CYGNSS set for air-launch on Pegasus rocket from L-1011
CAPE CANAVERAL, Fla. — A constellation of small spacecraft tasked with conducting Earth science, as well as monitoring hurricanes, is set to be launched on Dec. 12, 2016, from an Orbital ATK Pegasus rocket from a specially-modified L-1011 aircraft.
The Cyclone Global Navigation Satellite System (CYGNSS) of eight microsatellites is being prepared to fly from Cape Canaveral Air Force Station in Florida. Each satellite weighs less than 44 pounds (20 kilograms) and uses less than 50 watts of power. The mission’s flight will mark only the sixth time a Pegasus has taken to the skies from the Sunshine State.
It is hoped the CYGNSS constellation will provide a better understanding of how hurricanes form and grow in strength. The satellites will also provide improved weather forecasts, including information about wind speeds and storm surges – some of the most destructive components of any hurricane.
“This is a first-of-its-kind mission,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate via a release issued by the agency. “As a constellation of eight spacecraft, CYGNSS will do what a single craft can’t in terms of measuring surface wind speeds inside hurricanes and tropical cyclones at high time-resolution, to improve our ability to understand and predict how these deadly storms develop.”
From non-synchronous orbits 317 miles (510 kilometers) above Earth’s surface, the CYGNSS observatories will continuously monitor surface winds over the tropic latitudes where hurricanes (also called typhoons or cyclones) form. Each satellite can capture four wind measurements per second, with the entire constellation collecting as many as 32 wind measurements per second.
Looking storms in the eye
CYGNSS will be using technology familiar to many of us when it reaches its orbital destination. The same GPS technology used by people to reach their destinations is used on the microsatellites as part of an instrument called the Delay Doppler Mapping Instrument.
Once in orbit, CYGNSS’s eight microsatellite observatories will receive both direct and reflected signals from GPS satellites. The direct signals pinpoint CYGNSS observatory positions, while the reflected signals respond to ocean surface roughness, from which wind speed will be derived.
“Today, we can’t see what’s happening under the rain,” said Chris Ruf, the principal investigator for the CYGNSS mission. “We can measure the wind outside of the storm cell with present systems. But there’s a gap in our knowledge of cyclone processes in the critical eyewall region of the storm – a gap that will be filled by the CYGNSS data. The models try to predict what is happening under the rain, but they are much less accurate without continuous experimental validation.”
Unlike current weather satellites, CYGNSS will be able to penetrate the heavy rain in a hurricane’s eyewall, enabling the system to collect data about the storm’s inner core.
The eyewall is the thick ring of thunderstorms surrounding the calm low-pressure eye at the center of a hurricane. The inner core acts like a heat engine, extracting energy from warm surface sea water via evaporation. The heat from the water vapor is then released into the atmosphere through condensation (clouds) and precipitation (rain). The intense rain in the eye blocks most satellites’ view of the inner core, preventing scientists from gathering much information about this region of the storm.
CYGNSS is the first complete orbital mission selected under NASA’s Earth Venture program, which concentrates on providing low-cost, rapidly developed science missions to enhance NASA’s understanding of Earth’s climate system and improve the ability to predict future changes.
Video courtesy of NASA Langley Research Center
Bart Leahy is a freelance technical writer living in Orlando, Florida. Leahy's diverse career has included work for The Walt Disney Company, NASA, the Department of Defense, Nissan, a number of commercial space companies, small businesses, nonprofits, as well as the Science Cheerleaders.