Having been attached to the International Space Station for six months, the Bigelow Expandable Activity Module, better known as BEAM, is already providing data that will inform the design of future human-rated expandable space habitats. The module was launched on April 8 by SpaceX's CRS-8 Dragon cargo vessel and was attached to the station's Tranquility module and expanded in late May.

BEAM was designed to be the first expandable module for the International Space Station (ISS). Engineers and scientists wanted to learn how such a structure operates in real space conditions. They intended to see just how feasible an expandable living module would be, not only for the ISS but also for future manned habitats for deep space missions such as to the Moon and to Mars.

On Sept. 5, Expedition 48 astronaut Kate Rubins entered BEAM to conduct tests and replace various sensor parts. Photo Credit: NASA

Despite some initial difficulties expanding the habitat in late May 2016 – probably due to the module being tightly packed for over one year before its launch – the Expedition 47 astronauts aboard the ISS were eventually able to get the large, white, spherical module to expand to its full extent.

On June 6, 2016, NASA astronaut Jeff Williams entered BEAM for an initial inspection. Over the next two days, he added more sensors and air ventilation ducts inside the module and also took surface and air samples to see if any microbes were living inside.

Sensor Success

Inside the module, there are many different kinds of sensors, each serving a different purpose. Bulkhead accelerometers measured the structural dynamics of BEAM as it was first deployed. Wireless thermal sensors assess the performance of the module's exterior fabric shell layers and the metallic bulkheads. Active and passive dosimeters measure how much cosmic radiation gets through the habitat's hull. Sensors for the Distributed Impact Detection System (DIDS) monitor for any impacts on the module's exterior by space debris and indicate where the hits occur.

Steve Munday, BEAM Manager at NASA's Johnson Space Center (JSC) in Houston, Texas, noted that the module and its sensors have mostly performed as designed. "Through the NASA sensor suites on board, our teams on the ground, and astronaut support on [the] station, we're gaining extremely valuable data about the performance of expandable structures and habitats in space," he said.

Among the sensor data returned to Earth, BEAM was actually found to be warmer than predicted; in particular, during its packed mode right before being deployed. One suggested reason for this result was that less contact between the folded layers of the technology demonstrator module actually produced more heat insulation than engineering models predicted. This finding is useful, as the module requires circulated air from the rest of the ISS for its warmth.

"A colder-than-expected BEAM would have increased the risk of condensation, so we were pleased when Jeff first opened the hatch and found the interior to be bone dry," said Munday. "BEAM is the first of its kind, so we're learning as we go and this data will improve our structural and thermal models and analyses going forward."

BEAM Testing Continues

Temperature data for various sensors on BEAM graphed from June 7 to Aug. 22, 2016 (click to enlarge). Image Credit: NASA

ISS astronauts were especially busy with their newest station section in September. Among their tasks was the rebooting of a crashed sensor-data relay laptop, reinforcing instruments that had loosened since the module's installation, as well as collecting additional samples for examination back on Earth.

On Sept. 5, NASA Astronaut Kate Rubins entered BEAM and replaced the DIDS battery packs after the system's drained batteries began to disrupt wireless communications with the sensors. DIDS had its power settings remotely configured by ground operators as well, to be more efficient and prevent further disruptions.

Rubins entered BEAM again on Sept. 29 to conduct a series of modal tests. These tests assess how the module responds to vibrations due to impacts and how the habitat is able to reduce and dampen these vibrations.

NASA and BEAM's manufacturer, Bigelow Aerospace, both find the module to be functioning mostly as expected and returning valuable engineering data. The initial deployment, back in May, created loads on the rest of the space station that were quite manageable. There have, so far, been no large debris impacts on the module, and the cosmic radiation levels it receives are no different than those throughout the rest of the ISS.

Although scientists at JSC want to keep monitoring how the module handles pockets of radiation "trapped" in Earth's orbit, especially from the South Atlantic Anomaly. This data will be particularly important for future inflatable modules traveling on deep space missions lasting years.

"The two-year BEAM mission on ISS provides us with an early opportunity to understand how expandable habitats perform in space," said Munday. "We're extraordinarily fortunate to have the space station and its crew to help demonstrate and assess BEAM technology for use in future exploration missions."