Cyclone Global Navigation Satellite System
Mission type | Weather research | |
---|---|---|
Operator | NASA | |
COSPAR ID | 2016-078A, 2016-078B, 2016-078C, 2016-078D, 2016-078E, 2016-078F, 2016-078G, 2016-078H | |
SATCAT no. | 41884, 41885, 41886, 41887, 41888, 41889, 41890, 41891 | |
Website | cygnss-michigan | |
Mission duration | Planned: 2 years Elapsed: 7 years, 5 months, 30 days | |
Spacecraft properties | ||
Manufacturer | ||
Launch mass | 28.9 kg (64 lb) each[1][2] | |
Dimensions | 163.5 × 52.1 × 22.9 cm (64.4 × 20.5 × 9.0 in)[1] (L x W x D) | |
Power | 34.7 watts | |
Start of mission | ||
Launch date | December 15, 2016, 13:37:21 Orbital ATK | |
Entered service | March 23, 2017[3] | |
Orbital parameters | ||
Reference system | Semi-major axis 6,903 km (4,289 mi) | |
Eccentricity | 0.00162 | |
Perigee altitude | 514 km (319 mi) | |
Apogee altitude | 536 km (333 mi) | |
Inclination | 35 degrees | |
Period | 95.1 minutes | |
Epoch | April 15, 2017, 22:21:25 UTC[5] | |
Instruments | ||
Delay Doppler Mapping Instrument | ||
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.
In June 2012, NASA sponsored the project for $152 million with the University of Michigan leading its development.[6][7] Other participants in CYGNSS' development include the Southwest Research Institute, Sierra Nevada Corporation, and Surrey Satellite Technology.[8]
The plan was to build a constellation of eight
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.[15][16]
CYGNSS will measure the ocean surface wind field using a bi-static
CYGNSS is the first of NASA's Earth Venture-class spaceborne missions, part of NASA's Earth Science System Pathfinder program;[8] 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,[17] and December 12, 2016.[12][18]
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.[11] 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.[11]
Instruments
Each CYGNSS satellite carries a Delay Doppler Mapping Instrument (DDMI), consisting of:
- a Delay Mapping Receiver (DMR)
- two nadir-pointing antennas
- one zenith-pointing antenna
The instrument receives
Launch and early orbit operations
The CYGNSS mission was launched on December 15, 2016, at 13:37:21 UTC from a single
Use of Differential Drag to Adjust Satellite Spacing
Early mission operations focused on engineering commissioning of the satellites[24] and adjustments to the spacing between them. Their relative spacing is important for achieving the desired spatial and temporal sampling.[25] Inter-satellite spacing is controlled by adjusting spacecraft orientation and, as a result, the difference in atmospheric drag between satellites. This technique is referred to as differential drag. An increase in drag lowers a satellite's altitude and increases its orbital velocity.[26] The distance between spacecraft changes as a result of their relative velocities. This is an alternate way of managing the spacing between a constellation of satellites, as opposed to using traditional active propulsion, and is significantly lower cost. It allows for more satellites to be built for the same net cost, resulting in more frequent sampling of short lived, extreme weather events like tropical cyclones.[16] Differential drag maneuvers were conducted throughout the first year-and-a-half of on-orbit operations, and have resulted in a well-dispersed constellation that is able to make measurements with the desired sampling properties.[27][28]
Wind Observations over the Ocean
Wind speed measurements are made by CYGNSS in a manner analogous to that of previous spaceborne ocean wind sensing radars, by detecting changes in surface roughness caused by near surface wind stress.[29][30] The quality of the measurements is determined by comparisons to nearly coincident observations by other wind sensors. Comparisons at low to moderate wind speeds (below 20 m/s, 45 mph, 72 km/h) are made to the NOAA Global Data Assimilation System numerical reanalysis wind product and indicate an uncertainty in CYGNSS winds of 1.4 m/s (3 mph; 5 km/h), with higher uncertainty at high wind speeds.[31] Above 45 mph, and in particular for measurements made within tropical cyclones, comparisons are made to nearly coincident observations by wind sensing instruments on NOAA P-3 hurricane hunter aircraft which were flown into hurricanes in coordination with satellite overpasses by CYGNSS.[32] The comparisons indicate an uncertainty in CYGNSS winds of 11%.[33] As was the case at lower wind speeds, the uncertainty increases with wind speed. CYGNSS ocean wind speed measurements are currently being incorporated into hurricane numerical forecast models[34][35][36][37] and storm surge models[38] to assess the improvement in their performance. Images of recent and archival ocean wind measurements, both globally and centered on individual storms, are available at [1] Archived January 21, 2019, at the Wayback Machine. Numerical data files of ocean wind speed measurements are available at [2].
Observations over Land
CYGNSS operates continuously, over both ocean and land, and the land measurements also contain useful information. The measurements are sensitive to surface soil moisture and to the presence and extent of inland water bodies.[27] Soil moisture has been estimated using CYGNSS data at numerous sites in the continental U.S. and is found to be in close agreement with independent measurements made by ground sensors and by another satellite.[39][40] Numerical data files of soil moisture measurements are available at [3]. The ability of CYGNSS land data to detect and map the extent of flood inundation under dense forest canopies has also been demonstrated[41] and this capability has been used to produce time lapse images of flooding in and around Houston and Havana after landfalls by Hurricanes Harvey and Irma, respectively.[42]
See also
References
- ^ a b "CYGNSS Press Kit" (PDF). NASA. December 16, 2016. Archived from the original (PDF) on May 8, 2018. Retrieved April 17, 2017.
