The Engines of Our Ingenuity 2638: Artificial Gravity

0:00This programming is sponsored by Metro. World Cup planning includes transit improvements intended to serve Houston after the final match. Metro provides bus, rail, and para transit service and continues mobility enhancements across the region. More at ridemetro.org forward slash Metro now. This is the engines of our ingenuity, made possible by the friends of KUHF Houston. Today, astronaut Michael Barrett discusses the pros and cons of artificial gravity. The University of Houston presents this series about the machines that make our civilization run and the people whose ingenuity created them. Contrary to what science fiction would have us believe, we cannot control gravity. We can neither create it nor switch it off. But we can provide an artificial acceleration in the mimics gravity. A rotating structure creates angular acceleration, which gives rise to a centripetal force at the rim,

1:01pushing back on an object that would otherwise fly off. You may have experienced this on a spinning merry-go-round. It's easy to stand at the center, but you better hold on at the edge. For spacecraft, this was described as early as 1928 by the Slovene space pioneer Hermann Nordung. He envisioned a 100-foot diameter rotating structure with a centralized airlock and crew quarters around the rim. The idea was brought vividly to the big screen in Stanley Kubrick's 2001, a space odyssey. So we have an interesting situation. We're on Earth, we are stuck with gravity, but in space we have a choice of emulating it or living without it in a weightless environment. There are, of course, trade-offs. The force is related to the radius and the rate of spin. Increase either one and you increase the apparent gravity or G. You would need a structure with a radius of about 900 meters spinning at a gentle one revolution per minute to create the equivalent of 1G. On the other hand, a 10 meter radius spinning at 10 RPM would give about the same force, but such spin rates can be highly disorienting

2:03to the human sensory system. And there are other effects. Standing with your feet on the rim, the floor you will experience higher gravity at your feet than your head. Walking in the direction of spin, you increase your rotational velocity and get heavier. Moving in the opposite direction, you get lighter. Most of these effects would be less noticeable in very large structures at slow rates. A practical structure might be smaller and offer less G, but there are positive aspects of weightlessness you would give up. Once adapted, a human can move himself and large objects almost effortlessly. In addition, the habitable volume increases from a functional standpoint. This was brought home to me during a two days commute to the International Space Station in the tiny Soyuz spacecraft, which becomes much more livable when three dimensions are available. The station itself has storage and work areas arranged in all axes, which makes for very efficient use of space. And we use artificial gravity nearly every day.

3:04We remove air bubbles from water bags by holding them and pirouading around a central point. The same technique is used to eat a bag of pretzels without shedding crumbs. You can slowly swing an arc with your arms to retrieve a single object from a plastic bag, then close it before the contents fly out. In a sense, we do control artificial gravity, turning it on and off on a very local scale. Ultimately, we likely will build large rotating space structures. The positive effects for the human and for systems operating in familiar conditions are too enticing. But for travel beyond Earth vicinity, the ultimate artificial gravity will be linear along a line of constant acceleration provided by new engines producing continual thrust. This, of course, unless we really do one day learn to control gravity. I'm Michael Barrett for the University of Houston, where we're interested in the way inventive minds work.