and incredibly, a google for "Kilmer Sojourner" yielded your own analysis from 2004 as the 3rd hit:

djellison
Nov 3 2004, 04:04 PM

Most likely a dead lander battery.

Yup - Sojourner was still working perfectly well - and they had plans to send if off on quite a long drive.

Sojourner would, after a few sols of no comms, gone back to its previous position to see if it had gone somewhere that blocked the radio waves and waited for instructions there.

If that hadnt worked - it would then have started attempting to circle the lander at about a 5m radius.

How or when Sojourner died is probably never going to be known, unless someone can actually pick the thing up, and inspect the contents of the memory

If and how-much it started to circle Pathfinder might POSSIBLY be visible by MRO in 18 months time.

Congratulations Doug - your prediction was only a couple of months off, too!