以下为转载的电子邮件: CHAMP End of Mission Dear colleagues, after 3718 days in orbit the CHAMP spacecraft re-entered on Sun- day, Sept.19, around midday over the Sea of Okhotsk. The last ra- dio contact was established on the same day at 08:26 UT over the German ground station Weilheim at an altitude of only 150 km. This marks the end of a geoscience mission, which exceeded the expectations by far. With CHAMP almost continuous observation series over an unprecedented long time period have been generated for the Earth gravity field, the magnetic field and the atmo- sphere. Modeling activities were and will continue to be largely dependent on the high quality POD/OCC results as obtained with the BlackJack SGPS- and the SLR- observations for CHAMP. The CHAMP mission team wants to express its sincere thanks to both the ILRS and the IGS for the tremendous support all their service entities , in particular the station crews, have provided for the CHAMP mission, a mission covering the full Decade for Geopoten- tials. Many thanks again Chris Reigber Rolf Koenig From: Rolf Koenig rolf.koenig@gfz-potsdam.de GFZ的消息---- http://www.gfz-potsdam.de/portal/gfz/Public+Relations/Pressemitteilungen/aktuell/100920_PM_CHAMP-End CHAMP: A Fiery End Scheme picture of the GeoResearch-Satellite Champ 20.09.2010 | Potsdam: CHAMP: A Fiery End After 58277 orbits it was finally all over: in the afternoon of 19. September the georesearch satellite CHAMP burned up in space . Exactly 10 years, two months and 4 days after going into orbit, the satellite ended its mission over the Sea of Okhotsk. Professor Hermann Lhr, GFZ German Research Centre for Geosciences, communicated this news. Up until the end, Hermann Lhr was responsible for the evaluation of the magnetic field data measured by CHAMP: CHAMP was last located above the German station Weilheim on Sunday at 10:26 CEST. At this time it was flying at only 150 kilometres above the Earth and had been in orbit for 3718 days. The Federal Ministry for Education and Research initiated a satellite mission in 1995 as a flagship project for the East German space industry, in order to promote the existing know-how in Eastern Germany in this field. The concept CHAMP (Challenging Mini Satellite Payload), proposed by the GFZ (Helmholtz Association), was selected for the realisation of this mission. As a result, a 522 kg heavy satellite with a total length of 8.33 m was developed. It was used to measure the Earth's gravity field, the Earths magnetic field and to probe the atmosphere. Ten years ago CHAMP was put into orbit at an altitude of approximately 460 kilometres . Originally it was expected that CHAMP would have a lifetime of four to five years. Due to its design, however, the satellite had such a stable flight even at a low flight path that the mission time could be more than doubled. The satellite owes its long life span to the fact that the cold gas originally intended for position control could additionally be used to raise CHAMP four times. Now, after a full decade of orbiting, the following conclusion can be drawn: Internationally, CHAMP has been one of the most successful satellite missions for Earth observation. Professor Dr. Reinhard Httl, Scientific Executive Director and Chairman of the GFZ Board, said with respect to the end of CHAMP: The success of the Champ Mission shows the scientific and economic potential of Earth observation satellites. For the GFZ, satellite missions are indispensable also in future; TandemX, EnMap, SWARM and GRACE-C stand for our priorities in the Earth's gravity field, the Earths magnetic field and surface observations. The initiator of the CHAMP Mission was Professor Christoph Reigber, at that time Director of the Department Geodesy and Remote Sensing at the GFZ. In November, the French Air and Space Academy will be awarding him the Grand-Prix for his achievements in connection with the CHAMP and GRACE Missions
