SpaceX closes in on human spaceflight with this weekend’s debut of a new capsule designed for astronauts. The six-day test flight will be real in every regard, beginning with a successful Florida liftoff and docking with the International Space Station. But the Dragon space capsule won’t carry humans, rather a test dummy — named Ripley after the tough heroine in the “Alien” films — in the same white SpaceX spacesuit that astronauts will wear. If all goes well with this flight and an upcoming emergency-escape test, Crew Dragon could fly two NASA astronauts to the orbiting lab this summer. Operational missions, which would carry four people per trip, would begin sometime thereafter.