NavList:

Using the satellites in orbit depends on sufficient radio energy being radiated at the surface.  That is energy needing to be budgeted for.  No satellite will broadcast sufficient energy towards the surface unless it is communicating with a lander of some sort and even then will depend on how directional an antenna it uses.  If you want to use satellites you will need to make arrangements for them which means trading or paying for broadcast time except for the occasional pass that happens to provide data.

INS drifts over time and needs updates.  Speed will have an impact.  Slow speeds mean slower drift but distance between needing updates is going tobe the same or worse.  At low enough speed position can be updated weekly from whatever source.

Re: Celestial Navigation on the surface of Mars
From: John D. Howard
Date: 2018 Nov 10, 20:03 -0800

Not to burst anyone's bubble, but I do not think there will be any cel nav on Mars.  Why would there be?  People will need a satilite to radio commumate with earth - why not use the ( many ) satilites that will be around Mars for position finding?  INS would be a better opition than cel nav..

But really, a sextant?  No oceans - no boats.  Like others have said, a transit would be better on dry Mars land.

It would be fun for the computer programing folk to get a Mars almanac and sight reduction tables to play with.

John H.  41N 100W