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’
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.