NASA release It’ll be the first time we see the Advanced Composite Solar Sail System (ACS3) in orbit. NASA explains that the device is currently “slowly rotating” at an altitude of about 600 miles above Earth, but this free-spinning phase is all part of a bigger plan. And with the help of a new feature on NASA’s mobile app, interested spectators on the ground may be able to observe the sail in the sky.
ACS3 launched in April and has since spent its time rotating in sun-synchronous orbit while engineers monitor its instruments and prepare for the next stage of its deployment. It’s intended to serve as a prototype for a new portable sail design, and the results of its upcoming tests could help pave the way for a larger version capable of ferrying satellites and spacecraft throughout the solar system. First, though, NASA needs to be sure that ACS3’s basic dynamics are reliable enough to scale up for future missions.
[Related: NASA will unfurl a 860-square-foot solar sail from within a microwave-sized cube.]
The solar sail concept has been around for some time. Using ultra-thin reflective sheets to capture the sun’s ionic energy emissions, solar sails can propel cargo at incredibly high speeds without the need for an additional fuel source. In this case, the ACS3 prototype relies on a set of specially crafted, folding booms made from a flexible carbon-fiber-reinforced composite polymer. When fully extended to their 23-foot length, the four booms support 860 square feet of ultra-thin plastic sheeting while maintaining tension that allows them to collect solar energy.
Despite the ACS3’s overall size, its secret weapon is its size before it’s deployed: In its shipping package, the boom fits into a roughly envelope-sized case before being deployed via a device that resembles a tape spool.
For now, only the sails have been removed from the hangar in orbit. As NASA explained Thursday, the booms will be deployed once engineers are satisfied they’re ready, at which point ACS3’s “attitude control system” will re-engage to stabilize it in orbit. Teams will then begin maneuvers to raise or lower the overall orbit.
But NASA says that if you look carefully, you may still be able to catch a glimpse of ACS3 as it orbits Earth at night. NASA says ACS3 “may become invisible” during the night, and its brightness will change as it continues to rotate. NASA’s mobile app now has an ACS3 tracker that can pinpoint its location in orbit. NASA is also inviting anyone to participate by taking photos of ACS3 and sharing them online with the #SpotTheSail hashtag.
