Sure, spacewalks sound cool – but have you ever thought about how difficult they actually are?

The reason that astronauts stumble and fall so often in space is because of the difference between the Earth’s gravitational pull and that on other moons and planets.

On the moon, for example, the low levels of gravity make it really difficult for someone who is used to walking around on Earth to get used to traversing its surface.

As a result of this notable challenge, engineers from MIT have, with the support of NASA, been developing a solution for future spacewalks. Known as “SuperLimbs”, their invention is worn like a backpack, with extending robotic limbs helping to support an astronaut on a spacewalk, and helping them to get back to their feet once more if they do happen to fall over.

In a recent statement, MIT’s Professor Harry Asada explained the team’s motivation for creating the Supernumerary Robotic Limbs:

“Astronauts are physically very capable, but they can struggle on the moon, where gravity is one-sixth that of Earth’s but their inertia is still the same. Furthermore, wearing a spacesuit is a significant burden and can constrict their movements. We want to provide a safe way for astronauts to get back on their feet if they fall.”

The team’s prototype SuperLimbs were developed in part to help super fit astronauts to conserve their valuable energy during important work in space. That’s because working out in space can take its toll on the body; and constricting and complicated space suits really don’t help matters.

As our space explorations continue, every moment an astronaut can be gathering essential data out in space is imperative to our understanding of what lies beyond our own planet. Thus, SuperLimbs aim to safeguard their valuable time, by limiting the amount of it spent merely trying to traverse other planets, and get up after a fall.

Erik Ballesteros, a doctoral student at MIT, explained the potential importance of SuperLimbs as we continue to investigate our solar system:

“During the Apollo era, when astronauts would fall, 80 percent of the time it was when they were doing excavation or some sort of job with a tool. The Artemis missions will really focus on construction and excavation, so the risk of falling is much higher. We think that SuperLimbs can help them recover so they can be more productive, and extend their EVAs.”

So how was this revolutionary technology developed?

Well, the team started by gaining an understanding of the natural ways in which humans get back to their feet after falling over.

Participants in their study were asked to get back to their feet again after lying down on their back, front, and side; after mapping their movements, the scientists then observed the participants standing up from a lying position when wearing heavy, constricting gear similar to that an astronaut wears when out in space.

And, as Ballesteros confirmed, each participant’s movements – both within and when free of the suit – were quite predictable, enabling their designs to come to fruition:

“Those ergonomic experiments helped us to model in a straightforward way, how a human stands up. We could postulate that about 80 percent of humans stand up in a similar way. Then we designed a controller around that trajectory.”

They moved to develop software that would allow robotic limbs to support a human who was undergoing those motions, before attaching robotic limbs to a backpack and controlling them with the software.

Once more, the participants were asked to don the backpack, and stand up from various lying positions. The robotic limbs were able to sense the position and movements of the participants, assisting them in the process of being upright again.

The participants reported that robotic limbs made it much easier to stand up, especially when wearing the cumbersome space suit. In particular, the responsive nature of the limbs was appreciated, as Ballesteros reported after trying the suit himself:

“It feels kind of like an extra force moving with you. Imagine wearing a backpack and someone grabs the top and sort of pulls you up. Over time, it becomes sort of natural.”

Check out the video with more shots of this prototype in action:

Now that the researchers have their prototype, they are hard at work progressing the software and finessing the robotic technology. In 2025, in NASA’s Jet Propulsion Laboratory, the team plan to streamline their design, including reducing its weight, using NASA’s advanced technology and lightweight components.

Next, SuperLimbs will be tested by astronauts in low-gravity simulators for further expert feedback and finessing. Professor Asada hopes that the technology will help them to overcome some of the difficulties of wearing such an impeding suit in difficult conditions for the human body:

“Wearing a spacesuit can be a physical burden. Robotic systems can help ease that burden, and help astronauts be more productive during their missions.”

If all goes well in these next stages of testing, the team hope that SuperLimbs will be rolled out to space missions in the future.

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