How Cats Helped Us Understand Movement in Space

Ever since my article with ThinkFun about science activities you can do at home with your cat, I've gotten requests for more cat science. I am more than happy to fill that request.

IT STARTED WITH A GIF

At some point in college, a friend sent me a GIF of cats spinning in what seemed like zero gravity.

Cats in Microgravity.gif

At first I thought it was edited, but came to the conclusion that it was real. The men in the GIF are wearing military-style uniforms, so I started searching there. 

THE BACKSTORY

Decades before the historic flights of Yuri Gagarin and Alan Shepard, we knew we where going to space, we just didn't know how or when. Research started in all fields, from engineering and physics to anatomy and physiology. No one was really sure how the human body would react when it was in a low or zero gravity environment. Beyond normal medical questions (such as whether or not you would be able to eat and drink in space), doctors weren't sure if people could even move in space. The Air Force recognized that astronauts would be able to position themselves if they had something to hold on to, but what in future space stations that had wide open rooms? At that point, the astronaut would only have their own body to move about and get in the correct orientation. 

In 1947, the Air Force decided in order to study this, there was only one thing to do: play with kittens in mircogravity. When cats fall, they use what we call the cat righting reflex to correct themselves and land on their feet. This reflex requires at least a 12 inch drop in order to work and appears in kittens as young as 3 weeks. Despite the popular belief that cats do this with their tails, cats use basically their whole body except the tail to achieve this. The steps in the cat righting reflex are as follows:

  1. Bend in the middle. This causes the front half of the body to rotate at a different axis than the rear half.
  2. Tuck in front legs and extend rear legs. This reduces the moment of inertia of the front half while increasing the moment of inertia in the rear half so the front half rotates up to 90 degrees while the rear half rotates in the opposite direction less (as little as 10 degrees).
  3. Tuck in rear legs and extend front legs. This allows them to achieve the opposite of Step 2. The rear half rotates up to 90 degrees while the front half rotates little in the opposite direction. 

This reflex requires to be able to determine which way is down though, and therefore doesn't work in space. In the GIF, what looks like the kittens flailing around is really just the kittens trying to use the cat righting reflex but not being able to. The important thing here is the kittens are using their bodies to rotate themselves.  

THE RESULT

In 1962, the Aerospace Medical Research Laboratories at Wright-Patterson Air Force Base in Ohio published a report entitled "Weightless Man: Self-Rotation Techniques." It detailed several ways that astronauts in space would be able to move themselves using only self-rotation based on what they learned from observing the kittens in mircogravity.