Pathfinder's Legacy: Opening The Doors To Mars' Past And Present

The mission included three science and ten technology experiments, which sent back 2.3 gigabits of new data, including over 17,000 images, 16 chemical analyses of rocks and soil, and 8.5 million measurements of temperature, pressure, and wind.

Around the world, Pathfinder was one of the most popular space exploration programs ever; its web site received 566 million visits during the first month alone, including a one-day record 47 million on July 8, 1997. Millions also viewed television images of the Martian surface beamed back from the landing site, which was named the Sagan Memorial Station in honor of the late astronomer, Carl Sagan.

Scientists at the Jet Propulsion Laboratory in Pasadena, California, which ran the Pathfinder mission for NASA, and colleagues around the world have been analyzing and interpreting the data beamed back from Mars. They have now published their major findings in a special section of the Journal of Geophysical Research, published by the American Geophysical Union. The journal's April 25 issue devotes 576 pages to Pathfinder, consisting of 35 papers grouped in thematic areas, such as geology and geomorphology, magnetic properties, atmosphere, and cartography. It is the first detailed, published account of science results from the entire mission and is the largest ever issue of JGR-Planets, since it was launched in 1991. Planets is one of five thematic editions of the journal.

Dr. Matthew P. Golombek, Mars Pathfinder Project Scientist at JPL, says that although Pathfinder's general results were widely reported at the time, the peer-reviewed papers in JGR are "the first in depth publication of scientific results from the mission." Papers in the journal also describe the events of the mission and the analysis of the data.

An introductory article by Golombek and others lists some of Pathfinder's main achievements:

* Determined the spin pole and the precession rate of Mars since Viking, 20 years ago; results require a central metallic core 1,400-2,200 kilometers [900-1,350 miles] in radius;

* Dark rocks appear to be high in silica, while lighter ones richer in sulphur and lower in silica, consistent with being covered with varying amounts of dust;

* Rocks have a variety of morphologies, fabrics, and textures;

* Rounded pebbles and cobbles on the surface and other evidence suggest a warmer and wetter past;

* Airborne dust consists of silicate particles with a small fraction of a highly magnetic mineral, probably maghemite, suggesting an ancient hydrological cycle;

* The landing site appears little changed since its formation billions of years ago, other than by the action of winds;

* The lower atmosphere is dusty, and "dust devils" are common in the Martian afternoon;

* Ice clouds are common in the early morning, and morning near-surface temperatures change abruptly with time and height.

In addition, scientists developed and perfected many investigational techniques, reported in JGR, that will be employed in future unmanned missions to the planets. The April 25 JGR report on Pathfinder is replete with color and black and white images, charts, graphs, and other figures. Copies may be ordered from AGU customer service at 1-800-966-2481 (outside North America: 1-202-462-6900). The cost is $40 for nonmembers of AGU.