Humans were never really meant to live in space, but that hasn't stopped us from trying. The lack of gravity wreaks havoc on the body, while radiation exposure leaves astronauts with an increased risk of cancer and other diseases. A team from Australian National University (ANU) has developed a new nanomaterial that could protect space travelers with a thin film that dynamically reflects harmful radiation.
Beyond the safety bubble of the Earth's magnetosphere, radiation from the Sun and more distant sources can do some serious damage. Spacesuits, spacecraft and instruments all have thick shielding to protect people and objects from harmful infrared and ultraviolet rays, but the materials are usually big and bulky. That's not ideal in space, where mobility and minimizing weight are paramount.
The ANU nanomaterial could perform much the same function at a fraction of the thickness. The surface is made up of nano-particles that can reflect certain wavelengths of light as needed – in this case, infrared and ultraviolet. Better yet, different layers of the material could selectively allow or prevent this light from passing through, and a user could change it on the fly by altering the temperature. By heating and cooling the material, the nano-particles become more or less refractive as it expands or contracts.
"The important factor about our work is that, by changing the temperature of nano-particles, we change the refractive index of them and it leads to a variation in the optical properties of nano-particles," lead researcher Mohsen Rahmani tells New Atlas. "By calculating those variations in the optical properties we managed to design and fabricate resonant nano-particles, which can act differently before and after changing the optical properties. Therefore how they interact with light can be controlled and designed on demand."
It's not simply a case of switching refraction on or off. Rahmani says that the individual nano-particles are capable of operating on a sliding scale, fully transmitting light, reflecting it, or anywhere in between. The heating source that triggers the reaction can either be external or built in, and potentially controlled by a user or wearer of the material.
"Controlling the temperature of material can be done by many means," Rahmani tells us. "For example using an additional laser beam, which can heat the surface, or using micro-heaters embedded inside the substrate. The latter one can be very similar to a series of parallel resistive wires on the back windscreen to defog the rear view. A similar arrangement could be used with our invention to confine the temperature control to a precise location."
Effective as the material may be against infrared and ultraviolet radiation, it won't do much to shield astronauts from highly energetic particles – but then, neither do existing spacesuits. The ANU researchers say the material will increase the "resistance threshold" against harmful radiation, and if tweaked to work with other wavelengths of light, it also could find other, more domestic uses.
"For instance, you could have a window that can turn into a mirror in a bathroom on demand, or control the amount of light passing through your house windows in different seasons," Andrey Miroshnichenko, co-researcher on the project, says in a statement.
Source: Australian National University
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