Scott Kelly

[Mugwump]

...after a year in space....

Preliminary findings from NASA indicate that 7% of Scott Kelly's genes did not return to normal once he was back on Earth.

..so he's no longer an identical twin to his brother......

[BillT]

I am interested in finding out more about this.
Both twins were in space before Scott's most recent year in space, although not for so long.
They  started out the same when they were born (or more correctly conceived) and due to random mutations, diverged genetically since then.
The idea is that most of this divergence happened in space (due to more radiation), but some of it could have happened during their previous space activities. I don't see how there is a control for that, though I would expect it to be less.

[Mugwump]

I am interested in finding out more about this.
Both twins were in space before Scott's most recent year in space, although not for so long.
They  started out the same when they were born (or more correctly conceived) and due to random mutations, diverged genetically since then.
The idea is that most of this divergence happened in space (due to more radiation), but some of it could have happened during their previous space activities. I don't see how there is a control for that, though I would expect it to be less.

   I'm thinking gravity and diet......

[wallace]

Cosmic radiation has apparently increased. This is from 2009. I haven't looked for more recent info.

Now, the influx of galactic cosmic rays into our solar system has reached a record high. Measurements by NASA's Advanced Composition Explorer (ACE) spacecraft indicate that cosmic rays are 19 per cent more abundant than any previous level seen since space flight began a half century ago.

"The space era has so far experienced a time of relatively low cosmic ray activity," says Richard Mewaldt of Caltech, who is a member of the ACE team. "We may now be returning to levels typical of past centuries."

The sun's magnetic field normally blocks some of the cosmic rays, preventing them from entering the solar system. But that protection has weakened of late. The solar wind, which helps project the sun's magnetic field out into space, has dropped in pressure to a 50-year low. And the strength of the magnetic field in interplanetary space is down to just 4 nanoTesla, compared to the more typical 6 to 8 nanoTesla.

https://www.newscientist.com/article/dn17882-space-radiation-hits-record-high/

[waterboy]

Pretty hard to say if his changed or his brothers changed while he was gone.  But I suppose they have a sample of his from before he left.  Doesn't say too much for  human colonization of Mars.  After a generation or two the people there may no longer be human. 7% a year mutation rate seems like an awful lot to me.

[BillT]

One of the biggest problems of getting people to Mars is the unshielded exposure they would have to radiation during their trip between the planets. There would be much more radiation further from the earths magnetic field. The space station is in a low earth orbit and therefore gets relatively little radiation.  Sufficient shielding would be very heavy and therefore very expensive.

The best idea so far is to shoot them over to Mars very rapidly, to reduce their time of exposure.

[BillT]

Also, Mars does not have much of a magnetic field or atmosphere to keep out radiation.
People there would have to live underground.