Briefs: Cooling the Venus rover

One of the main technical challenges in sending a probe on Venus is the searing temperatures on the planet's surface: 450°C, enough to melt lead! Several probes landed on Venus in the 1970s and early 1980s, but never lasted more than two hours. Two NASA researchers have designed a refrigeration system aiming at keeping a robotic rover operative for up to 50 Earth days. Keeping the electronics cool is the main concern: these would be contained in a ceramic-based insulator, within a metal sphere the size of a grapefruit. The sphere would be cooled thanks to a Stirling cooler, which works with a double-piston system that alternately compresses and expands gas. This produces cryogenic temperatures on the one hand, while dissipating high temperatures on the other, via a radiator. But, in this case, in order to dissipate heat, the radiator would have to be hotter than the surrounding atmosphere, so the newly-designed radiator can reach 500°C, and cool the rover's electronic components at a mere 200°C!