Purdue University engineers have developed a space-debris-clearing drag sail called Spinnaker3 that is designed to speed up the deorbiting of space junk up to 400 miles (645 km) high so it safely burns up in the Earth’s atmosphere. The sail will be put to the test next month on a spent rocket booster at an orbit altitude of about 200 miles (322 km).
Under law, US-flagged satellites must be either deorbited or sent into a safe graveyard within 25 years of ceasing operations. The standard way of doing this is for the spacecraft to use its thrusters to put it into the right disposal orbit. The problem is that such thruster systems and the extra fuel needed for the final trajectory change increase the mass of the satellites, increasing costs and reducing their capabilities.
The alternative is to use a system that doesn’t require propellants and complex plumbing. One example of this is a drag sail, which spreads out and passively catches the stray molecules of the remarkably tenuous atmosphere in low Earth orbit, causing the craft’s orbit to decay until it hits the atmosphere proper.
Such sails have been tested before, but Spinnaker3 ups the game a bit by wielding 3-meter-long (10-ft) booms to unfurl a 194-sq-ft (18-sq-m) shimmering, translucent fluorinated-polyimide plastic sail. This sail is large enough to help deorbit not only a satellite, but also a booster rocket upper stage from an altitude of up to 400 miles.