Comment by wongarsu

Listening to hours of recording doesn't even seem like a lot considering this is the only microphone we have on another planet. You would need like 4 people doing this full time, which is a drop in the bucket for a project on this scale.

Of course this is not how it's done and almost all of the recording will just be wind or noise from the rover itself, which can easily be filtered out.

This doesn't require anything fancy. I haven't used my sound engineering qualification in 14 years and I could do it by hand. You can visually scan through the recorded waveform and look for shapes that stand out. Simple audio processing techniques like using a noise gate to shut off the volume whenever the input level is below some configured threshold can make this even easier.

If you have enough RAM, start with a ring buffer.

On interesting event: compress and transfer the relevant chunk of audio from the ring buffer back to Earth.

Interesting event trigger ideas:

1) loud sound after quiet time

2) manual timestamp request from control

3) video clip recording

4) midnight, sunrise, noon, sunset. These are mostly so you have some daily baseline.

5) science package running

6) rover moving

7) abrupt camera change

Well, there are these things called computers, and they’re really very good at this stuff. It’s not exactly rocket science (heh) to write a program to listen to an audio stream and mark and log every occurence of something else than background noise and ambient wind sounds (if Martian winds are even loud enough to make sound). Everything else that the rover has to do automatically is way more complicated.

It’s pretty likely that the entire stream of silence isn’t being stored, or sent to Earth, only the interesting parts. There isn’t any way for people to listen in real time anyway, because communications (can) only happen at specific times of the day. Every interplanetary mission works by sending a preplanned sequence of commands one day, then coming back the next day to see what the probe/rover/whatever sent back, then planning the next set of commands, and so on.

Yes, and don't forget that you need to modify & certify it to work in 1% of Earth atmospheric pressure and down to -75C, and get it integrated into flight software running on a RAD750.

Bandwidth and storage.

The Viking landers (1975) were very sophisticated with robotic arms and mass spectrometers, adorable little anemometers, digital colour cameras, the whole deal, with 5 megabytes of digital tape storage.

The downlink rate was 16 kbps when related by the matched orbiter; otherwise direct communication was at 250 bps.

The digital cameras were pushing the absolute limit of technology at the time. The digitizer produced a 16 kbps bitstream that fed the uncompressed image directly to the transmitter taking four minutes to send an image. It could also be stored on tape for later transmission, but it used much of the tape to do so.

If it had included a microphone and ADC, it would have been technically possible to record a few minutes of audio and then spend hours transferring it back to Earth. But the kind of constant monitoring now done really depends on the more than 1 Mbit/s of bandwidth now available thanks to half a dozen Martian orbiters, and all the fancy processors and gigabytes of storage the landers and rovers now have.