Since then, the group has succeeded at manufacturing and processing relatively large, high-quality pieces of graphene, and is now ready to apply its expertise to advance other applications. "One of the most promising applications of this material is as a chemical sensor," Sultana said.
She has teamed with retired Goddard scientist Fred Herrero, who is pursuing the research in an emeritus capacity, to develop a miniaturized, low-mass, low-power, graphene-based detector that could measure the amount of atomic oxygen in the upper atmosphere. Atomic oxygen in the upper atmosphere is created when ultraviolet radiation from the sun breaks apart oxygen molecule (O2). The resultant reactive element is highly corrosive. As satellites fly through the upper atmosphere, the chemical strikes them at about five miles per second. The impacts destroy commonly used spacecraft materials, such as Kapton.
Although scientists believe atomic oxygen makes up 96 percent of the thin atmosphere in low-Earth orbit, Herrero is interested in measuring its density and determining more precisely its role in creating atmospheric drag, which can cause orbiting spacecraft to lose altitude prematurely and plunge to Earth. "We still don't know the impact of atomic elements on spacecraft in creating a drag force," he said. "We don't know how much momentum is transferred between the atom and the spacecraft. This is important because engineers need to understand the impact to estimate the lifetime of a spacecraft and how long it will take before the spacecraft reenters Earth's atmosphere."
Research has shown that graphene-based sensors offer a good solution, Sultana said. When graphene absorbs atomic oxygen, it oxidizes, producing a change in the material's electrical resistance that a graphene-based sensor could then quickly count to
|Contact: Lori Keesey|
NASA/Goddard Space Flight Center