Artist’s concept of LightSail 2 above Earth. Image: The Planetary Society
Yesterday, a SpaceX Falcon Heavy rocket successfully launched NASA’s STP-2 mission from Cape Canaveral, Florida, carrying with it a whole raft of technology demonstrations that will one day aid in smarter spacecraft design and help the agency’s efforts in getting to Mars.
Some of the more high profile projects included a Deep Space Atomic Clock that could change the way deep-space navigation is conducted, and a new propulsion system that runs on a high-performance and non-toxic spacecraft fuel called the Green Propellant Infusion Mission (GPIM).
However, also stashed amongst NASA’s payloads was a small satellite built by Georgia Tech students, called Prox-1 and packed safely within that like a Russian nesting doll, is a citizen-funded project that originally sprang from the mind of Carl Sagan.
Called LightSail, the design is pretty much what it sounds like; a huge sail made of Mylar – polyester resin that is stretched into flat sheets thinner than a human hair – and when deployed from its shoe box-sized CubeSat spreads out to the size of a boxing ring.
The sail itself is not one big sail, but rather four triangular sails that connect via four metallic booms to form a square. Once spread out, the total sail area is a huge 32 square metres (344 square foot).
LightSail aims to become the first spacecraft in orbit around Earth propelled solely by sunlight; an idea that has already seen one incarnation put to the test in 2015.
LightSail’s provenance has a long history. The notion that a spacecraft could ’sail’ through space propelled by nothing more than the power of photons, may not have ultimately started with Carl Sagan – the philosophy behind light sails started as early as 1608 with Johannes Kepler – but the well-known American astronomer, author and science populariser, was engrossed with seeing if the theory was a viable one.
In 1980, along with Bruce Murray and Louis Friedman, Sagan co-founded The Planetary Society to “empower the world’s citizens to advance space science and exploration.” With his celebrity and political status blooming, Sagan hoped the US government would invest in making LightSail technology a reality, but after settling on more traditional means of propulsion for their space programmes, the Planetary Society decided to tackle the project themselves.
The Society’s first prototype of a solar sail in 2005, the Cosmos-1 project, unfortunately never reached space as the Volna rocket it was launched on failed shortly after liftoff and the payload was subsequently lost. Not put off, they pushed ahead with LightSail 1, which although suffered several technical problems, has led to a much-improved version that is now drifting in a circular orbit 720km above the Earth’s surface.
The goal of LightSail 2 is to raise its orbit by a measurable amount, and show, finally, that solar sails are a viable means of propulsion for CubeSats. It will remain at its current altitude until 2 July, still tucked away within Prox-1, to give other vehicles released into the same orbit time to drift away.
“After that spectacular nighttime launch, the flight team is ready to operate the LightSail 2 spacecraft,” said LightSail 2 project manager David Spencer. “We will be listening for the radio signal in a week, following the release of LightSail 2 from Prox-1.”
The three-unit CubeSat will then be subjected to a week’s long system testing by the project’s team members, in preparation for the unfurling of the dual-sided solar sails, approximately 2 weeks after launch day commenced.
Both LightSails (1 and 2) have been designed and constructed by Stellar Exploration, Inc; a small aerospace product-oriented company, focused on innovative and low-cost scientific and space exploration projects, that was started by Tomas Svitek, a former political refugee from Czechoslovakia.
The project cost around $7 million and funds were raised by Planetary Society members, private citizens and a KickStarter campaign four years ago that raised $1.24 million. “After years of hard work we are ecstatic with the launch and looking forward to doing some solar sailing,” concluded Bruce Betts, Planetary Society chief scientist and LightSail 2 program manager.