The past, present and future of inflatable space habitats

The past, present and future of inflatable space habitats

Recently, a prototype of an inflatable space station module built by Sierra Space violently exploded on a test stand at NASA’s Marshall Space Flight Center in Alabama. Under normal circumstances, this would be a bad thing. But in this case, Sierra was looking to blow off her handiwork. In fact, there was some disappointment when it failed to explode during a previous test run.

Explosion test unit life

That’s because the team at Sierra was looking to find the final thoracic pressure for the Large Integrated Flexible Environment (LIFE) module with a diameter of 8.2 meters (26.9 ft) — a realistic demonstration of how much air could be pumped into the pre-expanding structure. He twisted. NASA recommended a release of just under 61 psi, which is four times the expected operational pressure for a habitable habitat module.

By the time the LIFE prototype ruptured, its internal pressure was 77 psi. The results so far look very promising, but Sierra will need to repeat the testing at least two more times to ensure its materials and construction techniques can withstand the rigors of spaceflight.

Sierra is targeted for no later than 2026 for testing in space, but even if they set the date (which is always a questionable possibility for cutting-edge space projects), they would still be about 20 years late to the party. Despite how futuristic the idea of ​​inflatable space stations seems, NASA first began experimenting with the concept of expandable habitat modules in the 1990s, and there were practical examples launched into orbit by the early 2000s.

NASA TransHab

When NASA finalized plans for what we now know as the International Space Station, it was understood that most of the components of the orbital complex would need to be housed inside the space shuttle’s payload bay. In practice, this meant that the station units had to be largely cylindrical in shape, and no more than 18 meters (60 ft) in length. These standards alone were not particularly difficult to work with, as previous space stations from the United States and the Soviet Union faced similar limitations from their launch vehicles. The tricky thing was that the shuttle’s payload bay was only 4.6 meters (15 ft) wide.

While this allowed for slightly wider units than had been used hitherto Mer, it was a significant reduction when compared to Skylab’s 6.6 m (21.6 ft) diameter “Orbital Workshop” module. Seeing this as a potential long-term problem, NASA engineers turned to an idea originally conceived for a theoretical mission to Mars: an inflatable habitat module that could be packed into the shuttle’s payload bay and then expanded to its final size of 8 m (26 ft) once in a while. Orbit and filled with air.

The proposed module, known as TransHab, was to be divided into several floors providing living and work areas for the astronauts as well as ample storage space. There would have been six individual crew cabins, a designated exercise area, medical facilities, a fully equipped galley, and a large bedroom table that could be used for all-hands meetings or group meals.

Unfortunately, due to delays and cost overruns in the overall ISS program, NASA was ordered to halt research and development on inflatable modules like the TransHab in 2000. Instead, construction began on a simpler habitation module that could fit inside the shuttle, but ironically , this too was eventually cancelled.

Even today, there is no official “habitat” module on the International Space Station, but instead sleeping, eating and exercise facilities are spread throughout the station.

Bigelow Aerospace

While NASA was barred by House Resolution 1654 from working on its own inflatable station modules, the bill included language saying the space agency could lease such a module if it was built by private industry. After hearing about TransHab’s cancellation, entrepreneur Robert Bigelow contacted the space agency and was able to secure the rights to commercialize the research they had already conducted on inflatable modules through his company Bigelow Aerospace.

TransHab’s development was largely conceptual at this point, and Bigelow Aerospace spent the next several years taking NASA’s ideas and turning them into a practical test article. One of the improvements they made was adding Vectran to the inflatable hull. This synthetic fiber is twice as strong as Kevlar, is woven from a liquid crystal polymer, and has previously been used in an airbag that allowed… Pathfinder To land safely on Mars in 1997.

Genesis I

In 2006, Bigelow Aerospace advanced NASA’s original concept to the point that they were ready to launch a working prototype.

the Genesis I The unit is 4.40 meters (14.4 ft) long, and was expanded from its original diameter of 1.60 meters (5 ft 3 in) at launch to 2.54 meters (8 ft 4 in) in a process that took approximately 10 seconds to complete. Its solar arrays provided power for the onboard diagnostic systems and more than a dozen cameras that recorded inflation from inside and outside the unit.

Designed to work for six months, and Genesis I The unit transmitted data back to Bigelow Aerospace for two and a half years before finally disappearing. While the onboard systems stopped transmitting useful data, the structure itself remained completely intact with no signs of loss of pressure or other deterioration.

currently, Genesis I It remains in a stable orbit of 463 x 471 km (287 x 292 mi) with an inclination of 64.5 degrees, and is designated as NORAD 9252 and COSPAR 2006-029A.

