LightSail - Flying to Other Worlds on Sunlight

by The Planetary Society
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LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
LightSail - Flying to Other Worlds on Sunlight
CEO Bill Nye with LightSail at the FUTURES exhibit
CEO Bill Nye with LightSail at the FUTURES exhibit

Our scale model of LightSail, that is...


Since November of 2021, our LightSail model has been in Washington, D.C. as part of the FUTURES exhibit at the Smithsonian Institution's Art + Industries Building. FUTURES is an incredible collection of art and technology representing the future of humanity, and it's been a great honor for The Planetary Society to be a part of it. Our CEO Bill Nye was at the opening of the exhibit, as seen in the photo above.

Before the FUTURES exhibit closes later this month, Bill and Planetary Society staff members are traveling to Washington, D.C. for the Smithsonian Solstice Saturday. Several of the museums there will be open until midnight, and the Astronomy Festival on the National Mall will run from 6:00 to 11:00 pm.

It's going to be a wonderful event, and if you're in the D.C. area, do try to see LightSail before the exhibit ends. If you find yourself at the Astronomy Festival on the National Mall, be sure to stop by The Planetary Society's table on the Mall and say hello. Planetary Society members wearing their membership tee or pin, or carrying their membership card, will get swag!

Your support and enthusiasm for solar sailing are making a mark on the future of space exploration. Thank you for your support of LightSail.


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Tropical Storm Mirinae near Japan, 8/7/2021.
Tropical Storm Mirinae near Japan, 8/7/2021.

Nearly two-and-a-half years after launching into Earth orbit, The Planetary Society's LightSail 2 solar sail mission is still going strong. 

The spacecraft is currently operating in an extended mission to further advance solar sailing technology. The LightSail 2 team is gathering vital data about the performance of the solar sail and using imagery to track its condition over time. 

Ten new processed pictures from space have been added to the mission's image library, which you can access here

The Planetary Society shares mission data with NASA to assist three upcoming solar sail missions: NEA Scout, Solar Cruiser and ACS3. NEA Scout is scheduled to hitch a ride to lunar space as early as this month on NASA's Space Launch System rocker during the Artemis 1 test flight.

At LightSail's altitude above Earth - currently about 687 kilometers - there is still enough atmosphere to counteract the thrust gained from solar sailing and slowly pull it back to Earth. The spacecraft will eventually succumb to drag and reenter Earth's atmosphere.

There are signs that the spacecraft's solar sail may be starting to degrade, although the extent is under study. The mission team will continue to track and analyze the sail's condition, as the data could prove valuable to other solar missions.LightSail 2 monitors its sails condition using two fish-eye cameras mounted at the end of two solar panels.

Almost 30 months after liftoff, the mission continues to impress. For now, LightSail 2 will continue to teach the world about solar sailing, returning inspiring images and helping prepare for the next generation of solar sail mission.

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LightSail 2 image of central northern South Africa
LightSail 2 image of central northern South Africa

Since launching LightSail 2 in 2019, all of us at The Planetary Society, along with our donors and members, continue to be surprised and enchanted by all things LightSail. Whether it's the stunning photographs of our world taken by LightSail's cameras or the contributions LightSail is making towards the future of solar sailing, LightSail's "flight by light" continues to inspire!

LightSail is now officially in an "extended mission" phase. We recently celebrated by holding an online auction for one-of-a-kind LightSail swag to help raise funds to keep the mission going and also premiered "Sailing The Light", a 35-minute documentary about the game-changing LightSail 2 mission.

We plan to operate LightSail 2 as long as possible in order to learn more about solar sailing and solar sail spacecraft operations. We also want to continue raising the profile of solar sailing by sharing the excitement of the mission with the public, while documenting our results to ensure the strongest possible legacy for the LightSail program.

NASA's Advanced Composite Solar Sail System, or ACS3, is slated to launch in 2022 and will build on the groundwork we have established with LightSail 2. Carl Sagan's long-held dream of sailing the solar winds has come true, and you have helped make this citizen-funded project a reality. Thank you for your support!

