A "Gravity Suit" Could Protect Astronauts From the Dangers of Weightlessness

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Researchers at UC-San Diego have engineered a negative-pressure gravity suit that could slow or even prevent the ravages of microgravity on astronauts' bodies suffered during extended spaceflight. They recently detailed their creation in the journal Frontiers in Physiology.*

Prolonged weightlessness can wreak havoc on spacefarers' bodies. Outside of Earth's gravity, bones swiftly lose mass at a rate of roughly 1.5% per month and muscles atrophy. Even more disconcertingly – fluids accumulate near the top of the body and blood fluid volume decreases. These changes worsen eyesight and weaken the heart muscle, potentially hampering the flow of oxygen to the brain.

Astronauts partially counteract microgravity's deleterious effects through regular exercise, but exercise can only do so much. The "mobile gravity suit" could help. It applies negative pressure to the lower body (LBNP), which both shifts blood to the lower body and generates ground reaction forces to help maintain muscle and bone density. A Ground reaction force is exerted by a surface on a body in contact with it. In short, it is the "equal and opposite force" from Newton's Third Law.

"The mobile gravity suit is a small, untethered, and flexible intravehicular activity (IVA) suit," the authors described. "This trouser-like suit is designed for astronauts to comfortably wear and begin applying the LBNP technique without reducing crew time. The negative pressure is generated by its own portable vacuum system, ensuring full mobility, and user-control. Additionally, the gravity suit’s endoskeleton is equipped with its own pressure/thermal control system and three safety features."

Mobile gravity suit force balance analysis.

The researchers tested the suit's capabilities against a lower body negative pressure chamber, a device that performs the same function as the suit but restricts the user's movements and is too large and unwieldy to be useful for space missions. They found that the suit more effectively generated ground reaction forces, generating a mean maximum bodyweight of 125% for subjects who wore it.

The researchers envision a future where mobile gravity suits could become a staple of human spaceflight.

"With the gravity suit, astronauts will be able to float freely around the space station while adhering to their every day tasks. However, this device is not just relevant for astronauts. Once space travel becomes commercialized, this device may ensure the health of future civilian space travelers. It is important to develop effective devices, like the mobile gravity suit, that simulate the very conditions our bodies on Earth depend on."

The suit's construction was funded by NASA grants, so it's highly likely that we'll see the mobile gravity suit tested on the International Space Station soon.

*Article updated to reflect conflicting information about who actually created the gravity suit.

Sources: Neeki Ashari and Alan Hargens. "The Mobile Lower Body Negative Pressure Gravity Suit for Long-Duration Spaceflight." Front. Physiol., 05 August 2020 | https://doi.org/10.3389/fphys.2020.00977

Lonnie G Petersen, Alan Hargens, Elizabeth M Bird, Neeki Ashari, Jordan Saalfeld, Johan C G Petersen. "Mobile Lower Body Negative Pressure Suit as an Integrative Countermeasure for Spaceflight." Aerosp Med Hum Perform . 2019 Dec 1;90(12):993-999. doi: 10.3357/AMHP.5408.2019

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