The Planetary Society's LightSail to Launch Aboard Atlas-V May 20

From The Planetary Society: "  The Planetary Society’s LightSail solar sailing spacecraft is scheduled to ride a SpaceX Falcon Heavy rocket to orbit in 2016 with its parent satellite, Prox-1." Image Credit: Josh Spradling / The Planetary Society (

From The Planetary Society: “The Planetary Society’s LightSail solar sailing spacecraft is scheduled to ride a SpaceX Falcon Heavy rocket to orbit in 2016 with its parent satellite, Prox-1.” Image Credit: Josh Spradling /The Planetary Society (

The idea of solar sails carrying satellites and humans into space has been something bandied about for decades, but has only been relegated to the pages of science fiction. Now, in 2015, science fiction is about to become science reality: On Wednesday, May 20, LightSail, a citizen-funded project by The Planetary Society, will ride its way into space aboard a United Launch Alliance Atlas V Centaur upper stage. According to the organization, this prototype of LightSail won’t travel high enough above the Earth’s atmosphere to “sail,” but it will test its sail deployment sequence. In 2016, LightSail will be ejected into space by the satellite Prox-1 following their delivery to an orbit with an altitude of approximately 720 kilometers (450 miles). These payloads will be launched by a SpaceX Falcon Heavy.

Solar sail technology has the potential to send payloads such as CubeSats to planetary destinations without the use of expendable chemical fuels. The project, which is being funded by Planetary Society members and public donors, was discussed by the organization’s CEO Bill Nye in a Reddit “Ask Me Anything,” on Tuesday, May 12. When asked to best explain the concept of sails, Nye answered: “Photons (particles of light) have no [mass], but they are pure energy, and they have momentum. So, in the vacuum of space, we can design a very low mass spacecraft with a very large reflective area, and it will get a continuous push.” LightSail is 344 square feet across and is in line with the spaceflight innovations envisioned by The Planetary Society upon its founding, which took place in 1980.

Jason Davis, embedded reporter with The Planetary Society, spoke with AmericaSpace about the project, its heritage, and where it is going.

From The Planetary Society: "When its solar sails are unfurled, LightSail may be visible to observers on the ground." Image Credit: Josh Spradling / The Planetary Society (

From The Planetary Society: “When its solar sails are unfurled, LightSail may be visible to observers on the ground.” Image Credit: Josh Spradling /The Planetary Society (

AmericaSpace: Carl Sagan (co-founder of The Planetary Society) discussed the concept of using solar sails as far back as the 1970s. Now, in 2015, the prototype for LightSail is about to be launched. How do you think this further contributes to Sagan’s legacy?

Jason Davis: The Planetary Society was originally founded to demonstrate popular support for planetary exploration. In the first issue of our member magazine (The Planetary Report, which we still publish today), Sagan wrote that he also believed we could “provide some carefully targeted funds for the stimulation of critical activities.” We’ve supported dozens of such projects over the years, but LightSail, as well as its short-lived predecessor, Cosmos 1, is one of the most ambitious. Projects like LightSail are exactly what Sagan had in mind, so we’re proud to be a part of that legacy.

AmericaSpace: This concept was previously explored with Cosmos I and NanoSail-D (the first version), but neither payload made it into orbit. This launch must be bittersweet in that it seems like it was a long time in coming. What is the excitement level concerning LightSail’s “birth”?

Davis: Actually the second Nanosail-D made it into space and had a deployment issue that eventually worked itself out, and it lasted in orbit for quite some time. It was part of the inspiration for LightSail—Louis Friedman, one of our co-founders, believed we could build our own Nanosail-D and improve upon the design.

Nonetheless, it’s been a long time coming for the Society. Friedman and Bruce Murray (another co-founder) worked on a Halley’s Comet solar sail concept at NASA in the late ’70s and early ’80s, and then there was Cosmos 1. LightSail itself faced funding and technical challenges, but we finally got this test flight to the launch pad. The atmosphere at the Society is pretty incredible right now. We keep reminding ourselves that this is just a test (things are bound to go wrong), with the real show scheduled for 2016, but it’s hard not to get swept up in the excitement.

AFSPC-5 payload mate to Atlas-V rocket. Photo Credit: ULA

AFSPC-5 payload being mated to an Atlas-V rocket. LightSail will be deployed during this mission, to be launched on Wednesday, May 20th. Photo Credit: ULA

AmericaSpace: What kinds of functions on LightSail will be tested during this mission? Approximately how “high up” will LightSail be traveling?

Davis: The main objective is to verify sail deployment. That’s currently scheduled to occur autonomously 28 days after deployment, with an option for an earlier manual deployment. We still can’t disclose the orbital parameters at this time due to the nature of the primary payload, the Air Force’s X-37B spaceplane, but we’ll be in low-Earth orbit. We’ll have a real-time Google map showing some of those details after launch.

