SHORT HISTORY OF SOLAR SAILS
The concept out using solar shields for planetary cooling was first discussed by Freeman Dyson. In 1989, Freeman was working on a concept to terraform Venus. He planned to use a giant space screen to collapse the atmosphere into lakes of liquid CO2 on the surface. He estimated that it would take 1000 years complete the project. In an extended conversation with him, I proposed that a flock of small robotic solar sails could navigate to Venus and cool the planet. Freeman was delighted: “In that case, it would only take 200 years!”
In 2021, former astronaut Christer Fuglesang, et al. published Realistic sunshade system at L1 for global temperature control, where he predicted solar sails launched in a 2000 km orbit could travel to L1 in about 600 days.
Solar sails are being developed for solar system exploration. The Planetary Society launched Lightsail 2 in 2019; it was deorbited Nov 17, 2022. The NASA NEA Scout was a CubeSat solar sail designed to study asteroids close to Earth; NEA Scout was launched with the Artemis Moon Mission and was declared lost in Dec 2022. The Solar Cruiser, designed to demonstrate the feasibility of large solar sails in 2025, is in danger of being cancelled by NASA. NASA has announced ACS3, NASA’s Advanced Composite Solar Sail System. ACS3, scheduled to launch in 2023, it is similar in scale to NEA Scout, with a payload the size of a "toaster oven." "ACS will test sail boom materials that could enable much larger solar sails."
It is important to note that, to date, no solar sail has demonstrated true free flight in space. Lightsail 2 experienced tumbling and has been confined to Earth orbit. Even the famous Ikaros Solar Sail, launched by the Japanese Space Agency in 2010, which flew to Venus and has demonstrated solar acceleration and attitude control, was primarily propelled by initial thrust from the second stage of the JAXA H-IIB rocket.
LARGE VS SMALL SOLAR SAILS
Large Solar Sails Small Solar Sails
PICO SOLAR SAIL
TARGET SPECIFICATIONS FOR L1 PICO SOLAR SAILS
- Small Diameter ≈ 1m2
- Mass Less than ≈ 30 g/m2
- Thin-film components & electronics
- Spin Stabilized
- Radio Controlled (receiver, no transmitter)
- Rapid Attitude Control (needed for navigation)
- Hybrid Mirror & Diffractor Surfaces
- Mass-produced on Earth using Photolithography
- Deployed to MEO by the Mass Launch System rockets
- Autonomous Navigation from MEO to L1
- Station-keeping at L1 using “drone swarms”
- Trillions of Pico Sails are required at L1
- Long lifetime in space
See: Prototype Deployment
See: Prototype Testing
See: Mass Launch System
See: MLS Spaceport https://www.planetary.org/space-missions/acs3