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Mars2020 landing cameras
Gerald
post Aug 28 2016, 12:34 PM
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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 0C with 10% relative humidity, and
0.0255 dB / m for 0.6 kPa at -20C 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.
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rlorenz
post Oct 12 2016, 05:33 PM
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QUOTE (Gerald @ Aug 28 2016, 07:34 AM) *
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
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pioneer
post Sep 18 2020, 12:42 AM
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I know this is an old thread, but I was wondering if the video from the EDL cameras will be compressed before being sent to Earth like the first images from Curiosity's MARDI camera were compressed as the bandwidth was limited in the early days after landing. Does anyone know if Mars Odyssey and MRO will be in position to receive signals from Perseverance on landing day?
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mcaplinger
post Sep 19 2020, 10:54 PM
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QUOTE (pioneer @ Sep 17 2020, 04:42 PM) *
Does anyone know if Mars Odyssey and MRO will be in position to receive signals from Perseverance on landing day?

Regardless of phasing, there are typically two passes per day per orbiter (see https://trs.jpl.nasa.gov/handle/2014/44382 ) and MAVEN and perhaps TGO will also be available, but there's usually some uncertainty about the performance of early relay ops.

From the April 2020 MRO status for MEPAG https://mepag.jpl.nasa.gov/meeting/2020-04/...202020_post.pdf
QUOTE
Cover mission critical events at Mars: Mars 2020 EDL in 2021

As for data return from the EDL cameras, that will probably be discussed in the pre-landing press kit and press conference.


--------------------
Disclaimer: This post is based on public information only. Any opinions are my own.
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pioneer
post Sep 20 2020, 06:56 PM
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QUOTE (mcaplinger @ Sep 19 2020, 11:54 PM) *
Regardless of phasing, there are typically two passes per day per orbiter (see https://trs.jpl.nasa.gov/handle/2014/44382 ) and MAVEN and perhaps TGO will also be available, but there's usually some uncertainty about the performance of early relay ops.

From the April 2020 MRO status for MEPAG https://mepag.jpl.nasa.gov/meeting/2020-04/...202020_post.pdf

As for data return from the EDL cameras, that will probably be discussed in the pre-landing press kit and press conference.


Thanks.
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