Characterization of the Thermal and Solar Plasma Noise on the Doppler Performance for the MESSENGER Mission
- Paper number
IAC-07-A3.I.A.24
- Author
Mr. Dipak Srinivasan, Johns Hopkins University Applied Physics Laboratory, United States
- Coauthor
Dr. Mark Perry, The John Hopkins University Applied Physics Laboratory, United States
- Year
2007
- Abstract
In 2011, MESSENGER will be the first mission to orbit the planet Mercury. MESSENGER will achieve several scientific objectives, including the radio science requirement of determining the planet’s gravity field to degree 16. The primary data product for assessing the gravity field is the Doppler data provided by the spacecraft radio frequency (RF) telecommunication system and the NASA Deep Space Network. The two strongest Doppler error sources for the MESSENGER mission include thermal and solar plasma noise. Special spacecraft pointing constraints while in orbit about Mercury prevent most of the RF Doppler data from being captured using the spacecraft’s high-gain antenna. Instead, a large portion of the Doppler data will be provided by a low-power RF link via the spacecraft’s low-gain antennas, a configuration that increases the thermal noise contribution to the Doppler measurement error. The solar plasma noise is also large due to Mercury’s close proximity to the Sun. A calibration and characterization plan to take place during the cruise to Mercury has been implemented with the first test results showing fairly close agreement with the modeled error sources; this test measured the Doppler data and ranging quality as a function of power level in the presence of solar plasma noise. Subsequent calibration and characterization activities will ensure the radio science concept of operations once at Mercury will result in an accurate mapping of the gravity field.
- Abstract document
- Manuscript document
IAC-07-A3.I.A.24.pdf (🔒 authorized access only).
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