Compasses don't work on Mars, so how do you navigate?

Re:Compasses don't work on Mars, so how do you navigate? by cc438 on Thursday July 02, 2015 @10:46PM (#9823124)

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% of reading, that puts the trip described in The Martian off by ~90km.

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Re:Compasses don't work on Mars, so how do you navigate? by stephentmcm on Friday July 03, 2015 @12:43AM (#9823527)

Thanks, I was being mildly sarcastic in my post but having the math laid out is great.

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Re:Compasses don't work on Mars, so how do you navigate? by cc438 on Tuesday July 07, 2015 @09:20AM (#9845218)

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.

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