For the last few years, NASA has promoted solar electric propulsion (SEP) as a key aspect of its long-term plans to send humans to Mars. While SEP systems can’t generate much thrust, they can run for long periods and are far more efficient than chemical systems. That makes SEP useful for sending cargo, rather than crew, where travel time is less of an issue.
“SEP systems are equivalent to the cargo ship for deep space missions,” said Joe Cassidy of Aerojet Rocketdyne at a June 29 House space subcommittee hearing focused on in-space propulsion technologies.
Electric propulsion is not new: it has been used on commercial communications satellites for years for stationkeeping and, more recently, orbit raising. Those thrusters, though, have been far less powerful that the SEP systems needed for interplanetary missions. NASA has been working with Aerojet and other companies on advanced, higher thrust SEP technologies.
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