Mars Society Succeeds in Spinning Mice

!splut writes "Having recently finished with making humans live in the large, circular kitchen that is the Flashline Arctic Station , the forward thinking Mars Society has found a new organism to confuse. An experiment being conducted at Pioneer Astronautics for the Society is examining whether or not Coriolis effects will severely disorient mice in the Mars Society's upcoming Translife Mission , which will eventually place a colony of mice in low earth orbit in a small rotating satellite for 50 days. The current experiment involves placing a mouse habitat at the end of a turntable spinning at 25rpm, and has been going on 24-7 since August 30! Amazingly, the mice seem to be doing fine. Think they'll be able to walk straight when they stop the turntable?"

RPM limits for spacecraft/stations?

[Christopher Thomas]

There have been speculative non-fiction books describing the construction of spinning space stations for years.

A major design constraint is that they try to keep the rotation rate as low as possible. Original designs used a rate of about 1 RPM, but later designs cited a requirement to push this to about 1/4 RPM for humans' long-term health.

I have no idea why such a low rate would be required. Neither does a doctor friend I queried.

Is there any physiological basis for needing a slow rotation rate for long-term habitation, or were these numbers pulled out of a hat by the profs designing the stations?

[My doctor friend says that as long as there isn't much of a "gravity" gradient between a person's head and feet, he couldn't thinnk of any difficulties offhand. I noted that the speed of the station's rotation should be much greater than the speed of blood moving through the body to avoid coriolis effect concerns, but the number he cited for blood velocity is low enough that this is a non-issue. Disclaimer: These were all off-the-cuff answers, and not official medical advice.]

Re:RPM limits for spacecraft/stations?

[zardor]

Here [ednet.ns.ca] is a good description of rotating space stations and the coriolis effect.
Basically, if you run 'with' the rotation of the station, you will get heavier, and if you run 'against' the rotation, you will get lighter. That can be a little confusing. It also makes ball games a little difficult, since the trajectory of a ball will change depending on which direction you throw it!
Another good site explaining the effect and its problems is here [complete-isp.com]

Re:RPM limits for spacecraft/stations?

[Winged Cat]

In addition to the coriolis effect mentioned, RPM * radius is proportional to gravity. So, for the same gravity, lower RPM = higher radius. Higher radius means that any unit length (say, six feet, or however tall your average adult human body is) along that radius will encompass a lesser gravity gradient - so, higher radius = less gradient from head to feet.

At least, that seems to be why you'd care about RPM if gravity gradient was of any concern. (Though the coriolis effect is important, too.)

Re:RPM limits for spacecraft/stations?

[Christopher Thomas]

so, higher radius = less gradient from head to feet.

At least, that seems to be why you'd care about RPM if gravity gradient was of any concern. (Though the coriolis effect is important, too.)

It turns out that any rotation rate below about 10 RPM involves a large enough station to make gravity gradients small, so this most likely isn't the factor that was limiting the rotation rates in the original thought experiments.

Re:RPM limits for spacecraft/stations?

[nusuth]

It might be because of motion sickness associated with coriolis effect in inner ear. when you turn your head, or move in direction that is not exactly perpedicular or parallel to rotation direction, you would get different signals for the definition of "up" from different ears which might result in severe motion sickness. Then again it might not, after all people are doing fine without gravity which mess with sense of balance too.

the great escape?

[zardor]

So this is how the mice are planning to get off the planet before the Vogons get here with their yellow ships and the poetry [worldofyak.com]

Yes, but this still doesn't answer the question:

[jd]

Why is a mouse when it spins?

Re:Yes, but this still doesn't answer the question

[anvilmark]

"The higher the fewer!!!"

possible explanation here... [jadebox.com]