Sierra Space, a commercial space company, is gearing up for a momentous event as it prepares to conduct its largest-ever “burst test” of its inflatable, expandable space station technology. This groundbreaking endeavor is a crucial step in Sierra Space’s collaboration with Blue Origin on the development of Orbital Reef.
The company plans to stress test a full-scale version of its LIFE habitat structure, pushing it to failure under pressure for the first time in history. The LIFE habitat is made of high-strength “softgoods” materials, such as sewn and woven fabrics, that become rigid structures when pressurized in space. Sierra Space has previously conducted five stress tests on smaller versions of the habitat, but this upcoming test will be 18 times larger, with nearly 300 cubic meters of pressurized volume.
Scheduled for December 2023 at the NASA Marshall Space Flight Center in Huntsville, Alabama, the Ultimate Burst Pressure (UBP) test is expected to provide Sierra Space and the Orbital Reef program team with crucial data to support NASA’s softgoods certification guidelines. The test, which involves over-pressurizing the habitat until it fails, will not only demonstrate its capabilities but also pave the way for structural enhancements.
Sierra Space’s expandable space station module technology is highly scalable and flexible, compatible with various launch vehicle fairing sizes. The softgoods structures are packed inside conventional rocket fairings and inflate to their full capacity in space. This means that low-volume launches can transform into high-volume space stations. The volume of the module will always be the square of its expansion diameter. For example, a 2.5x expandable configuration would result in a volume 6.25 times that of a rocket fairing.
According to Sierra Space CEO Tom Vice, their inflatable space station module technology offers the largest in-space pressured volume, the best unit economics per on-orbit volume, and the lowest launch and operating costs. This positions Sierra Space as the leader in microgravity research and product development, providing customers with an attractive return on investment.
The full-scale LIFE habitat has a height of 20.5 feet (29.5 feet including ground support equipment) and a diameter of 27 feet. Its volume is approximately 10,000 cubic feet (283.17 cubic meters). Currently, all components and ground support equipment are in the integration phase at the NASA Marshall Space Flight Center.
The next steps involve integrating the softgoods into the test stand, followed by transportation to the testing location using the NASA KAMAG transporter tractor. The testing will take place adjacent to the flame trench of the Saturn 1/1B test stand, where NASA tested rockets for the Apollo program. Setup, calibration of sensors and cameras, and operational run-throughs will prepare for the full-scale UBP test in December 2023.
The objectives of this test include refining Sierra Space’s technical approach to safety factors and structural integrity, as well as advancing their manufacturing processes based on insights gained from previous tests. The company’s confidence in undertaking the full-scale burst test has been bolstered by the recent successes of subscale tests.
The LIFE habitat’s restraint layer is made of high-strength softgoods materials, primarily Vectran, which become rigid structures when pressurized. Under normal operating pressure, these materials become five times stronger than steel, surpassing safety factors for the lifetime performance of the station. The restraint layer also includes a bladder for controlled inflation and pressurization during the ultimate burst pressure test failure. Additionally, two metallic blanking plates are strategically inserted into the restraint layer to seamlessly integrate windows, airlocks, robotic arms, and other features into the softgoods layer with minimal performance degradation or knockdown.