The Mars Pathfinder lander and rover continue to operate flawlessly on the surface of Mars, 19 days after landing in an ancient outflow channel called Ares Vallis.

Pathfinder's 1-foot-tall roving geologist -- named Sojourner -- continues to collect data on crustal materials and rocks in the immediate vicinity to provide scientists with new information on the geology of this region. The Pathfinder lander, on the other hand, has become a virtual weather station, using its wind socks, wind sensors and image magnets around-the-clock now to profile the pressure, temperature, density and opacity of the Martian atmosphere.

Two downlink sessions were successfully completed by 11 a.m. today, using the 70-meter (230-foot) antenna of NASA's Deep Space Network facility in Madrid, Spain, reported David Gruel, Mars Pathfinder flight director for Sol 19. The flight team retrieved a total of 45 megabits of data over night, most of which was imaging data from the ongoing science experiments.

"The lander and rover are in excellent health and continue to operate flawlessly," Gruel said. "Meteorological data are being gathered around the clock."

First on Sojourner's list of activities tonight is a wheel abrasion experiment, in which the 10.5-kilogram (23-pound) vehicle will turn and dig some of its wheels into the fine Martian sand to measure material properties of the surface. Next the rover will position its alpha proton X-ray spectrometer face- down in the soil next to a rock called "Lamb" and make measurements of the rock's chemical composition.

On this Martian day, Sol 19, Earth rose over the Sagan Memorial Station at 9:30 p.m. PDT yesterday, July 22. Sunrise was at 12:30 a.m. July 23, and Earth set occurred at 11:04 a.m. PDT today.

An audio update on Pathfinder's status can be heard by calling 1-800-391-6654.

For more information, please visit our website at http://mpfwww.jpl.nasa.gov.