This artist’s concept shows the Advanced Composite Solar Sail System spacecraft sailing in space using the energy of the Sun. Credit: NASA/Aero Animation/Ben Schweighart.
Once promoted by Carl Sagan to Johnny Carson on the Tonight Show, the idea of traveling through space via a reflective “sail” - powered by the momentum of photons radiating out from the sun - continues to command attention. Why?
Because NASA believes pushing a spacecraft around without depending upon heavy, chemical propulsion systems could enable longer and cheaper missions. Moreover, LightSail2, a crowd-funded test launched in 2019 by The Planetary Society, proved a small spacecraft’s orbit can be controlled through adjustments to the sail’s angular position to sunlight (photons).
So, sometime in late April, a NASA solar sail mission, one designed to test an upgraded, structurally sounder sail in Earth’s orbit, is scheduled to begin when an Electron rocket rises from Rocket Lab’s launching pad in Māhia, New Zealand.
If successful, this effort will mark the beginning of NASA’s Advanced Composite Solar Sail System era.
We wonder, since LightSail2 began by orbiting at an altitude of 440-451 miles and was expected to survive for one year but stayed in orbit for three years before atmospheric drag caused it to drop into the Pacific Ocean, by choosing a low-earth-orbit of 600 miles above the Earth for the new sail, how much extra life is NASA is expecting for the new sail.
Meanwhile, the new sail is large (860 sq. ft.), and if the lighting conditions and orientation of the sail are just right, the sail’s reflective material will shine down on Earth as brightly as Sirius, the brightest star in the night sky.
For some, the chance to spot a sail being pushed by photons in the sky will be thrilling. Others might just mutter about the government polluting the sky for no good reason.