LightSail#LightSail 2

{{Infobox spaceflight

| name = LightSail

| names_list = LightSail A
LightSail 2

| image = LightSail 2 Deployment Test.jpg

| image_caption = LightSail 2 after a boom deployment test

| image_alt = LightSail 2 after a boom deployment test at Cal Poly San Luis Obispo

| image_size = 300px

| mission_type = Technology demonstration

| operator = The Planetary Society

| COSPAR_ID = 2019-036AC

| SATCAT = 44420

| website = {{URL|http://sail.planetary.org/}}

| mission_duration = LightSail 1 Final: {{time interval|20 May 2015|14 June 2015}}
LightSail 2 Final: {{time interval|25 June 2019|17 November 2022}}

| spacecraft =

| spacecraft_type = Solar sail

| spacecraft_bus = 3U CubeSat

| manufacturer = Stellar Exploration, Inc.,
Ecliptic Enterprises Corporation,
Cal Poly San Luis Obispo

| launch_mass =

| dimensions = Core: {{cvt|30 × 10 × 10|cm}}
Sail: {{cvt|32|m2}}

| power =

| launch_date = LightSail 1: 20 May 2015
LightSail 2: 25 June 2019[https://www.newsweek.com/spacecraft-light-sails-spacex-falcon-heavy-rocket-1424896 Spacecraft Powered by 'Light Sails' Set to Launch Aboard SpaceX Falcon Heavy Rocket] Aristos Georgiou, Newsweek 14 May 2019

| launch_rocket = LightSail 1: Atlas V
LightSail 2: Falcon Heavy

| decay_date = LightSail 1: 14 June 2015{{cite web|last1=Davis|first1=Jason|title=LightSail Test Mission Ends with Fiery Reentry|url=http://www.planetary.org/blogs/jason-davis/2015/20160615-lightsail-test-mission-ends.html|website=planetary.org|publisher=The Planetary Society|access-date=24 July 2019}}
LightSail 2: 17 November 2022

| insignia =

| insignia_caption =

| insignia_size = 200px

}}

LightSail is a project to demonstrate controlled solar sailing within low Earth orbit using a CubeSat. The project was developed by The Planetary Society, a global non-profit organization devoted to space exploration.{{cite web|url=http://www.planetary.org/blogs/jason-davis/2017/20170320-ls2-pre-ship-review.html|title=Signed, sealed but not delivered: LightSail 2 awaits ship date|last=Davis|first=Jason|date=3 March 2017|publisher=The Planetary Society|access-date=29 March 2017}} It consists of two spacecraft — LightSail 1 and LightSail 2. LightSail 1 was an engineering demonstration mission designed to test its new sail deployment method in space, it did not perform solar sailing. LightSail 2 was a fully functional spacecraft intended to demonstrate true solar sailing{{cite news|last=Stirone|first=Shannon|title=LightSail 2 Unfurls, Next Step Toward Space Travel by Solar Sail – The Planetary Society deployed LightSail 2, aiming to further demonstrate the potential of the technology for space propulsion|url=https://www.nytimes.com/2019/07/23/science/lightsail-solar-sail.html|date=23 July 2019|newspaper=The New York Times|access-date=24 July 2019}} and incorporated the lessons learned from LightSail 1. LightSail is a follow-on project to Cosmos 1 — a solar-sail spacecraft designed by The Planetary Society in the early 2000s, which was destroyed during a launch failure in 2005.

Both LightSail spacecraft measured {{cvt|30 × 10 × 10|cm}} (3U CubeSat) in their stowed configuration. After sail deployment, the total area of each spacecraft was {{cvt|32|m2}}.{{cite web |url=http://www.planetary.org/explore/projects/lightsail-solar-sailing/#the-spacecraft|title=LightSail|publisher=The Planetary Society|access-date=2017-03-29}}

History

In 2005, The Planetary Society attempted to send a solar sail satellite named Cosmos 1 into space, but the spacecraft's Russian Volna launch vehicle failed to reach orbit.{{cite news|last=Antczak|first=John|url=https://www.nbcnews.com/id/wbna33812469|title=After letdown, solar-sail project rises again|publisher=NBC News|agency=Associated Press|date=9 November 2009}} In 2009, the Society began working on a CubeSat-based solar sail based on NASA's NanoSail-D project,{{cite news|url=https://www.nytimes.com/2009/11/10/science/space/10solar.html|title=Setting Sail Into Space, Propelled by Sunshine|newspaper=The New York Times|date=9 November 2009}} which was lost in August 2008 due to the failure of its Falcon 1 launch vehicle.{{cite news |url=http://www.space.com/5693-spacex-falcon-1-falters-time.html|title=SpaceX's Falcon 1 Falters For a Third Time|publisher=Space.com|access-date=29 March 2017}} (A second unit, NanoSail-D2, was successfully deployed in early 2011.)

