A new plastic skin that could protect satellites from both searing and freezing temperatures in space could allow for a new generation of miniature spacecraft, researchers announced yesterday. Satellite designers had hit a wall in the quest to create tiny "micro-spacecraft" that weigh no more than 50 pounds because the temperature controls used on conventional satellites can't be scaled down. Lead researcher Prasanna Chandrasekhar says the development could allow small companies to send up individual satellites that better suit their needs rather than sharing space on one large one. As might be expected, the technology also has some other potential uses:
"For the military, undetectability is also important, either for surveillance applications or when it comes to zapping other satellites," Chandrasekhar added. "And when it comes to a [nano-spacecraft] less than 5 kilograms (10 pounds), you can't really detect it unless it's within a quarter of a mile of you. Larger spacecraft can be detected from farther, and consequently blasted out of the sky" [SPACE.com].
Chandrasekhar's company, Ashwin-Ushas Corporation, is developing the technology in partnership with NASA.
Spacecraft can be in blazing sunlight or in the cold shadow of Earth or further out in space, and different operating conditions generate different amounts of heat from electronics. That makes temperature control difficult for craft of all sizes. "For large spacecraft, this is done with mechanical louvers—basically glorified window blinds—that open and close to allow in or reflect heat" [BBC News]
, says Chandrasekhar. But the weight and high cost of these systems make them impractical for smaller satellites. The new system, which was described at a meeting of American Chemical Society, uses a plastic skin that can switch from reflecting to absorbing light in both the visible and infrared spectra when an electric current passes through it. When positive voltage is applied, the material darkens and absorbs heat; negative voltage makes it lighten and reflect heat. This flexibility could allow tiny spacecraft to travel far from Earth, constantly adjusting their temperature as their distance from the sun changes. Says NASA engineer Jason Hines:
"It's our dream and vision and hope that eventually we can place smaller spacecraft in all types of missions, not just in near-earth orbit" [Wired News].
Image: Prasanna Chandrasekhar