stellar inertial navigation - It means that as well as an inertial system you track the stars... which are actually visible even during daylight through an automated telecope system... although not through cloud I guess. Pricey but so is getting to Mars
Compasses don't work on Mars, so how do you navigate?
21–30 of 87 posts
Re: Compasses don't work on Mars, so how do you navigate?
#22Venus too - and this is also why neither have water - no strong magnetic field to hold the heliopause at bay, so the solar wind blows water out of the atmosphere.
Mars doesn't have hydrogen because at temperatures where water is liquid, the speed of hydrogen atoms due to temperature is greater than the escape velocity from Mars.
Re: Compasses don't work on Mars, so how do you navigate?
#23Already done? More than 40 years ago, but probably still workable: https://en.wikipedia.org/wiki/Lunar_Roving_Vehicle#Control_a...
Did you read the article? That's exactly what the author was pointing out. Also this article and wiki have ruined The Martian for me.
Re: Compasses don't work on Mars, so how do you navigate?
#24Earlier quoted context omitted.
The planet doesn't have to rotate to use celestial navigation. As long as you can see the stars you are fine. So the dark side of mercury would work fine. On the hot side as long as you are not exactly on the equator the sun acts as a fixed direction and you can use that. > Anyone know if Mars has any polar stars? The orbital tilt of Mars is 1.85 degrees (vs 0 for earth) and the Axial tilt is 25.19 vs 23.44 for Earth…
On the hot side as long as you are not exactly on the equator the sun acts as a fixed direction and you can use that. ISTM this would work on the equator too?
it would work anywhere you could figure out the direction of the light. An example might be a tree on top of a hill, compare that to that tree's shadow on some high cliffs. That's not going to be particularly accurate, but it would get you going in the right general direction.
If you can figure out where the sun is, and you know what time it is, you're in good shape.
Re: Compasses don't work on Mars, so how do you navigate?
#25Venus too - and this is also why neither have water - no strong magnetic field to hold the heliopause at bay, so the solar wind blows water out of the atmosphere.
Mars doesn't have hydrogen because at temperatures where water is liquid, the speed of hydrogen atoms due to temperature is greater than the escape velocity from Mars.
Wouldn't they be held by surface tension?
Re: Compasses don't work on Mars, so how do you navigate?
#26Earlier quoted context omitted.
Mars doesn't have hydrogen because at temperatures where water is liquid, the speed of hydrogen atoms due to temperature is greater than the escape velocity from Mars.
Wouldn't they be held by surface tension?
Surface tension is magnetic attraction between molecules. There's not enough negative magnetic attraction to hold them; they're repelled by all the other molecule nuclei.
Re: Compasses don't work on Mars, so how do you navigate?
#27Venus too - and this is also why neither have water - no strong magnetic field to hold the heliopause at bay, so the solar wind blows water out of the atmosphere.
Mars doesn't have hydrogen because at temperatures where water is liquid, the speed of hydrogen atoms due to temperature is greater than the escape velocity from Mars.
I thought it was just pressure - the more dense molecules push the Hydrogen out of the way as gravity pulls at them.
Re: Compasses don't work on Mars, so how do you navigate?
#28Earlier quoted context omitted.
The planet doesn't have to rotate to use celestial navigation. As long as you can see the stars you are fine. So the dark side of mercury would work fine. On the hot side as long as you are not exactly on the equator the sun acts as a fixed direction and you can use that. > Anyone know if Mars has any polar stars? The orbital tilt of Mars is 1.85 degrees (vs 0 for earth) and the Axial tilt is 25.19 vs 23.44 for Earth…
That's still like a couple of degrees (4 full moons) away so not sure how accurate it would be. Still the thought of seeing literally the same stars on an alien world is blowing my mind. Just imagine the same sky, but different planet... wow
> That's still like a couple of degrees (4 full moons) away so not sure how accurate it would be.
It depends on how the two tilts interact - do they cancel or add? I don't know.
Re: Compasses don't work on Mars, so how do you navigate?
#29Earlier quoted context omitted.
That's still like a couple of degrees (4 full moons) away so not sure how accurate it would be. Still the thought of seeing literally the same stars on an alien world is blowing my mind. Just imagine the same sky, but different planet... wow
I wonder if "giant head" enhanced depth perception works across planets? https://xkcd.com/941/
Fun link. I was planning on similar setup using a couple of remote linked Celestron C8s separated by 5 miles to observe thunderhead cloud formation in SW Florida. Average natural IPD is around 64mm so it should be interesting to see what the occipital lobe does when this is expanded to over 8km. (IPD = InterPupillary Distance; eyeball separation)
Re: Compasses don't work on Mars, so how do you navigate?
#30Earlier quoted context omitted.
The planet doesn't have to rotate to use celestial navigation. As long as you can see the stars you are fine. So the dark side of mercury would work fine. On the hot side as long as you are not exactly on the equator the sun acts as a fixed direction and you can use that. > Anyone know if Mars has any polar stars? The orbital tilt of Mars is 1.85 degrees (vs 0 for earth) and the Axial tilt is 25.19 vs 23.44 for Earth…
On the hot side as long as you are not exactly on the equator the sun acts as a fixed direction and you can use that. ISTM this would work on the equator too?
On the equator the sun could be directly overhead - so you have no idea what any directions are, the sun is equally far from all horizons. (Remember the sun does not move on mercury.)
If you are on the equator, but not directly under the sun then you can figure things out.
I guess I should have said equator on the central meridian.
Edit: I was under the mistaken assumption that Mercury is tidally locked.
So it would sort of work on the equator as well, but you might have to wait a bit for the sun to move enough to tell where you are.