During interviews from space station with school children I am often asked what on Earth I miss the most. On one occasion a little girl asked a most astute question, “What from space will you miss the most once you return to Earth”? I had to think for a moment. Was it the views of Earth, a blue jewel surrounded by inky blackness, the heavens filled with stars that don’t twinkle, or perhaps the aurora, pure occipital pleasure seen on the length scale of half a continent? I decided it was none of these. Such wonders can be experienced in some form from Earthly perspectives. What is truly unique to living in orbit is a byproduct of being weightless. Here I can fly. I can fly without wings dictated only by Newton’s laws of motion without the complications of aerodynamics.
As subjects of Earth, we grow up with no innate knowledge of maneuvering in weightlessness. This is a skill that has to be learned on the job. In a matter of minutes, we can learn to move about but to gracefully conduct ourselves takes a few weeks. During my first expedition, after a month I thought, “Wow, I am really getting good at this”. Then another month went by and I would think, “Last month I thought I was really good but now I am really getting good”. I found this pattern repeated over the six month mission. When I returned to space station as a space shuttle crew member on Endeavour, our mission was only 16 days, a mere flash in the pan by space station standards. Sixteen days is barely enough time for your bowel to become regular let alone learn how to translate in weightlessness. Newly arrived Shuttle crew members typically would miss a hand rail and bounce off of a rack panel with the same grace as an albatross coming in for a landing. There would be a cloud of items knocked off of their Velcro wall tacking in their wake. The station crew members were constantly following our shuttle crew picking up the flotsam. One station crew member mocked, “Next time before the shuttle arrives I will have to kid-proof the stack”.
To improve your translation skills, it helps to apply some basic concepts of physics. When flying like “Superman”, the first and most natural method for beginners to translate, your arms are outstretched in front thus grasping onto any fixed object in which to give a little push or pull as well as offering a measure of security for protecting the tender parts on top of the head. But this is not the best way to fly. In this position your center of gravity is located somewhere around the belly button so controlling motion with outstretched arms also imparts rotational components and complicates the movement. Beginners flail with these yaw and pitch motions and struggle to compensate for their unwanted effects. Thus I learned the best way to fly is head first with arms at your side like “Ironman”. Pushing and pulling from this position goes nearly through your center of mass, thus does not impart rotation. On space station Ironman becomes your role model for flying, leaving Superman for the comic books.
With practice I progressed from flying like Ironman to fly-walking. Fly-walking looks like normal walking with the body “standing upright” and motion perpendicular to the chest. In fly-walking your motion is controlled by the legs through tactful forces exerted through the feet when hooked under a deck mounted handrail. This motion does not seem possible, however; when pressed into a new environment, humans readily discover, learn, and adapt. Fly-walking offers a real advantage because it frees your arms for carrying loads.
There is recreational flying. This is fun flying, perhaps in a gymnastic pike, an iron cross, or a cannon ball. You try to shoot down a module corridor without touching anything thus having a visceral experience with the First Law of Motion. We fly like this for no reason other than you are in space and you can. It is the equivalent of a kid skipping to school. In the frontier we once again become school kids.