HR: 0800h
AN: G51A-0808    [Abstracts]
TI: An asynchronous laser transponder experiment in deep space using MESSENGER's Mercury Laser Altimeter
AU: * Neumann, G A
EM: neumann@tharsis.gsfc.nasa.gov
AF: Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Smith, D E
EM: David.E.Smith@nasa.gov
AF: Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Zuber, M T
EM: Zuber@mit.edu
AF: Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Zuber, M T
EM: Zuber@mit.edu
AF: Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307 United States
AU: Sun, X
EM: Xiaoli.Sun@nasa.gov
AF: Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Cavanaugh, J F
EM: John.F.Cavanaugh@nasa.gov
AF: Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: McGarry, J F
EM: Jan.F.McGarry@nasa.gov
AF: Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Zagwodski, T W
EM: Thomas.W.Zagwodzki@nasa.gov
AF: Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AB: The Mercury Laser Altimeter (MLA) aboard the MErcury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft ranged to Earth as part of its in-flight calibration activities, while NASA's Goddard Geophysical Astronomical Observatory (GGAO) fired laser pulses at MLA. On two separate afternoons, while MESSENGER was visible above the horizon at a distance of 24 million km, trains of 16 and 25 consecutive pulses were detected at GGAO with inter-arrival times matching those transmitted by MLA, while on one afternoon, 90 pulses from GGAO were detected by MLA during a 30 minute time span. A linear fit to the MLA pulse time-of-flight revealed a 4.154 km/s Doppler shift in the nominal 8-Hz firing rate, with the majority of pulse centroid times fit to within 300 ps, or less than 10 cm in range, and for the extended but weaker detections at MESSENGER, the majority could be fit by a quadratic curve within 2.5 ns. The ability to make such precise measurements, together with MESSENGER's stable on-board clock, allows a solution with formal covariances for two-way range, range-rate, and acceleration, as well as clock parameters. We discuss the implications of this calibration experiment for the measurement of orbital and geodetic parameters via asynchronous laser ranging.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1294 Instruments and techniques
SC: Geodesy [G]
MN: Fall Meeting 2005