They need at least one module lined with thin sheet aerogel, which exists, and is an astoundingly efficient insulator. A sheet just 3 millimeters thick insulates as well as several feet of fiberglass.
http://www.jetsongreen.com/2010/02/aerogel-ultra-thin-super-insulation.html
https://www.youtube.com/watch?v=5sw1tNeJ0Rw
I’m curious how they’re still tweeting.
I need that for my icehouse.