The Planetary Society, a non-profit organization which engages the public in space exploration, has announced test flights for the citizen-funded LightSail project will begin in May 2015.
LightSail will primarily consist of four deployable solar sails inside a 3U (10x10x30cm) nanosatellite. The sails, made from mylar, will be 4.5 microns in thickness and 32 metres squared. For perspective, a hair strand is about 100 microns thick.
The flight test in May will be a shakedown cruise test launched onboard an Atlas V rocket. This test will ensure funcionality of LightSail before it is tested in space. The solar sails should be viewable from the ground, and the Planetary Society intends on holding viewing events.
A full test flight is planned for 2016, launching onboard SpaceX’s new Falcon Heavy rocket. LightSail will be deployed at 720 km in low Earth orbit from Prox-1, a small satellite designed and built by Georgia Tech students.
Prox-1 will be testing its automated trajectory control systems, which will use passive image processing to maintain relative distance to LightSail. It is planned for Prox-1 to capture images of LightSail as it deploys its solar sails.
Solar sails are a developing propulsion method which relies on light to operate. It works by absorbing momentum from light photons which reflect off the solar sails. Over time, the solar sails will gain speed.
Such technology will help overcome some of the challenges faced in long-distance space flight relating to fuel cost and energy, and will have other possible applications such as orbit control, trajectory correction, or accelerating the deorbiting time of satellites.
Solar sails have been tested in the past with varying levels of success.
In 2010, JAXA launched the Interplanetary Kite-craft Accelerated by Radiation of the Sun (IKAROS), which contained a 200 metre squared polyamide solar sail. IKAROS spent six months sailing to Venus, and is currently on a flight path to the far side of the Sun.
NanoSail-D is a solar sail project intended for use as a passive deorbiting method on satellites. It is the result of a collaboration between the NASA Marshall Space Flight Center and the NASA Ames Research Center. These solar sails will help satellites deorbit faster to avoid creating space debris. The first NanoSail-D launch in 2008 was a failure. NanoSail-D2 made it to low Earth orbit in 2010 and successfully deployed and collected data.
Sunjammer, a NASA project named after an Arthur C. Clarke sci-fi story, was planned for launch in January 2015. However, the project was cancelled in October 2014, due to “lack of confidence in its contractor’s ability to deliver.” Sunjammer would have used the solar sails to maintain a distance of three million km from Earth, collecting data on the Sun’s coronal mass ejections.
LightSail is the continuation of a collaboration between the Planetary Society, Cosmos Studios, and the Russian Academy of Sciences. The initial collaboration resulted in two failed attempts, one in 2001 and the second in 2005. In 2009 it was decided to continue with the development of LightSail-1, LightSail-2, and LightSail-3. This decision was made on Nov.9, what would have been Carl Sagan’s 75th birthday.