Once the checks and installations were complete, Williams left the module and closed the hatch. ISS crew will enter BEAM a few more times through Wednesday to check sensors and gear inside.

NASA astronaut Jeff Williams is shown here in the Bigelow Expandable Activity Module (BEAM) on June 6, 2016 (the picture was taken from outside the BEAM hatch). Astronauts will not occupy BEAM ...

The second Mercury mission was going according to plan until the Liberty Bell 7 capsule sank in the ocean. NASA exonerated astronaut Gus Grissom, and two researchers now say they know what happened.