The batteries on board Sojourner, Mars Pathfinder鈥檚 rover, are dead. Although
the rover can work under solar power, its progress will be slowed. Sojourner is
analysing the composition of rocks with its alpha proton X-ray spectrometer
(APXS). Each measurement takes more than 10 hours, and without battery power to
allow work to continue after dark, many rocks will take two days to analyse.
The Sojourner team predicted that the battery would allow more than 30 APXS
measurements, but less than 20 have been possible. Engineers suspect that the
APXS used more power than expected. 鈥淲e don鈥檛 think there was anything wrong
with the batteries,鈥� says Ron Banes of the Jet Propulsion Laboratory in
Pasadena, California.