A small crowdfunded satellite has become the first 'spacecraft' to be propelled only by the energy of the sun.
The craft, LightSail 2, successfully unfurled its solar sail on Tuesday.
Like the wind thrusts the sails of a boat forward, the satellite is propelled by the push of light particles, called photons, from the sun.
The operation has been postponed several times so the successful launch of its solar sail brought delight to the American organisation behind the project.
The sail, measuring 32 square metres and roughly the size of a boxing ring, was unfurled after the final tests were positive.
The solar sail will remain in orbit around the Earth and, if all goes well, it will gradually increase its altitude thanks to the pressure of solar radiation.