Our original cryostat for the friction rig was awesome. We made lots of improvements to the way that temperature is monitored (with RTDs now, which have much less error) and in the insulation, etc. We started using a protocol of placing the rocks and metal at the desired testing temperature in a chest freezer over night before we start an experiment. So we've got it to where we can load a sample, give it an hour or two to really level out to a steady temperature, and then we can just let it run for hours to days of testing at constant T. Using that cryostat, we ran our first series of experiments on the temperature dependence of ice on rock friction, which was written up in this paper.
However, the lowest temperature it could achieve was about -20 deg C, determined by the chiller that circulates methanol+water through cooling blocks on the side of the cryostat. That's completely fine for terrestrial applications, but we want to also test planetary ice. So we need to go colder. Much much colder! That's why Mike has begun working on Cryostat 2.0. This cryostat will instead use methanol cooled by liquid nitrogen to flow through copper coils directly adjacent to the sample. The plus-shaped sample housing sits on top of stiff, insulating material.
It sits inside a box that will be insulated by creating a vacuum. More to come!
