Chuck Bednar for redOrbit.com – Your Universe Online

A next-gen, skintight spacesuit that would improve astronaut mobility, provide support and reduce mass in comparison to current gas-pressurized models is in the works at MIT, officials the Cambridge-based research university revealed on Thursday.

Dava Newman, a professor of aeronautics and astronautics and engineering systems at MIT, and her colleagues have engineered active compression garments which include small, spring-like coils that contract when exposed to heat. Those coils are developed from a type of material known as a shape-memory alloy (SMA), which can recall an engineered shape, and even when bent or deformed, it can spring back to this pre-programmed shape.

Newman and her colleagues incorporated the coils in a tourniquet-like cuff, and then applied a current to generate heat. Once the temperatures reached a pre-determined level, the coils contracted and returned to their desired form, tightening the cuff in the process. During the course of their tests, the researchers said they discovered that the pressure produced by those coils was equal to that required to fully support an astronaut while in space.

“With conventional spacesuits, you’re essentially in a balloon of gas that’s providing you with the necessary one-third of an atmosphere [of pressure] to keep you alive in the vacuum of space,” explained Newman, who has spent more than 10 years designing a new type of flexible, form-fitting spacesuit.

“We want to achieve that same pressurization, but through mechanical counterpressure – applying the pressure directly to the skin, thus avoiding the gas pressure altogether,” she added. “We combine passive elastics with active materials… Ultimately, the big advantage is mobility, and a very lightweight suit for planetary exploration.”

The coil design, which was conceived by Bradley Holschuh, a postdoc in Newman’s lab, is one step towards the ultimate goal of replacing the conventional gas-pressurized suit with one that is less bulky, more form-fitting and able to plug into a spacecraft’s power supply to essentially cause the material to “shrink-wrap” around an astronaut’s body. Holschuh, Newman and their colleagues detail their efforts in the journal IEEE/ASME: Transactions on Mechatronics.

While this is not the first attempt to develop a skin-tight spacesuit, the one obstacle that designs have been unable to overcome is how to make an extremely snug pressurized suit that astronauts can still easily get into and out of. The MIT team has turned to shape-memory alloys as a possible way to solve this problem, since the materials only contract when they are heated and can easily revert to a looser shape once they cool down.

Holschuh’s team looked at more than a dozen different types of shape-changing materials to find the one most suitable for space. They finally opted for nickel-titanium shape-memory alloys, which Jennifer Chu of the MIT News Office said was “ideal for use in a lightweight compression garment” because when it is “trained as tightly packed, small-diameter springs,” the material “contracts when heated to produce a significant amount of force.”

Since nickel-titanium shape-memory alloys are typically produced in reels of thin, straight fibers, Holschuh used a technique devised by another team of MIT researchers to engineer a heat-activated robotic worm. The researchers first trained the material to return to its original shape by winding raw SMA fiber into extremely tight, millimeter-diameter coils. They then heated the coils to 450 degrees Celsius to set them into an original shape.

“At room temperature, the coils may be stretched or bent, much like a paper clip. However, at a certain ‘trigger’ temperature (in this case, as low as 60 C), the fiber will begin to spring back to its trained, tightly coiled state,” Chu explained. “The researchers rigged an array of coils to an elastic cuff, attaching each coil to a small thread linked to the cuff. They then attached leads to the coils’ opposite ends and applied a voltage, generating heat.”

Between 60 degrees and 160 degrees Celsius, the coils contracted, pulling on the attached threads and causing the cuff to tighten. Holschuh described them as “basically self-closing buckles. Once you put the suit on, you can run a current through all these little features, and the suit will shrink-wrap you, and pull closed.”

The research team now needs to find a way to keep the suit tight. They are said to be considering two options: either maintaining a constant temperature that is warm enough, or including some kind of locking mechanism that prevents the coils from loosening. The first option would require astronauts to carry around heavy battery packs, which would impede mobility, so Holschuh and Newman are currently exploring the latter option.

“As for where the coils may be threaded within a spacesuit, Holschuh is contemplating several designs,” Chu said. One would feature a coil array at the suit’s center that is connected to each of the limbs, and when activated the coils would pull on attached threads to tighten and pressurize the suit. Alternatively, smaller arrays could be places in multiple strategic locations to produce localized tension and pressure, she added.

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FOR THE KINDLE – The History of Space Exploration: redOrbit Press



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