What have the astronauts been doing aboard the space station?
Originally, the mission was to last only up to two weeks, but Mr. Behnken and Mr. Hurley ended up with a longer and busier stay at the space station. Because of repeated delays by SpaceX and Boeing, NASA ended up short-handed, with only one astronaut, Christopher J. Cassidy, aboard the space station when the Crew Dragon and its two passengers docked.
They stayed two months, helping Mr. Cassidy with space station chores. Mr. Behnken and Mr. Cassidy performed four spacewalks to complete the installation of new batteries on the space station. Mr. Hurley helped by operating the station’s robotic arm.
The men have also been contributing to science experiments in low earth orbit. They assisted in a study of water droplet formation in the low gravity environment of the space station using a shower head, and another that used fruit punch and foam to look at how to manage fluids in space. They also helped install new equipment inside the station that will be used in future scientific research.
Mr. Cassidy will remain aboard the station with two Russian astronauts, Anatoly Ivanishin and Ivan Vagner. All three are to stay on board through October when another crew of one American and two Russian astronauts will replace them.
When are the next Crew Dragon flights, and who will they carry?
The first operational flight of the Crew Dragon will launch no earlier than late September. It will take three NASA astronauts — Michael S. Hopkins, Victor J. Glover and Shannon Walker — and one Japanese astronaut, Soichi Noguchi, to the space station.
The second operational flight, tentatively scheduled for February 2021, will carry two NASA astronauts, Robert S. Kimbrough and K. Megan McArthur; Akihiko Hoshide of Japan; and Thomas Pesquet of the European Space Agency.
Ms. McArthur is married to Mr. Behnken.
Which other companies are building rides to space?
SpaceX’s counterpart in the commercial crew program, Boeing, will almost certainly not be able to launch astronauts until next year. An uncrewed flight last year suffered significant software errors, which prevented the spacecraft from achieving its primary goal of docking at the space station, and could have led to a loss of the spacecraft during its orbital test. Boeing will now repeat the uncrewed test later this year before putting astronauts aboard.
Closer to Earth, a couple of companies — Blue Origin and Virgin Galactic — are developing spacecraft that provide brief up-and-down tourist rides to the edge of space, although neither is capable of making the trip to the space station, or even to orbit.