Weightlifting in weightlessness is now my favorite oxymoron. (It has surpassed my previous favorite: reality TV.) Living in weightlessness causes our bodies to slowly degenerate, and for long-duration missions something has to be done to prevent, or at least mitigate, this degeneration. While the reasons are not fully understood, we have discovered an empirical solution, which also is not fully understood: an intense blend of cardiovascular and weightlifting exercises.
To accomplish the weightlifting—properly called resistive exercise—NASA has invented a machine that provides forces of up to 270 kilograms (600 pounds) that remarkably mimic the experience of weightlifting on Earth. When I finish a 1½-hour session on this machine, my muscles have been turned into salty limp noodles. (Heavy lifting also makes for heavy appetite. Here, I can truly claim to be able to eat my weight in barbeque). The weightlifting machine is called ARED, an acronym whose meaning I have long forgotten. I like to refer to this machine as The Beast.
When we lift weights under the influence of gravity, the force throughout the motion is constant. On Earth, we are used to this feeling. Normal weightlifting machines use springs, bows, bungees, or pneumatic cylinders to provide the load, with the resistive force increasing in proportion to the distance traveled. Most weightlifting machines rely on simple pulleys and weights, which of course do not work in weightlessness.
To make a resistive exercise machine for space that feels like lifting weights on Earth requires a different approach. It is possible to design springs that yield a constant force over a small displacement, but to make these operate over large motions, with user-selected loads that remain calibrated, leads to complicated mechanisms.
The invention in The Beast that solves the spring problem (giving force independent of displacement) uses something we have plenty of in space: vacuum. There are two large cylinders, with a vacuum behind each piston. The atmospheric pressure in the cabin pushes on the other side of the piston, thus creating a force independent of displacement (vacuum behind a piston does not “compress” like air does). Using a simple lever with a ball screw adjuster gives continuously variable, calibrated, and reproducible forces. These forces are transferred to a standard weightlifting bar through a yoke. When I stand on a platform attached to The Beast, the forces from my exercise are balanced within its structure, so that no unwanted vibrations are transferred to Space Station, which could spoil the environment for scientific experiments. The Beast is an engineering marvel that is central to maintaining crew health.
When living on a frontier, we move away from the standard way of doing things. The frontier spawns a class of invention that would never materialize if we remained comfortably surrounded by that which is familiar.
Don’s blog also appears at airspacemag.com.
10 thoughts on “The Beast”
i would appreciate you great people up there to clean up the space trash,,grab a fish net or something..put the brains on cleanup of trash floating by
Sooo, you basically work against the life-support systems which maintain air pressure inside the Station?
Thanks alot for your Blog posts! Good luck!
Tunes always helps and makes time fly. Guess the next best thing to feeling like you’re at a public gym would be to hook up through video? if not, least with another colleague. Awesome information to share with our future generations.
As you say, we will have to learn new ways of doing things in the microgravity and zero-G environment. I have heard you explain several times how the “coffee maker” recycles urine. Obviously it doesn’t seem to bother you now how you get your is made. I cannot help but wonder if it ever did bother you, or any of the other astronauts and if it took some getting used to. Your recycle system isn’t necessarily a new idea. Those of us that have read the “Dune” books by Frank Herbert are very familiar with the idea of the “still suit” that recycled not only waste to reclaim water, but also captured the moisture lost through exhaling and sweat. Do you see that kind of technology being developed in the future?
I love these elegant solutions to the problems that weightlessness introduces. Any video links on it being used?
I wonder NASA’s scientists to build such complicate equipments.
I have seen this articule and consider it very interesting and at the same time an evolution in NASA tech MY CONGRATS TO YOU ALL!
Do your muscles feel exercised and “pumped” like they do when finished lifting back on the Earth?
Interesting explanation of the “Beast”, this engineering marvel.
You make me laugh whe you say : “After doing my exercises on this machine, I could eat my weight in barbecue”.
When I’m very thirsty, I always say ” I could drink a lake”.
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