So working out longitude requires Phobos to set, and working out latitude requires it to be night so I can sight Deneb. It’s not a very fast system. But I only need it once a day. I work out my location when I’m parked, and account for it in the next day’s travel. It’s kind of a successive approximation thing. So far, I think it’s been working. But who knows? I can see it now: me holding a map, scratching my head, trying to figure out how I ended up on Venus.
