Mars2020 landing cameras Options

[Stratespace]

I am so enthusiastic about the (proposed) Mars2020 camera suite during EDL, as presented today at IPPW:
- 3 PointGrey Chameleon 3 that will be on the skycrane and look up, to monitor parachute deployment at 150 fps.
- 1 GoPro Hero 4 on the skycrane, looking down to monitor the rover descent and landing
- 1 GoPro Hero 4 on the rover, looking up to monitor the skycrane and fly-away
- 1 GoPro Hero 4 on the rover, looking down like MARDI did on Curiosity
- MARDI, of course.

All GoPro have microphone that will be activated, and have been tested successfully in the proper thermal and radiative environment. We should have some awsome footage if it actually flies.

[Gerald]

I don't think, that sound attenuation poses any significant issue on Mars on the meter scale, especially when relative humidity is very low.
With this calclulator for atmospheric absorption, for sound of 1000 Hz, I get
0.014 dB / m for 103 kPa at 0°C with 10% relative humidity, and
0.0255 dB / m for 0.6 kPa at -20°C with 1% relative humidity.

Above 10 kHz, it may be going to become an issue on the meter scale.

The microphone membrane, however, might be required to deal with reduced sound intensity, since the low-pressure atmosphere transports less sound energy for the same amplitude.

[rlorenz]

I don't think, that sound attenuation poses any significant issue on Mars on the meter scale,
The microphone membrane, however, might be required to deal with reduced
since the low-pressure atmosphere transports less sound energy for the same amplitude.

Yes, 6mb CO2 conveys sound quite happily over distances of a few meters. Here is some music played ('quite loud' in 1 bar air, but considerably
quieter here at 6mb simply because a loudspeaker diaphragm displacement at a given speed produces a lower sound pressure level simply because the
air density is lower, as you note). The sound is a bit distorted (ethereal, dare I say..?) because of reverberation/multipath between the parallel
metal walls of the chamber (these were tests I did a couple of weeks ago at the Mars Environment simulation chamber in Aarhus, Denmark).
There's also a lot of plant noise (electrical, rather than vibration/acoustic)

http://www.lpl.arizona.edu/~rlorenz/oxygene_on_Mars.mp3

More details to be presented at the Mars Atmosphere workshop in Granada in January

Ralph Lorenz