University of Chicago scientists will start the new year at the Jet Propulsion Laboratory in Pasadena, Calif., with a heavy agenda of extraterrestrial activities. They are participating in NASA missions that are scheduled to visit a comet Jan. 2 and land on Mars Jan. 3.

The Stardust spacecraft, carrying the University’s dust instrument, will fly within 190 miles of comet Wild 2 (pronounced vilt 2) on Jan. 2. Then one of NASA’s twin Mars rovers, Spirit, will land in the Gusev Crater, where an instrument that uses a technique invented at the University of Chicago will identify the chemical composition of local rocks and soil.

Stardust’s primary mission is to capture microscopic particles of comet and interstellar dust and return them to Earth in January 2006. The University’s dust detector will help scientists estimate the number of particles they will be able to collect during its half-hour rendezvous with the comet Jan. 2. Scientists expect analysis of the particles to provide new insights into the formation of the solar system.

Anthony Tuzzolino, Senior Scientist at the University of Chicago’s Enrico Fermi Institute, said that his instrument might get pelted by particles ranging in size from two to 200 microns (a human hair measures 50 to 100 microns in diameter). “I just don’t know. Every comet is different,” he said. “That’s why we’re going out there.”

This is the 35th space mission to which Tuzzolino has contributed in collaboration with the late John Simpson, the Arthur Holly Compton Distinguished Service Professor in Physics at the University of Chicago. In previous missions, Simpson and Tuzzolino developed and tested a dust detector that flew aboard the former Soviet Union’s Vega 1 and Vega 2 missions to Halley’s comet in 1986.

Stardust was launched Feb. 7, 1999. Tuzzolino has patiently awaited the comet encounter ever since.

“I’m anxious for it to happen now,” he said.

Assisting Tuzzolino with Stardust’s dust detector is Thanasis Economou, Senior Scientist at the Enrico Fermi Institute. Economou also helped develop the technique at the University of Chicago that is being used for the alpha particle X-ray spectrometer for the Spirit rover as well as for its twin, Opportunity, which will land on the opposite side of Mars in late January. Both instruments were manufactured by the Max Planck Institute in Germany. The APXS instruments are similar to one that Economou and the late Anthony Turkevich, the James Franck Distinguished Service Professor Emeritus, provided for the successful Mars Pathfinder mission in 1997.

Mars has become an especially difficult destination in the risky business of interplanetary space exploration. Despite Pathfinder’s success, most missions sent to Mars by the world’s space agencies have failed. “NASA put all of JPL’s might into this mission to make it a successful one,” Economou said.

The Spirit rover is expected to begin rolling a week after it lands. “By the time that they do all the data housekeeping, the engineering assessment of the rover’s status, take the first panorama image and direct the rover to one side of the lander or the other, it will take about a week,” he said.

Mission objectives call for the Spirit rover, the size of a golf cart, to cruise at least 600 meters (660 yards) over a three-month period collecting data regarding the Martian geologic past. Scientists hope to learn enough along the way to determine if environmental conditions were adequate to sustain life. Gusev Crater, the landing site for the first rover, is punctured by an outflow channel and may once have held standing water.

Economou will be at JPL for several months to monitor the performance of the APXS instrument and also to work with other scientists in planning the rover’s daily agenda. Spirit’s camera will snap photographs that scientists will use to analyze the site and to select targets for investigating with the rover’s two chemical detection instruments, microscope and scraping too.

“January is going to be an interesting month. We are very optimistic,” he said.