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NASA Releases Details of Titan Submarine Concept
Zothecula writes: Now that NASA has got the hang of planetary rovers, the space agency is looking at sending submarines into space around the year 2040. At the recent 2015 NASA Institute for Advanced Concepts Symposium, NASA scientists and engineers presented a study of the Titan Submarine Phase I Conceptual Design (PDF), which outlines a possible mission to Saturn's largest moon, Titan, where the unmanned submersible would explore the seas of liquid hydrocarbons at the Titanian poles.
"At its heart, the submarine would use a 1 kW radiothermal Stirling generator. This would not only provide power to propel the craft, but it would also keep the electronics from freezing. Unfortunately, Titan is so cold that it's almost a cryogenic environment, so the waste heat from the generator would cause the liquids around it to boil and this would need be taken into account when designing the sub to minimize interference. However, NASA estimates that the boat could do about one meter per second (3.6 km/h, 2.2 mph)."
"At its heart, the submarine would use a 1 kW radiothermal Stirling generator. This would not only provide power to propel the craft, but it would also keep the electronics from freezing. Unfortunately, Titan is so cold that it's almost a cryogenic environment, so the waste heat from the generator would cause the liquids around it to boil and this would need be taken into account when designing the sub to minimize interference. However, NASA estimates that the boat could do about one meter per second (3.6 km/h, 2.2 mph)."
What you're describing is an incredibly challenging tasks. One needs several missions to get to better know Europa in general, and specific potential entry areas in particular, first. These missions are going to be expensive and have long lead times. And an actual boring / submersible mission is going to be extremely expensive.
Titan has one main strike against its exploration, that it's so dang far away. But almost everything else about it is tailor-made for exploration. It's ideal for aerocapture. It's trivial to stay aloft, at an altitude of your choice, be it by hot air or lifting gas balloon, blimp (likewise), helicopter, fixed-wing aircraft, tilt-wing aircraft, etc. Low temperatures pose some difficulties but can be nice for electronics, and the rate of heat loss (even in a hot air balloon concept) is so low at such low temperatures that you don't need very big heat sources. The hydrocarbon seas are permanently exposed for whatever means of exploration (aerial, boat, submarine) you choose. Ascent requirements (sample return, for example) are surprisingly low versus a body of that size due to the ability to fly so high in the significant pressure / low gravity environment before needing to fire rockets. And so forth. And there's so darn much we don't know about Titan, perhaps even more than Europa. There's constant complex organic chemistry going on in the upper atmosphere of which we know almost nothing, and probably even some on the surface. There's probable liquid water under the surface and cryovolcanoes that erupt it to the surface. There's earthlike weathering processes done with/to completely different materials, and the entire gas cycle is a giant mystery right now. So yes, I'm pretty excited about whatever mission goes to Titan next.
Too bad the next launch window to Saturn (2018, 4,13km/s delta-V, 8,2 years) is simply not going to happen. : There's not going to be such a low delta-V/time window for a long time - 2020 is 5,18 km/s / 11,0y; 2021 is 4,80km/s / 8,8y; 2024 is 4,81km/s / 10,4y; etc. So if we're lucky maybe we could get the 2021 window (though the increased delta-V reqs would significantly hurt the payload)... otherwise, there won't be a spacecraft getting to Saturn before the mid 2030s. :
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Yes it's used. Yes even for space applications. No it have nothing to do with perpetual motion machines...