Science

How SodaStream Gives You the Perfect Space Mission Finale

How does a do-it-yourself space architect keep his capsule upright? With soda pop carbonation canisters, of course. Rocket Shop blogger and Copenhagen Suborbitals co-founder Kristian von Bengston explains why.
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Apollo 11. Image: NASA

I have written many blog posts about the uprighting system for space capsule Tycho Deep Space. This is yet another (short) chapter in the saga.

The bags must be inflated when the capsule splashes down into the ocean to maintain a correct orientation of the capsule (also known as stable-1). Each of the four inflatable bags has a diameter of 700 mm.

AGA CO2 canister used for SodaStream: Image: AGA

We want to carry pressure tanks with us (NASA used a compressor on Apollo CM) and it will be CO2 due to volumetric challenges in the capsule design. So, how much CO2?

You can roughly state that 44 grams of CO2 will gives you 24 litters of atmospheric gas in normal room temperature.

Bag diameter: 700 mm
Bag volume: app 180 liters
To inflate 1 bar you need: 180/24*44 = app 330 grams of CO2

We have been looking around for off-the-shelf CO2 canisters, mainly used in maritime operations. There are canisters with 355 grams and 460 grams. All good because you need to inflate your bags just above 1 atm without destroying the bags. (How much will show in future tests.) They are also expensive and not easy to refill.

But just five hours ago I used my domestic SodaStream at home to create a nice cool bottle of club soda. And it hit me: Why not SodaStream bottles? They have optimal dimensions, hold 425 grams of CO2, are cheap, reliable and easy to refill in the city. 425 grams of CO2 may be too much (final bag pressure: 1.29 bars) but you can easily remove some of the pressure with your thumb. For those of the readers who do not know SodaStream, it is an old-school home soda maker which apparently has its revival at the moment..

Back in the days when SodaStream was combined with funny clothing. Image: Unknown

So, right now I want to place four SodaStream bottles in the space capsule. One next to each bag with an adapter bought on eBay providing a direct connection to some of our solenoid valves and from there to the bags.

If there are some CO2 left after splashdown you might make yourself a nice club soda while waiting for the recovery team to find you, way out in the Pacific Ocean.

Cheers!

Ad Astra
Kristian von Bengtson

Older posts related to uprighting system:
http://stag-mantis.wired.com/wiredscience/2011/11/space-capsule-buoyancy-and-uprighting-studies/
http://stag-mantis.wired.com/wiredscience/2012/01/tycho-deep-space-uprighting-work-continues/