Aerospace Plays Key Role in CYGNSS Mission That Uses GPS Technology to Improve Hurricane Forecasting

CYGNSS microsatellite (Illustration: Southwest Research Institute)

Commonly used GPS technology that many people have in their cars is being used in space to improve hurricane forecasting, with Aerospace playing a key role in testing a critical subsystem of the eight-satellite constellation at the heart of the mission.

GPS technology is a key capability in the NASA mission called the Cyclone Global Navigation Satellite System (CYGNSS), part of the NASA Earth System Science Pathfinder Program. The satellites were launched in December and are expected to be fully operational before this year’s hurricane season.

The CYGNSS mission uses eight microsatellites developed by the Southwest Research Institute (SwRI) under contract to the University of Michigan, the institution of the principal investigator. Aerospace provided support to Southwest from mid-2013 through the launch last December, primarily in developing a Spacecraft Dynamics Simulator (SDS) for use in end-to-end testing of the microsatellite attitude determination and control subsystem.

CYGNSS is using a novel mission architecture to calculate wind speeds that both reduces the mission’s cost and gathers more data.

The measurement of wind speed over the oceans from space typically uses a technique called scatterometry. A radar instrument aboard a satellite transmits a signal to the surface, and receives the signal reflected back to it.

The CYGNSS satellites don’t transmit; they receive only. They make use of signals broadcast from GPS satellites already orbiting the Earth that reflect off the ocean in addition to reaching the satellites directly. Consequently, CYGNSS microsatellites are smaller and less complex compared to satellites that transmit and receive, resulting in significant cost savings for the mission. Each CYGNSS microsatellite is roughly the size of a small suitcase when its solar arrays are stowed.

In building the SDS units, Aerospace’s Civil Systems Group  and Engineering and Technology Group (ETG) staff utilized their extensive expertise for developing and delivering similar hardware-in-the-loop and software-in-the-loop simulators used by traditional launch and satellite programs as part of the mission assurance process. A total of eleven SDS units were integrated and tested at Aerospace before delivery to SwRI.

A key benefit of using a constellation of microsatellites is that they will pass over a given location on the Earth’s surface more frequently than a single satellite would, resulting in a more detailed view of changes in the ocean winds.

The added quality and quantity of surface wind data, combined with precipitation fields produced by NASA’s Global Precipitation Measurement (GPM) mission, will provide data that will allow the hurricane forecasters to improve weather forecast models used to predict both the track and intensity of land-falling hurricanes. This data also will enable more accurate weather forecasts of wind speeds and storm surges — the walls of water that do the most damage when hurricanes make landfall.

Key Aerospace personnel who supported CYGNSS include: Dr. Robert Kinsey, Dr. Margaret Abraham, and Gary Boggan from Civil Systems Group; Andrew Hsu from the Systems Engineering Division; Pat Doyle, Nicholas Lin, Barry Pataky, Constantine Solomos, James Cowan, and Chris Reed from the Vehicle Systems Division; Robert Wallsgrove from the Computers and Software Division; and Dr. Richard Briet and Jeff Sokol from the Electronics and Sensors Division.