<p>I think Mars would be even better then the Atacama Desert for radio astronomy, even at low Martian altitude. We probably won't see MLMA (Mars Large Millimeter Array) in our lifetimes, but if would have extraordinary observing potential!</p>
<p><strong>Atmospheric interference:</strong>  Water vapor is the worst for millimeter radio astronomy, but carbon dioxide and oxygen also absorb RF at those frequencies.  Mars's atmosphere is mostly composed of carbon dioxide, but the average surface pressure is less than one percent of Earth's. <a href="https://commons.wikimedia.org/wiki/File:2013_Atmospheric_absorption_of_electromagnetic_waves.svg" rel="nofollow noreferrer">Image Credit wikimedia</a></p>
<p><a href="https://i.sstatic.net/IeWrG.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/IeWrG.png" alt="enter image description here" /></a></p>
<p>The Martian atmosphere would be very good for observing since it is a <a href="https://www.universetoday.com/139666/mars-is-1000x-drier-than-the-driest-places-on-earth/" rel="nofollow noreferrer">thousand times drier than even the atmosphere in the Atacama Desert</a>.  For even less atmospheric interference, we could consider putting out array on the gentle sloped of Olympus Mons, the giant Martian volcano.  However, then we would be subject to Orographic clouds in Olympus Mons local weather systems, so perhaps the best location would be in the plains.</p>
<p><strong>Extremely Long Baseline Interferometry:</strong>
ALMA fills an important role in radio astronomy not only as a stand-alone array, but as one of many radio-telescopes which can be used in collaboration.  As an example, ALMA contributed to the Event Horizon Telescope (EHT) which produces images of a Black Hole (Image Credit: EHT Collaboration):
<a href="https://i.sstatic.net/otHi7.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/otHi7.jpg" alt="enter image description here" /></a></p>
<p>MLMA could fill a similar role.  An important equation in Radio Astronomy determines angular resolution <span class="math-container">$R$</span> as a function of observed frequency <span class="math-container">$\lambda$</span> and distance between baseline elements <span class="math-container">$B$</span> as:</p>
<p><span class="math-container">$$R=\frac{\lambda}{B}$$</span></p>
<p>If we used MLMA in concert with ALMA, we would have a ELBI (Extremely Long Baseline Array) with unprecedented angular resolution to distant RF emitters.</p>
<p><strong>Man-made RF Noise:</strong>  Even though the Atacama Desert is still a relatively quiet RF region, as it is not well developed, there are still a number of interfering frequencies, such as Space-To-Ground Comms, Space-To-Space Comms, and SAR Earth imaging satellites.  At least right now, Mars is relatively RF quiet.  Hopefully, <a href="https://space.stackexchange.com/questions/18778/how-is-rf-spectrum-usage-coordinated-in-mars-orbit">when frequencies are allocated for use on Mars</a>, radio astronomy frequencies get favorable allocations!</p>

CC BY-SA 4.0
2021-11-02T16:16:24.257Z
2021-11-02T16:16:24.257Z
Connor Garcia
<p>In <a href="https://space.stackexchange.com/a/55626/12102">this answer to <em>What kind of experiments would a scientist do on Mars?</em></a> I suggest that the resemblance of the ALMA array's site in the Atacama Desert to the surface of Mars suggests millimeter wavelength astronomy might work well there.</p>
<p><strong>Question:</strong> How would the surface of Mars compare with the Atacama desert for millimeter wave (and shorter) radio astronomy?</p>
<hr />
<blockquote>
<p>Where on Earth do we find scientists living in a place like that?</p>
<p><a href="https://i.sstatic.net/wmAju.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/wmAju.jpg" alt="enter image description here" /></a></p>
<p>Source: <a href="https://noticias.usm.cl/2018/11/05/profesores-y-alumnos-del-departamento-de-construccion-y-prevencion-de-riegos-usm-visitan-observatorio-alma/" rel="nofollow noreferrer">Profesores y alumnos del Departamento de Construcción y Prevención de Riegos USM visitan Observatorio ALMA</a> (google: &quot;Teachers and students from the USM Department of Construction and Risk Prevention visit ALMA Observatory&quot;)</p>
<p>Atmospheric water is the bane to short wavelength (millimeter wavelengths and shorter, all the way to infrared) radio astronomy. There's still the vibrational and rotational bands of N2, O2 and CO to worry about, but a second <a href="https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array" rel="nofollow noreferrer">ALMA</a> on mars, (MALMA, MLMA, ALMAM?) would be a wonderful idea. You could even to incredibly long baseline interferometry with Earth!</p>
</blockquote>

<radio-astronomy><mars><planetary-atmosphere><radio-telescope><atmospheric-effects>
How would the surface of Mars compare with the Atacama desert for millimeter wave (and shorter) radio astronomy?
uhoh
# How would the surface of Mars compare with the Atacama desert for millimeter wave (and shorter) radio astronomy?

