Earth’s atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases. Trace amounts of carbon dioxide, methane, water vapor, and neon are some of the other gases that make up the remaining 0.1 percent.

Mars' atmosphere is 95% carbon dioxide, 3% nitrogen, 1.6% argon, and it has traces of oxygen, carbon monoxide, water, methane, and other gases, along with a lot of dust.


1) But I am sure there is a lot of absortion of EM radiation in the atmosphere, due to water vapor, so is this absorption really caused by these trace amounts of water vapor?

2) If one were to make observations from the surface of Mars instead of that of the Earth, what radiation windows will (mostly) open ?

I know that on the Earth execpt for the radio and visible spectrum which are open, the other EM windows of the spectrum are closed due to absorption, diffraction, Ionization and photodissociation whcih are the 4 main ways in which EM radiations interacts with the Earth 's atmosphere. I am basing this claim on the following picture: enter image description here

My guess is that the gamma ray and UV should open, because there is no ozone, which is what blocks them right? I also thought about IF, becuase I though there was no water in Mars's atmosphere. But both Earth and Mars atmospheres contain traces of water so now I am not sure that the IR window would really open, maybe just like in the Earth there s still absortion.

  • $\begingroup$ I’m voting to close this question because the user already asked it on Physics SE at physics.stackexchange.com/q/810722/6319 $\endgroup$
    – gerrit
    Apr 17 at 11:53
  • $\begingroup$ The fact that Mars's atmosphere is only about 1% as thick as Earth's probably has a much larger impact on observation than the composition does. The equivalent density on Earth would be like building an observatory on a tower 28 miles tall. $\endgroup$ Apr 17 at 19:23
  • $\begingroup$ (or you could just put in an orbital observatory and skip the whole mars thing entirely, or build on Deimos or Ceres if you really want to glue it to a rock) $\endgroup$ Apr 17 at 19:26
  • 1
    $\begingroup$ Atmospheric composition data usually omits the water content, because it's so variable. Warm moist air may have >2% water (by mass). See en.wikipedia.org/wiki/Humidity $\endgroup$
    – PM 2Ring
    Apr 18 at 4:53


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