A futuristic spacesuit will adapt itself to the astronaut's skin

For the astronauts of the future, the process of putting on the space suit may be like this: instead of squeezing into a normal and bulky pressure suit, the astronaut will only have to get into a light-weight suit that stretches according to his body dimensions

[Translation by Dr. Nachmani Moshe]
For the astronauts of the future, the process of putting on the space suit may be like this: instead of squeezing into a normal and bulky pressure suit, the astronaut will only have to enter a light-weight, stretchy suit bounded by tiny coil-like belts. In the next step, the suit will be connected to the spacecraft's electrical system and the belts will tighten and wrap the suit around the astronaut's body.

The body-hugging suit will not only support the astronaut, but it will also give him much more freedom of movement during space experiments. In order to remove the suit, all that is needed is to apply a little force that returns the suit to its relaxed and loose state.

Now, researchers from the Massachusetts Institute of Technology (MIT) are one step closer to the development of such an active suit, a kind of "second skin" on the body: Dava Newman, professor of aeronautics and astronautics and engineering systems at the institute, and her colleagues, have succeeded in developing a compression-activated garment that includes Tiny spring-like coils that tighten in response to heat. The coils consist of "memory alloys" (or shape-memory alloys or nitinol or smart alloys, Wikipedia) - a type of material that "remembers" its original shape and, after bending or deforming its shape, can jump back to its original shape in response to heating.

The researchers included these coils inside an inflatable tourniquet-like cuff and applied an electrical voltage to generate heat. At a defined initiation temperature the coils shrunk back to their original shape, like springs returning to their original length, while tightening the cuff. In subsequent experiments, the research team found that the pressure created by the coils is equal to that required to fully support an astronaut in space conditions.

"When talking about normal space suits, the astronaut is actually inside a gas balloon that provides a third of the normal atmosphere, when this is the amount necessary for him to survive in the vacuum of space," says the lead researcher, who has been working for the past decade on the development of a futuristic flexible space suit. "We wanted to achieve the same pressure, but through mechanical equivalents - applying direct pressure to the body, which eliminates the need for gas for compression. In our development we combined tolerant elastic materials together with active materials. Bottom line, the main advantage of our system lies in its high mobility and being a light-weight suit suitable for experiments in space."

Despite the fact that body-tight suits have been proposed in the past, one consistent and stubborn design problem has remained since then: how to compress and release a pressure suit that would also be lightweight. At this point Zochro alloys may provide the solution. Such materials only contract in response to heat, and can be easily relaxed to their original shape after cooling. In order to find the most suitable material for use in space, the researchers examined 14 types of memory materials - ranging from dielectric elastomers to memory polymers - until they chose nickel-titanium memory alloys. When this alloy is shaped into very tight springs of small diameter, they contract when heated and create significant force, and given their low mass, they are ideal for use in light-weight tight fitting clothing. The material itself is usually produced in the form of coils of straight and extremely thin fibers. In order to turn the fiber into coils, the researchers used another method developed at the same institute (MIT) and which used nickel-titanium coils to develop a heat-activated robotic worm (video).

Practically speaking, nickel-titanium type memory alloys can be "trained" to return to their original shape in response to a specified temperature. At room temperature the coils can be stretched or bent, similar to a paper clip. However, at a defined initiation temperature (in this case 60 degrees Celsius) the fiber begins to stretch back to its original state. The researchers added an array of such coils to an elastic cuff, where each coil was tied with a tiny thread to the cuff. Next they attached metal lugs to the ends of the coils and applied an electrical voltage to generate heat. In a temperature range of 160-60 degrees Celsius the coils shrunk while pulling the bound fibers with them and thereby tightening the cuff. "These are actually self-closing buckles," explains the lead researcher. "Once you put the suit on, you just run an electric current through all these tiny coils and then the suit will tighten around your body and protect it in its entirety."

The next step for the researchers was to find a way to keep the suit airtight. To this end, the researcher explains, there are only two ways: either maintain the constant heating or implement a locking mechanism inside the suit that prevents the coils from unraveling. The first solution may overheat the astronaut and will require the use of bulky battery cases - a design that will make mobility significantly more difficult and may even lack any feasibility given the limited energy sources in space conditions. The researchers are currently examining the second solution and trying to find possible mechanisms to lock the coils in place.

As for the exact location of the coils inside the suit, the researcher compliments several possible designs. For example, a network of coils running through the center of the suit, with each coil connected to a fuse that spans the width of the suit at several points along its length. When the coils are activated (with heat), they are able to pull the fuses connected to them - similar to marionette strings - that tighten and press the suit to the body; Or networks of coils can be placed in strategic locations inside the suit to obtain local tension and pressure, depending on the optimal place where they are required to maintain uniform pressure on the entire body. Although the researchers are mainly focused on applications suitable for the space field, the lead researcher claims that the designs and active materials that came under their control can also be used for other purposes, for example in sports suits and military uniforms: "Our design can be used as a tourniquet in cases where someone loses a lot of blood on the battlefield," she says the researcher "If your suit has sensors, it will be able to tighten on your body automatically without you even thinking about it."

"A tailored bodysuit is a fascinating idea for improving human performance," adds the lead researcher. "Our job is to maintain the survivability, safety and mobility of our astronauts, but the new designs could be useful not only in space."

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