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Two years after launching into Earth orbit aboard a SpaceX Falcon Heavy rocket, LightSail 2 is still solar sailing. The spacecraft has completed its first year of extended operations and is still healthy. 

We can’t say for sure when LightSail 2 will reenter Earth’s atmosphere. Its average altitude has only dropped about 20 kilometers since the start of the mission in 2019. Below-average Sun activity has kept Earth’s upper atmosphere calm, creating less drag on the sail. The spacecraft also offsets the drag with the thrust gained by solar sailing.

We plan to operate LightSail 2 as long as possible in order to learn more about solar sailing and solar sail spacecraft operations. We also want to continue raising the profile of solar sailing by sharing the excitement of the mission with the public, while documenting our results to ensure the strongest possible legacy for the LightSail program.

Here are some of our goals for LightSail 2’s ongoing extended mission, along with updates on what we’ve learned.

Improve solar sailing performance as much as possible 

As LightSail 2 dips lower and lower into Earth’s atmosphere and the sail itself degrades, improving the spacecraft’s performance will only get more difficult. 

We monitor daily the decay rate of our average orbital altitude, which is affected by the efficiency of solar sailing versus atmospheric drag. We have also experimented with different frequencies and durations of the modes used to desaturate the spacecraft’s momentum wheel, which is used to rotate the spacecraft. 

We regularly monitor and analyze the spacecraft’s attitude, or orientation, in order to determine how accurately we are pointing the sail where we’d like. 

Operate the spacecraft in different modes and observe the results 

Like NASA’s Ingenuity helicopter on Mars, LightSail 2 is a technology demonstration mission meant to push the envelope of what is possible and pave the way for future spacecraft.

We have operated LightSail 2 in several different modes to see how well it maintains its desired orientation, and the resulting effect on its orbit. Four modes we’ve experimented with are:

Solar sailing mode: a standard sailing mode where we turn edge-on to the Sun when traveling towards it to turn off thrust, and face-on when traveling away from the Sun to gain a push from solar photons. This is our most-used mode.

Desaturation mode: currently in use once every two days, this mode uses magnetorquers to desaturate our momentum wheel. 

Sun pointing mode: the spacecraft maintains a face-on Sun pointing mode throughout its orbit to optimize power generation on the solar panels. We have recently been testing this out more frequently.

Drag maximizing mode: LightSail 2 maintains a face-on attitude to the direction of motion to study how solar sails can intentionally generate drag and de-orbit spacecraft. We use this mode occasionally and will probably use it more when LightSail 2 gets lower in the atmosphere.

We also developed and tested techniques to improve attitude determination and control. In one example, we noticed a gyroscope was slowly falling out of calibration. We determined the proper offsets to fix this, tested them on our BenchSat spacecraft model, uplinked the corrections to the spacecraft, and evaluated how well we had fixed the problem. We are continuing to monitor the gyroscopes and make periodic adjustments.

Continue taking pictures for public and engineering analysis

We love sharing pretty pictures from LightSail 2 with the public. These pictures also serve an important engineering purpose by showing us how the sail is degrading and how the four metallic booms that hold the sail tight are behaving.

Recently we have seen possible degradation of the sail through shrinkage, crinkles and likely delamination of the sail’s reflective coating in some areas. This is perhaps caused by interaction with atomic oxygen; an analysis is ongoing. 

We have also noticed systematic changes in the sail boom tips, as well as non-systematic changes that may be caused by thermal expansion and contraction of the sail booms. An analysis is in progress.

Automated fault protection

Whether it’s a big-budget NASA mission or a crowdfunded CubeSat, computer glitches and unexpected behaviors are part of every space mission. Automated fault protection and recovery software can help spot problems before they happen and keep ground teams from getting overwhelmed by spacecraft bugs. 

