In our younger and more vulnerable years nothing was greater than visiting a museum, going to the gift shop, and badgering our parents to buy a pack of astronaut ice cream. Freeze dried ice cream leaves a taste of nostalgic chalky sweetness in our mouths, so we’re very excited to see that [Ben Krasnow] is now making his own astronaut ice cream.
The basic principle of freeze drying is simple. All you have to do is reduce the pressure and temperature of the food below the triple point of water and pump the sublimated water vapor out. For [Ben], this meant he needed to cool his Neapolitan Klondike bar to -30° C in a bath of chilled ethanol and pump out the air with a vacuum pump.
Interestingly, [Ben] found it necessary to heat his ice cream while under vacuum to extract more water vapor. This makes sense; at the pressures he was dealing with, [Ben] would never come across water in a liquid state. The entire process took about 18 hours. [Ben] admits this may have been a little longer than necessary, but it’s a small price to pay for reliving childhood memories.