Q&A with Keith Gendreau, principal investigator of the first X-ray space communications experiment (members only)

Juggling simultaneous launch campaigns on both coasts, a team of SpaceX engineers put a Falcon 9 rocket through a customary countdown rehearsal and hold-down firing Tuesday at Vandenberg Air Force Base in California ahead of a scheduled liftoff Sunday.

Blue Origin launched its New Shepard suborbital rocket to the edge of space Tuesday from the company’s remote desert test site in West Texas on an experimental flight to test precision lunar landing technology for NASA.

SpaceX’s launch team fueled up a Falcon 9 rocket on a California launch pad Thursday, fired the booster’s nine Merlin engines, and passed a key preflight test for the first time since a Falcon 9 exploded during a similar practice countdown in September.