Before snagging a chunk of space junk, Astroscale must first catch up to one

Astroscale, a well-capitalized Japanese startup, is preparing a small satellite to do something that has never been done in space. This new spacecraft, delivered into orbit Sunday by Rocket Lab, will approach a defunct upper stage from a Japanese H-IIA rocket that has been circling Earth for more than 15 years. Over the next few months, the satellite will try to move within arm’s reach of the rocket, taking pictures and performing complicated maneuvers to move around the bus-size H-IIA upper stage as it moves around the planet at nearly 5 miles per second (7.6 km/s). These maneuvers are complex,…