Inflatable space habitat passes first hurdle, now on to radiation testing

It has now been a year since NASA successfully expanded a habitat attached to the International Space Station, the experimental Bigelow Expandable Activity Module. Initial tests on the module suggest that expandable habitats may play an important role as NASA considers how best to expand human activity into deep space.

During the first year, NASA and its astronauts on board the station have sought primarily to test the module's ability to withstand space debris—as a rapidly depressurized habitat would be a bad thing in space. And indeed, sensors inside the module have recorded "a few probable" impacts from micrometeoroid debris strikes, according to NASA's Langley Research Center. Fortunately, the module's multiple layers of kevlar-like weave have prevented any penetration by the debris.

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While NASA will continue to monitor the module for debris, the agency's focus is now turning toward radiation. Bigelow officials have said the company's inflatable habitats should be as good as, or better than, the space station in terms of limiting radiation. Unlike the station’s metallic shell, which scatters radiation from solar flares, the non-metallic skin of the expandable module should reduce this scattering effect.

3D printing radiation shields

With the installation of two "radiation environment monitors" inside the Bigelow module, researchers at NASA have measured radiation levels and found the dose of cosmic rays to be comparable to those inside the rest of the station. This work will continue to try to understand whether the Bigelow module is any better than the station's aluminum shell.

Now, scientists will take that a step further. Using a 3D printer manufactured by Made in Space, which produces materials from a low-temperature plastic feedstock, astronauts have made "shields" to cover one of the two radiation sensors inside the Bigelow module. The first hemispheric shield is just 1.1mm thick, but successive shields will be thicker, 3.3mm and 10mm. The basic idea is to understand the shielding protections of the module, and other materials, as NASA contemplates human missions beyond the protection of Earth's magnetosphere.

At present NASA is holding a competition among several aerospace firms, including Bigelow, to design concepts for a deep space gateway that will orbit around the Moon and represent humanity's first toe hold beyond low Earth orbit. Tests during the next year will go a long way toward determining whether inflatables, which weigh less, offer more habitable volume, and can be folded into a smaller rocket payload fairing, will play a significant role in NASA's next step.