The module, called the Bigelow Expandable Activity Module (or BEAM for short), is a prototype for future space habitats. BEAM was developed for NASA by Bigelow Aerospace and launched to the station on a SpaceX Falcon 9 rocket in April. The module was then installed on the station's exterior on April 16, with the expansion set for May 26.
Wednesday's planned test was scheduled to last for two hours as astronauts used the station's Intermodule Ventilation fans to move air from the station to the BEAM. During April's prelaunch press conference, Robert Bigelow, the company CEO, explained that the module packed its own supply of gas and will use that to reach station pressure after it's been initially inflated.
At first, Wednesday's test seemed to go as planned. The restraining straps securing the BEAM in place were released as scheduled. Ground controllers then gave NASA astronaut Jeff Williams the go ahead to begin inflation. By turning a valve, Williams began to slowly transfer air from the station into BEAM.
At that point, the BEAM should have started expanding, but the module didn't expand as expected. Due to BEAM's lack of movement, NASA and Bigelow decided to pull the plug and review their data before making another attempt.
Engineers have spent the past 24 hours studying data collected from the expansion attempt and are confident that it will work the second time around. The BEAM is connected to the space station, so if anything goes wrong with the expansion, it could potentially have a disastrous effect on the ISS. So, NASA and Bigelow are being cautious.
One of the goals of this first test was to determine how soft materials (like the BEAM) interface with metallic structures (like the ISS). The module is made of a kevlar fabric much like a bullet-proof vest. As compressed fabric expands, it can rub against itself, creating friction.
The BEAM module was packed up for longer than first expected due to launch delays resulting from last year's launch failure. It takes time for fabric to relax once it's been compressed, so during their first attempt, engineers noticed more forces acting against the expansion than computer models had predicted. After analyzing the data, engineers think this was due to fabric friction.
"While we were expanding, we experienced higher forces than our models predicted," Jason Crusan, director of Advanced Exploration Systems at NASA Headquarters in Washington, explained during a media teleconference. "We think that friction forces between the fabrics were working against us."
On Friday, NASA announced that they would make a second attempt at expansion today (May 28) at 9 A.M. EDT, which you can watch live on NASA TV right now.
To prepare for today's attempt, the BEAM was fully depressurized.
According to both NASA and Bigelow, cycling the pressure by deflating and reinflating should help relieve the friction forces and make it easier to inflate. Today's test will start from an unpacked position, which will hopefully solve the friction issue. Once the module is inflated, there will be an 80-hour leak test before the crew is allowed inside to check it out.
On Friday, both NASA and Bigelow stressed that since the module will be on station for two years, there's no rush to expand it. They will take their time and if today's expansion attempt proves to be unsuccessful, we won't see another one before next Thursday.