This novel, three-dimensional, foldable radiator is inspired by the art of paper folding. Still early in its development, researchers are experimenting with different shapes to determine which configuration would work best as a radiator. Photo: Brigham Young University.The ancient Japanese art of paper folding has inspired the design of a potentially trailblazing ‘smart’ radiator that a NASA technologist is now developing to remove or retain heat on small satellites.
Vivek Dwivedi, a technologist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, has teamed up with a couple of researchers at Brigham Young University in Utah to advance an unconventional radiator that can fold and unfold, much like the V-groove paper structures created with origami. NASA's Center Innovation Fund (CIF), which supports potentially ground-breaking, high-risk technologies, is funding the effort.
Under the partnership, Brigham Young University assistant professor Brian Iverson and doctoral student Rydge Mulford are advancing the design of a three-dimensional, foldable radiator, while Dwivedi is developing a coating to enhance the radiator's heat-shedding or -conservation capabilities.
This novel radiator controls the rate of heat loss by performing shape-shifting maneuvers. These topographical changes can be achieved by using temperature-sensitive materials like muscle wire or shape-memory alloys. As these temperature-sensitive materials experience a change in temperature, which in satellites could be caused by spacecraft electronics or the absorption of heat from the Earth or sun, the radiator would automatically change its shape to either shed or conserve heat.
The deeper the folds or cavities in the radiator, the greater the heat absorption, explained Mulford, adding that scientists have investigated the use of cavities to affect heat loss for nearly 100 years, but no one had approached the challenge in quite this way. "Origami allows you to change the depth of these cavities in real time, thereby changing the heat loss from a surface in real time," he said.
Dwivedi, meanwhile, is working to advance a highly emissive coating principally made of vanadium oxide, a transition metal oxide, which would be applied to the origami radiator. In addition, he is also investigating the coating’s potential for use on other spacecraft components, including solar-array panels.
In tests, vanadium oxide has proved able to change from a semiconductor to a metal when it reaches 154°F, leading to an increase in emissivity, Dwivedi said. Because satellites encounter wildly fluctuating temperature changes on orbit, Dwivedi's goal is to lower this transition temperature.
In collaboration with Raymond Adomaitis, a professor at the University of Maryland, Dwivedi plans to do this by applying very thin films of silver and titanium to the vanadium oxide. These films will be applied using a combination of sputtering and a technique called atomic layer deposition (ALD), which is performed in a state-of-the-art reactor developed by both Dwivedi and Adomaitis. With ALD, engineers can literally apply atomic-sized layers of different materials onto intricately shaped structures – much like how a cook layers different ingredients to make a pan of lasagne.
"The combination of origami and a vanadium oxide-based coating would be the first time two different variable emissivity devices have been combined into one structure," Iverson said. By combining both technologies, the team believes it can create a smaller, more efficient radiator ideal for use on CubeSats, tiny spacecraft that are growing in popularity due to their relatively low cost. Such a radiator, Iverson said, could be easily attached to any spacecraft surface where heat needed to be expelled.
While early in its development, the origami radiator can't come too soon, particularly for use on CubeSats. Traditional radiators are typically flat and heavy, not lending themselves to installation on a satellite measuring as little as four inches on a side. "This approach has the potential to be a game changer in thermal design," Dwivedi said. "Our goal is to replace traditional radiators with dynamic ones, period."
This story is adapted from material from NASA's Goddard Space Flight Center, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.