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You've Heard of the Karman Line, well here's the Ripley Line

#1
Yazata Offline
This new science from astrophysicist Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics (the Jonathan's Space Report guy)

https://planet4589.org/space/gloss/

https://www.planet4589.org/

https://www.cfa.harvard.edu/people/jonathan-mcdowell

It is well known that in space, no one can hear you scream (Scott, R. et al 1979.) Following a suggestion by Mark Harrison (twitter.com/meh130), I proposed in July 2021 that this defines an alternative boundary of space which I call the Ripley Line: space starts at the altitude at which the loudest possible scream becomes inaudible. Using the US Standard Atmosphere 1976, and the absolute hearing sound threshold of 20 micropascals, and assuming that the loudest possible sound wave is of order the total air density, the Ripley Line is at about 250 km altitude.

Much higher than I would have thought! Apparently you could still hear a scream in the lower reaches of low earth orbit! (The regions where satellite orbits decay quickly.) 2X to 3X higher than Bezos and Branson propose to go. But sorry International Space Station, at ~420 km you are above the Ripley Line, where if your space helmet breaks, nobody can hear you scream.
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