Scientists from several nations begin an unprecedented 3-and-1/2-week pilot field experiment on the Santa Cruz flats near Eloy, Arizona, today, May 20, 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’ Human Exploration and Development of Space program and by the National Science Foundation’s Division of Atmospheric Sciences.