There are two primary systems of navigation on Earth today, using maps/compass, and using GPS satellites. It seems unlikely there will be a full constellation of GPS satellites prior to the first humans landing on Mars. In addition, Mars doesn't have a magnetic field like Earth, so a compass is out. It also seems like many long trips will be taken on Mars, even by the first group landing there, requiring accurate navigation. How will this be accomplished?
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asked Oct 28, 2013 at 12:48
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3$\begingroup$ By the stars for the latitude and accurate clocks for the longitude? $\endgroup$– gerritOct 28, 2013 at 12:58
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1$\begingroup$ You'd think that there would be a need for at least a small constellation of communication satellites; perhaps in the Mars case, such satellites might be dual-purposed for communication and GPS-style navigation. $\endgroup$– Anthony XNov 3, 2013 at 19:08
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1$\begingroup$ Already decided. $\endgroup$– Mark AdlerDec 29, 2014 at 6:03
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1$\begingroup$ The information at the link is correct. The location was refined at the time of Mariner 6/7, and nailed down by MGS. Airy-0 marks the prime meridian. $\endgroup$– Mark AdlerDec 29, 2014 at 19:28
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1$\begingroup$ In addition to what gerrit suggested (stars and clocks), there is also Mars' two moons, which pass over at predictable intervals in known paths, so using accurate clocks with observations of Phobos and Diemos could give accurate position data. $\endgroup$– KirkaiyaMar 26, 2015 at 19:57
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8 Answers
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If long-range navigation is necessary, a combination of inertial navigation with occasional position fixes using stars gives reasonably accurate navigation. Inertial navigation has a few drawbacks: high cost and these systems become less accurate over time (hence the need for occasional position fixes).
For short-range navigation, dead reckoning may be sufficient. For dead reckoning, you use sensors on the wheels of your vehicle to keep track of how far it travels and which way it turns. This was used on the lunar rover.
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4$\begingroup$ One may also point out, that a small tablet these days has enough memory and computing power to hold an "eternal" star almanac, thus making it capable to compute the precise position of observer on the Mars surface by means of a single night sky snapshot. $\endgroup$– oakadOct 29, 2013 at 1:36
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$\begingroup$ Hmm; how large a PV array would be needed to charge the batteries to the extent a tablet would work through the dark night? $\endgroup$– EveryoneNov 20, 2014 at 5:04
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$\begingroup$ @Everyone not nearly as big as the one needed to power the life support systems and comms in the suits worn by the humans. $\endgroup$– uhohSep 22, 2016 at 5:55
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There are a few things that could be done (Using pretty heavily "A Case for Mars" second edition):
- There will not be full constellation of satellites, but undoubtedly there will be satellites orbiting Mars at that time that are functioning. Each Mars orbiter since Mars Global Surveyor has included some sort of a beacon which could be heard. Measuring Doppler shift and listening to the time you hear it can give you your latitude, and approximate longitude. This could be easily found via a look up table of some sort on the rover.
- Stars could be observed at night, which gives you a reference point. In addition, if you are low enough in latitude, you can use Deimos and Phobos to give you a pretty good latitude/longitude estimate. If you keep careful time, you can use the same trick that mariners have used for a long time to find longitude, in addition, you can use the moons as an additional reference point. In fact, given 2 of the 3 objects (Sun, Phobos, Deimos), a sextant, a clock, and an almanac, one could determine one's location exactly.
- Some sort of a inertial navigation system could be used, as Hobbes mentioned.
- Use the North Star, or best equivalent.
answered Oct 28, 2013 at 13:44
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1$\begingroup$ Another point of reference for your point 2 might be Earth itself. A little primitive, but (I guess) Earth is transmitting enough radio waves at high enough strength that they can be detected on Mars. $\endgroup$ Oct 28, 2013 at 15:13
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1$\begingroup$ @AndrewThompson: Mars won't be able to hear many Earth signals, unless said Earth signals are transmitted directly to Mars. The signal just falls off too quickly. Still, the DSN could probably be used, if Earth is in sight. Hmmm... $\endgroup$– PearsonArtPhoto ♦Oct 28, 2013 at 15:20
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$\begingroup$ +1 for mentioning Phobos and Deimos, I just made the same suggestion as a comment to the original question. $\endgroup$– KirkaiyaMar 26, 2015 at 19:58
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I'm a little surprised nobody has mentioned markers. As in flags, signposts, and splashes of paint on rocks.
Astronauts on the first missions to Mars are not going to go all that far from their base. Vehicles won't have the range and safety considerations would limit them. Vehicle tracks remain visible for a very long time, dust storms lay down a thin layer of dust over them but don't rub them out. So there will quickly be a network of trails to follow.
As activity expands on Mars the network of trails and the distribution of markers will expand with it. These are by far the most reliable navigation tools and I'm sure mission members will be careful to create a dense, easy to use, widely distributed array of them. They don't unexpectedly break, or suffer from interference, or run out of power. Finding them in the reduced visibility of a dust storm might be hard - it might be prudent to set up networks of blinking light posts and beacons for such cases. But any radio-based system would have trouble at such times too.
