ESTCube-1: a high wire-act (Image: Taavi Torim)

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. It is within the Earth’s magnetosphere, so is shielded from the solar wind, but it will still interact with charged particles, says Mart Noorma of Tartu University in Estonia, who helped develop the satellite.


Once the wire is fully extended and powered up, the satellite’s rotation rate should alter, letting the team measure the thrust generated by the electric sail. If the tests are successful, the hope is that a full-sized craft with 100 wires, each 20 kilometres long, could reach speeds of 30 kilometres per second, fast enough to get to Pluto in under five years.

Smaller sails could act as a brake for retired satellites, slowing them down enough to fall safely back to Earth.