BEAM successfully expanded at International Space Station
The Bigelow Expandable Activity Module (BEAM) was successfully expanded today, May 28, on board the International Space Station (ISS), two days after an attempt to inflate the module brought an unexpected pressure increase with little-to-no increase in size.
Expansion started just after 8 a.m. CDT (13:00 GMT) when NASA astronaut Jeff Williams opened the Manual Pressure Equalization Valve (MPEV) for 22 seconds to let in a burst of air inside BEAM. This got the pressure back and size back to where the module was two days prior.
Williams let in air manually in order to methodically increase the size of BEAM before the onboard tanks take over to pressurize the internal volume. The goal was to get the module to 68 inches (172 centimeters) above its packed length before using the onboard tanks.
At 8:13 a.m. CDT (13:13 GMT), Williams let in another 8 seconds of air through the MPEV. Williams began hearing popping sounds, which was to be expected. The sounds were reminiscent of the early stages of a bag of popcorn popping in a microwave.
“Pop, pop, one more pop,” Williams reported to ground teams.
Every burst of air resulted in a series of these sounds, heralding an increase in size of the module. The popping comes from the various ripstop stitches inside the module ripping out, as expected, to let the “skin” of the module expand outward.
At 8:38 a.m. and 8:52 a.m. CDT (13:38 and 13:52 GMT), Williams let in three-second and one-second bursts of air in, respectively, before the Ku-band video communications cut out, as expected. As such, expansion of the module was put on hold for about 40 minutes. The process requires video and daylight to proceed.
By the time of the loss of the video signal, the module had increased its length by about 14 inches (36 centimeters) with the diameter increasing as well. Also, the pressure in the module was approximately where ground teams had expected it to be.
Once video returned, there was one more one-second burst of air introduced into the Bigelow Aerospace module via MPEV. However, the pressure once again began to rise near the safe pressure limit.
This pressure curve is not a hardware limit on the module; rather, a precaution to ensure that if BEAM suddenly expanded rapidly, the inside pressure wouldn’t cause it to go so fast as to disrupt the stability of the ISS. As such, ground teams once again began to take the time to assess the situation to determine what to do next.
Ultimately, ground teams asked Williams to let an additional five-second burst of air into the module at 10:10 a.m. CDT (15:10 GMT) to see if that caused any more expansion. Williams then heard more popping sounds, indicating the module was, in fact, expanding.
After a few more pulses of air, for a total of 44 seconds so far, the module had expanded to just over 21 inches (53 centimeters) in length before going into another Ku blackout.
Once back, the module showed a vast increase in size. Williams then introduced another four seconds’ worth of air into BEAM, for a total of 48 seconds.
Over the next 30 minutes, the module expanded to 34 inches (86 centimeters) past the modules packed length—about half-way to the 68-inch (172-centimeter) goal.
“OK, Jeff, another lavish one second,” said the Capsule Communicator Jessica Meir, asking Williams to open the valve for the 15th time.
But for the longest time, no significant new motion was detected. That all changed just after 2 p.m. CDT (19:00 GMT).
“OK, Jeff, brace yourself for this one: eight seconds!” Meir said.
All of a sudden, the sound echoing into the Tranquility module sounded like fireworks going off as all the rip stop straps holding the layers down snapped, as expected.
“I gave it a little more persuasion,” Williams to another crew member.
Then Williams gave another 10 seconds of air, followed by 14 seconds a few minutes later.
“OK Jeff, great news for you, we’re gonna have you give it 30 seconds,” Meir said, accelerating the expansion process.
Finally, at about 3:10 p.m. CDT (20:10 GMT), after 25 bursts of air—for a total of 147 seconds—were released into BEAM, it expanded to nearly its full length and diameter. Ground teams declared the primary expansion complete.
The module increased from its original packed dimensions of 7.1 feet (2.16 meters) long and 7.7 feet (2.36 meters) in diameter to an expanded dimension of 12.2 feet (4.01 meters) long and 10.6 feet (3.23 meters) in diameter. The total expanded volume is 565 cubic feet (16 cubic meters).
Next, the secondary expansion process was achieved by eight tanks on board BEAM itself—pressurizing the module to 14.7 pounds per square inch. This took about 10 minutes and was completed at 3:44 p.m. CDT (20:44 GMT).
For the next 80 or so hours, ground teams will monitor pressure to assess if there are any leaks. If everything checks out as normal and safe, astronauts will enter the module to set up sensors for data collection. This will be the first time that astronauts have entered an expandable module in space. It was expected that crews would begin entering the module on June 2; however, with the delay, it is unclear if that date will hold.
The process originally started at 6:10 a.m. (10:10 GMT) May 26 when restraint straps were cut by pyrotechnics. Just like today, Williams was stationed in the vestibule between Tranquility and BEAM to monitor the process.
After a few bursts of air, the pressure began to rise resulting in an initial “bulge” at the Tranquility side of the module. However, the operation took longer than expected as slightly higher pressure than anticipated was observed. Just after 7:30 a.m. CDT (12:30 GMT), the ground team called off the rest of the expansion to assess the data before trying again today—successfully.
BEAM was delivered to the International Space Station by the CRS-8 Dragon capsule, which launched on April 8. It was attached to the aft berthing port of the Tranquility module just a few days later. The module will assess the viability of crewed expandable habitats in the future. After about two years, it will be unberthed and released from the station to burn up in the atmosphere a few months later.
Video Courtesy of SpaceFlight Insider
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.