(Asked by: username_0 on 2021-11-01)

In [this answer to *What kind of experiments would a scientist do on Mars?*](https://space.stackexchange.com/a/55626/12102) I suggest that the resemblance of the ALMA array's site in the Atacama Desert to the surface of Mars suggests millimeter wavelength astronomy might work well there.

**Question:** How would the surface of Mars compare with the Atacama desert for millimeter wave (and shorter) radio astronomy?

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> Where on Earth do we find scientists living in a place like that?
>
> [![enter image description here](https://i.sstatic.net/wmAju.jpg)](https://i.sstatic.net/wmAju.jpg)
>
> Source: [Profesores y alumnos del Departamento de Construcción y Prevención de Riegos USM visitan Observatorio ALMA](https://noticias.usm.cl/2018/11/05/profesores-y-alumnos-del-departamento-de-construccion-y-prevencion-de-riegos-usm-visitan-observatorio-alma/) (google: "Teachers and students from the USM Department of Construction and Risk Prevention visit ALMA Observatory")
>
> Atmospheric water is the bane to short wavelength (millimeter wavelengths and shorter, all the way to infrared) radio astronomy. There's still the vibrational and rotational bands of N2, O2 and CO to worry about, but a second [ALMA](https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array) on mars, (MALMA, MLMA, ALMAM?) would be a wonderful idea. You could even to incredibly long baseline interferometry with Earth!

**Tags:** radio-astronomy, mars, planetary-atmosphere, radio-telescope, atmospheric-effects

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## 1 answers

### Answer by username_1 on 2021-11-02. Score: 1 | Accepted answer

I think Mars would be even better then the Atacama Desert for radio astronomy, even at low Martian altitude. We probably won't see MLMA (Mars Large Millimeter Array) in our lifetimes, but if would have extraordinary observing potential!

**Atmospheric interference:** Water vapor is the worst for millimeter radio astronomy, but carbon dioxide and oxygen also absorb RF at those frequencies. Mars's atmosphere is mostly composed of carbon dioxide, but the average surface pressure is less than one percent of Earth's. [Image Credit wikimedia](https://commons.wikimedia.org/wiki/File:2013_Atmospheric_absorption_of_electromagnetic_waves.svg)

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

The Martian atmosphere would be very good for observing since it is a [thousand times drier than even the atmosphere in the Atacama Desert](https://www.universetoday.com/139666/mars-is-1000x-drier-than-the-driest-places-on-earth/). For even less atmospheric interference, we could consider putting out array on the gentle sloped of Olympus Mons, the giant Martian volcano. However, then we would be subject to Orographic clouds in Olympus Mons local weather systems, so perhaps the best location would be in the plains.

**Extremely Long Baseline Interferometry:**
ALMA fills an important role in radio astronomy not only as a stand-alone array, but as one of many radio-telescopes which can be used in collaboration. As an example, ALMA contributed to the Event Horizon Telescope (EHT) which produces images of a Black Hole (Image Credit: EHT Collaboration):
[![enter image description here](https://i.sstatic.net/otHi7.jpg)](https://i.sstatic.net/otHi7.jpg)

MLMA could fill a similar role. An important equation in Radio Astronomy determines angular resolution $R$ as a function of observed frequency $\lambda$ and distance between baseline elements $B$ as:

$$R=\frac{\lambda}{B}$$

If we used MLMA in concert with ALMA, we would have a ELBI (Extremely Long Baseline Array) with unprecedented angular resolution to distant RF emitters.

**Man-made RF Noise:** Even though the Atacama Desert is still a relatively quiet RF region, as it is not well developed, there are still a number of interfering frequencies, such as Space-To-Ground Comms, Space-To-Space Comms, and SAR Earth imaging satellites. At least right now, Mars is relatively RF quiet. Hopefully, [when frequencies are allocated for use on Mars](https://space.stackexchange.com/questions/18778/how-is-rf-spectrum-usage-coordinated-in-mars-orbit), radio astronomy frequencies get favorable allocations!


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