Finding the North on Mars

N_Molson

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Just a thought I had... Given there is no stable magnetic field on Mars, our old-fashioned compasses would do no good there. Also, given there is no GPS (or MPS) network there, it isn't an option. So, what kind of technology stuff like rovers can use to keep track of what is North, East, etc... Do they rely on the Sun and other stars, relying on ephemerides and other astronomical data ? Or do rover operators navigate on sight, like knowing what those hills in the distance are, and instructing the rover to go straight on them, or leave them at a given angle on one side ? Just curious.
 

Arvil

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I imagine it's mostly that, since the orbiters can see them from orbit, images locate them pretty close, then images from the rovers themselves get location fine tuned. Since they only drive only a few meters at a time, the operators back home have plenty to time to tune in location. They won't drive over a cliff, and there's not much traffic there, or wrong turns.
 

llarian

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It's a good question actually. Is it possible that a gyroscope is on the craft that rotated to align itself to Mar's rotation and alignment when it landed?
 

Urwumpe

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There is no northern star for Mars. The axis points somewhere between Swan and Cepheus, there is only a star nearby, that is pretty much invisible to the human eye.
 

ChrisRowland

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Local navigation can be done using local features, 'towards that rock'. That's what we do here. A rough idea about North can be got from the Sun, the rise and set points are the same angle from North.

By the time there are occupants on Mars there will be some sort of GPS system - and a Starlink Constellation.
 

francisdrake

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Finding North is rather easy with a Gyrocompass.
But to determine your actual location may be more difficult. The most accurate way is probably to triangulate satellites orbiting Mars. The position of these satellites is well known using space navigation techniques (star tracker, doppler navigation, etc.)

For an independent ground navigation classical techniques can be used, like dead reckoning, or measuring the height of the sun or stars above the horizon at a given time.
 

Notebook

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Have to find a stick of course, could be tricky.
 

MaxBuzz

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Consult Google Mars.
this approach guarantees a small chance of survival in unforeseen situations (in unforeseen situations, all electronics are useless junk)
 

Fabri91

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Barring feature recognition against a known map, I'm not sure what the options are.

This both for position determination and attitude determination near the surface without using stars.

This also means that no "cheap" quadcopter which relies on a magnetometer and GPS would be able to fly (ignoring the whole aerodynamics issue) - in order to measure movement something like an optical flow sensor would be needed, which "sees how the terrain moves", but without necessarily comparing the image to a known map.

In order to determine heading automatically from a standstill nothing comes to mind besides a visual reference to known features or star tracking if available.
 

N_Molson

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The axis points somewhere between Swan and Cepheus, there is only a star nearby, that is pretty much invisible to the human eye.

Do you know the name of that star ? Could be useful to add it to the Star Markers. Space probes and rovers are usually better equipped than the human eye ;)

Deneb (+1.25) seems the closest :

MartianNorth.png

Seems our candidate is :

near the 6th-magnitude star BD +52 2880 (also known as HR 8106, HD 201834, or SAO 33185), which in turn is at R.A. 21h 10m 15.6s Decl. +53° 33′ 48″.

Any idea how to convert it into and Orbiter Star Marker ?
 
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4throck

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The Apollo guys were able to orient the capsule using a sextant. Satellites and probes use star trackers.
Of course, this forces you to make night observations after landing.
 

N_Molson

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The Apollo guys were able to orient the capsule using a sextant. Satellites and probes use star trackers.
Of course, this forces you to make night observations after landing.

That was something I was wondering about. Is Mars atmosphere thick enough to completely prevent using stars during days ? Not only for the human eye, but for instruments that can see in the IR or UV spectrum ? That "North Star" is probably too faint for that though, but maybe Deneb, Vega, Altair ?
 

llarian

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Given my earlier answer, the question really fascinated me. So, employing Google as my friend, found this method employed by Insight:

 

Notebook

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They took a stick with them, good planning.
 
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