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