|Mission type||Technology Demonstration|
|Operator||The Planetary Society|
|Start of mission|
|Launch date||Early 2018|
|Launch site||LC-39A, Kennedy Space Center|
LightSail 2 is a project to demonstrate controlled solar sailing using a CubeSat developed by The Planetary Society, a global non-profit organization devoted to space exploration. The spacecraft core measures 10 by 10 by 30 centimeters, and its kite-shaped solar sail deploys into a total area of 32 square meters (340 sq ft).
On May 20, 2015, a nearly identical demonstration spacecraft, LightSail 1 (formerly called LightSail-A), was launched, and deployed its solar sail on June 7, 2015.
In 2005, The Planetary Society attempted to send a larger solar sail named Cosmos 1 into space, but the spacecraft's Russian Volna launch vehicle failed to reach orbit. In 2009, the Society began working on a CubeSat-based solar sail based on NASA's NanoSail-D project, which was lost in August 2008 due to the failure of its Falcon 1 launch vehicle. (A second unit, NanoSail-D2, was successfully deployed in early 2011.)
By 2011, the LightSail project had passed its critical design review, which was conducted by a team including JPL project veterans Bud Schurmeier, Glenn Cunningham, and Viktor Kerzhanovich, as well as Dave Bearden of Aerospace Corporation. The original estimated cost of the LightSail project was US$1.8 million, which was raised from membership dues and private sources. The prototype spacecraft LightSail 1 (or LightSail-A) was built in San Luis Obispo by Stellar Exploration Incorporated , and final integration and testing prior to launch occurred at Ecliptic Enterprises Corporation in Pasadena, California.
In March 2016, The Planetary Society announced they decided to use the convention on naming the spacecraft with the program name followed by a sequential number; the test flight or LightSail-A, became LightSail 1, and the upcoming larger spacecraft is now called LightSail 2.
As a solar sail, LightSail 2's propulsion is dependent on solar radiation alone. Solar photons exert radiation pressure on the sail, producing a small degree of acceleration. Thus, the solar sail will be propelled by pressure from sunlight itself, and not by the charged particles of the solar wind. The Planetary Society expects LightSail 2's orbit to increase by as much as a kilometer per day.
LightSail 2's modular design is based on a modular three-unit CubeSat, a small satellite format created for university-level space projects. One CubeSat-sized module carries the cameras, sensors and control systems, and the other two units will contain and deploy the solar sails.
LightSail 1 flight
A preliminary technology demonstrator spacecraft, LightSail 1 (formerly LightSail-A), was launched as a secondary payload aboard a United Launch Alliance Atlas V rocket at 15:05 UTC on 20 May 2015 from Cape Canaveral Air Force Station, Florida. The mission delivered the satellite to an orbit where atmospheric drag was greater than the force exerted by solar radiation pressure.
Two days after the launch, however, the spacecraft suffered a software malfunction which made it unable to deploy the solar sail or to communicate. On 31 May 2015, The Planetary Society reported having regained contact with LightSail 1. After the solar panels were deployed on 3 June 2015, communications with the spacecraft were lost once more on 4 June. In this case, a fault with the battery system was suspected. Contact was then reestablished on 6 June, and the sail deployment was initiated on 7 June. At a conference on 10 June 2015, after photos of deployment were downloaded, the test flight was declared a success. The spacecraft reentered the atmosphere on 14 June 2015, ending the test flight.
LightSail 2 will demonstrate controlled solar sailing in Earth orbit. By controlling the orientation of the sail relative to the Sun, the flight team will attempt to raise the orbit apogee and increase orbital energy following sail deployment. The flight team will evaluate the evolution of LightSail 2's orbit after the spacecraft is deployed from a partner spacecraft, Prox-1, at an altitude of 720 kilometers. Prox-1 and LightSail 2 are secondary payloads aboard the first operational SpaceX Falcon Heavy launch, which will carry the STP-2 payload for the U.S. Air Force.
- IKAROS, a Japanese solar sail, launched in May 2010
- NanoSail-D2, the successor to NanoSail-D, launched in November 2010
- Near-Earth Asteroid Scout, a solar sail planned to launch in 2018
- Sunjammer, a solar sail that was cancelled before launch in 2014
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