In case the other thread doesn't make the front page, they also added a microphone to this lander and managed to capture the sound of Mar's wind, which to me is almost more amazing:
https://soundcloud.com/nasa/first-sounds-from-mars-filters-o...
https://soundcloud.com/nasa/first-sounds-from-mars-filters-o...
With annotations: https://www.reddit.com/r/venus/comments/7vpr1w/sound_recordi...
>The minimum safe lower limit for the partial pressures of oxygen in a gas mixture is 0.16 bars (16 kPa) absolute.
https://en.wikipedia.org/wiki/Partial_pressure
If it was 20% that would be survivable with just an oxygen mask fwiw. Humans can go down to 16% atm pressure safely if they breathe 100% oxygen. The rest of the body can easily handle the pressure difference (1 full atm of pressure is equivalent to being 10meters underwater as a guide, human orifices have no issue with it contrary to pop sci beliefs).
So yes it's not 20% and it would be nice if it was.
It’s an additional atmosphere. On top of...the one we live in at sea level.
Also 100% O2 anything past about 4 msw will kill you. The MOD of pure o2 is 13 feet. Which is about 3.9 msw
There's a myth that at low atm of pressures you pop and such. This is not true. You may need to breathe in/out to adjust but pretty much every part of the body can handle 1atm of pressure difference just fine. The 10meters below was intended as a reverse example but the point holds.
Its why in SCUBA you have to calculate MOD for nitrox. Because the partial pressures of oxygen will kill you. We only breath about 21% oxygen in air. And after rec depths, you often using different mixtures and take on decompression obligations, trimix, heliox etc. At certain pressures, things like HPNS will also have an effect.
You definately cant survive in a vacuum either with just a mask. Its why pressure suits are a thing.