The FOTON is a highly sensitive GPS receiver, designed to withstand the rigors of spaceflight while detecting subtle fluctuations in the signals from GPS satellites.

These fluctuations help us learn about the ionosphere in which the signals travel, says Powell, who returned to Ithaca in early March after spending 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 says, but they are the scientific gold nuggets in the data analysis process.

Powells experiment is one of a number of projects studying the Earths atmosphere and ionosphere. It shares a mounting palette on the outside of the ISS, 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-Cs position onboard the ISS will allow it to study the ionosphere at an edge-on perspective, Powell said, to measure variations in electron density. The Cornell teams 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 says, 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 says.

This experiment builds on a short-duration NASA sounding-rocket mission Powell led in 2012, which was sent into the aurora to study the ionosphere at high latitudes, near the North Pole.

This experiment will allow us to study different, but equally interesting, effects in the ionosphere closer to the equator, where most of the worlds population lives, Powell says.

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 says. Ive 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 says, so the quantity of data and the potential for meaningful scientific discovery is huge.

Source: Cornell University

Link:

GPS Monitors Space Weather from Space Station - Controlled Environments Magazine