Just to add, many non scientists seem to think that there's a chance that Mars has a breathable atmosphere. But there is no chance of that at all.
Some of the fringe websites will tell you that NASA found a breathable atmosphere with their rovers, and haven't told anyone as some of these fringe sites will tell you.
However a bit of background will show how absurd that idea is. No need to go into present day science even.
We already knew that it had very little oxygen back in the 1920s. Indeed the John Carter novels were already out of date soon after they were published.
This is supposed to be set on Mars, book published 1917
By 1926, scientists had already proved that the air on Mars wasn't breathable by humans as it had almost no oxygen. Basically they didn't detect oxygen by sensitive spectroscopic measurements, and so got an upper bound on how much there could be.
The method was very clever for its day, involving disentangling doppler effects due to relative speed of Mars to Earth depending on the time in the Mars and Earth year. They had to disentangle absorption lines in the Mars atmosphere from absorption lines in the Earth atmosphere, which were shifted just a tiny amount due to the changing relative velocities due to the doppler effect.
But that's 1920s technology and of course what was a world class challenge and major breakthrough in 1926, isn't any more.
So, we don't depend on the landers on Mars by the US and Russia to know that there is no oxygen there to speak of and hardly any atmosphere. We can tell that by direct observation from Earth.
There's a bit of a lag of course. Edgar Rice Borroughs went on writing his books about Barsoom until 1940.
As late as 1943, C. S. Lewis in Perelandra describes a Mars with oxygen rich atmosphere which his hero breathes with no ill effects, just finds it a little thin.
But that just shows that science fiction writers often lag behind science. If you knew about cutting edge astronomical work on Mars, you already knew that it had almost no oxygen for about 17 years by then.
It was "almost no oxygen" but it was just an upper bound, and there remained a possibility of a small amount of oxygen, which some science fiction writers exploited exploring ideas of specialist animals, even intelligent life, that lived on Mars that had evolved ways to survive on almost no oxygen - until maybe mid century or so (I'm not sure when).
There is a very tiny amount of oxygen in the atmosphere, even in the latest observations. About 0.13% of the atmosphere. But remember the atmosphere is about 1% of the pressure of Earth's. So that is about 0.0013% of the Earth's pressure of oxygen.
Even microbes on Mars would need to be comfortable living without oxygen, i.e. anaerobes, at least if they depended on the atmosphere for it. Mars' Atmosphere: Composition, Climate & Weather
I'd be interested if anyone else likes to share any other post 1940 science fiction books that depict humans on Mars able to breath the air without a spacesuit.
Read more: How Life May Exist On Mars With Atmosphere Close To Equilibrium
Some of the fringe websites will tell you that NASA found a breathable atmosphere with their rovers, and haven't told anyone as some of these fringe sites will tell you.
However a bit of background will show how absurd that idea is. No need to go into present day science even.
We already knew that it had very little oxygen back in the 1920s. Indeed the John Carter novels were already out of date soon after they were published.
By 1926, scientists had already proved that the air on Mars wasn't breathable by humans as it had almost no oxygen. Basically they didn't detect oxygen by sensitive spectroscopic measurements, and so got an upper bound on how much there could be.
Lick observatory in 1900. First conclusive proof that there is almost no oxygen on Mars was a paper from this observatory in 1926
The method was very clever for its day, involving disentangling doppler effects due to relative speed of Mars to Earth depending on the time in the Mars and Earth year. They had to disentangle absorption lines in the Mars atmosphere from absorption lines in the Earth atmosphere, which were shifted just a tiny amount due to the changing relative velocities due to the doppler effect.
But that's 1920s technology and of course what was a world class challenge and major breakthrough in 1926, isn't any more.
So, we don't depend on the landers on Mars by the US and Russia to know that there is no oxygen there to speak of and hardly any atmosphere. We can tell that by direct observation from Earth.
There's a bit of a lag of course. Edgar Rice Borroughs went on writing his books about Barsoom until 1940.
As late as 1943, C. S. Lewis in Perelandra describes a Mars with oxygen rich atmosphere which his hero breathes with no ill effects, just finds it a little thin.
It was "almost no oxygen" but it was just an upper bound, and there remained a possibility of a small amount of oxygen, which some science fiction writers exploited exploring ideas of specialist animals, even intelligent life, that lived on Mars that had evolved ways to survive on almost no oxygen - until maybe mid century or so (I'm not sure when).
There is a very tiny amount of oxygen in the atmosphere, even in the latest observations. About 0.13% of the atmosphere. But remember the atmosphere is about 1% of the pressure of Earth's. So that is about 0.0013% of the Earth's pressure of oxygen.
Even microbes on Mars would need to be comfortable living without oxygen, i.e. anaerobes, at least if they depended on the atmosphere for it. Mars' Atmosphere: Composition, Climate & Weather
I'd be interested if anyone else likes to share any other post 1940 science fiction books that depict humans on Mars able to breath the air without a spacesuit.
Read more: How Life May Exist On Mars With Atmosphere Close To Equilibrium
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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