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But then there seems to be a contradiction here. If the ESA was planning to use an RHU powered by plutonium-238, which resource (your word) or technological cap
by guscost 12y ago
But then there seems to be a contradiction here. If the ESA was planning to use an RHU powered by plutonium-238, which resource (your word) or technological capacity (from the IANUS paper) were they missing that prevented them from using a plutonium-238 RTG? Money?
- alexbecker 12y agoIt would have made the lander heavier, thereby increasing the size and cost of everything else.
- fbender 12y agoRHUs are in no way comparable to RTGs: They are basically very small amounts of radioactive material fully enclosed in a thermally conductive container. Think of it as an always warm pebble stone. They are unregulated sources of (almost) constant heat and have no other purpose. In aerospace engineering, they are used in just a few circumstances to augment the active heaters in a spacecraft: Heater lines, which are resistive heaters in a foil with a PI controller. You need active thermal control since your environment changes a lot (launch, preliminary orbit, transit, orbit) and thus its thermal parameters (some parts of a spacecraft may experience temperature gradients of a few hundred Kelvin within a few minuts). Most spacecraft designs have issues with overheating and thus RHUs cannot be used here. An RTG's primary objective is to produce electrical energy (at an abysmal efficiency). The excess heat generated by an RTG is seldomly used for thermal control since it can also not be regulated and it emits simply too much heat energy.