Mars Microphone

Description

The Mars Microphone is designed to detect sounds in the martian environment and record and transmit them back to Earth, and to record frequency spectrum information on sounds. The instrument consists of a microphone typically used in hearing aids and an off-the-shelf digital sound processor chip with digital electronics and internal memory to acquire and store sound samples. These are contained on a printed circuit board about 5 x 5 cm in dimension, the entire package is about 1 cm thick and is mounted on the LIDAR instrument on top of the instrument deck. The microphone is expected to detect sounds from sand blown against the lander and surrounding terrain, wind sounds, possible sounds from electrical discharges in the dust clouds, as well as sounds the lander makes operating its motors, robotic arm, and other apparatus.

The instrument can operate in one of two modes. Very short records of sound can be recorded directly by the microphone and stored in the limited memory for later transmission to Earth. The instrument can sample at high frequency (20 kHz) which will allow 2.6 second samples, or low frequency (5 kHz) giving 10.6 second samples. Due to the large sample size and limited transmission capability, it will probably take days or weeks to return each sound sample. The instrument can also operate in a mode to record the integrated power in 6 filter bands, 5 filters which cover the sound spectrum (approximately one octave each) and one which gives the total power in the instrument pass band. In this mode the sample time can range from 1 second at very high time resolution to 10 minutes. The Mars Microphone has 12-bit dynamic range and amplifiers which can provide a boost by a factor of 1, 4, 16, or 64. The amplifiers will be necessary because the thin martian atmosphere will not transmit sounds well.