If you were so far away from any explored area with a base that there were no markers at all, about the only way that could happen is if you landed off course. Even in that case, you probably wouldn't strike out on your own, you'd wait to be found. You'd activate a radio beacon and try to establish radio contact, which you'd likely then use to tell the base where you figure you are based on how you came in and what you can see around you. (And quite likely, figuring out where you were would be the least of your problems.)
answered Dec 29, 2014 at 16:34
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$\begingroup$ KISS, right? It ain't always about the technology. $\endgroup$ Dec 29, 2014 at 16:35
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1$\begingroup$ Flags, signposts, and splashes of paint on rocks are technology, just not as cutting edge like chisels. :) $\endgroup$ Dec 17, 2015 at 19:33
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If you can afford to get people to Mars, then you can easily afford a navigational satellite or two. Since you asked how it will be accomplished (as opposed to how it perhaps could be accomplished, with lots of interesting answers to that question here), then I can answer with some confidence that they will use navigational satellites for safety and reliability. It won't be much different than GPS here. The main difference will be satellite availability and accuracy. There probably won't be 31 of them flying around Mars.
answered Oct 28, 2013 at 18:11
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$\begingroup$ I don't doubt that there could be a few satellites to aid in communication and navigation. Just not a full GPS constellation of them. $\endgroup$– PearsonArtPhoto ♦Oct 28, 2013 at 18:15
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4$\begingroup$ Specifically they will have atomic clocks on those satellites just like our GPS satellites, though smaller, providing much better solutions than the Doppler measurements we can get from our relay satellites at Mars today. There will need to be a fixed ground station to update the orbital elements of the satellites to sufficient accuracy. $\endgroup$ Oct 28, 2013 at 18:23
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$\begingroup$ What about the control segment? What would be required for this use? $\endgroup$– minsMar 26, 2015 at 6:49
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$\begingroup$ As noted in the comment just above your question, a ground station taking measurements from the satellites whenever they are in view in order to update their on-board orbit models and to synchronize their clocks. It could all be done autonomously. You could have two such ground stations for redundancy, and they could be in different locations to increase accuracy. $\endgroup$ Mar 26, 2015 at 10:14
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You could try old school navigation. Like the one they did in the past when sailing ships. They dint have navigation back then so they used a "tool" to calculate the angle of the horizon and the sun. And then according to the specific time they took the angle they could calculate there exact position. Now this is still ment to work only on earth. Because of all the calculation specific to earth and at the beginning it did took a lot of time to calculate where you are.
This video could explain a little more: http://youtu.be/AGCUm_jWtt4
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$\begingroup$ The tool is called a sextant, and it would only be one piece to solving the puzzle. $\endgroup$– PearsonArtPhoto ♦Oct 28, 2013 at 14:45
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$\begingroup$ yes I think it was called so.. My idea is that knowing how they did it before, perhaps someone can make an electronic device that can do all the calculation for you.. All you do is point it at the sun and the horizon... But it is just a thought.. $\endgroup$– kmsOct 28, 2013 at 15:14
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$\begingroup$ I have no doubt that computers will do a lot of that kind of measurement. Still. Hmmm... $\endgroup$– PearsonArtPhoto ♦Oct 28, 2013 at 15:19
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During daylight, it may be possible to adapt a technique used on Earth for locating North that requires an analogue watch/clock and for the sun to be visible. Of course, for Mars, the clock would need to be made for Martian Sols, not Earth days.
The technique for locating North on Earth is:
In the Southern Hemisphere
Hold the watch horizontal with the '12' pointing directly towards the sun. Look at the hour hand, half the angle between '12' and the hour hand points towards north.
In the Northern Hemisphere
Hold the watch horizontal with the hour hand pointing directly towards the sun.
Half the angle between '12' and the hour hand points towards south.
Don't forget to make allowances for daylight savings.
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1$\begingroup$ That works, but it's a very limited approach to navigation. It doesn't tell you where you are, it just allows you to set a course. You'd have to already know the azimuth of your destination. And it only works if you synchronize the clock so that the sun is at the highest point above the horizon at 12 o'clock. On Earth, time zones and DST mean you could easily be 15° off course. $\endgroup$– HobbesDec 29, 2014 at 8:36
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You do realise people navigated before compasses existed, right? So obviously they'd do it the same way they did back then; using the sun and stars.
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$\begingroup$ Back then they didn't have cars. It can't be done by eyeballing any more. Have you taken the tour? $\endgroup$ Sep 20, 2016 at 14:54
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1$\begingroup$ Welcome to the site! This answer doesn't really add anything that hasn't already been said. While answering older questions is not at all discouraged, in doing so, you should take care to make your answer as good as it can possibly be, adding elements not already discussed in other answers or basing your answer on more recent material not considered by other answerers. In addition to the site tour suggested by @kimholder, I suggest reviewing space.stackexchange.com/help/how-to-answer. $\endgroup$– userSep 20, 2016 at 15:01
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Basically this is a non-problem because any place on Mars is as good as any other. You don't achieve anything by moving to a specific location.
Suppose people settle on Mars. At first, the settlements will probably be close together. Either within sight of each other or nearly so, so that people can go from one to the other by landmarks.
You need a way to explore such that you can find your way to the base, even if you cannot see it and don't recognize landmarks. Building a very tall tower to serve as a beacon could help. It could give off light, or perhaps also a long range radio signal.
A simple navigation device would tell you what direction the beacon signal is coming from.
As for me, being lazy, I will just download the Google Mars Navigation application from the Play Store for my Marsphone.
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6$\begingroup$ "You don't achieve anything by moving to a specific location." Yes you do, for example when after an excursion you want to return to the base to refuel your vehicle, analyze samples, replenish supplies (oxygen, water, ...) and so on. A navigation beacon will only function in line-of-sight range, as I doubt Mars' atmosphere allows anything beyond line-of-sight transmissions, and it only solves the "getting back" half of the problem; consider the possibility of making some really interesting finds at a particular site but being almost out of consumables. How to return to the same place? $\endgroup$– userOct 29, 2013 at 12:30
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$\begingroup$ Resupply missions would need to land close but not too close to the target settlement. I'd imagine this would create a navigation problem for the landing craft and/or colonists which might not be solved by anything less than a GPS-style system (if perhaps not as elaborate). $\endgroup$ Nov 3, 2013 at 19:04
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