company.

While confident in their individual technical approaches, none of the companies thought their particular solution would dominate a market, given the wide range of requirements for propulsion systems.

“At the end of the day, there will not be a one-size-fits-all solution, or even a category of technology,” said Reissner. “Electrical propulsion will not replace all of chemical propulsion.”

Neumann agreed, noting as one example that Orbital ATK’s satellite servicing vehicle uses Hall Effect thrusters for some applications, but a monopropellant hydrazine thruster for “short, sharp” maneuvers. “Each of these different technologies has its place,” he said. “Everything has its niche.”

The diversity of propulsion startups could lead to a shakeout in the near future, though. “There are rather a lot of new propulsion companies coming along with bright new ideas,” said Neumann. “How many of those will survive? How many of those will be viable business? How many of those will remain independent propulsion subcontractors?”

Reissner said he’s already starting to see signs of change the sector. “There was lot of VC funding going into these companies in the last four to five years,” he said. “This funding is drying up because people want to see results, they want to see revenue, they want to see demonstrations.”

This could lead to mergers and acquisitions among propulsion companies, or acquisition of those companies by satellite manufacturers interested in specific technologies. “This is true for the whole smallsat industry,” he added, “but in propulsion it’s really true.”