NASA is building an extension to the International Space Station, the agency announced this week. It has awarded a $17.8m contract to Bigelow Aerospace to build the "Bigelow Expandable Activity Module".

Bigelow is company which specialises in expandable – inflatable, basically – orbital habitats. The module on the ISS is intended to be a trial run for the viability of that technology for future exploration, and commercial, endeavours.

NASA's Deputy Administrator, Lori Garver, said:

This partnership agreement for the use of expandable habitats represents a step forward in cutting-edge technology that can allow humans to thrive in space safely and affordably, and heralds important progress in U.S. commercial space innovation.

The inflatable technology allows much bigger habitats to be shipped in the same rockets that are currently used for launching standard ISS modules. A comparison on Bigelow's website [2] shows one of their proposed modules, a BA 330, alongside an ISS module:

Mark Thompson, writing for Sen, explained the technology behind the proposals [3]:

At the heart of the inflatable technology is a material called Vectran, twice as strong as Kevlar and present in several layers of the 15cm thick skin of the Genesis craft. The flexible nature of the material results in further added safety for potential station inhabitants, a benefit supported by laboratory tests. It was found that micrometeoroids that would puncture the rigid skin of the International Space Station only penetrated half way through the skin of the Genesis craft.

Tangentially relevant, but I've wanted to get it on the site for weeks, this video of Commander Sunita Williams giving a tour of the ISS is the longest YouTube video I have watched all the way through, because it is astonishing. Imagine how much better it will be when there's an inflatable module of twice the size attached: