Seems like it might need GPS at times, or some other means to know where it is at certain moments. Once it establishes where it is then I could see it no longer needing GPS, as it should be bright enough to keep track of location by itself using a map.

Using just dead reckoning you would pretty quickly have issues with accumulated error.

Apparently not. There's a pretty fascinating story about Etak, who made a dead reckoning-based car navigation in the mid 1980's: http://www.fastcompany.com/3047828/who-needs-gps-the-forgott...