Purdue researcher Justin Mansell developed a fault protection algorithm for LightSail 2 as part of his Ph.D. dissertation. When applied to LightSail 2 telemetry data, Mansell’s software has successfully spotted anomalies that may have otherwise been overlooked. 

Sharing, coordinating, and archiving 

LightSail 2 is meant to enable and support future solar sailing missions. A big part of our extended mission is sharing what we are learning. We publish peer-reviewed journal articles, make conference presentations and conduct public outreach through social media and articles like the one you’re reading right now.

We also interface directly with other solar sailing missions. NASA has three such missions planned: NEA Scout, Solar Cruiser, and ACS3. We share data and facilitate additional studies to help these mission teams learn from our experiences. Furthermore, we document and archive our LightSail 2 data so that it will be available for analysis by future missions.

Fly the spacecraft

There’s one more important aspect of the LightSail 2 extended mission: we have to fly the spacecraft! 

Our team carries out ongoing maintenance and monitoring to keep the spacecraft functioning properly. We uplink orbital elements twice a week so that it knows where it is. Maintenance activities also include clearing file space on the onboard computer as needed, working issues and anomalies as they arise, and monitoring engineering telemetry.

These past two years of LightSail 2 operations would not have been possible without the support of our members and donors. Thanks to your support, we’ll be able to continue learning as much as we can from this unique mission!

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A pair of upcoming NASA solar sail missions will take flight by light to new heights, revealing the surface of an asteroid and testing a sail large enough to cover six tennis courts.

NEA Scout is a NASA mission launching to the Moon in 2021 that will use a solar sail to visit a near-Earth asteroid. NASA has also greenlit Solar Cruiser, a mission launching in 2025 to test a giant sail measuring 1,650 square meters (17,800 square feet) at an artificial orbit between the Earth and Sun.

The Planetary Society’s LightSail 2, which has spent 18 months in Earth orbit, is part of a solar sail lineage that makes NEA Scout and Solar Cruiser possible. Based on NASA’s Nanosail-D2 sail spacecraft, LightSail 2 became in 2019 the first spacecraft to demonstrate controlled solar sailing in Earth orbit, a feat that requires continual, quick maneuvers. NASA and The Planetary Society collaborate and exchange data on LightSail 2 and NEA Scout through a Space Act Agreement.

“People often ask us whether there will be a LightSail 3, and in many ways, that’s what NEA Scout and Solar Cruiser are,” said Bruce Betts, Planetary Society chief scientist and the LightSail program manager. “These missions are logical next steps that further advance solar sail technology. We’re honored to contribute by sharing what we’ve learned through our ongoing LightSail 2 mission and are thrilled that NASA is moving forward with these exciting solar sail missions.”

NEA Scout launches to the Moon in 2021 with a fleet of other small satellites aboard Artemis 1, the inaugural test flight of NASA’s Space Launch System rocket. SLS will blast the Orion crew vehicle on a mission to lunar orbit and back.

In 2025 Solar Cruiser will take solar sailing to a new level by testing a sail an order of magnitude larger than any flown before. Solar Cruiser will hitch a ride to space with NASA’s Interstellar Mapping and Acceleration Probe, IMAP. IMAP will study how the constant flow of charged particles coming from our Sun known as the solar wind interacts with cosmic radiation coming from the rest of the universe. This interaction creates a bubble that surrounds and protects our solar system.


Les Johnson, the principal investigator for NEA Scout and Solar Cruiser at NASA’s Marshall Space Flight Center, credits LightSail for bringing solar sailing into the mainstream.


“I think the technical work that The Planetary Society did, as well as the outreach and awareness and education component, has been really critical toward making this capability more real in the minds of decision-makers and scientists and people interested in sailing,” he said during a recent Planetary Radio interview.



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The Planetary Society

Location: Pasadena, CA - USA
Facebook: Facebook Page
Twitter: @exploreplanets
Project Leader:
Richard Chute
Pasadena, CA United States
$2,437 raised of $99,999 goal
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