Would Starship's Hull Be Safe After Returning To Earth From Mars... Or Would It Be Radioactive?

[Spacescifi]

Just curious. Like I already know the crew will just have to tough it out hecause they signed up for the cutting edge of science (can't make an awesome omelette without breaking eggs), but even once the starship returns and lands, would workers working on starship repair have any increased cancer risk just working on a returned spaceship that has been in space getting battered by radiation for months?

Or is this not really anything to worry about?

So really that is perhaps one of the few things scifi gets right lol?

If you could have SSTOs that have been in space for years, the hull could be safe to come near without getting lethal doses of radiation after it landed.

Edit: Actually... it depends. If said ship has been flying around uber radioactive space (near or around jupiter) or been shot up with particle beams or nuclear howitzers... the hull could very well be radioactive. So instead of landing a damaged and radiated ship you would just use escape pods to reach a planetary surface.

Just another reason why real science makes scifi require more steps for safety than scifi which either eliminates them or drastically reduces them.

[Nuke]

no i dont think so, that would require neutron activation and heavy elements to be activated. alpha and beta radiation dont have much penetration capability. ionizing radiation can just strip electrons and have no effect on the nucleus. cosmic rays might do something. its not like its corium though.

[darthgently]

Are meteorites typically extremely radioactive after being in space millions of years prior to hitting Earth?  Not so much

[farmerben]

Jupiter has a radiation belt 1000 times stronger than Earth's Van Allen belt.  It's full of high energy protons.

 

We should study Io.  I predict that certain isotope ratios which we use for atomic mass will be different there.

Edited August 5 by farmerben

[magnemoe]

5 hours ago, darthgently said:

Are meteorites typically extremely radioactive after being in space millions of years prior to hitting Earth?  Not so much

Excellent point and they been in space for billions of years. 

[RCgothic]

Also it isn't just a case of "get bombarded by radiation, get activated".

Some materials are susceptible to activation by particular forms of radiation, such as cobalt to neutron bombardment by, and if there's a perceived risk of activation by particular forms of radiation then materials containing susceptible elements can be avoided.

[farmerben]

There are practically zero neutrons in space.  Because a radical neutron has a half life of about 14 minutes before becoming a proton and an electron.  

Proton induced fission is a thing for very heavy elements and high energy protons.

[DDE]

On 8/5/2024 at 8:35 AM, Spacescifi said:

battered by radiation

TL;DR: the kind of radiation that causes other stuff to become radioactive is virtually exclusive to fission reactions, and thus very difficult to find in nature.

Edited August 8 by DDE

[RKunze]

22 minutes ago, DDE said:

TL;DR: the kind of radiation that causes other stuff to become radioactive is virtually exclusive to fission reactions, and thus very difficult to find in nature.

Nope. Most fusion reactions  (including those occurring in stars) also put out plenty of neutrons. And some events (supernovae and neutron star mergers) put out huge quantities of neutrons (if they did not, most heavy elements would not exist).

The reason that there are almost no neutrons in cosmic radiation around earth is that free neutrons decay in about 10 minutes and thus don't reach us.

[farmerben]

Yeah it's 611 seconds.  Most neutrons do not escape from the surface of stars.

[RKunze]

52 minutes ago, farmerben said:

Most neutrons do not escape from the surface of stars.

Small wonder. Neutrons are generated deep within the star, in the middle of a dense plasma. Which means they are either absorbed quickly by some other atom, or deflected often enough to decay while still deep within the star.

Heck, the interior of a star is so dense that even the photons generated in the fusion zone don't normally get outside the star. They basically just heat up the plasma, and the photons we see from a star are generated at the "surface" (or more correctly, the "photosphere", because a ball of hot plasma does not really have a surface) of the star. That's why a stars' spectrum is very close to an ideal black body spectrum, which in turn means you can directly tell the stars' "surface" temperature from its spectrum.

[kerbiloid]

On 8/8/2024 at 6:14 PM, RKunze said:

free neutrons decay in about 10 minutes

A little more than 1 AU distance.

[darthgently]

39 minutes ago, kerbiloid said:

A little more than 1 AU distance.

It would be interesting if the amount of neutrons that do reach Earth's zone are a factor in the emergence of life in some obscure way and so yet another factor in what makes Earth, so far, unique.  Who knows?

[RKunze]

1 hour ago, kerbiloid said:

A little more than 1 AU distance.

In vacuum, at almost lightspeed. But where neutrons are generated deep within the sun is anything but vacuum, and most of those neutrons are considerable slower than c.

[kerbiloid]

6 hours ago, RKunze said:

In vacuum, at almost lightspeed. But where neutrons are generated deep within the sun is anything but vacuum, and most of those neutrons are considerable slower than c.

I mean the possible maximum distance from the source.