vlad the impaler

Well, I feel I must respond to this. I do know a fair amount about fission-fusion weapon design.

I can tell you 100% that this assertion is total rubbish. For fission to occur, you can do it one of two ways.

You either a) fire two sub-critical masses together as in the 'Little Boy' design , or b) compress a non-critical mass into a critical one using some sort of force be it explosive, magnetic, laser whatever.

Now, Pu239 will fizzle if you try to use method a), so in order for 'Project Satan' to work, we will need some explosive packed around the RTGs on the spacecraft. Add to that, we also need an initiator (polonium works well), which is by design highly radioactive, and as such has a short half life. How long was that ship flying for?

Even if the Lizards, or whoever did manage to do all of the above, a fission bomb going off surrounded by hydrogen will not cause a fusion reaction! For fusion, you need very very high temperatures, and very very high pressure! In effect the Deuterium needs to be imploded from all sides. The Teller-Ulam two stage hydrogen bomb design used styrofoam as a plasma generator to create the hard X-rays required for the radiation implosion of the secondary fusion stage. Whist inside the tank of Deuterium, a fissile 'spark plug' was placed to provide imploding force in the opposite direction. The whole lot was levitated (spaced) to increase the 'hammer on anvil' blow of the fission shock on the Deuterium. Basically, it was very carefully designed to make it work. (Not all Hydrogen bombs have worked. The first British one for example was a failure).

Not much chance of implosion in the atmosphere of the planet is there? There is nothing to squeeze from the other side of the explosion!

So, you can all rest easy. Physics in on our side on this one....