Zeolite-loaded aerogel as a primary vacuum sorption pump in planetary instruments

Abstract

Zeolite-loaded aerogel (ZLA) getters were devised and developed for maintaining vacuum in the Seismic Experience for Interior Structure (SEIS) instrument on the NASA InSight mission to Mars. The ZLA are very lightweight compound materials (~ 0.1 g/cm3) with tunable density and high surface area (~ 500 m2/g), capable of maintaining high vacuum (HV, < 10−3 mbar) for extended periods of time at room temperature without any maintenance or consumption of power. Low temperatures, such as the surface environments on Mars and the icy worlds, enhance the ZLA adsorption by orders of magnitude, extending their capacity to the deep HV range sustainable over multi-year missions. Selective adsorption properties for species of interest can be further enhanced by cation exchange (Na+, Ca2+, Mg2+, Pd2+, etc.) prior to the zeolite incorporation in the material. The sol–gel process was formulated to produce homogeneously dispersed micron-sized zeolite particles embedded in the aerogel matrix. The ZLA liquid precursor can be cast in practically any shape prior to the formation of the solid wet gel, which is then dried supercritically. The resulting mesoporous aerogel network provides excellent molecular transport to the zeolite particles. For particle sensitive instruments such as SEIS, the ZLA adsorbers can be isolated by sub-micron filters without noticeable effects on their performance.