[ExI] Astronauts Suffer Significant, Permanent Bone Density Loss in Space

[Stuart LaForge]

Quoting BillK:

> Message: 11
> Date: Sat, 2 Jul 2022 16:42:15 +0100
> From: BillK <pharos at gmail.com>
> To: Extropy Chat <extropy-chat at lists.extropy.org>
> Subject: [ExI] Astronauts Suffer Significant, Permanent Bone Density
> 	Loss in Space
> Message-ID:
> 	<CAL_armgSkh0mJg4UuRhOTtrY6VAzC=YpmcL0k328zazuEf=RPA at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> <https://www.extremetech.com/extreme/337611-astronauts-suffer-significant-permanent-bone-density-loss-in-space>
> By Ryan Whitwam on July 1, 2022
>
> Quotes:
> Even after a year back on Earth, bone density does not fully recover.
> Essentially, being in space for even a few months causes your bones to
> age at an increased rate ? as much as 10 years per flight.
> Astronauts who were on the International Space Station for longer than
> six months recovered less of their bone density after returning. That
> suggests that long-term missions, like the ones planned for the
> Artemis Program, could have serious impacts on astronaut health down
> the road. It also raises more questions about how humans would fare
> long-term in an environment where there is less gravity than Earth,
> for example on the Moon or Mars.
> --------------------
>
> Astronauts do exercise while on the ISS, to help prevent muscle wastage.
> But 2 hours of exercise per day means that the other 22 hours are the
> equivalent of lying in bed. I think long-term missions over six months
> duration will have to have a rotating section that provides an earth
> gravity environment using centrifugal force.

If manatees, dugongs, and hippopotami can keep their bone density high  
while almost never actually feeling their actual weight, then other  
mammals like humans should be able to also. It is all about correctly  
tuning gene expression for some hormones and cytokines. Inhibiting the  
osteoclasts and/or stimulating the osteoblasts would seem to be the  
way to go. Based upon the natural history of such species, I think it  
is reasonable notion that we could accomplish the same feat by  
naturally or artificially mutating and selecting genes.

https://crimsonpublishers.com/oara/pdf/OARA.000537.pdf

On the other hand, if mass savings are more important than bone  
density in space, then maybe we ought to go the route of the birds and  
develop hollow but reasonably durable bones. My point is that with  
CRISPR and perhaps a few rounds of selective breeding, we would be  
able to specialize people to survive all manner of environments:  
space, the deep sea, underground, mars, etc. Baseline humans might not  
be able to be able to conquer space, but genetically and  
technologically enhanced transhumans probably could.

Stuart LaForge