Scientists from several nations began an unprecedented 3-and-1/2-week pilot field experiment on the Santa Cruz flats near Eloy, Ariz., Monday to discover how dust devils may affect atmospheres on Earth and on Mars.

The 2002 MATADOR Field Test, led by Nilton Renno and Peter Smith of the University of Arizona Lunar and Planetary Laboratory, is being funded by NASA's Human Exploration and Development of Space program and by the National Science Foundation's Division of Atmospheric Sciences.

Major collaborators include scientists from the University of California-Berkeley Space Sciences Laboratory, the Wageningen University Department of Environmental Sciences in the Netherlands, and IMADES, or Instituto del Medio Ambiente y el Desarrollo Sustentable del Estade de Sonora, in Hermosillo, Sonora, Mexico. Participants are bringing science instruments from countries as far as the Netherlands and Israel.

Smith, head of the Imager for Mars Pathfinder (IMP) camera on the hugely successful Pathfinder mission that landed on Mars July 4, 1997, and Renno, an atmospheric scientist and sailplane pilot who is an expert on atmospheric convection, began collaborating in dust devil research in 1996. Their analysis of Mars Pathfinder meteorological data showed that dust devils blast over the Mars Pathfinder landing site with windspeeds greater than 140 mph and are an important source of dust in the martian atmosphere.

Smith heads the NASA-funded MATADOR project to help define instruments needed for studying enormous martian dust devils, instruments that will be deployed on Mars-bound spacecraft later this decade.

Dust devils -- 100 times larger than those on Earth -- churn tons of electrically charged dust particles through the martian atmosphere. Not only does dust possibly play an important role in climate change, it poses a major hazard to both robotic and human exploration, for the charged particles could trigger lightning bolts and discharges that might fry computers and delicate electronics, interfere with radio communications, or rip apart pressurized human habitat.

Earth's dust devils may play a more important role in climate change, atmospheric photochemistry and ocean biochemistry than previously thought, scientists now suspect. Convective air and dust devils are a known hazard for aviation -- up to 10 percent of accidents with light aircraft, sailplanes, helicopters and blimps are caused by gusts associated with these convective winds.

The 2002 field test expands on a NASA-funded MATADOR experiment that Smith and Renno organized at the same southern Arizona location last June. One surprising result from that four-day experiment is that even small terrestrial dust devils produce radio noise and electrical fields greater than 10,000 volts per meter. That is, as puny as Earth's dust devils are by comparison to martian dust devils, if they were on Mars, they would generate long-lived, charged particles powerful enough to trigger electrical discharges in the martian atmosphere.

The major goal of the 2002 field test is to learn how much heat and dust is carried vertically through the atmosphere by dry convective plumes and dust devils, said Renno, who won NSF support for this year's more elaborate experiment.

"Unfortunately, during the 2001 campaign we were not able to do simultaneous measurements in a single dust devil with most MATADOR instruments," Renno said.

This year, the collaborating teams have revised their operations. Rather than trying to deploy their sensitive instruments where dust devils are seen forming, they will station themselves and their instruments at the chosen location and gather data as individual dust devils sweep through. Simultaneous measurements with various instruments of single dust devils will give them the measurements they need to test their basic dust-devil theories and models.

Such data "would allow us to replay a large (dust devil) event with accurate, sub-second resolution of position, velocity, size, wind speed, dust concentration, and radio noise," Renno said. "We should be able to completely characterize a dust devil as it moves over our sensors."

"The idea that dust devils and convective plumes play an important role in the vertical transport of heat and aerosols is novel and needs testing," Renno added. "It's also risky: No one has experience in measuring what convective plumes and dust devils contribute to heat and aerosols transport. This pilot study will be a learning experience for us."

UA's MATADOR Project scientists began collaborating with Hendrick de Bruin's research team at Wageningen University last December because of their complementary expertise and interest in convective plumes and dust devils. IMADES research scientist Christopher Watts has joined the 2002 project as a senior collaborator. Greg Delory of UCLA, who managed the data systems during the 2001 experiment, is co-principal investigator on this year's project.

MATADOR team scientists involved in the 2001 and 2002 experiments also include John Marshall of NASA Ames Research Center, an expert on dust properties; William Farrell of NASA Goddard Space Flight Center, an expert on the electrical properties of dust devils; Allan Carswell of Optech, Ontario, Canada, who will be operating LIDAR to track and measure dust devils; and Barry Hillard of the NASA John Glenn Research Center, who will measure changes in Earth's electric field using an electric field mill made by Global Atmospherics of Tucson.