Polly Estabrook

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For planetary lander missions, the most challenging phase of the spacecraft-toground communications is during the entry, descent, and landing (EDL). As each 2003 Mars Exploration Rover (MER) enters the Martian atmosphere, it slows dramatically. The extreme acceleration and jerk cause extreme Doppler dynamics on the 8.4-GHz (X-band) signal received on Earth.(More)
In the Mars rover missions the signals transmitted back to Earth travel under low SNR conditions in highly non-stationary channels [1, 2]. During the entry, descent and landing phase (EDL), the spacecraft high dynamics yields severe Doppler effects. We propose a robust and low complexity scheme to estimate and track carrier frequency from the received(More)
AbetractData centric sensor networks will play an important role in planetary explorations. In the future JPL envisions sending in-situ missions with distributed instruments and sensors capable to cooperate autonomously and to collect scientific measurements (gases, chemicals, temperature, etc.). A lander or a rover functioning as a base station collects(More)
In this article we characterize the effect of transmitter clock jitter upon receiver symbol synchronization performance. Using a sinusoidal model for the timing jitter, we evaluate the bit error rate (BER) degradation and cycle slip probabilities of receivers via analysis as well as simulation for uncoded offset quadrature-phase-shift-keying (OQPSK). We(More)
During the entry, descent and landing phase (EDL) of the missions to Mars, the spacecraft's high dynamics imprints severe Doppler swings on the signals transmitted via the direct-to-Earth (DTE) channel. In order to recover the data that record the mission status from the received signal, a reliable estimate of the Doppler profile is required. We extend(More)
One of the most crucial stages of the Mars exploration missions is the entry, descent, and landing (EDL) phase. During EDL, maintaining reliable communication from the spacecraft to Earth is extremely important for the success of future missions, especially in case of mission failure. EDL is characterized by very deep accelerations, caused by friction,(More)
1. INTRODUCTION In January 2004, the two NASA Mars Exploration Rovers (MER) – also known as Spirit and Opportunity-arrived at Mars. Before they could start their scientific investigation looking for traces of water and evidence of possible life in the past, the two rovers had to pass through a dangerous stage of entry, descent and landing (EDL). Each rover(More)
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