Orbit Characteristics The CHAMP satellite was launched with a Russian COSMOS launch vehicle on July 15, 2000 into an almost circular, near polar (i = 87) orbit with an initial altitude of 454 km. The design lifetime of the satellite system is 5 years. The 87 degree inclination is the maximum inclination which can be served from the Plesetsk cosmodrome. The reason for choosing an almost circular and near-polar orbit is the advantage of getting a homogeneous and complete global coverage of the Earth's sphere with orbit and magnetometer measurements, being important to resolve the gravitational and magnetic geopotentials. An advantage of the 87 orbit vs. a dawn-dusk sun-synchronous orbit is the local time variation of the satellite's ground track which is essential for all three scientific applications in order to enable the separation of constituents of periodic phenomena like tides and day-night variations. An initial altitude of about 454 km is chosen (a) to guarantee a multi-year mission duration even under severe solar activity conditions, (b) to account for the requirement imposed by the atmosphere/ionosphere application to look from the outside through the different atmospheric layers, i.e., an even higher altitude would be the optimum in this regard, and (c) because 454 km is the adequate altitude to observe the Earth's magnetic main field. From the gravity field's point of view an even lower initial altitude would be desirable. Due to atmospheric drag the altitude will decrease over the 5 years mission lifetime. As CHAMP will pass through the solar activity maximum in about 2001, the predicted natural decay depends on the magnitude of the actual solar activity cycle and may amount to more than 200 km or only 50 km within the 5 years.. Therefore at least one velocity change manoeuvre by the 40 mN thrusters cold gas was foreseen, correcting for orbit injection errors and rising or lowering the orbit of the S/C to guarantee a 5 years observation period above 300 km and some months of observation time below 300 km altitude towards the end of the mission. After 2 orbit changes in 2002 CHAMP will provide further highly valuable data for another 2-3 years from low altitude. The International Laser Ranging Service (ILRS at http://ilrs.gsfc.nasa.gov ) provides tracking from its global network of laser ranging stations to support the project. Launch The CHAMP satellite was launched from the cosmodrome Plesetsk (north of Moscow) aboard a Russian COSMOS launch vehicle. The launch took place on July 15, 2000 at 11:59:59.628 UTC. Plesetsk Cosmodrome The launch site Plesetsk is located 800 km north-east of Moscow and has historically been the most active launch site on earth, from which over one third of all launches ever realized took place. From this site a wide range of up to almost polar inclinations can be served. COSMOS Launch Vehicle The POLYOT Design Bureau, Omsk has manufactured the Cosmos launch vehicle for nearly 30 years. The two-stage booster burns unsymmetrical dimethyl hydrazine (UDMH) as a fuel and either nitric acid or nitrogen tetroxide (N 2 O 4 ) as the oxidiser. The first stage employs two 11 D614 (RD216) main engines, while the second stage relies on a single, restartable 11D49 main engine. The second stage also carries an independent propulsion system for coast and spacecraft deployment operations. Used only for low earth orbit missions, the Cosmos-3M has a demonstrated payload capacity of 1,500 kg to a low altitude, 51 inclination parking orbit. However, since 1988 all Cosmos-3M missions have originated from the Plesetsk Cosmodrome with inclinations of 66, 74, 83, 87 and SSO. Main characteristics of the COSMOS launch system: Launch facility: ground supported, stationary Total launch mass: 109 metric tons Payload mass: up to 1500 kg Payload orbits: 250 to 1700 km Total length of launcher: 32.4 m Core diameter: 2.4 m Launches: 700 Success Rate: 97.4 %
With a completely new generation of low-orbiting satellites, equipped with highly precise inter-satellite and accelerometry-instrumentation observing the Earth gravitational field and its temporal variability, space geodesy has entered the 21 century. Section 1.2 had a leading role in setting up the operational processing systems for CHAMP (lauch July 2000) and GRACE (lauch March 2002) and is handling a great deal of the data preprocessing, precision orbit determination and generation of monthly gravity field solutions for both missions on a routine basis. Section 1.2 is also heavily engaged in the preparation of upcoming national (TerraSAR, Tandem-X) and European missions (GOCE, SWARM, GRACE-follow on). Section 1.2 together with Section 1.3 in addition is involved in the analysis of historical tracking data including the first GFZ geopotential satellite GFZ-1, and in the analysis of gravity data over land and oceans. By combination of different data subsets the EIGEN satellite and combination models are computed. Section 1.2 is involved in research and development activities as well as in operational and coordination tasks for various gravity and altimetry missions and the related tracking support. Research is done primarily in support of precision orbit determination of near Earth satellites, high resolution gravity field modelling and the use of satellite altimetry for oceanography and geodetic / geophysical applications. 来源:http://www.gfz-potsdam.de/pb1/op/index_GRAM.html
