Brian,

I don't know what RAH had in mind, but I suspect that any planet capable of supporting humans will have to have a fairly robust magnetic field. http://tinyurl.com/dg32e

Worst case, it is useless. Best case, one can determine local N-S using one of several simple methods, and then note the correction for the compass (or in my case, adjusting the compass).

Other thoughts?

Regards,

Tom