NASA is wrestling over how and when to bring two astronauts back from the International Space Station, after repeatedly delaying their return aboard Boeing’s troubled capsule. Do they take a chance and send them home soon in Boeing’s Starliner? Or wait and bring them back next year with SpaceX? Butch Wilmore and Suni Williams have been up there since early June, their planned eight-day mission at the two-month mark and possibly surpassing eight months. Testing continues, with Boeing expressing confidence in its spacecraft but NASA divided. A decision is expected next week. WHAT’S WRONG WITH BOEING’S STARLINER? This is Boeing’s first time launching astronauts, after flying a pair of empty Starliners that suffered software and other issues. Even before Wilmore and Williams blasted off June 5, their capsule sprang a leak in propulsion-related plumbing. Boeing and NASA judged the small helium leak to be stable and isolated, and proceeded with the test flight. But as Starliner approached the space station the next day, four more leaks erupted. Five thrusters also failed. The capsule managed to dock safely, and four of the thrusters ultimately worked. But engineers scrambled, conducting thruster test-firings on the ground and in space. After two months, there’s still no root cause for the thruster malfunctions. All but one of the 28 thrusters seem OK, but the fear is that if too many conk out again, the crew’s safety could be jeopardized. The thrusters are needed at flight’s end to keep the capsule in the right position for the critical deorbit burn. ARE THE TWO ASTRONAUTS STRANDED? NASA bristles at suggestions that Wilmore and Williams are stranded or stuck. NASA has stressed from the get-go that in an emergency at the space station — like a fire or decompression — Starliner could still be used by the pair as a lifeboat to leave. A former NASA executive said Thursday the astronauts are “kind of stuck,” although certainly not stranded. They’re safe aboard the space station with plenty of supplies and work to do, said Scott Hubbard. If NASA decides to go with a SpaceX return, Starliner would be be cut loose first to open up one of two parking spots for U.S. capsules. Before that happens Wilmore and Williams would fashion seats for themselves in the SpaceX Dragon capsule currently docked at the space station. That’s because every station occupant needs a lifeboat at all times. Once Starliner’s docking port is empty, then SpaceX could launch another Dragon to fill that slot — the one that Wilmore and Williams would ride. WHY MIGHT THEY HAVE TO WAIT UNTIL NEXT YEAR? Like Boeing’s Starliner, SpaceX’s Dragon is meant to carry four astronauts. To make room for Wilmore and Williams, NASA said Wednesday it could bump two of the four astronauts due to launch to the space station next month with SpaceX. The empty seats would be reserved for Wilmore and Williams, but they would have to remain up there until February. That’s because station missions are supposed to last at least six months. Some have lasted a year. Two Russians up there right now will close out a yearlong stint when they return in a three-seat Soyuz capsule in September alongside a NASA crewmate. There’s no thought given to ordering up a special SpaceX express, and the Dragon at the station now […]