Browsing by Author "Yen, Nick L."

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Constellation Deployment for the FORMOSAT-3/COSMIC Mission
(2008-11-01)
Fong, Chen-Joe
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Shiau, Wen-Tzong
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Lin, Chen-Tsung
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Kuo, Tien-Chuan
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Chu, Chung-Huei
The FORMOSA Satellite Series No. 3/Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC) spacecraft constellation consisting of six low-earth-orbiting satellites is the world's first operational Global Positioning System (GPS) radio occultation mission. The mission has been jointly developed by the National Space Organization of Taiwan and the University Corporation for Atmospheric Research of the U.S. in collaboration with the Jet Propulsion Laboratory, NASA, and the Naval Research Laboratory for three onboard payloads, including a GPS Occultation Receiver, a triband beacon, and a tiny ionospheric photometer. The FORMOSAT-3/COSMIC mission was successfully launched from Vandenberg into the same orbit plane of the designated 516-km circular parking orbit altitude on April 15, 2006. After the six satellites completed the in-orbit checkout activities, the mission was started immediately at the parking orbit for in-orbit checkout, calibration, and experiment of three onboard payloads. Individual spacecraft thrust burns for orbit raising were performed to begin the constellation deployment of the satellites into six separate orbit planes. All six FORMOSA717-3/COSMIC satellites are maintained in a good state of health except spacecraft flight model no. 2, which has had power shortages. Five out of the six satellites had reached their final mission orbits of 800 km as of November 2007. This paper provides an overview of the constellation spacecraft design, constellation mission operations, constellation deployment timeline evolution, associated spacecraft mass property and moment of inertia results, orbit-raising challenges, and lessons learned during the orbit-raising operations.
FORMOSAT-3/COSMIC Constellation Spacecraft System Performance: After One Year in Orbit
(2008-11-01)
Fong, Chen-Joe
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Yang, Shan-Kuo
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Chu, Chung-Huei
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Huang, Cheng-Yung
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Yeh, Jia-Jing
The FORMOSAT-3 mission, also known as Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), is the third major project of the Formosa Satellite (FORMOSAT) series implemented by the National Space Organization of Taiwan. FORMOSAT-3/COSMIC is a joint Taiwan/U.S. mission consisting of six identical low Earth orbit satellites. All six cluster satellites were successfully launched by a single Minotaur launch vehicle on April 15, 2006. The retrieved global positioning system (GPS) radio occultation (RO) data have been freely available online to the science community since shortly after the completion of satellite bus in-orbit checkout. Having completed the verification and validation, the worldwide science communities are highly satisfied with the RO data. Scientists have hailed the RO sensors as offering the most accurate, precise, and stable thermometers in space. After one year in orbit, all six FORMOSAT-3/COSMIC satellites were in good condition (except FM2, which had power shortage issues) and were on their way toward the final constellation of six separate orbit planes with 30 degrees separation. Four out of six satellites had already reached their final mission orbit of 800 kin by mid-May 2007. Together, the six satellites have generated a total of more than 2500 RO data per day. However, only 50%-70% of the RO data as received one year after launch could be retrieved into useful atmosphere profiles. The retrieved RO data, about 1800 per day on average, have been assimilated into numerical weather prediction models by many major weather forecast centers and research institutes. This paper provides an overview of the constellation mission, the spacecraft system performance after one year in orbit, the technical challenges we have encountered, and the performance enhancements we have accomplished.
FORMOSAT-3/COSMIC Spacecraft Constellation System, Mission Results, and Prospect for Follow-On Mission
(2009-02-01)
Fong, Chen-Joe
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Yen, Nick L.
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Chu, Chung-Huei
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Yang, Shan-Kuo
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Shiau, Wen-Tzong
The FORMOSAT-3/COSMIC spacecraft constellation consisting of six LEO satellites is the world's first operational GPS Radio Occultation (RO) mission. The mission is jointly developed by Taiwan's National Space Organization (NSPO) and the United States' UCAR in collaboration with NSF, USAF, NOAA, NASA, NASA's Jet Propulsion Laboratory, and the US Naval Research Laboratory. The FORMOSAT-3/COSMIC satellites were successfully launched from Vandenberg US AFB in California at 0 140 UTC 15 April 2006 into the same orbit plane of the designated 516 km altitude. The mission goal is to deploy the six satellites into six orbit planes at 800 kin altitude with a 30-degree separation for evenly distributed global coverage. All six FORMOSAT-3/COSMIC satellites are currently maintaining a satisfactory good state-of-health. Five out of six satellites have reached their final mission orbit of 800 kin as of November 2007. The data as received by FORMOSAT-3/COSMIC satellites constellation have been processed in near real time into 2500 good ionospheric profiles and 1800 good atmospheric profiles per day. These have outnumbered the worldwide radiosondes (similar to 900 mostly over land) launched from the ground per day. The processed atmospheric RO data have been assimilated into the Numerical Weather Prediction (NWP) models for real-time weather prediction and typhoon/hurricane forecasting by many major weather centers in the world. This paper describes the FORMOSAT-3/COSMIC satellite constellation system performance and the mission results that span the period from April 2006 to October 2007; and reviews the prospect of a future follow-on mission.
In Quest of Global Radio Occultation Mission for Meteorology beyond 2011
(2009)
Fong, Chen-Joe
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Yen, Nick L.
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Chu, Chung-Huei
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Hsiao, Chun-Chieh
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Yang, Shan-Kuo
The FORMOSAT-3/COSMIC mission consisting of six satellites is the world\'s first demonstration of near real-time operational GPS Radio Occultation (RO) constellation mission. The success of the mission expected to operate through 2011 has initiated a new era for operational GPS RO soundings. The World Meteorological Organization had recommended continuing RO observations operationally and urges planning for a complementary follow-on mission. The follow-on mission will be a new constellation of 12 to 18 satellites equipped with the GNSS RO payload and collect over 9000 soundings per day. This higher density of sounding profiles will be useful for global and mesoscale models, and also severe weather forecasting. The follow-on mission will establish international standards so that future RO missions deployed by any country can be used together for operations and research. In this paper, we present the state-of-the-art achievements and the results of the current mission; as well as the follow-on mission planning progress.(1) (2)
Space-Based Global Weather Monitoring System: FORMOSAT-3/COSMIC Constellation and Its Follow-On Mission
(2009-07-01)
Fong, Chen-Joe
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Yen, Nick L.
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Chu, Vicky
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Hsiao, Chun-Chieh
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Liou, Yuei-An
The FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission consisting of six low-Earth-orbit satellites is the world's first demonstration of Global Positioning System radio occultation in a near real-time operational constellation for global weather monitoring and research. The mission has produced over 1800-2200 high-quality good atmospheric sounding profiles per day. Currently, the atmospheric soundings data are assimilated into operational numerical weather prediction models for global weather prediction, including typhoon/hurricane forecasts. The radio occultation data have been shown to have a positive impact on weather predictions at many national weather forecast centers. The goal of a proposed follow-on mission is to transfer from the current experimental research mission to a significantly improved real-time operational mission, which will reliably provide no less than 8000 soundings per day. We envision a new and improved mission to be a constellation of 12 satellites with data latency less than 1.5 h, which will provide greatly enhanced opportunities for operational forecasts and scientific research. In this paper, we describe highlights of the results of the current mission, the follow-on mission definition trade analysis results, and the new spacecraft constellation system design with the next-generation radio occultation receiver onboard.