Speaker:  Dr. David H. Atkinson Department of Electrical and Computer Engineering, University of Idaho

Title:   " Measuring the Zonal Winds on Titan: The Huygens Probe Doppler Wind Experiment"

Abstract:  The ESA Huygens Probe entered the atmosphere of Titan, the largest moon of Saturn, and descended for nearly 2.5 hours on 14 January 2005. Huygens survived impact on the surface and continued its telemetry broadcast to the NASA Cassini spacecraft on two separate radio links, denoted Channels A and B, respectively, for an additional 1.2 hours. Throughout the descent and onto the surface, six experiments studied the composition, structure and dynamics of the Titan atmosphere and the surface. One of these experiments, the Doppler Wind Experiment (DWE), was designed to measure the zonal (east-west) wind speeds from an altitude of 150 km to the surface. The instrumentation for the Doppler Wind Experiment (DWE), comprising two Ultra-Stable Oscillators in the transmitter (TUSO) and receiver (RUSO), was implemented only in Channel A. Whereas Channel B functioned flawlessly during the entire mission, the receiver for Channel A was never able to lock onto the Huygens signal because the DWE-RUSO had not been properly programmed into the critical probe radio relay sequence. All data on Channel A, including the DWE measurements and probe telemetry, were thus lost. In spite of this setback, the Channel A signal was successfully received at many radio telescopes on Earth. The precision of these Doppler measurements, considered as an aggregate, is roughly equivalent to that which had been foreseen from the measurements on board Cassini. In this presentation I will provide an overview of Huygens probe mission, describe the DWE ground-based observations, and discuss the Titan wind profile derived from them.

Host: Bill Hiscock