Last week, LightSail 2 successfully deployed its solar sail and began the exciting part of its month-long mission. After receiving the deployment signal, mission controllers tried to access images of the deployment but unfortunately, possibly due to some orientation issues, they couldn’t immediately download them.
But now they have and we can see the solar sail stretching out in all its glory. On July 23, the 32-square-meter (344-square-foot) sail took about 12 minutes to be completely released by the spacecraft, and this can be seen in footage captured by the two fish-eye cameras aboard the spacecraft.
Each camera provides a 185-degree field of view of the sail, meaning that combined images will allow the team to monitor the whole apparatus. The cameras are located on the loaf-sized spacecraft the sail is currently hauling.
“The successful deployment of the solar sail and the onset of sail control completes our critical post-launch phase,” LightSail 2 project manager David Spencer said in a statement. “Now we are prepared for the solar sail's mission, to track how the orbit changes and evaluate solar sailing performance.”
The mission will see the spacecraft's orbit increase slowly as the light from the Sun slowly propels the sail. Photons, the particles of light, have no mass but they can impart momentum. And solar sails are designed to harness that. The sail is extremely thin (thinner than a spider web strand) and light, and made of a special material called mylar.
For every orbit, the sail receives a push equivalent to the weight of a paperclip. This might be small but without (much) air resistance the craft is expected to be pushed into a higher orbit, rising several hundred meters by the end of the mission in four weeks' time.
The whole project has been designed to demonstrate the capability of solar sails as a viable technology to move small satellites in Earth’s orbit. The mission didn’t include ways for the orbit to be circularized, so as one side increases, the other decreases. It will eventually start slowing down thanks to Earth's atmosphere and in about a year, it will burn up during re-entry.
LightSail 2 is a crowdfunded project planned and built by The Planetary Society.