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After flying by the moon, the Artemis II mission is in the homestretch of its 10-day journey. Even a few days off Earth can significantly alter the human body. That's why the four astronauts aboard are using a specifically designed exercise machine, the flywheel. NPR's Katia Riddle reports.
KATIA RIDDLE, BYLINE: The first thing to know about the flywheel - it's small, smaller than a carry-on suitcase. That's because the space shuttle Orion is tight quarters - only 316 cubic feet, about the size of a smallish bedroom. With four people in it, no one's going to be doing any Olympic weightlifting. But with the flywheel, here's what the astronauts can do.
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JEREMY HANSEN: Rowing, like a cardiovascular workout where you row at a lower resistance and a fast pace.
RIDDLE: In this video blog, taken before the crew launched, Canadian astronaut Jeremy Hansen demonstrates the flywheel. Astronauts strap their feet onto a small platform and then pull a handle connected to a cable. This cardiovascular workout is one of several of its functions.
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HANSEN: We can also change the dynamics of this device so that we can do weightlifting with it. So we can do squats. We can do dead lifts. We can do curls. We can do high pulls.
RIDDLE: It can provide up to 400 pounds of resistance training. Astronaut Reid Wiseman gave this report from space after his first time using the flywheel for a 30-minute aerobic session.
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REID WISEMAN: It is a really good piece of gear, and we can actually get a nice workout.
RIDDLE: In addition to being a good workout, says Wiseman, he was happy to report it did not drive his roommates too crazy. No one had to wear earplugs to block out the sound.
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WISEMAN: I look forward to the next time I get to try a resistance workout.
RIDDLE: Having both resistance training and cardiovascular exercise is critical in space, says Jessica Scott.
JESSICA SCOTT: The human body deconditions very quickly in space.
RIDDLE: Scott is an exercise physiologist at Memorial Sloan Kettering Cancer Center. She worked with NASA on developing early prototypes of the flywheel. She says without the constant pull of gravity on the skeleton, humans lose bone and muscle in a short amount of time. The heart weakens. The atrophy, says Scott, is equivalent to lying down in a bed. Imagine what would happen if you did that for 10 days.
SCOTT: You would feel very weak, and your muscle starts to lose size very quickly.
RIDDLE: When they were recruiting people to study these early flywheel prototypes, they looked for 30 research subjects who were willing to lie in bed for 70 days. Scott says they thought, at first, it might be difficult to find such subjects. But it turns out people were eager to spend hours a day reclining in the name of science.
SCOTT: We had over 10,000 people apply.
RIDDLE: They called themselves the Pillownauts (ph). Researchers divided these participants into different groups. Some of them stayed in bed all day. Some of them broke their bed rest in order to work out on a more traditional suite of exercise equipment, and some of them used the flywheel. The goal was not to improve fitness but to prevent declines.
SCOTT: What was really exciting was that the small device could prevent the declines the same amount that a full gym could do.
RIDDLE: Even for people who are not planning on orbiting the moon, the research has important applications, says Thomas Lang. He's a radiologist who studies bone and muscle loss.
THOMAS LANG: You start in childhood. And then, as you grow, your bone density and mass reach a peak.
RIDDLE: Somewhere in your late 20s or early 30s - anyone who's lucky to live to old age, says Lang, will experience hormonal changes that lead to bone loss over time. For women, that starts in menopause.
LANG: That's a big, whopping decline.
RIDDLE: Men's decline may not be as dramatic, says Lang, but they are also vulnerable, especially as they live into their 70s and 80s. NASA researcher Jessica Scott says she's been proud of her work as she's watched the Artemis mission unfold and not just because it's helping these astronauts.
SCOTT: One day, we could all be having our own flywheel.
RIDDLE: If 30 minutes a day on a flywheel can help people in space, says Scott, just think what it might be able to do for those of us back on Earth. Katia Riddle, NPR News. Transcript provided by NPR, Copyright NPR.
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