HR: 0800h
AN: G51A-0810    [Abstracts]
TI: Global and Local Gravity Field Determination From Lunar Prospector Tracking Data
AU: * Goossens, S
EM: sander@miz.nao.ac.jp
AF: National Astronomical Observatory of Japan, Mizusawa Astrogeodynamics Observatory, 2-12 Hoshigaoka, Mizusawa-city, 023-0861 Japan
AU: Matsumoto, K
EM: matumoto@miz.nao.ac.jp
AF: National Astronomical Observatory of Japan, Mizusawa Astrogeodynamics Observatory, 2-12 Hoshigaoka, Mizusawa-city, 023-0861 Japan
AU: Visser, P
EM: pieter.visser@lr.tudelft.nl
AF: Department of Earth Observation and Space Systems, section Astrodynamics and Satellite Systems, Delft University of Technology, Kluyverweg 1, Delft, 2629 HS Netherlands
AB: In the near future a number of satellite missions are foreseen to be launched to the Moon. These missions include the Japanese Lunar-A and SELENE missions, as well as initiatives by China, India and the USA. They will collect a wealth of lunar data, thus improving our knowledge of the Moon and address questions concerning origin and constitution of the Moon. One of the main topics that will be addressed is the lunar gravity field. The SELENE mission will especially contribute to improving our knowledge of this. SELENE consists of a main orbiter and two relay subsatellites. By means of 4-way Doppler tracking between the main orbiter and a subsatellite, SELENE will provide the first truly global tracking data set of the Moon. Since the main orbiter will fly at an average altitude of 100 km, and the relay satellites are in high-altitude, highly elliptical orbits, SELENE will mostly be sensitive to the lower degrees. Lunar Prospector on the other hand flew at extremely low altitudes in its extended mission, making these data very well suited to extract the high-frequency gravity field information from the data. A combination of both data sets will allow using the best of both worlds. This work focuses on the use of Lunar Prospector tracking data for gravity field modelling purposes in preparation of the SELENE mission. A normal matrix for the Lunar Prospector data can be generated to be included later on in SELENE-derived solutions. Both global and local gravity fields have been determined. Local gravity fields have been created by means of a complete and independent processing of Lunar Prospector extended mission data. By using a pre-Lunar Prospector a priori gravity field model, it is shown that the local recovery method can extract the high-frequency signal from the actual data. The use of a priori information in the solutions is also addressed. The first three months of Lunar Prospector data have been used to derive a 75-degree global lunar gravity field model. Results for this model show a data fit that is at a lower level than a comparable JPL model using the same Lunar Prospector data. Despite relatively large differences in terms of anomalies on the far side, both models perform equally well in terms of data fit and overlap statistics when independent data are used. Results of the newly derived model however depend solely on Lunar Prospector data. It is expected that the use of Clementine and historical tracking data can help to determine the lower degrees better, until SELENE data become available.
DE: 1221 Lunar and planetary geodesy and gravity (5417, 5450, 5714, 5744, 6019, 6250)
DE: 5417 Gravitational fields (1221)
DE: 5450 Orbital and rotational dynamics (1221)
SC: Geodesy [G]
MN: Fall Meeting 2005