"It's part of the Mission to Planet Earth (program), to help us understand human impact on the environment so that we can rationally develop countermeasures," astronaut David Wolf said in a preflight interview.
After leaving the orbiting station, the shuttle crew set up the experiment, called SHIMMER, in the side hatch window.
"We just kind of aim the shuttle where the window is, so SHIMMER can look at the upper atmosphere," said flight engineer Sandra Magnus.
The SHIMMER experiment -- for Spatial Heterodyne Imager for Mesospheric Radicals -- was built by the Naval Research Laboratory. It tests a new technique for measuring and analyzing ultraviolet light emitted by hydroxyl molecules located 19 to 62 miles above the planet's surface.
Hydroxyl plays a critical role in ozone chemistry throughout the atmosphere and has been tied directly to ozone destruction above 30 miles.
SHIMMER, which is about the size of a deskjet printer, is about one-seventh the size of conventional upper-atmospheric spectrometers but has sharper resolution.
"The great speed of the shuttle allows us to scan large areas of the atmosphere," Wolf said. "SHIMMER has very sensitive detectors ... which allow us to analyze the components of the upper atmosphere as part of the full understanding of the human impact on our environment."
The information is expected to help engineers design atmospheric sensors for future Earth-monitoring satellites.
"This is the first orbital operation of the instrument," said University of Wisconsin physicist Fred Roesler, who designed SHIMMER with a colleague at the Naval Research Laboratory.
"We anticipate getting new science from this flight."
The instrument is expected to operate for about three hours, collecting data during two daylight passes around Earth and a night-time pass with SHIMMER aimed at the moon for a calibration test. If successful, the instrument could be flown again on another shuttle mission, said Roesler.
"The long-term objective is to get global hydroxyl distribution data," he said, "and for that we need satellite observations. But there are a number of issues we can address with the data even from a short pass."
SHIMMER was developed through the Department of Defense Space Test Program, with support from NASA and the National Science Foundation.