- ^ a b Graham, William (December 15, 2016). "Pegasus launches CYGNSS constellation following Stargazer release". NASA Spaceflight. Retrieved April 17, 2017.
- ^ "NASA's CYGNSS Satellite Constellation Enters Science Operations Phase". NASA. March 31, 2017. Archived from the original on June 29, 2017. Retrieved April 16, 2017.
- ^ a b Clark, Stephen (December 15, 2016). "Flock of 'microsats' launched to measure winds inside hurricanes". Spaceflight Now. Retrieved April 16, 2017.
- ^ "CYGNSS - Orbit". Heavens-Above. April 15, 2017.
- ^ "U-M To Lead $152M NASA Satellite Project". Associated Press. June 19, 2012. Retrieved June 22, 2012.
- ^ a b Clark, Stephen (June 21, 2012). "NASA funds satellite mission to measure hurricane winds". SpaceflightNow. Retrieved June 22, 2012.
- ^ a b "NASA Selects Low Cost, High Science Earth Venture Space System". NASA. June 18, 2012. Retrieved June 24, 2012.
- ^ "U-M to Lead $150M NASA Hurricane Prediction Project". University of Michigan. June 19, 2012. Archived from the original on June 23, 2012. Retrieved November 14, 2016.
- ^ Aldridge, James (June 21, 2012). "NASA taps SwRI on research effort to map hurricanes". San Antonio Business Journal. Retrieved June 22, 2012.
- ^ a b c d e f "CYGNSS Factsheet October 2014". Archived August 4, 2016, at the Wayback Machine University of Michigan. Retrieved: September 27, 2015.
- ^ a b "CYGNSS Mission". University of Michigan. Retrieved February 11, 2016.
- ^ "University of Michigan, NASA team up for hurricane satellite project". Michigan Radio. June 19, 2012. Retrieved April 11, 2023.
- ^ "Notes from the Field - Happy Sixth Birthday to the CYGNSS Constellation". NASA Earth Observatory. December 15, 2022. Retrieved October 3, 2023.
- ^ a b c "CYGNSS." Archived March 15, 2013, at the Wayback Machine University of Michigan. Retrieved: August 15, 2015
- ^ S2CID 10991111.
- ^ "Missions - CYGNSS". NASA. April 30, 2013. Archived from the original on April 7, 2014. Retrieved September 8, 2013.
- ^ Leone, Dan (June 19, 2012). "NASA To Fund Wind-monitoring Smallsat Constellation". Space News. Archived from the original on February 3, 2013. Retrieved June 22, 2012.
- ^ "NASA Hurricane Science Satellites sent into Orbit by Air-Launched Pegasus Rocket". Spaceflight 101. December 15, 2016. Retrieved April 16, 2017.
- ^ "'Valiant Troubleshooting in the Air' - CYGNSS Hurricane Mission". blogs.nasa.gov. December 12, 2016. Retrieved December 12, 2016.
- ^ Allen, Bob (December 15, 2016). "First CYGNSS micro-satellite is healthy!". NASA. Retrieved April 16, 2017.
- ^ Atkinson, Joseph (December 15, 2016). "Eight for Eight! All Satellites Contacted!". NASA. Retrieved April 16, 2017.
- ^ Ruf, Chris (December 15, 2016). "A Message From CYGNSS Principal Investigator Chris Ruf". NASA. Retrieved April 16, 2017.
- ^ Killough, Ronnie; Scherrer, John; Rose, Randall; Brody, Antonina; Redfern, Jillian; Smith, Keith; Ruf, Christopher; Yee, Terrance (August 9, 2017). "CYGNSS Launch and Early Ops: Parenting Octuplets". AIAA/USU Conference on Small Satellites.
- S2CID 19175653.
- ISBN 978-087703605-0.
- ^ PMID 29884899.
- S2CID 59234996.
- ISSN 2156-2202.
- ISSN 0196-2892.
- S2CID 13966928.
- ^ "Notes from the Field - Flying into Hurricane Harvey". earthobservatory.nasa.gov. January 20, 2019. Retrieved January 20, 2019.
- ^ "Notes from the Field - Two year anniversary of CYGNSS on orbit". earthobservatory.nasa.gov. January 20, 2019. Retrieved January 20, 2019.
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- ^ Cui, Z., Z. Pu, C. Ruf, V. Tallapragada, 2019a: Impact of CYGNSS Data on Tropical Cyclone Analysis and Forecasts Using the Operational HWRF. 23rd IOAS-ALOS Conference, AMS Annual Mtg, Jan 6-10, 2019, Phoenix, AZ.
- S2CID 25898619.
- S2CID 53379291.
- S2CID 134962064.
- ISSN 2072-4292.
- PMID 29921941.