UA-Led Scientists Begin Unprecedented Dust-Devil Experiment

Scientists from several nations begin an unprecedented
3-and-1/2-week pilot field experiment on the Santa Cruz flats near Eloy,
Ariz., 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’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.

EarthB9s 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 AD 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 EarthB9s electric field using an electric field mill made
by Global Atmospherics of Tucson.

*** DIRECTIONS TO FIELD SITE: Drive Interstate-10 to Eloy, turn south on
Sunshine Boulevard and drive 4 miles. Then turn east and drive another
four-tenths mile. The station will be on your right. Contact Re