CAPE CANAVERAL, Fla. — Space station astronauts opened the world’s first inflatable space habitat today and floated inside.

NASA astronaut Jeffrey Williams swung open the door to the newly expanded chamber today and was the first to enter.

The room — called the Bigelow Expandable Activity Module, or BEAM — arrived at the International Space Station in April, packed in the trunk of a capsule loaded with supplies. It was inflated just over a week ago.

Williams reported that the room was pristine but cold. There was no trace of condensation, he noted. Mission Control said the temperature registered 44 degrees, as anticipated, at one end of the 13-foot-long, 10 ½ -foot-wide chamber.

For now, BEAM is empty and dark; Williams and Russian cosmonaut Oleg Skripochka wore head lamps to illuminate the crinkled, silver walls. They collected air samples, took expansion measurements and made sure the air-pressurization tanks were empty, before exiting and closing the door behind them.

The six-man station crew will deploy more sensors and other gear over the next few days. After each brief entry, the hatch will be sealed. Mission Control anticipates just six or seven entries a year.

NASA wants to make certain the multi-layered BEAM — an experiment led by Bigelow Aerospace — can withstand wide temperature fluctuations, radiation and debris impacts over time. It will remain at the orbiting lab for two years.

The Nevada-based Bigelow is developing even bigger and better inflatable habitats for space travel. Until BEAM, the company founded by hotel entrepreneur Robert Bigelow had flown only a pair of inflatable satellites in orbit for testing.

Both Bigelow and NASA envision using pumped-up habitats for Mars expeditions. Inflatable spacecraft are lighter and more compact for launch than the traditional metal housing for astronauts, yet provide roomier living quarters once expanded.

First Published June 6, 2016, 5:11 p.m.