Bending Mirrors in Space: How a New Technology Increases the Efficiency of Space Telescopes
In 1609, Galileo Galilei, an Italian physicist and astronomer, became the first person to point a telescope toward the sky. Since then, telescopes have gotten bigger and better, peering into the distant reaches of space and time. However, as ground-based telescopes improved past a certain point, astronomers encountered a problem unrelated to the telescope’s design.
Earth’s atmosphere allows visible light and radio waves to pass through but blocks most other radiation, including X-rays and gamma rays. Infrared or ultraviolet rays are also partially blocked.
With telescopes placed in space, images are free of the distorting and shielding effects of the Earth’s atmosphere. Producing these space observatories, however, requires significantly larger expenditures than ground-based observations. Space observatories also have size limitations, as they must be launched into space.
Telescopes in space feature reflective mirrors that concentrate the radiation reaching them from distant stars and planets. The larger these mirrors are, the more radiation they reflect. This is important because more radiation equates to an increased visibility of dimmer objects, allowing them to be further analyzed.
Victoria Coverstone, professor and chair of the Department of Mechanical and Aerospace Engineering, is leading the research of a technology that will allow the launch of visible-to-infrared (Vis-IR) mirrors with diameters much larger than what the current launch vehicle fairings allow.
“Our concept is to replace traditional thick-ridged mirrors with foldable mirrors that are only a fraction of a millimeter thick,” says Coverstone. “This technology will allow large mirrors to be folded up for launch.”
This would enable small satellites, such as CubeSats (a type of miniaturized satellite no larger than a toaster) to take over roles that are currently being filled by larger, more expensive satellites.
“Due to the mirrors being much thinner than traditional mirrors,” explains Coverstone, “the concept also has the potential to significantly decrease the satellite weight compared to satellites with similar-sized conventional mirrors, increasing the ease to move the satellite.”
The research project will test and analyze the deformation of the mirror as it folds and the accuracy with which it returns to its original shape. Ultimately, a model of the mirror material will be developed to provide practical information on the mirror’s use, e.g., the radius of curvature that the mirror can be bent without fracturing, or the effect of temperature variations on the material and deformations.
The research project, titled “DOMinATE (Deployable Optical MembrAne Telescope),” is funded by the National Reconnaissance Office’s (NRO) Director’s Innovation Initiative (DII) program. As a response to the Soviet launch of Sputnik, the NRO was established as a joint U.S. Department of Defense-Intelligence Community organization responsible for developing, acquiring, launching and operating America’s signals, imagery and communications intelligence satellites. The DII is a program within the NRO designed to provide disruptive, exponential technologies that offer radical breakthroughs to solve some of the NRO’s greatest challenges.