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October 8, 1999

Mars Microphone Ready for Duty

Mars Polar Lander is nearing Mars for its scheduled December 3 arrival. A trajectory correction maneuver will be applied this week to target it for the final selected landing site on Mars (76 degrees south latitude, 195 degrees west longitude). Following the loss of Mars Climate Orbiter due to a navigation error, this maneuver and all the project navigation is being watched closely.

The Planetary Society's Mars Microphone is on board the lander, and as far as we can tell, in good shape. We hope to hear sounds from Mars within the first day after landing. The Mars Polar Lander project just completed its Operations Readiness Test, which involved simulating commands and telemetry for all the science data.

Microphone data will be obtained at the beginning of the mission as part of the LIDAR instrument data stream. The University of California built the microphone, which is included within the Russian-built LIDAR experiment. The LIDAR is the first Russian instrument to fly on a U.S. planetary spacecraft. It will measure the haziness and particle content of the atmosphere.

Communications from the spacecraft had been planned to be relayed through Mars Climate Orbiter once it landed. Now, however, it will go over backup communication links -- direct to Earth from the lander (at lower data rates, but with more frequent communications periods) and through Mars Global Surveyor, now carrying out a successful mission in Mars orbit. The Mars Global Surveyor link will not occur, however, until after the first few days of landing, since it will be preoccupied with data from the Deep Space 2 microprobes, which are also landing on Mars this December 3.

The data received from the lander depends on how much power is available for the spacecraft and how accurately the antenna is pointed to Earth. The power depends on how much of the solar panels face the sun and how hazy the atmosphere is and whether any dust gets on the solar panel. None of these conditions will be known until the spacecraft lands.

But assuming all goes as expected (and it could go better, or worse), Mars Microphone data will be part of the early data streams from the spacecraft. Once it is received, it will take several hours to process (after all, no one has ever received microphone data from Mars before), and then it will be made available to the world. You will be able to hear the first sounds from Mars as part of our Planetfest '99 program, and witness the first three days of the Mars Polar Lander mission.

The first sounds will most likely be that of the spacecraft itself -- those of the robotic arm being un-stowed and deployed. We want to experience the loudest sounds we can find at first. By the second or third day, we will try to correlate the sound recording with periods of quietness, to see what natural sounds we might discover on Mars.

The Planetary Society funded the microphone onboard the Mars Polar Lander at no cost to NASA and with no interference to the project’s science goals. We owe tremendous gratitude to our Russian colleagues from the Space Research Institute who integrated into their LIDAR instrument and tested it, as well as to the University of California, Berkeley, Space Science Labs who built it, the Mars Volatiles and Climate Surveyor payload team, and the Mars Surveyor Operations Project personnel now conducting the mission.

Read more: Planetary Society Projects, mission status

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