EIGEN-1S is a satellite-only gravity field model including 88 days of CHAMP data. The model is a combination of GRIM5-1S normal equation system More can be found on the section 1.3 webpages Lageos-1,-2, Starlette derived constraints on zonals additional Lageos-1,-2, Starlette and Stella laser tracking data (year 2000) CHAMP GPS satellite-to-satellite tracking data: 88days within the periods 2000, July 30 - Aug. 10, and Sept. 24 - Dec. 31 (accelerometry used for surface force reduction) Please note: although higher degree/order terms are solved in EIGEN-1S, the solution has got full power only up to about degree/order 35, which is typical for a satellite-only solution. Higher degree/order terms are solvable applying stochastic a priori information according to a degree variance model (regularization of the normal equation system). The EIGEN-1S data set contains fully normalized spherical harmonic coefficients complete to degree/order 100 with higher degree terms up to maximum degree 119 for CHAMP sensitive and resonant orders permanent tide is not included in C(2,0) C(0,0) and degree 1 terms are not solved DOT-terms (C(2,0) to C(4,0)) represent drifts per year, epoch for corresponding static terms: 1997.0 standard deviations are given along with the coefficients. The standard deviations were posteriori calibrated applying a degree dependent calibration factor (cf. header of EIGEN-1S data set) The EIGEN-1S correlation matrix of the spherical harmonic coefficients is available as a CHAMP OG Level 4 product through the CHAMP Information System and Data Centre (ISDC) the formats are described on the CHAMP web pages (op.gfz-potsdam.de/champ) under 'Online Available Documents' in the document 'CHAMP gravity field solution data formats'. from:http://www.gfz-potsdam.de/pb1/op/champ/results/index_RESULTS.html
EIGEN-CHAMP03S is a CHAMP-only gravity field model derived from CHAMP GPS satellite-to-satellite and accelerometer data out of the period October 2000 through June 2003. EIGEN-CHAMP03S is the final version of the preliminary model EIGEN-3p and results from a homogeneous reprocessing of all normal equations including the improved parametrization of the accelerometer calibration parameters. Normal equation regularisation starts at degree 60. from:http://www.gfz-potsdam.de/pb1/op/champ/results/index_RESULTS.html
The first word of CHAMP is Challenging. T the small satellite liked CHA llenge. CHAMP satellite has flied seven years... CHAMP Mission Elapsed Time: 2530 days, 0 hours and 27 minutes CHAMP satellite in healthy condition; June 19, 2007 ------------- 参考文献来源:http://www.gfz-potsdam.de/pb1/op/champ/ CHAMP ( CHA llenging M inisatellite P ayload) is a German small satellite mission for geoscientific and atmospheric research and applications, managed by GFZ. With its highly precise, multifunctional and complementary payload elements (magnetometer, accelerometer, star sensor, GPS receiver, laser retro reflector, ion drift meter) and its orbit characteristics (near polar, low altitude, long duration) CHAMP will generate for the first time simultaneously highly precise gravity and magnetic field measurements over a 5 years period. This will allow to detect besides the spatial variations of both fields also their variability with time. The CHAMP mission will open a new era in geopotential research and will become a significant contributor to the Decade of Geopotentials . In addition with the radio occultation measurements onboard the spacecraft and the infrastructure developed on ground, CHAMP will become a pilot mission for the pre-operational use of space-borne GPS observations for atmospheric and ionospheric research and applications in weather prediction and space weather monitoring.
标签: CHAMP
