Weightlessness doesn’t appear to impact the heart’s ability to beat
While long term exposure to weightlessness has been found to impose a strain on the bones, muscles, back, and vision, new research on ISS using mice strongly suggests that it does not affect the heart’s ability to operate, on a fundamental level.
Researchers analyzed heart cells from five mice that were on board the International Space Station for 38.5 days. The researchers specifically looked at the mice’s sarcomeres, the motors in the cells that make the heart contract.
The contracting force in the sarcomeres was the same in mice on the space station as it was in the control mice that stayed on the ground. Molecular testing also found no major differences in the proteins that make up sarcomeres between the two groups of mice, the U of C said.
You can read the paper here [pdf].
This experiment is still of limited value, as it only lasted a little over one month, and involved a small population of mice. The results of manned missions of six months or more has shown that though the cardio-vasular system is weakened by weightlessness, it appears to eventually recover upon return to Earth. Whether there is any specific temporary impairment to the human heart, such as its sarcomeres, is not yet known. This research is a good first step to finding out.
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We are sooooo looking forward to private space stations that spin up “artificial” gravity.
Then again, could you spin a single Starship to have gravity?
After writing this, I realized that the Starship pilots would have to deal with a constantly spinning view. Then again, with today’s and future technology, the view screen algorithm could compensate and provide a non-rotating image.
I had wondered about the spin inducing some sort of vertigo, your screen idea may solve this if it becomes a problem.
The dizziness (vertigo) from spinning is not a visual phenomenon but is related to the inner ear. This has been studied in anticipation of rotating a space station in order to produce artificial gravity. As I recall, the findings are that four revolutions per minute (RPM) is too fast for some people but three RPM affects very few. Much of science fiction and many futurists describe space stations and space colonies that are large enough in diameter (almost 2 kilometers or about 1 nautical mile) so that 1 RPM generates the equivalent of 1G (Earth surface gravity). 1 RPM over long periods of time has not been shown to cause problems, at least not in humans.
SpaceX’s Starship is not large enough in diameter to produce much artificial gravity when spinning at a rate that can be sustained by humans.
a = r * w^2 (equation 1)
where
a is acceleration from spinning
r is radius of surface from the spin center (center of mass) = ~5meters
w is spin rate in radians per second = 3RPM
a = 4.5m * (2Ο * 3RPM/(60seconds per minute))^2
a = 0.44m/s = 0.044G = ~1/3 lunar gravity
Due to the greater distance (r) from the center of mass to the nose of a Starship, tumbling it end-over-end would result in better gravity at the extreme ends, and an additional benefit is that this is a more stable spinning mode. Block 4 Starship is 142 meters including the ~72 meter Super Heavy, so the Block 4 Ship is ~70 meters tall.
r = ~35meters
a = ~35m * (2Ο * 3RPM/(60seconds per minute))^2
a = ~3.5m/s = ~.35G, almost martian gravity
Will SpaceX consider spinning or tumbling Starships on their way to Mars? My guess is no. It may be a good idea, but everything in the Starship will change orientation once it has landed on Mars. Either up becomes down, or the walls become the floor and ceiling. One of the lessons from Skylab is that it is disorienting to have equipment and panels be at different orientations; the planners had thought that it would not matter, so they arranged things in different orientations. It may do better to have “up” on Starship be the orientation as when it has landed, or it may be better to have the astronauts more used to martian gravity when they arrive. This may require another lesson from practical experience.
There is also some indication that keeping the head in a stable orientation prevents the inner ear shifts that cause the disorientation. There is possibly a situation with the head restrained in orientation that allows much higher rpms without serious problems. If correct, this might allow astronauts to spend a few hours a day on mundane tasks in the high spin area to maintain health. Think eating, showers, toilets, standing desks, etc with the majority of the day in microgravity.
Some combination of neck restraint and training might give beneficial results. Could be tested on the ground fairly economically even if it hasn’t already been checked out. 8-meter diameter at moderate to high rpms could be checked out for rpm tolerance on the ground in a matter of weeks.
Starship pilots? Optimus-1 (pilot) and Optimus-2 (copilot) will manage that easily.
Not related: Q: How are you going to make a nice beef soup in space?
https://www.sigma3ioc.com/post/in-the-sigma3ioc-kitchen-making-the-cure
The first thing you need is that spinning space station.
The ship doesn’t need to spin when actual piloting is required or you have a spin hab and the rest of ship doesn’t spin.
Good to see that the heart doesn’t turn the beat around; as per the discussion.
I found Elon’s comments on the rescue of the astronauts interesting besides the fact that the Leftist / political media is in control of the message and squashes any positive news regarding anything but the Leftist agenda.
https://youtube.com/shorts/RJmuted21WI?si=rPCiHiPAMqhOPiBb
“You are not supposed to be at the space station (in zero gravity) for more than 3 to 6 months”.