Mission type Weather research Website cygnss-michigan.org Launch mass 28.9 kg (64 lb) each | Operator NASA Mission duration Planned: 2 years | |
Manufacturer University of Michigan and
Southwest Research Institute | ||
The Cyclone Global Navigation Satellite System (CYGNSS) is a space-based system developed by the University of Michigan and Southwest Research Institute with the aim of improving hurricane forecasting by better understanding the interactions between the sea and the air near the core of a storm.
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In June 2012, NASA sponsored the project for $152 million with the University of Michigan leading its development. Other participants in CYGNSS' development include the Southwest Research Institute, Sierra Nevada Corporation, and Surrey Satellite Technology.
The plan was to build a constellation of eight micro-satellites to be launched simultaneously in a single launch vehicle into low Earth orbit, at 500 km altitude. The program was scheduled to launch December 12, 2016, and then observe two hurricane seasons. Problems with a pump on the launching aircraft prevented this first launch, but a second launch attempt took place successfully on December 15, 2016.
Overview
Forecasting the tracks of tropical cyclones since 1990 has improved by approximately 50%; however, in the same time period there has not been a corresponding improvement in forecasting the intensity of these storms. A better understanding of the inner core of tropical storms could lead to better forecasts; however, current sensors are unable to gather a sufficient quality of data on the inner core due to obscuration from rain bands surrounding it and to infrequent sampling. In order to improve the models used in intensity forecasts, better data are required.
CYGNSS will measure the ocean surface wind field using a bi-static scatterometry technique based on GPS signals. Each satellite receives both direct GPS signals and signals reflected from the Earth's surface; the direct signals pinpoint the microsatellite position and provide a timing reference, while the reflected or "scattered" signals provide information about the condition of the sea's surface. Sea surface roughness corresponds to wind speed. Using a network of eight small satellites enables frequent observations: the mean revisit time is predicted to be 7 hours. The eight microsatellites orbit at an inclination of 35°, and are each capable of measuring 4 simultaneous reflections, resulting in 32 wind measurements per second across the globe.
CYGNSS is the first of NASA's Earth Venture-class spaceborne missions, part of NASA's Earth Science System Pathfinder program; the previous EV selections were divided among five airborne remote sensing missions. The two-year mission launched on December 15, 2016, after postponements from November 2016, and December 12, 2016
Science goal
The CYGNSS science goal is to understand the coupling between ocean surface properties, moist atmospheric thermodynamics, radiation, and convective dynamics in the inner core of a tropical cyclone. To achieve this goal, the system will measure ocean surface wind speed in all precipitating conditions, including those experienced in the eyewall. The mission will also measure ocean surface wind speed in the storm's inner core with sufficient frequency to resolve genesis and rapid intensification. As secondary goal, the project will support the operational hurricane forecast community by producing and providing ocean surface wind speed data products.
Instruments
Each CYGNSS satellite carries a Delay Doppler Mapping Instrument (DDMI), consisting of:
The instrument receives GPS signals scattered by the ocean surface for the purposes of bi-static scatterometry.
Launch and early orbit operations
The CYGNSS mission was launched on 15 December 2016 at 12:37 UTC from a single Pegasus XL air-launched rocket. The rocket was deployed from a customized Lockheed L-1011 aircraft, Stargazer, from a position 125 miles (200 kilometers) off the coast of Cape Canaveral Air Force Station, FL. A launch attempt on 12 December was aborted due to problems with the hydraulic system that separates the Pegasus rocket from the carrier aircraft. After launch, the eight microsats were released into orbit beginning at 12:50 UTC and ending at 12:52 UTC by a deployment module attached to the Pegasus third stage. Successful radio contact with the first microsat was made at 15:42 UTC. The eighth microsat was successfully contacted at 19:30 UTC. By the end of the day on 15 December, all eight microsats had their solar arrays deployed and were sun-pointed with batteries charging in safe condition, ready to begin engineering commissioning.