(September 11, 2017 at 3:18 pm)vorlon13 Wrote: A more specific concern about that was the RTGs on Cassini. After an impact onto an icy surface, the RTG 'debris' will continue to radiate heat for thousands of years. In fact, since the RTGs were engineered to withstand a worst case launch failure scenario at Cape Kennedy, it is possible there would be somewhat intact, or 'less dispersed' RTG debris in a possibly aqueous environment. Additionally, the radiation dosage Cassini received at Saturn was far less than Galileo, for instance, received at Jupiter. Also, Cassini itself has numerous heaters throughout, and there are areas in it that have not been outside of a rather tolerable temperature environment since it's construction and launch.
So, the possibility of culturing live bio samples from Cassini even today is not a zero, and an impact onto an icy surface would not necessarily kill them, and the on board RTGs would continue to maintain a possibly benign environment for them for potentially thousands of years after such an impact.
And we (the US) has signed a treaty controlling disposition of such space flown hardware . . . .
A construction designed to not be too shattered by an impact with the ground at terminal velocity in earth's atmosphere does not stand an RTG in good stead in the case of an impact at orbital speeds with a large solid body. There is an 2 order of magnitude difference in impact velocity and 4 order of magnitude difference in pact energy. If the RTG shatters any warmth the smitherines provide will be attended by lethal radiation. Even if the RTG were to survive more or less intact and melt a patch of ice and keep it liquid for thousands of years with its waste heat, that is still a very short period for microbes to evolve. Any microbe adopted to the pool heated by the RTG is unlikely to survive once RTG's heat output peters out.
Last but not least, we need a lifeboat for some life on earth! Damn it!
