From: Cornell University
Posted: Wednesday, March 15, 2017
Cornell University engineers have developed a new piece of technology to study charged particles in the plasma of space, on the edge of Earth’s atmosphere – known as “space weather.” These particles affect the performance of communications and navigation satellites.
To study conditions in the ionosphere, a band between 50 and 600 miles above the Earth, Steven Powell and others in Cornell’s College of Engineering have developed the highly sensitive FOTON (Fast Orbital TEC for Orbit and Navigation) GPS receiver. FOTON is designed to withstand the rigors of spaceflight while detecting subtle fluctuations in the signals from GPS satellites. Last month, the FOTON hitched a ride aboard the SpaceX Falcon 9 rocket to begin a long-term project at the International Space Station.
The project, which could last two years, is called GROUP-C (GPS Radio Occultation and Ultraviolet Photometry-Colocated), and is headed by Scott Budzien of the Naval Research Laboratory. Powell, a research support specialist in electrical and computer engineering, is the Cornell principal investigator for the project.
“These fluctuations help us learn about the ionosphere in which the signals travel,” said Powell, who spent six weeks in Alaska on a project to send two sounding rockets into the aurora borealis, also to study the ionosphere.
“These fluctuations are typically filtered out by standard GPS receivers,” he said, “but they are the scientific ‘gold nuggets’ in the data analysis process.”
Powell’s experiment is one of a number of projects studying the Earth’s atmosphere and ionosphere. It shares a mounting palette on the outside of the international space station, receives power from large solar arrays, and uses the data communications system onboard the station to quickly distribute data back to Earth.
Powell and Hysell will collect data from the GROUP-C experiment.
GROUP-C’s position onboard the space station will allow it to study the ionosphere “at an edge-on perspective,” Powell said, to measure variations in electron density. The Cornell team’s GPS receiver and antenna – actually a suite of three antennas, configured to maximize GPS signals and minimize unwanted reflections from the large metal portions of the ISS – will focus on GPS satellites as they move across the sky and set behind the Earth.
As they set, Powell said, the radio signals travel through the ionosphere and are subtly delayed by the denser regions of the ionosphere. “From that, we obtain a vertical profile of the electron density,” he said.
“This experiment will allow us to study different, but equally interesting, effects in the ionosphere closer to the equator, where most of the world’s population lives,” Powell said.
The Feb. 19 liftoff of the SpaceX rocket, and docking with the ISS four days later, was the culmination of a nearly four-year effort to get GROUP-C built.
“It was extremely exciting and satisfying to see the GROUP-C experiment [launch],” Powell said. “I’ve been involved in more than 50 space-based research efforts over a 30-year period, but most have been using suborbital NASA sounding rockets, with mission durations of just 10 to 30 minutes.
“The GROUP-C experiment duration will last up to two years,” he said, “so the quantity of data and the potential for meaningful scientific discovery is huge.”
Cornell University has television, ISDN and dedicated Skype/Google+ Hangout studios available for media interviews. For additional information, see this Cornell Chronicle story.
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