Magical Thermal Insulation Material - Aerogel

The surface of Mars is much cooler than Earth, with a minimum temperature below -100°C. In such a low temperature environment, how does the rover solve the problem of thermal insulation?

In fact, spacecraft in Earth orbit and probes on the lunar surface are also faced with harsh temperature environments. In order to maintain spacecraft equipment working in a relatively comfortable temperature environment, generally by putting on the spacecraft a kind of insulation called multi-layer thermal insulation components "Clothes" so that the spacecraft will not be affected whether the external environment is cold or hot.

However, the multi-layer thermal insulation component has good thermal insulation performance only in a vacuum. In the carbon dioxide gas environment of about 800Pa on the surface of Mars, its thermal insulation effect is lost. That's why the rover needs to be insulated with aerogel.

Aerogel is a nanoporous solid material in which the dispersion medium is gas, and the colloidal particles or polymer molecules are aggregated into a network structure. The basic particle diameter of the aerogel network structure is 1-20 nm, and the pore size is 1-100 nm. Since the pore size in the material is smaller than the mean free path of air molecules, gas convection can be effectively suppressed.

So, what's so magical about aerogels?

1) Good thermal insulation performance

The thermal conductivity of PTFE used for thermal insulation is 0.27W/(m•K), while the thermal conductivity of nano-aerogels is generally 0.02W/(m•K), which is only 1/13 of that of PTFE. . This is because carbon dioxide gas is stagnant in small gaps in the Martian atmosphere, so that convective heat transfer cannot be developed. The microstructure of aerogel is relatively thin, and the heat transfer path is long, which reduces the heat conduction capacity. Therefore, the low-density nano-aerogel material is the best thermal insulation material for the thermal control system of the Mars rover.

(2) Light weight

The density of iron is 7800kg/m3, which means that 1 cubic meter of iron weighs 7.8 tons; the density of air is 1.29kg/m3, which means that 1 cubic meter of air weighs 1.29 kilograms. The density of the aerogel used by the Mars rover is 30kg/m3, which is about 23 times that of air. During the production of aerogel, the liquid in the gel is replaced by gas, forming a lot of holes and structural cells, so the density is extremely low.