ABSTRACT
This overview of low temperature materials in the universe is by no means exhaustive or unbiased. However, it is intended to give the reader a quick glance into the low temperature materials present in space, what we know, and what we still need to understand. When we speak about cryogenic temperatures, we would like to de†ne the temperature as
the meaning varies for different communities. The general de†nition is unconstrained-very low temperature. For the purposes of this section, we will use the cosmic microwave background (CMB) thermal radiation at 2.72548 K [Fixsen 2009] as the lowest limit and the crystalline water-ice sublimation temperature at ~160 K as the higher temperature limit. This range covers a wide variety of bodies in the solar system and beyond into the interstellar medium. Although sub-Kelvin temperatures are reached in laboratories on Earth, their relevance to astrophysics and planetary sciences (space conditions in general) is not immediately evident. Our sun is one of the few billion stars in our galaxy and our Milky Way galaxy is one
among the several billion galaxies in the universe that are visible both to the naked eye and to instruments in our possession such as space telescopes. Recent developments in exoplanet research increased the potential for the existence of habitable solar systems like ours in our galaxy [Kerr 2013; Schilling 2007; Schwarzschild 2014]. Thus, understanding materials in our solar system that occur under cryogenic conditions would help in understanding many other such solar systems as well as the interstellar medium.
