| Date: | 1998-02-25 22:00:00 | |
| Sender: | David Carter, NASA <[Mailed David L. Carter <dcarter@eib1.gsfc.nasa.gov>]> | |
| Subject: | [SLR-Mail] No. 104: GFO-1 Satellite Launch | |
| Author: | David Carter, NASA | |
| Content: | ******************************************************************************** SLR Electronic Mail 1998-02-25 22:00:00 UTC Message No. 104 ******************************************************************************** Author: David Carter, NASA Subject: GFO-1 Satellite Launch Subject: GFO-1 Satellite Launch Dear Colleagues: On February 10, 1998 the long awaited U.S. Navy GEOSAT Follow-On 1 (GFO-1) Satellite was successfully launched by a Taurus launch vehicle at 5:20 a.m., Pacific Time, from Vandenberg Air Force Base in California, U.S.A. The initial orbit was 881 X 789 km at 107.9846 degrees inclination. As was presented at the CSTG conferences in Porto, Portugal and Maratea, Italy, in June of 1996 and June of 1997 respectively, the GFO program is an initiative to develop an operational series of radar altimeter satellites to maintain continuous ocean observation from the GEOSAT Exact Repeat Orbit (ERO). The applications of GFO-1 will include use of altimeter data in coastal oceanography, in mapping mesoscale fronts and eddies, and in using basin-scale data for generating eddy-resolving global ocean models. The GFO-1 satellite has a mass of 300 kg and is approximately 3 meters long. The payload consists of the following equipment: a radar altimeter, a water vapor radiometer, a GPS-based precision tracking system, a Doppler beacon, and a laser retroreflector assembly. Tracking data generated from these systems, especially in combination, can support GFO-1 orbit accuracies approaching those achieved on TOPEX/Poseidon despite the lower altitude and increased atmospheric drag modeling errors. NASA Headquarters has requested the NASA Goddard Space Fight Center´s Space Geodesy Networks and Sensor Calibration Office (SGNSCO) to provide SLR support of the GFO-1. A number of NASA supported scientists will use these data for ocean, polar, and geophysical science studies. To most effectively support these studies, the best possible accuracy and precision must be obtained from GFO-1. International SLR support is needed to improve the overall precision orbit determination, including gravity model tuning, reference frame adjustment, and measurement calibration. International SLR support of GFO-1 is requested to commence following the establishment of the GEOSAT ERO. This should occur approximately in the middle of March. NASA SLR will generate acquisition data that will be distributed to all SLR organizations by conventional methods following the establishment of the ERO and the verification of all onboard subsystems. Currently, all NASA SLR stations will support the GFO-1 mission in the following four phases: Initial Acquisition, Intensive Tracking, Operational, and periodic Special Intensive Tracking Campaigns. A summary of these phases with planned durations are provided below. This mission has been thoroughly discussed at previous CSTG sub-commission meetings and it is requested that the global SLR community supports the GFO-1 mission in a similar fashion. 1) Initial Acquisition Phase: Priority: Top Priority Purpose: Achieve stable SLR Orbit for acquisition data generation Duration: 1-3 days Start Date: Tentatively, middle of March 1998 2) Intensive Tracking Phase: Priority: Top Priority Purpose: Altimeter Calibration Cross-comparisons of orbits produced by SLR and GPS Tuning of the gravity model Tuning of the non-conservative force model Duration: Approximately four 17-day orbital cycles 3) Operational Phase: Priority: Below TOPEX/Poseidon Purpose: Precise Orbit Determination Duration: Remainder of GFO-1 planned 10-year mission 4) Intensive Tracking Campaigns: Priority: Top Priority Purpose: Validation, Cross-calibration of orbits produced by SLR and GPS Duration: Each campaign will last approximately one 17-day cycle The following numbers are forms of identification and data information for the GFO-1 satellite: COSPAR #: 9800701 SIC #: 8501 NORAD #: 25157 NORMAL POINT BIN SIZE: 30 sec Thank you in advance for supporting the GFO-1 project. Additional information on the GFO-1 satellite and the formal start of SLR ranging will be forthcoming as information on the readiness of the satellite for SLR operations is made available. Best Regards, David Carter NASA Satellite Laser Ranging Networks Manager Space Geodesy Networks and Sensor Calibration Office NASA Goddard Space Flight Center Code 920.1 Greenbelt, MD 20771 (301) 286-6319 David L. Carter NASA/GSFC Code 920.1 Greenbelt, MD 20771 301-286-6319 dcarter@eib1.gsfc.nasa.gov [Mailed From: ”David L. Carter” ******************************************************************************** |