Solar electric propulsion

[1] SEP has a significantly higher specific impulse than chemical rocket propulsion, thus requiring less propellant mass to be launched with a spacecraft.

It is also possible to generate electricity from the Sun without using photovoltaic panels, such as with solar concentrators and a Stirling engine.

[3] In February 2012, NASA awarded a contract for a Solar Electric Propulsion Flight System.

[2] In particular the high specific impulse of the ion engines could lower overall mass and avoid having to use nuclear technology for power when coupled with solar panels.

[2] A 1998 study for SEP for a human mission suggest that a human-sized spacecraft would need 600 to 800 kilowatts of electrical power coupled with ion engines with a specific impulse of 2000 to 2500 seconds.

Artistic view of Deep Space 1 , showing both the solar panels and ion engine (with blue exhaust), major aspects of this solar electric design. Solar energy may also be temporarily stored in chemical batteries inside the spacecraft bus .
The Dawn spacecraft's xenon tank prior to integration with spacecraft. The xenon was the propellant for the solar-power ion drive of the spacecraft which would go on to orbit two different asteroids in the early 21st century.
Roll-out solar panel tested in Earth Orbit at the International Space Station (ISS), 2017.