Is there plutonium in space?

[Drakkith]

I think some of the other posters here missed your intent because, generally, "harder to find" is mentally conflated with "fewer." Your point is, "easier to find" may equal "easier to detect."

Perhaps, but the problem with that is that we don't detect radon in people's lungs, we detect it in the air.

 

[Dragrath]

In the context of Pu 244 the most common due to its "long" lifetime of 80 Myrs as had been noted we have found it in sedimentary layers. Most notably is it has been found in the 2.5 to 2.6 million year old radioisotope layer which notably includes short lived radioisotopes like Fe 60 which suggests it was at least delivered to earth alongside the most recent nearby (~150 ly) supernovae.

There is last I checked an unresolved argument over whether the plutonium was swept up by the supernovae shock front or indicates that some amount of high atomic number r process nucleosynthesis does occur.

In the context of radioactive decay chains often they are too short lived for the intermediate chain products to separate out geologically meaning their concentrations tend to be dependent on the source material. In this sense their abundance is going to depend on their decay parent usually Uranium as its the most likely to concentrate due to the reaction between uranium and molecular oxygen which creates a water soluble oxide that can be concentrated geologically where salt deposits form sepecally in relation to the closure of ocean basins via volcanic arcs and the likes. This is why the bottom of such salt deposits where hydrocarbons accumulate tend to have such high amounts of Uranium and its decay products