<p>Wikipedia xites <em><a href="https://www.cambridge.org/us/catalogue/catalogue.asp?isbn=9780521844123" rel="nofollow noreferrer">Atmospheric Evolution on Inhabited and Lifeless Worlds</a></em> giving this composition:</p>
<pre><code>Carbon dioxide  95%
Nitrogen    2.8%
Argon   2%

Oxygen  0.174%

Carbon monoxide 0.0747%
Water vapor 0.03% (variable)
</code></pre>
<p>That's an order of magnitude lower than 1.3%</p>

CC BY-SA 4.0
2023-07-05T02:40:39.507Z
2023-07-05T02:40:39.507Z
James K
<p>The Sample Analysis at Mars (SAM) in <em>Curiosity</em> rover measured the air of <a href="https://en.wikipedia.org/wiki/Gale_(crater)" rel="nofollow noreferrer">Gale Crater</a> and analyzed its composition: 95% by volume is carbon dioxide (CO2), 2.6% molecular nitrogen (N2), 1.9% argon (Ar), <strong>0.16% molecular oxygen (O2)</strong>, and 0.06% carbon monoxide (CO). Note that amount of oxygen in Mars has a seasonal variation rising upto 30% during Spring and Summer and then dropping back to levels in fall. This pattern repeated each spring implying that something was producing it and then taking it away.</p>
<p><a href="https://i.sstatic.net/Vkvzr.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Vkvzr.png" alt="enter image description here" /></a></p>
<p>Source: <a href="https://www.nasa.gov/feature/goddard/2019/with-mars-methane-mystery-unsolved-curiosity-serves-scientists-a-new-one-oxygen" rel="nofollow noreferrer">https://www.nasa.gov/feature/goddard/2019/with-mars-methane-mystery-unsolved-curiosity-serves-scientists-a-new-one-oxygen</a></p>

CC BY-SA 4.0
2023-07-05T04:44:36.177Z
2023-07-05T04:44:36.177Z
Nilay Ghosh
<p>In the early 1970's and prior to the Viking landers, T. Owen measured the oxygen in the Martian atmosphere at 0.3%, I believe by doppler shift methodology through the Earth's atmosphere (wow).  During entry, the Viking spacecraft reported 1.3%.  I've heard (but not confirmed) that the MOXIE experiment used 1.3% in its modeling.  Are there more recent measurements, perhaps spectral from nearby spacecraft?  The source of O2 includes photolysis of CO2 (2CO2&gt;2CO+O2), and the amount might provide some information on the sources and sinks in the Martian environment.</p>

<mars><planetary-atmosphere>
What is the concentration of molecular oxygen in the Martian atmosphere?
Incredible II
# What is the concentration of molecular oxygen in the Martian atmosphere?

(Asked by: username_0 on 2023-07-05)

In the early 1970's and prior to the Viking landers, T. Owen measured the oxygen in the Martian atmosphere at 0.3%, I believe by doppler shift methodology through the Earth's atmosphere (wow). During entry, the Viking spacecraft reported 1.3%. I've heard (but not confirmed) that the MOXIE experiment used 1.3% in its modeling. Are there more recent measurements, perhaps spectral from nearby spacecraft? The source of O2 includes photolysis of CO2 (2CO2>2CO+O2), and the amount might provide some information on the sources and sinks in the Martian environment.

**Tags:** mars, planetary-atmosphere

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## 2 answers

### Answer by username_2 on 2023-07-05. Score: 4 | Accepted answer

The Sample Analysis at Mars (SAM) in *Curiosity* rover measured the air of [Gale Crater](https://en.wikipedia.org/wiki/Gale_(crater)) and analyzed its composition: 95% by volume is carbon dioxide (CO2), 2.6% molecular nitrogen (N2), 1.9% argon (Ar), **0.16% molecular oxygen (O2)**, and 0.06% carbon monoxide (CO). Note that amount of oxygen in Mars has a seasonal variation rising upto 30% during Spring and Summer and then dropping back to levels in fall. This pattern repeated each spring implying that something was producing it and then taking it away.

[![enter image description here](https://i.sstatic.net/Vkvzr.png)](https://i.sstatic.net/Vkvzr.png)

Source: <https://www.nasa.gov/feature/goddard/2019/with-mars-methane-mystery-unsolved-curiosity-serves-scientists-a-new-one-oxygen>


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### Answer by username_1 on 2023-07-05. Score: 2

Wikipedia xites Atmospheric Evolution on Inhabited and Lifeless Worlds giving this composition:
Carbon dioxide  95%
Nitrogen    2.8%
Argon   2%

Oxygen  0.174%

Carbon monoxide 0.0747%
Water vapor 0.03% (variable)

That's an order of magnitude lower than 1.3%


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