Probably the most valuable things they could send back would be the vacuum Raptor engines they got there on, probably with their bells cut off.
If you can figure a way to get a million-person Mars colony together in under, say, a thousand years, with SpaceX hardware, go wild.
Freeze and stack colonists like cordwood? Nobody said they have to be alive, right? They'd keep. Maybe somebody will figure out how to revive them, someday.
I have some questions about this bit!
1.) Why would their bones dissolve? If bones aren’t used do they really just collapse? My hands don’t really experience gravity (I think!) and they are fine.
2.) Couldn’t you make some sort of exercise thingy that could simulate gravity?
Thanks!
"One of the major obstacles to long-term space missions in the threat of severe bone loss in astronauts. In the microgravity environment of space, astronauts lose on average 1% to 2% of their bone mineral density every month. For a short-duration flight, bone loss is a fairly minor consequence.
On a long-duration space flight, such as those planned for missions to Mars and beyond, bone loss can be a serious impediment. This loss may not hinder astronauts while they are in orbit, but upon return to Earth, their weakened bones will be fragile and at an increased risk of fractures. At this time, it is unknown whether this bone loss will eventually reach a plateau, or whether it will continue indefinitely." [1]
2) ISS astronauts spend a couple of hours every day exercising to keep the worst of the space-related medical issues at bay... but it's simply no substitute for real gravity.
Space has all sorts of weird effects on the human body: [2]
[1] https://www.asc-csa.gc.ca/eng/astronauts/space-medicine/bone...
[2] https://www.smithsonianmag.com/science-nature/nasas-twins-st...