LightSail 2 set to demonstrate solar sailing in Earth orbit

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A small satellite that will attempt the first controlled solar sailing in Earth orbit is set for launch on SpaceX’s Falcon Heavy rocket.

solar sailing
The Planetary Society's LightSail 2 spacecraft sits on its deployment table following a successful day-in-the-life test at Cal Poly San Luis Obispo on May 23, 2016 (Image: The Planetary Society)

Purdue University professor David Spencer is the lead for LightSail 2, part of a payload that is scheduled to launch on June 22. Once deployed, LightSail 2 will use reflective sails to harness the momentum of sunlight for propulsion.

“While there have been several previous solar sail deployment demonstration missions, if all goes as planned LightSail 2 will become the first spacecraft to increase its orbital energy through controlling the sail orientation relative to the sun,” said Spencer, an associate professor in Purdue’s School of Aeronautics and Astronautics and project manager for LightSail 2.

LightSail 2 arrived at Kennedy Space Center in Cape Canaveral, Florida on May 21. It was integrated on May 7 with Prox-1, a satellite that includes a spring-loaded deployer, at the US Air Force Research Laboratory in Albuquerque, New Mexico.

According to Purdue, the Falcon Heavy will place the combined Prox-1/LightSail 2 spacecraft into orbit at an altitude of about 450 miles. One week after launch, Prox-1 will deploy LightSail 2. Following a spacecraft checkout period, LightSail 2 will deploy its solar panels and then unfurl its four solar sail segments, providing a total sail area about the size of a boxing ring.

LightSail 2 will attempt to demonstrate solar sailing as a method for propulsion for CubeSats by performing two turns of the spacecraft, every orbit. The solar sail is expected to rotate edge-on and face-on to the Sun each orbit, giving the craft thrust to raise its orbit by about 500m per day during the early portion of the mission. The result is to increase the orbital energy about Earth, stretching the initial near-circular orbit into an ellipse.

“While solar sails have been described in literature for many decades, solar sailing technology is still in its infancy,” Spencer said in a statement. “Recently, solar sailing advancement has been enabled by miniaturised CubeSat technology.

“Through demonstrating controlled solar sailing, LightSail 2 provides an important advancement toward the realisation of solar sailing’s potential for space science applications.”

One long-term application could see a fleet of solar sail-propelled spacecraft monitoring the space between the sun and the Earth to provide Earth with an early warning for solar storms. Similarly, solar sailing has the potential to shorten the transfer times for missions that require large changes in velocity, including missions to the outer limits of the solar system and interstellar space.

“Solar sailing technology can enable missions to the extreme limits of our solar system with flight times of 25 years or less,” Spencer said.

Funding for the project has been through The Planetary Society’s members and private donors.

“The LightSail program was citizen-funded and implemented by a team composed of small companies and universities,” Spencer said. “The program demonstrates a new way of conducting space exploration, without relying on government agencies for funding.”

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