The Japanese space agency JAXA successfully unfurled the solar sail on the IKAROS demonstrator back on 10 June and now they have the photos to prove it.
Taken by a tiny camera module launched from IKAROS, the photo was transferred from the camera module to the probe and then on back to earth.
For those not up on what’s going on here, the concept is that a spacecraft can be accelerated slowly by the pressure of photons (light) hitting a solar sail. The idea’s been around for years but no-one’s really been able to test it out.
Amazingly the sail is not kept rigid by booms or struts but rather by the centripetal forces created by tiny masses on the edges of the sail as the craft rotates. JAXA is also going to see if the spacecraft can be steered by adjusting the angle of the sail relative to the sun. There’s a video of the sail technology here. It’s in Japanese but you’ll get the gist.
In earth orbit, satellites can use the concept to reduce their fuel costs maintaining orbit. In theory, spacecraft could travel between solar systems, using the sail to accelerate away from one and on arrival, decelerate using the same technique. Obviously, to achieve any significant acceleration, you’re going to need a really big sail.
It’s science-fiction made real!