Solar electric propulsion

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.

Solar electric propulsion (SEP) refers to the combination of solar cells and electric thrusters to propel a spacecraft through outer space.[1] This technology has been exploited in a variety of spacecraft by the European Space Agency (ESA), the JAXA (Japanese Space Agency), Indian Space Research Organisation (ISRO) and NASA.[1] SEP has a significantly higher specific impulse than normal chemical rockets, thus requiring less propellant mass to be launched with a spacecraft and it has been evaluated for missions to Mars.[2]


Solar electric propulsion combines solar panels on spacecraft and one or more electric thrusters, used in tandem. There are many different types of electric thrusters, including a so-called ion thruster, a term that is often incorrectly used to describe all types of electric thrusters.

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

A 50 kilowatt SEP system was studied in the 2010s for a mission to an asteroid.[3] In February 2012, NASA awarded a contract for a Solar Electric Propulsion Flight System.[4]

An example of work on this type of technology is Advanced Electric Propulsion System.[5]

The NASA Solar Technology Application Readiness (NSTAR) ion engine has been used with photovoltaic solar panels, which was tested on the Deep Space 1 mission along with Solar Concentrator Arrays (Launched in 1998 as part of the New Millennium Program).[6][7]

SEP has been studied as a technology for a mission to Mars.[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.[2]

Mission examples

Electric propulsion technologies

Category:Ion engines

See also


  1. ^ a b Mohon, Lee. "Solar Electric Propulsion (SEP)". NASA. Retrieved 24 April 2016. Public Domain This article incorporates text from this source, which is in the public domain.
  2. ^ a b c d "Solar Electric Propulsion for Mars Exploration". NASA. 1 April 1998. Retrieved 28 March 2021. Public Domain This article incorporates text from this source, which is in the public domain.
  3. ^ "Solar Electric Propulsion: NASA's engine to Mars and Beyond". SpaceFlight Insider. 26 February 2016. Retrieved 28 March 2021.
  4. ^ "NASA Awards Solar Electric Propulsion Flight System Contract".
  5. ^ "Advanced Electric Propulsion System successfully tested at NASA's Glenn Research Center - SpaceFlight Insider". Retrieved 28 July 2018.
  6. ^ "Advanced Technologies". NASA / Jet Propulsion Laboratory. Retrieved 20 November 2016.
  7. ^ "Deep Space 1 – Solar System Exploration". Solar System Exploration. NASA. Retrieved 8 August 2018. Public Domain This article incorporates text from this source, which is in the public domain.
  8. ^ BepiColombo Fact Sheet European Space Agency, 2010-07-05