In 2011, the LightSail project passed its Critical Design Review (CDR), which was conducted by a team including Jet Propulsion Laboratory (JPL) project veterans Bud Schurmeier, Glenn Cunningham, and Viktor Kerzhanovich, as well as Dave Bearden of Aerospace Corporation.{{cite web|url=http://www.planetary.org/blogs/guest-blogs/lou-friedman/20100625.html |title=LightSail 1 Passes Critical Design Review|author=Louis D. Friedman|publisher=The Planetary Society|date=25 June 2010}}

On 20 May 2015, LightSail 1 (formerly called LightSail-A) launched.{{cite news|last=Davis|first=Jason|url=http://www.planetary.org/blogs/jason-davis/2016/20160229-meet-lightsail-2.html|title=Meet LightSail 2, The Planetary Society's new solar sailing CubeSat|publisher=The Planetary Society|date=1 March 2016|access-date=1 March 2016}} It deployed its solar sail on 7 June 2015 and re-entered the atmosphere, as planned, on 14 June 2015.

In March 2016, The Planetary Society announced a new naming convention for the spacecraft: the test flight (originally LightSail-A) was renamed LightSail 1, with the second spacecraft named LightSail 2. LightSail 2 launched as a secondary payload on the Space Test Program (STP-2) on a Falcon Heavy launch vehicle on 25 June 2019. It deployed its solar sail on 23 July 2019, and successfully downlinked photographs of the deployed sail on 24 July 2019.

The Society has stated it has no plans for a LightSail 3.{{cite web|last=Foust |first=Jeff|url=https://spacenews.com/solar-sail-spacecraft-begins-extended-mission/|title=Solar sail spacecraft begins extended mission|publisher=SpaceNews|date=2 July 2020|access-date=2 July 2020}}

Design

File:LightSail 2.jpg

As a solar sail, LightSail's propulsion relies on solar radiation and not the charged particles of the solar wind.{{cite news|url=http://www.space-travel.com/reports/Planetary_Society_To_Sail_Again_With_LightSail_999.html|title=Planetary Society To Sail Again With LightSail|publisher=Space Travel blog|date=10 November 2009}} Solar photons exert radiation pressure on the sail, which produces an acceleration on the spacecraft relative to the ratio of the sail's area to its mass. As such, the design challenge was to maximize the surface area of the sail while minimizing the mass of the spacecraft — all while adhering to the standard 3-unit CubeSat size limitation.

LightSail's modular design is based on a modular 3-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 contain and deploy the solar sails.{{cite web|url=http://www.planetary.org/explore/projects/lightsail-solar-sailing/|title=LightSail|publisher=The Planetary Society|access-date=29 March 2017}}

The spacecraft contains four triangular sails, which combine to form a rectangular-shaped surface. The sails are made of Mylar, a reflective polyester film.{{cite web |url=http://sail.planetary.org/faq.html|title=Frequently Asked Questions|publisher=The Planetary Society|access-date=29 March 2017}}

LightSail has multiple configurations. It was launched in a stowed configuration with its sails folded within the spacecraft. After launch, it enters an intermediate phase by deploying a small antenna and flipping open its solar panels. This exposes the cameras and reveals the stowed solar sails. To achieve its final "solar sailing" configuration, LightSail extends four 4-meter cobalt alloy booms that slowly spread open the mylar sail material. Using an internal reaction wheel, LightSail 2 is able to orient itself against the Sun using Earth's magnetic field as a guide. By "tacking" in and out of the Sun, it can control the force on its sail and thus change its orbit.

