3 ms·

But it came back later! Frankly we're all surprised and a little confused how much audio we got while at 500km altitude before reentry.

mik3y 3y ago
It sounds like it indeed was a GoPro, neat! Were you not surprised to get video back, then? What steps were taken? I don't know much about Space Stuff but seems like even with shielding, you would expect off-the-shelf consumer hardware to fail somehow..
- enderfusion 3y ago
  Heavily modified. But it's the Gopro sensor and board.
bohanker 3y ago
How interesting... the anacoustic zone apparently begins at about 160km altitude.
- pfdietz 3y ago
  What's the maximum voltage in a GoPro? In some ranges of air pressure, if the voltage is sufficiently high a discharge could occur, perhaps shorting out something temporarily.
kragen 3y ago
maybe a lot of that audio is electromagnetic interference? that's what it sounds like, and audio amplifiers can be pretty sensitive also, sometimes audio amplifiers oscillate on their own (though i think the single-jfet preamp in an electret mic is unconditionally stable); an amplifier that oscillates in space in a way that physically vibrates the microphone might be damped by air so that you don't notice it when air is present interestingly, microphone amplifiers oscillating and producing physical vibrations is not a phenomenon restricted to electronic systems: https://en.wikipedia.org/wiki/Otoacoustic_emission https://en.wikipedia.org/wiki/Otoacoustic_emission pfdietz seems to be suggesting corona discharge encouraged by the lowered paschen voltage in low vacuum, and of course the negative-resistance characteristic of gas discharges can easily set up a parasitic relaxation oscillator; all you need is some parallel capacitance or series inductance, plus some kind of ballast that quenches the discharge http://tinyurl.com/23dt3d5e http://tinyurl.com/23dt3d5e http://tinyurl.com/2de5uaog http://tinyurl.com/2de5uaog https://www.physics.purdue.edu/demos/display_page.php?item=6C-03 https://www.physics.purdue.edu/demos/display_page.php?item=6...

mik3y 3y ago

It sounds like it indeed was a GoPro, neat! Were you not surprised to get video back, then? What steps were taken? I don't know much about Space Stuff but seems like even with shielding, you would expect off-the-shelf consumer hardware to fail somehow..

enderfusion 3y ago
Heavily modified. But it's the Gopro sensor and board.

bohanker 3y ago

How interesting... the anacoustic zone apparently begins at about 160km altitude.

pfdietz 3y ago
What's the maximum voltage in a GoPro? In some ranges of air pressure, if the voltage is sufficiently high a discharge could occur, perhaps shorting out something temporarily.

kragen 3y ago

maybe a lot of that audio is electromagnetic interference? that's what it sounds like, and audio amplifiers can be pretty sensitive also, sometimes audio amplifiers oscillate on their own (though i think the single-jfet preamp in an electret mic is unconditionally stable); an amplifier that oscillates in space in a way that physically vibrates the microphone might be damped by air so that you don't notice it when air is present interestingly, microphone amplifiers oscillating and producing physical vibrations is not a phenomenon restricted to electronic systems: https://en.wikipedia.org/wiki/Otoacoustic_emission https://en.wikipedia.org/wiki/Otoacoustic_emission pfdietz seems to be suggesting corona discharge encouraged by the lowered paschen voltage in low vacuum, and of course the negative-resistance characteristic of gas discharges can easily set up a parasitic relaxation oscillator; all you need is some parallel capacitance or series inductance, plus some kind of ballast that quenches the discharge http://tinyurl.com/23dt3d5e http://tinyurl.com/23dt3d5e http://tinyurl.com/2de5uaog http://tinyurl.com/2de5uaog https://www.physics.purdue.edu/demos/display_page.php?item=6C-03 https://www.physics.purdue.edu/demos/display_page.php?item=6...