Cyclone Global Navigation Satellite System (CYGNSS) at SwRI

This article was written for SpaceFlight Insider, and is republished here with permission.

On August 11, Southwest Research Institute (SwRI) in San Antonio, Texas, opened its doors to media, sharing progress on its Cyclone Global Navigation Satellite System (CYGNSS). The independent, nonprofit, applied research and development (R&D) organization has a long history of involvement in our nation’s space program, including building two of the instruments on NASA’s Juno spacecraft now in orbit around Jupiter, but CYGNSS is the first mission in which SwRI has built the primary spacecraft as well.

CYGNSS is a constellation of eight small satellites whose goal is to improve hurricane (tropical cyclone) intensity forecasting. Citing National Hurricane Center forecast verification data, CYGNSS Principal Investigator Dr. Chris Ruf of the University of Michigan notes that while hurricane/tropical cyclone tracking improved nearly 50 percent since 1990, there has not been a corresponding improvement in the accuracy of intensity forecasts.

Each 64-pound CYGNSS satellite is equipped with four Global Positioning System (GPS) receivers to measure the signals scattered off the ocean’s surface. By measuring the distortion in the received GPS signals, scientists can determine surface wind speeds–the rougher the ocean, the more distorted the received signal, and thus, the higher the surface wind speed. Since GPS signals penetrate heavy rain, CYGNSS will be able to take wind speed measurements of areas other satellites cannot, including the eye wall and inner rain bands of hurricanes/tropical cyclones. The constellation of CYGNSS satellites will also provide more frequent measurements than existing stand-alone satellites.

CYGNSS Fact Sheet, October 2014 (Univ. of Michigan)
13 day sample run to test CYGNSS fidelity

Long before assembly of a single CYGNSS satellite began, the team utilized
“hundreds of hours of NASA supercomputer time to run countless simulations of CYGNSS fly-throughs,” according to Aaron Ridley, constellation scientist from the University of Michigan. These simulations helped the team determine not only how many satellites to include in the constellation, but also at what orbital inclination and altitude to place the satellites (this determines what “swath” of the Earth they monitor.) Aaron wrote a blog post about some of the decision-making process, as well as the deployment and constellation spacing.

CYGNSS is one of NASA’s new Earth Venture class missions, the agency’s low cost, rapid-turnaround Earth Science missions. In 2012, the University of Michigan’s proposal for the CYGNSS mission was competitively-selected from among 19 proposals submitted to NASA.

CYGNSS small satellites in launch configuration attached to deployment module

Each of the eight CYGNSS satellites was designed, built, tested, and validated at SwRI. The CYGNSS satellites’ GPS receivers and other antennas were provided by Surrey Satellite Technology, and the deployment module was provided by Sierra Nevada Corporation.

After SwRI’s environmental testing of the satellites is complete, the CYGNSS constellation will be transported to Vandenberg Air Force Base to be mated with the Orbital ATK Pegasus XL launch vehicle. The Pegasus XL is an air-launched rocket released from an Orbital ATK “Stargazer” L-1011 carrier aircraft at approximately 40,000 feet. After a five-second free fall, the Pegasus XL rocket’s first stage engine ignites, beginning its ascent to orbit.

CYGNSS will be the 43rd launch of a Pegasus XL rocket since 1990, joining the ranks of NASA missions such as NASA’s NuSTAR and IRIS. Launch of CYGNSS is scheduled for 1300-1430 GMT (8:00-9:30 am ET) on November 21, 2016, from the skies above Cape Canaveral Air Force Station in Florida.

Pegasus XL launch vehicle (Image Credit: Orbital ATK)

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