Costs and funding

The entire LightSail project cost US$7 million over 10 years and was paid for by approximately 40,000 individual donors,{{cite news|last1=Stirone|first1=Shannon|title=LightSail 2 Unfurls, Next Step Toward Space Travel by Solar Sail|url=https://www.nytimes.com/2019/07/23/science/lightsail-solar-sail.html|newspaper=The New York Times|date=23 July 2019|access-date=26 July 2019}} including US$1.24 million raised from a successful Kickstarter campaign in 2015.{{cite web|title=LightSail: A Revolutionary Solar Sailing Spacecraft|url=https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraft|publisher=Kickstarter|access-date=26 July 2019}} Launch costs were supported by NASA's Educational Launch of Nanosatellites program (LightSail 1) and the Air Force Research Laboratory's University Nanosat Program (LightSail 2).

LightSail 1

File:LightSail 1 with deployed solar sail.jpg

A preliminary technology demonstrator spacecraft, LightSail 1 (formerly LightSail-A), was launched as a secondary payload aboard a United Launch Alliance Atlas V launch vehicle at 15:05 UTC on 20 May 2015 from Cape Canaveral Air Force Station, Florida.{{cite news|last=Wall|first=Mike |url=http://www.space.com/29438-lightsail-solar-sail-x37b-space-plane.html?adbid=10152820300781466&adbpl=fb&adbpr=17610706465&short_code=30p5u|title=Tiny Solar Sail 'Cubesat' Launching with X-37B Space Plane on Wednesday|publisher=Space.com|date=10 May 2015|access-date=20 May 2015}}{{cite web|url=http://www.planetary.org/blogs/jason-davis/2015/20150413-lightsail-launch-delayed.html

|title=LightSail Launch Delayed until at least May 20|last=Davis|first=Jason|publisher=The Planetary Society|date=13 April 2015}} The mission delivered the satellite to an orbit where atmospheric drag was greater than the force exerted by solar radiation pressure.{{cite web|url=http://www.planetary.org/blogs/jason-davis/2015/20150112-lightsail-test-flight.html|title=It's Official: LightSail Test Flight Scheduled for May 2015|date=26 January 2015|last=Davis|first=Jason|publisher=The Planetary Society}}

Two days after the launch, however, the spacecraft suffered a software malfunction, which made it unable to deploy the solar sail or to communicate.{{cite news |url=http://www.space.com/29502-lightsail-solar-sail-software-glitch.html|title=LightSail Solar Sail Test Flight Stalled by Software Glitch|last=Wall|first=Mike|date=27 May 2015|publisher=Space.com|access-date=29 May 2015}} On 31 May 2015, The Planetary Society reported having regained contact with LightSail 1.{{cite web|last1=Fingas|first1=John|title=LightSail solar spacecraft gets back in touch with its ground crew|date=31 May 2015 |url=https://www.engadget.com/2015/05/30/lightsail-resumes-contact/?ncid=rss_truncated|publisher=Engadget|access-date=2015-05-31}}{{cite news |url=https://www.theverge.com/2015/5/31/8694001/bill-nye-lightsail-contact-earth-crew-reboot|title=Bill Nye's LightSail spacecraft is back in touch with Earth after rebooting itself|publisher=The Verge|date=31 May 2015|access-date=31 May 2015}} After the solar panels were deployed on 3 June 2015, communications with the spacecraft were lost once more on 4 June 2015. In this case, a fault with the battery system was suspected.{{cite web|url=http://www.planetary.org/blogs/jason-davis/2015/20150604-lightsail-silent-again.html|title=LightSail Falls Silent; Battery Glitch Suspected|last=Davis|first=Jason |publisher=The Planetary Society|date=4 June 2015}} Contact was then reestablished on 6 June 2015,{{cite news|url=http://www.planetary.org/blogs/jason-davis/2015/20150506-lightsail-wakes-second-time-1.html|title=LightSail Drama Continues as Spacecraft Wakes for Second Time|publisher=The Planetary Society|date=2015-06-06|access-date=2015-06-06}} and the sail deployment was initiated on 7 June 2015.[http://www.planetary.org/blogs/jason-davis/2015/20150607-lightsail-deployment-initiatied.html Deployment! LightSail Boom Motor Whirrs to Life] 7 June 2015 At a conference on 10 June 2015, after photos of deployment were downloaded, the test flight was declared a success.[http://www.planetary.org/blogs/jason-davis/2015/20150609-lightsail-test-mission-success.html LightSail Test Mission Declared Success; First Image Complete] 9 June 2015 The spacecraft reentered the atmosphere on 14 June 2015, ending the test flight.[http://www.space.com/29679-lightsail-solar-sail-reentry-death-fall.html?adbid=10152891021016466&adbpl=fb&adbpr=17610706465 LightSail Solar Sail Ends Test Flight with Fall Back to Earth] Leonard David, Space.com 18 June 2015{{cite web |url=http://www.satobs.org/LightSail-A.html|title=LightSail-A: Post-Sail Deployment Orbital Elements|last=Molczan|first=Ted|date=2015-06-14|access-date=15 June 2015}}

