# What's the farthest an ISS astronaut gets from the station's center of mass during routine activities? At 0.5°/s what centrifugal effects are there?

This answer to Are there really “Dead End” signs on the outside of the International Space Station? won't be helpful here since for the purposes of this question spacewalks aren't part of routine activities.

This answer to Do astronauts aboard ISS notice a change in ISS orientation? indicates that for the recent turn of events (pun intended) the rate of rotation of the ISS wasn't more than about 0.5 degrees per second or about $$8.7 \times 10^{-3}$$ rad/sec.

The largest centrifugal microgravity an astronaut aboard the ISS might have experienced will be something like the product of the largest angular rotation rate and the largest distance from the station's center of mass that they might have found themselves at the time.

Question: What's the farthest an ISS astronaut gets from the station's center of mass during routine activities?

This answer to Where is the center of mass of the ISS relative to it's internal coordinates? might be a good starting pont.

• It's something less than 0.2 Newton of force for an 80kg person. How much less depends on where they are, and specifically the other half of the question, how far out can one get while still withing ISS. I'm not convinced a 0.2N force is even perceivable, by human senses. If would be swamped by normal body motions, pulse,etc, as well as external factors like slight air movements. Jul 30, 2021 at 12:25
• @PcMan on the ISS wouldn't you'd find yourself starting to accelerate? The acceleration is a better metric since it would be the same for a pencil and a piano. Calculate their perceived radial velocity after 10 seconds and it's quite noticeable. Even if they were holding on, loose bits around them would start moving.
– uhoh
Jul 30, 2021 at 12:32
• Yes, after 10 seconds you will have drifted 13 cm. This is very much nonzero, and can be observed. This is almost 40 times the normal centrifugal force on the ISS. And it is still well below the random motion caused by air currents. You could observe it if you looked for it, expected it. If not, it is likely to be unnoticeable. Jul 30, 2021 at 16:09
• @uhoh great point about the drifting objects. There's a cockpit film from the launch of STS-88. A checklist or something drifts by over the crew's helmets at MECO. Twice you can see jets fire out the front windows and the checklist visibly "changes course" at each firing. (really the orbiter did, but all is relative) Jul 30, 2021 at 19:35