AmericaSpace: LightSail is being funded through the Planetary Society’s members and private citizens. How much did it take to bring this prototype to fruition, and how much will it take to get the 2016 version into Earth’s orbit? What does this effort say about the public’s interest in spaceflight and future space propulsion methods?

Davis: The project was started in 2009. It took a long time to find a free ride to orbit that’s high enough to escape most of Earth’s atmospheric drag (the Falcon Heavy flight will drop us into a 720 kilometer orbit). Combine that with a few technical problems, and the project was sent into temporary hiatus. That changed a couple of years back when we secured some new funding and brought in a new project manager, Doug Stetson, and a new prime contractor, Ecliptic Enterprises Corporation. Ecliptic is best known for the RocketCam systems used on space shuttle launches.

The full price tag for both missions is expected to be $5.45 million, and our Kickstarter aims to raise $200,000 of that. I think the fact that we’re on track to meet that goal within a couple days shows how eager folks are to contribute to space exploration.

(Author’s note: The Kickstarter quickly reached its $200,000 goal, but is still accepting donations through June.)

AmericaSpace: Where do you see LightSail or similar technologies going in 20 years?

Davis: CubeSats are already a cool way for universities and small groups to do an actual space mission on the cheap. The educational and real-world experience value of flying a CubeSat can’t be overstated—in many cases, these are scaled down versions of full-fledged NASA missions. Since a limiting factor of CubeSats is a lack of propulsion, solar sailing could be a game-changing technology. In 20 years, we’d be thrilled to see a fleet of low-cost solar sailing CubeSats leave Earth orbit for the Moon, Lagrangian points, or Mars. Hopefully with LightSail, we’ll help make that a possibility.


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12 comments to The Planetary Society’s LightSail to Launch Aboard Atlas-V May 20

  • CharlesHouston

    Isn’t this the satellite that was begun but assembly stopped at some point? Then Ecliptic Enterprises took up the project and completed assembly?

  • Gary Church

    “In 20 years, we’d be thrilled to see a fleet of low-cost solar sailing CubeSats leave Earth orbit for the Moon, Lagrangian points, or Mars. Hopefully with LightSail, we’ll help make that a possibility.”

    Talk about lowering expectations.

  • Jeff Wright

    I want to see a dedicated SLS block 2 with as big a sail as can be made.

    Marshall is looking at an X-Ray Surveyor–so that might be another mission for SLS

    • Gary Church

      Solar sails are useless but Medusa is a sail system and is the only practical interplanetary propulsion system that could be launched with a small number of SLS payloads. It would have to use the smallest bombs possible, probably fission devices, and not be very durable- probably only good for one deep space mission. Ceres would be a better destination than Mars.

      The more efficient monolithic plate designs researched during Project Orion mass thousands of tons and would require far more infrastructure- fabricating them out of lunar titanium being the best method but such a lunar factory base would take several decades and probably a half a century to create. It would be well worth it- such H-bomb propelled spaceships could explore the entire solar system.

      • Employing a complex nuclear pulse propulsion system in a 1 to 1,000 kg class interplanetary spacecraft when a solar sail like that the Planetary Society is testing here might suffice makes as much sense as dropping a 100,000 hp marine diesel engine into a ten-foot dingy when a small sail would do just fine.

        And forgive me for a moment but I do not understand the connection between your initial statement on nuclear propulsion and the seemingly random declaration “Ceres would be a better destination than Mars.” Seems to be a complete non sequitor to me.

        But I do agree with you that a monolithic plate design of the sort research for Project Orion make more sense than more flimsy systems.

        • Gary Church

          You just have to naysay every comment I make. And I can’t even call you what you are anymore without being censored into oblivion.

          Ceres is a better destination than Mars for several reasons. But I am not going to list them and let you continue to gratify yourself by using me as a punching bag. Sad.

          • “And I can’t even call you what you are anymore without being censored into oblivion.”

            That’s because attacking a person and his character is inappropriate in the comment section of this and most other web sites (not to mention that such ad hominem attacks are a classic logical fallacy and a poor substitute for intelligent discourse). The appropriate response is to provide a cogent counterargument to my on-topic, civil response to your original statement. If you don’t want to do that, then do not respond and skip the inappropriate personal attacks. If you don’t like people criticizing or disagreeing or otherwise responding to what you post in an open public forum like this whose purpose is to promote a civil discussion of the topic at hand, then don’t post. It is that simple.

  • […] An advanced NASA materials science experiment like one previously flown on the International Space Station (ISS) for 13 years will also be carried on the flight, as will the 344 sq ft. LightSail developed by The Planetary Society. […]

  • […] mechanism mounted at the aft end of the Centaur. This included a NASA/Planetary Society 344 sq. ft. LightSail that Bill Nye, who directs the group, said will unfold 28 days after […]

  • […] is the digital editor at The Planetary Society and spoke with AmericaSpace a few weeks back. In a previous AmericaSpace article, written by Emily Carney, she asks Davis about what their successful Kickstarter campaign says […]

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