Search for Electrostatic Discharges on Mars
Abstract
The Allen Telescope Array was used to monitor Mars between March 8 and June 1, 2010 over a total of approximately 42 hours, for signals indicative of electrostatic discharge using a wideband signal processor developed at the Center for Astronomy Signal Processing and Electronics Research (CASPER), following the report by Ruf et al., 2009, of the possible detection of electrostatic discharge on Mars. In conjunction with the ATA, simultaneous observations were done by JPL on the Deep Space Network antenna.
The 1024-channel spectrometer receives complex-baseband voltage data from the ATA beamformer, from which it computes power and spectral kurtosis of the input signal in real-time. For this experiment, the ATA beamformers, each of which delivers a 104.8 MHz bandwidth, were tuned to 3.2 and 8.0 GHz. The spectral kurtosis is calculated using the method suggested in Nita et al., 2007, using a ratio between power and power squared. Variations in the kurtosis are indicative of non-Gaussianity in the signal, which can be used to detect variable cosmic signals as well as radio frequency interference -- in particular, lightning discharge in the Martian atmosphere measurable as a variation in the kurtosis corresponding to Mars' Schumann resonance. In the presence of a Gaussian signal, the kurtosis takes on a constant value. Interference, and the non-thermal emission associated with electrostatic discharge, are non-Gaussian, and thus cause the kurtosis to deviate from the Gaussian value. The instrument and analysis were tested on a variety of known sources of non-Gaussian emission, including the Crab pulsar and a number of terrestrial sources, such as satellites, which showed appropriate deviations in power and kurtosis corresponding to radio interference, and in the case of the Crab pulsar, giant pulses.- Publication:
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American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011
- Bibcode:
- 2011AAS...21724003D