LightSail 2

File:LightSail 2 with deployed solar sail.png

LightSail 2 (COSPAR 2019-036AC) was a CubeSat fitted with a solar sail the size of a boxing ring, covering {{cvt|32|m2}}. The sail captured incoming photons from the Sun, just as a wind sail catches the moving air molecules, to propel the spacecraft.{{cite web|url=https://www.space.com/light-sail-2-solar-sail-still-flying-planetary-society|title=LightSail 2 solar sail is still soaring above Earth more than two years after launch|publisher=Space.com|date=19 November 2021|access-date=20 November 2021}}

LightSail 2 was launched on 25 June 2019 and deployed by the Prox-1 carrier satellite into a much higher low Earth orbit than LightSail 1, at over {{cvt|720|km}} orbital altitude.{{cite web|url=https://www.nasaspaceflight.com/2019/06/spacex-falcon-heavys-stp-2-mission/|title=SpaceX completes most-challenging flight with Falcon Heavy's STP-2 mission|date=June 24, 2019}} It was to demonstrate controlled solar sailing in low Earth orbit. By controlling the orientation of the sail relative to the Sun, the flight team hoped to raise the orbit apogee and increase orbital energy following sail deployment. Prox-1 and LightSail 2 were secondary payloads aboard the second operational SpaceX Falcon Heavy launch, which carried the STP-2 payload for the U.S. Air Force.{{cite AV media|last1=Nye|first1=Bill|title=Kickstart LightSail|url=https://www.youtube.com/watch?v=kDBzRa9RzfM |archive-url=https://ghostarchive.org/varchive/youtube/20211215/kDBzRa9RzfM |archive-date=2021-12-15 |url-status=live|time=3:20|access-date=15 May 2015}}{{cbignore}}

Researchers received the first pictures from LightSail 2 on 7 July 2019,{{cite news|last=Davis|first=Jason|title=Here are the First Pictures of Earth from LightSail 2 |url=http://www.planetary.org/blogs/jason-davis/lightsail-2-first-pics.html|date=7 July 2019|publisher=The Planetary Society|access-date=7 July 2019}} and its solar sails were deployed on 23 July 2019.[http://www.planetary.org/blogs/jason-davis/what-to-expect-lightsail-2.html What to Expect when LightSail 2 Launches into Space] Jason Davis, The Planetary Society 17 June 2019 On 31 July 2019, the Planetary Society stated that they had raised LightSail 2 orbit by a measurable amount,{{cite web|url=http://www.planetary.org/blogs/jason-davis/lightsail-2-successful-flight-by-light.html|title=LightSail 2 Spacecraft Successfully Demonstrates Flight by Light|website=planetary.org|access-date=2019-10-15}} although it spent a significant amount of its time randomly tumbling.{{cite web|url=https://arstechnica.com/science/2019/08/so-how-much-did-the-planetary-societys-light-sail-really-sail/|title=So, how much did the Planetary Society's light sail really sail?|last=Berger|first=Eric|date=2019-08-02|publisher=Ars Technica|access-date=2020-01-26}} LightSail 2 successfully demonstrated propulsion by solar sail.https://www.planetary.org/sci-tech/lightsail

Though initially planned to reenter Earth's atmosphere after approximately one year, an extended mission was approved on 25 June 2020. The Planetary Society website showed that the mission was continuously active until 16 November 2022.{{cite web|url=https://secure.planetary.org/site/SPageNavigator/mission_control.html|title=LightSail 2 Mission Control|publisher=The Planetary Society|date=16 November 2022|access-date=17 November 2022}} On 17 November 2022, LightSail 2 reentered the atmosphere.{{cite web |last=Davis |first=Jason |url=https://www.planetary.org/articles/lightsail-2-completes-mission |title=LightSail 2 completes mission with atmospheric reentry |work=The Planetary Society |date=17 November 2022 |access-date=17 November 2022}}