Is Plutonium Found in Space Naturally?

[sophiecentaur]

I'm not following you.

I think the argument goes like this: There's a lot of (solid) protactinium in some places, It produces radon at a more or less constant rate but radon doesn't last long. So people will be exposed to a constant., low level of radon. The level is an equilibrium condition of production and decay.
Perhaps @snorkack 's statement could be modified to include the words "only" and "locally" somewhere. That point is actually made higher up by someone.

Poor old Brian Cox does his best to present a suitable subset of the facts but people have to treat his sayings as oracular. Yer average viewer wouldn't be prepared to give what he says the PF treatment.

 

[Andy DS]

Wow, I really started something here. Many thanks for the insights from all contributors.

 

[sophiecentaur]

Wow, I really started something here. Many thanks for the insights from all contributors.

That's often the risk on PF. You can never say that PF is casual about its Physics.

 

[snorkack]

I think the argument goes like this: There's a lot of (solid) protactinium in some places, It produces radon at a more or less constant rate but radon doesn't last long. So people will be exposed to a constant., low level of radon. The level is an equilibrium condition of production and decay.
Perhaps @snorkack 's statement could be modified to include the words "only" and "locally" somewhere. That point is actually made higher up by someone.

No, my argument is different.
First, protactinium actually produces actinon, not radon.
But the thing is: we do not detect radon, or actinon, by observing the atoms during their existence (short or long). We detect them by observing their decays.
Therefore, since one radium atom decays into one radon atom but has 150 000 times the lifetime, there will be 150 000 radium atoms per each radon atom. But we don´t detect the radium atoms anyway. Thus we will see just 1 radium decay and 1 radon decay. Radon decay has higher energy and more importantly, while radium stays in the solid rock alongside its mothers, also radioactive, radon migrates before decaying and getting detected.
Protactinium is longer lived but harder to find because it stays in rock and its mother (U-235) is less common than U-238.

 

[gmax137]

But just because there are 150 000 times fewer radon atoms does not mean they are any harder to find than the radium atoms! Precisely because they are so short lived, there are as many radon decay events as radium decay events - and radon decays have higher energy.

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."

 

[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