NASA astronauts Bob Behnken and Doug Hurley will be geared up for the long haul when they launch from the Kennedy Space Center on a SpaceX Crew Dragon spacecraft later this month, but they won’t know exactly how long they will be in orbit until they are already aboard the International Space Station.

The Crew Dragon docked at the space-facing port of the lab’s forward Harmony module at 3:15 p.m. EST, 34 hours after launch Friday from the Kennedy Space Center atop a Falcon 9 rocket.

Eight days after a dramatic spacewalk to inspect the site of a leak in the hull of his Soyuz ferry ship, Russian commander Sergey Prokopyev, German flight engineer Alexander Gerst and NASA astronaut Serena Auñón-Chancellor geared up to depart the International Space Station Wednesday for a fiery plunge back to Earth.