A tiny new satellite is propelled by repulsion. ESTCube-1, which went into orbit on Tuesday, will put proton-powered electric solar sails to the test for the first time. It could pave the way for speedy trips through the solar system.
Regular solar sails have large, thin mirrors that reflect photons from the sun to push the spacecraft forward. The new electric sail, proposed in 2008, harnesses solar protons instead. Wires with a positive charge will extend from the craft and repel protons – also positively charged – to propel the tiny satellite.
ESTCube-1 is 10 centimetres wide and has a 10-metre-long wire just half the width of a human hair.