A smoothing technique for improving atmospheric reconstruction for planetary entry probes

Accelerometer instruments are commonly used on planetary entry probes to determine vertical profiles of atmospheric density, pressure, and temperature. A key consideration for the design and implementation of such investigations is extending the atmospheric results to the highest altitudes possible, which requires minimizing uncertainties in measured accelerations whilst maintaining adequate vertical resolution. Since atmospheric density depends exponentially on altitude, the arithmetic mean of a subset of raw acceleration data points is a biased estimate of the true acceleration at the center of the time interval in question. This diminishes the quality of derived atmospheric properties. Here we show how this problem can be alleviated by using a specialized averaging technique that takes advantage of the inherent exponential variation in acceleration with time at atmospheric entry. This technique is demonstrated successfully on Mars Phoenix data.

► We extend useful entry accelerometer data to higher altitudes.
► We demonstrate this technique on Mars Phoenix data.
► Exponential dependence of acceleration on time is significant.