Refractive index of Martian atmosphere near surface

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Discussion Overview

The discussion centers on the refractive index of the near-surface Martian atmosphere, specifically focusing on how to estimate or find reliable values for CO2 under Martian conditions, including low pressure and temperature considerations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant requests references or methods to estimate the refractive index of the Martian atmosphere, assuming it is primarily CO2 at approximately 6 mbar pressure.
  • Another participant provides a link to a resource but notes that it primarily addresses air rather than CO2, raising concerns about the applicability of the data.
  • A different participant shares a value for the refractive index of CO2 at 1 atm but cautions that the value is a guideline and emphasizes the need to adjust for Martian surface pressure.
  • One participant humorously suggests that the refractive index might be effectively 1 due to the high vacuum in Mars' atmosphere.
  • A follow-up question seeks clarification on whether the previous statement about the refractive index being effectively 1 applies specifically to the surface of Mars.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the appropriate values and methods for estimating the refractive index of CO2 in the Martian atmosphere, with no consensus reached on a definitive approach or value.

Contextual Notes

Participants note limitations in available data, including the lack of specific refractive index values for CO2 at low pressures relevant to Mars and the need for adjustments based on atmospheric conditions.

Ex1
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Hi folks,
Does anyone have a good reference for the refractive index of the near surface Martian atmosphere?
(Or alternatively, the means to estimate it from readily available data!)

I'm struggling to think of an equation for which I've got enough of the variables to be of use, (for example assuming the atmosphere is CO2, and the pressure is ~6mbar, temperature etc.)

Hope you'll be able to help. Thanks in advance!
 
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Thanks very much for your reply Janus. But am I missing something obvious? The section taken largely from Birch & Downs's "Correction to the Updated Edlh Equation for the Refractive Index of Air" deals specifically with air rather than CO2, and the tables don't give values for CO2 the pressure regime at the Martian surface. :confused:
 
http://www.ps.missouri.edu/rickspage/refract/refraction.html


CO2 n=1.000449 according to this page, but the page explicitly says the numbers are a guideline only and as far as I can tell there are no references. Since I am assuming this n value is at 1atm, you will have to convert the value to reflect the difference pressure at Mars' surface. I am not sure what forumula will help you do this, I am curious about this too, so if you find the formula post it for me.

Cheers.
 
Mars' atmo is 49 parts vacuum to 1 part air :wink:

I would think its refractive index is effectively 1.
 
DaveC426913 said:
Mars' atmo is 49 parts vacuum to 1 part air :wink:

I would think its refractive index is effectively 1.


Dave, is that at the surface of Mars?
 

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