Earlier quoted context omitted.
All of these things can be done remotely without any wetware on Mars.
"How?"
Like we do everything on and around Mars now.
Compasses don't work on Mars, so how do you navigate?
81–87 of 87 posts
Re: Compasses don't work on Mars, so how do you navigate?
#82Earlier quoted context omitted.
I don't think so. The gyrocompass relies on gyroscopic precession. The precession itself can be obtained by integration, which gives orientation. Of course, the precision of this process may well be very low or unusable.
you don't need an initial heading measurement but you still need to know where you are
It would suffice to know the radius of the planet and it's rate of rotation.
Re: Compasses don't work on Mars, so how do you navigate?
#83Earlier quoted context omitted.
An easier method than creating a star map is to use the brightest star in the sky (the sun) and an accelerometer. This is the method Opportunity uses to calibrate the gyroscopes/wheel encoders. [source pg 4] https://www-robotics.jpl.nasa.gov/publications/Reg_Willson/M... "The attitude of the rover is based on measurements from two vector instruments: (1) accelerometers that determine the vector towards the center of…
Star maps can be downloaded free. Because you generally only need the brightest subset of stars in any area, you don't even need a comprehensive one. A star map for Mars would functionally be pretty much equivalent to an earth one, I guess, given the distances involved.
The stars would be the same, of course. Out of curiosity, I launched Stellarium, moved to Mars, set myself at 90° latitude north, and watched directly overhead. Mars north pole seems to be aligned halfway between Cygnus and Perseus, so there is no "North Star" equivalent on Mars.
Re: Compasses don't work on Mars, so how do you navigate?
#84Earlier quoted context omitted.
you don't need an initial heading measurement but you still need to know where you are
It would suffice to know the radius of the planet and it's rate of rotation.
Using only a compass and the knowledge that you were somewhere on the planet earth, could you determine the shortest route from your locations to Chicago?
Re: Compasses don't work on Mars, so how do you navigate?
#85Earlier quoted context omitted.
It would suffice to know the radius of the planet and it's rate of rotation.
Using only a compass and the knowledge that you were somewhere on the planet earth, could you determine the shortest route from your locations to Chicago?
Ah I thought you were referring to the gyrocompass functionality. Yes, for general navigation you need an initial position to determine your position from inertial measurement alone (as I said, you can determine orientation and latitude, but not longitude).
Re: Compasses don't work on Mars, so how do you navigate?
#86[deleted]
Re: Compasses don't work on Mars, so how do you navigate?
#87Earlier quoted context omitted.
Gyroscopes accumulate error with time, they make sense for an application with a short range but they're useless over long periods of time without a reference standard to crosscheck and recalibrate. That's one part of The Martian the author got entirely correct despite the criticism. The mechanical odometer in your car is only accurate to +/-3% of reading and the best mechanical calibration standards are only 0.25% o…
Thanks, I was being mildly sarcastic in my post but having the math laid out is great.
NASA has the brains to design a better odometer but navigating by stars and GPS makes more sense.
Also, remember the +/-3% next time you're comparing a used cars. Worrying about 5-6,000 miles on a car with 100,000 is pointless since the odometer itself lies by up to 3,000 miles. Then you have further error introduced by new sets of tires which wear down 6-15mm depending on their tread depth and can vary several mm in diameter despite having the same nominal size as the OEM tires.