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The tides of Venus

Inflatable space modules: NASA’s exciting expansion plan

Jerry Downs/Flickr

I was sat in the garden over the weekend looking up at the cloudless blue sky and noticed what looked like a bright star moving steadily across the sky. My first thought was that I had spotted the International Space Station (ISS), which has been making a number of passes over Australia in recent weeks (have a look a Canadian astronaut Chris Hadfield’s twitter feed).

But closer inspection (with hastily grabbed binoculars) revealed that the object was in fact a group of four balloons floating to obscurity, probably with an ex-owner howling on the ground a few miles from me.

There’s going to be a few more balloons in the space above our heads in the near future, with NASA announcing last week that it had commissioned a new “expandable” space module from Bigelow Aerospace. It’s an exciting venture that will attach to the ISS and be tested by the astronauts on board as early as 2014.

How the Bigelow module will look attached to the ISS. NASA/Bigelow Aerospace

The use of inflatables in space is not a particularly new concept. Massive weather balloons that float to the edge of space are easy to pilot; even a chicken can fly one. And the plans for an expandable space module have been on the agenda for quite a while – in fact the original designs for the ISS incorporated one until it soared over budget.

It’s a stupendously good idea, given that every gram you send into space costs thousands. The more space you can pressurise for less money brings the ideas of inter-planetary travel and even habitats on Mars a step closer.

But in space there is nothing to slow you down, and the most microscopic of dust particles can become bullet-like in their impact on a structure. Any blow-up module needs to be strong enough to withstand this, almost constant, bombardment.

Creating a material that is both strong and light has been a grand challenge for scientists. Metals have been a staple in this search, with clever control of the microstructure producing some pretty amazing results. From the jet-engine alloys that get stronger with temperature to the memory metals, the understanding of their microscopic properties has been key to unlocking these properties.

Using microscopes to make metals strong and light, the winner of the 2012 ‘Dance your PhD’ competition from University of Sydney.

But metals are still too heavy, and are not flexible enough to make up most of the strength of the new space module’s skin. The plan is instead to have a number of layers, 6 inches thick, with the chief strength coming from a polymer material.

Similar to the material used in bullet-proof vests it’s hoped that the combination of layers will, once expanded, be like concrete in their strength. These (heavily patented) polymer materials also have an added bonus in that they provide better radiation protection for the astronauts, in that they avoid the secondary scattering that the current (metal based) space station induces.

2012 was the year that commercial space developments became a reality. The flight of the Dragon X spacecraft delivering to the ISS and now the news of Bigelow Aerospace’s “expansion” into the sector shows that private investment in space is fast becoming real and tangible.

I know I’ve expressed squeamishness before at the idea of private companies mining asteroids, but I’m rapidly coming around to these new developments in commercial space travel. If they need anyone to test the expandable spacecraft I’d be the first to put my hand up.

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