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Mike's Spacesuit Diary Day 1 2 3

Day Three

Well the idea’s worked – by lunchtime on day three I’ve retrieved enough zeolite from the washing powder to go into the vacuum pump that Kathy and Jonathan have designed. What’s more, Iain’s managed to locate a good source of natural zeolite, and he’s brought back enough to make sure the pump will work effectively even without my ‘artificial’ material.

Yesterday wasn’t just spent separating out zeolite though. The thought occurred to me that we might be able to cool the water circulating around our spacesuit down even more effectively by using a bit of chemistry. Dissolving certain inorganic salts in water can bring about a cooling effect – the temperature of the water will actually drop. Only a few inorganic salts are capable of producing this effect, and ammonium chloride is one of them. But where can I get some from? In the chest on day one was a bag of ammonium sulphate fertilizer. By boiling this ammonium sulphate in water for 30 minutes or so with an equivalent amount of sodium chloride (table salt) I could actually make some ammonium chloride. OK, it would be contaminated with sodium sulphate (a by-product of the reaction), and I’d have no way of separating the two products, but it might just work.

And it did! From the boiled ammonium sulphate/sodium chloride solution that I’d left to cool overnight last night, beautiful white crystals of (albeit contaminated) ammonium chloride had formed. All I had to do was filter off the solid, dry it in air and then test it to see if dissolving it in water did actually produce a cooling effect. Lo and behold, when I added some of the dried ammonium chloride crystals to water, the temperature of the water dropped by six degrees Celsius. Amazing!

By 2 pm we were headed off to Death Valley to test out our spacesuit and vacuum pump. By the time we'd arrived, it was hot; 37 degrees Celsius. When we came to film, I decided to add just a third of the ammonium chloride that I’d made over the last couple of days. I wish I’d added it all now, because it turned out that we’d only have one shot at filming it. It would have been much better to have used the lot in one go. Nevertheless, adding even this amount of ammonium chloride to the system did actually give us a small temperature drop.

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Scientists Diaries

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