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CHAllenging Minisatellite Payload for geoscience and application
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- Earth's gravity field recovery
- Earth's magnetic field recovery
- global Earth's atmosphere sounding
- Earth's ionosphere sounding
- Complimentary tracking system to onboard GPS for POD and gravity recovery
- Two-color ranging experiments
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Characteristics
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| Launch Date |
May 2000 |
| Mission Duration |
5 years |
| Altitude |
470 km - 300 km |
| Inclination |
87.3 deg |
| Eccentricity |
0.001 |
| Spatial Coverage |
global |
| Temporal Coverage |
all times |
| Data Accuracy |
Millimeter to centimeter ranging accuracy |
| Satellite Mass |
522 kg |
| Satellite Dimensions |
1621 mm in width and 8333 mm in length, including 4044 mm for the boom |
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CHAMP
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This mission is scheduled to last 5 years in
order to provide a sufficiently long observation time to resolve long-term temporal variations
primarily in the magnetic field, in the gravity field and within the atmosphere.
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.
Instrumentation
- Dual-frequency GPS receiver
- Three-axes accelerometer
- Magnetometer instrument package
- Digital ion drift meter
- Retroreflector array
The three primary science objectives of the CHAMP mission are to provide
- highly precise global long-wavelength features of the static Earth gravity field and the
temporal variation of this field.
- unprecedented accuracy global estimates of the main and crustal magnetic field of the Earth
and the space/time variablity of these field components
- with good global distribution a large number of GPS signal refraction data caused by the atmosphere
and ionosphere, which can be converted into temperature, water vapor and electron content
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Science Missions Objectives
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The geoid constitutes the surface which is most commonly known as 'sea level' in land surveying.
Topographic heights are related to the geoid: heights above 'sea level'. Modern satellite positioning systems,
like the American GPS, measure point heights which are related to a geometric surface the ellipsoid.
In order to transform ellipsoidal heights to topographic heights, the geoid undulations have to be subtracted.
To compete with the high GPS measurement accuracy, which is at cm-level, the geoid has to be known with the same accuracy.
Then, effective GPS-levelling could replace the man-power intensive geometric levelling in surveying.
With CHAMP, the broad signatures of the geoid will be recoverable with an unpreceded accuracy, i.e. the CHAMP derived
global geoid will serve as an ideal basis for a further refinement in regional and local areas evaluating existing or
dedicated high resolution gravity information for a detailed geoid computation. The long-wavelength geoid will also
give a reference for a unified global height system, being important when employing modern satellite surveying methods and
constructing digital terrain models covering large land and ice areas for remote sensing applications and for cartography.
Any progress in the accuracy and completeness of long-wavelength gravity field models will also directly improve the reliability
and accuracy of precise satellite orbit restitution as required in satellite altimetry and SAR-interferometry.
For the gravity field, CHAMP commences the international decade of geopotentials. The follow-up missions GRACE (launched 2001)
and GOCE (planned 2005) are consequent extensions on the way towards a detailed gravity field modelling for research of the Earth as a system.
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