Solar sailing

Solar sails have been long-discussed as a way to propel spacecraft.  The sails exploit the fact that solar wind exerts pressure on a mirrored surface.   This can be used for propulsion in a way that is akin to sails used by sailboats.

LightSail® is a solar sail project from the Planetary Society that has championed solar sailing for decades. The Society’s LightSail-2 spacecraft, launched 25 June 2019, is the first spacecraft in Earth’s orbit propelled solely by sunlight. On 31 July 2019, the LightSail-2’s orbit was raised, showing that solar sailing is a viable means of propulsion for CubeSats—small, standardised spacecraft that are part of a global effort to lower the cost of space exploration.

 The image above shows LightSail-2's sail after its deployment.