Watch replays of the Orion inflight abort test

Fueled segments of the solid rocket boosters that will lift off on the first flight of NASA’s Space Launch System have arrived at the Kennedy Space Center in Florida, but officials will hold off on stacking the boosters until the SLS core stage completes a crucial test-firing later this year.

Two U.S. astronauts and a Russian cosmonaut, all spaceflight veterans, launched from Kazakhstan aboard a Soyuz booster Wednesday to begin a two-day pursuit of the International Space Station. The crew docked with the orbiting research complex Friday at 1940 GMT (3:40 p.m. EDT) to begin a five-month stay.

Carrying a $2.7 billion NASA mission to Mars, a United Launch Alliance Atlas 5 rocket took off July 30 from Cape Canaveral and fired into a summer sky powered by four powerful solid rocket boosters and a kerosene-burning main engine.