Genesis II

Following the success of the unit’s prototype, Bigelow Aerospace was launched Genesis II A year later in 2007. This second unit was largely identical from an external and mechanical standpoint, but added more cameras and reaction wheels that allowed the unit to better orient itself in space, an improved gas inflation system, and an upgraded sensor suite.

Like its predecessor, Genesis II transmitted data for more than two years, remaining in a very similar 452 by 505 km (280 by 314 mi) orbit. It is designated as NORAD 31789 and COSPAR 2007-028A.

Bigelow Expandable Activity Module (BEAM)

After nearly a decade of additional development, Bigelow Aerospace finally supplied NASA with an inflatable module for the International Space Station in 2016. The space agency paid $17.8 million for the module, and it was delivered to the station inside the unpressurized box of a SpaceX Dragon vehicle. From there, the Canadarm2 robotic arm was used to attach the BEAM to the vehicle’s rear port Calm and tranquility lonliness.

The BEAM expansion progresses over seven hours.

Unlike twins origin Modules, BEAM can expand their length and diameter. When placed in the dragon’s chest, it was 2.16 meters (7 ft 1 in) long and 2.36 meters (7 ft 9 in) in diameter. After a seven-hour expansion process, it reached 4.01 meters (13.2 ft) in length and 3.23 meters (10.6 ft) in diameter.

The fully developed inflatable unit would have included internal fixtures and equipment, but being a test article, the interior of the BEAM was just an open space. After observing the unit for a year, it was decided to use it for storage, and the interior of the BEAM was fitted with fabric bags. After engineering evaluation in 2019, NASA determined that the module would remain attached to the International Space Station until at least 2028.

ESA astronaut Paolo Nespoli inside BEAM

Unfortunately, Bigelow Aerospace laid off all of its employees in March 2020, and the company ceased operations entirely in 2021. Although no official announcement was ever made, the company is now considered defunct.

Space Sierra

With Bigelow Aerospace out of the race, Sierra Space has emerged as a new leader in space-related expandable structures. The company spun off from Sierra Nevada Corporation in 2021, and is primarily focused on developing not only the Large Integrated Flexible Environment (LIFE) module, but also the Dream Chaser spaceplane. The ultimate goal is vertical integration, with the Dream Chaser transporting crew and cargo to a space station made up of LIFE modules.

Sierra’s multi-layer inflatable technology includes a Vectran “confining layer,” which the company says makes its units stiffer than steel once fully inflated. They also developed a way to place openings, such as windows or air locks, in the inflatable walls of the module while exceeding the pressure ratings required for NASA certification. This capability promises to significantly expand the potential functionality of inflatable units, which were previously designed only with openings at both ends of the cylindrical structure.

Each layer of the inflatable structure has a specific function.

The module Sierra Space recently tested was a full-scale prototype of what the company calls LIFE 1.0: an enlarged 300-cubic-meter structure that is 6 meters (19.6 ft) long and 9 meters (29.5 ft) in diameter, and can be launched in a standard 5-meter payload ( 16.4 feet). This would make it compatible with rockets like the SpaceX Falcon 9 and the Vulcan that debuted from United Launch Alliance.

The next development will be LIFE 2.0, which will double the length of the module to 12 meters (39.3 ft) to achieve an amplified volume of 600 cubic meters while retaining the same diameter to remain compatible with existing launch vehicles. Sierra Space also has long-term plans for LIFE 3.0, a massive 1,440-cubic-meter module that will have a usable volume larger than the entire International Space Station. With a length of 16.2 meters (53 feet), a bulbous diameter of 11 meters (36 feet), and a stuffed diameter of 7 meters (23 feet), putting LIFE 3.0 into orbit would require a next-generation launch vehicle like NASA’s. SLS Block 1B Cargo, SpaceX Starship, or New Glen from Blue Origin.

Next steps

Tropical coral reef concept

According to Sierra Space’s press release, 2024 will be a busy year. There will be several other tests, both full-scale and sub-scale, and they will also be working on micrometeoroid orbital debris (MMOD) layers that will be crucial to protecting the module from the inevitable impacts that will come with long-duration spaceflight.

As for the first practical application of this technology, Sierra Space and Blue Origin are working together to develop the Orbital Reef commercial space station, which is scheduled to have at least one LIFE module as part of its basic configuration. NASA awarded the Orbital Reef Project $130 million in December 2021, with the goal of having it up and running by the time the International Space Station retires, which is currently scheduled for sometime in 2030.

While it seems like it won’t happen on the International Space Station, with any luck, NASA’s dream of having astronauts living and working in an inflatable space station could become a reality before the end of the decade.

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