NASA Rover Providing New Weather and Radiation Data About Mars

Nov. 15, 2012

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@nasa.gov

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster@jpl.nasa.gov

RELEASE: 12-402

NASA ROVER PROVIDING NEW WEATHER AND RADIATION DATA ABOUT MARS

PASADENA, Calif. -- Observations of wind patterns and natural
radiation patterns on Mars by NASA's Curiosity rover are helping
scientists better understand the environment on the Red Planet's
surface.

Researchers using the car-sized mobile laboratory have identified
transient whirlwinds, mapped winds in relation to slopes, tracked
daily and seasonal changes in air pressure, and linked rhythmic
changes in radiation to daily atmospheric changes. The knowledge
being gained about these processes helps scientists interpret
evidence about environmental changes on Mars might have led to
conditions favorable for life.

During the first 12 weeks after Curiosity landed in an area named Gale
Crater, an international team of researchers analyzed data from more
than 20 atmospheric events with at least one characteristic of a
whirlwind recorded by the Rover Environmental Monitoring Station
(REMS) instrument. Those characteristics can include a brief dip in
air pressure, a change in wind direction, a change in wind speed, a
rise in air temperature or a dip in ultraviolet light reaching the
rover. Two of the events included all five characteristics.

In many regions of Mars, dust-devil tracks and shadows have been seen
from orbit, but those visual clues have not been seen in Gale Crater.
One possibility is that vortex whirlwinds arise at Gale without
lifting as much dust as they do elsewhere.

"Dust in the atmosphere has a major role in shaping the climate on
Mars," said Manuel de la Torre Juarez of NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, Calif. He is the investigation
scientist for REMS, which Spain provided for the mission. "The dust
lifted by dust devils and dust storms warms the atmosphere."

Dominant wind direction identified by REMS has surprised some
researchers who expected slope effects to produce north-south winds.
The rover is just north of a mountain called Mount Sharp. If air
movement up and down the mountain's slope governed wind direction,
dominant winds generally would be north-south. However, east-west
winds appear to predominate. The rim of Gale Crater may be a factor.

"With the crater rim slope to the north and Mount Sharp to the south,
we may be seeing more of the wind blowing along the depression in
between the two slopes, rather than up and down the slope of Mount
Sharp," said Claire Newman, a REMS investigator at Ashima Research in
Pasadena. "If we don't see a change in wind patterns as Curiosity
heads up the slope of Mount Sharp -- that would be a surprise."

REMS monitoring of air pressure has tracked both a seasonal increase
and a daily rhythm. Neither was unexpected, but the details improve
understanding of atmospheric cycles on present-day Mars, which helps
with estimating how the cycles may have operated in the past.

The seasonal increase results from tons of carbon dioxide, which had
been frozen into a southern winter ice cap, returning into the
atmosphere as southern spring turns to summer. The daily cycle of
higher pressure in the morning and lower pressure in the evening
results from daytime heating of the atmosphere by the sun. As morning
works its way westward around the planet, so does a wave of
heat-expanded atmosphere, known as a thermal tide.

Effects of that atmospheric tide show up in data from Curiosity's
Radiation Assessment Detector (RAD). This instrument monitors
high-energy radiation considered to be a health risk to astronauts
and a factor in whether microbes could survive on Mars' surface.

"We see a definite pattern related to the daily thermal tides of the
atmosphere," said RAD principal investigator Don Hassler of the
Southwest Research Institute's Boulder, Colo., branch. "The
atmosphere provides a level of shielding, and so charged-particle
radiation is less when the atmosphere is thicker. Overall, Mars'
atmosphere reduces the radiation dose compared to what we saw during
the flight to Mars."

The overall goal of NASA's Mars Science Laboratory mission is to use
10 instruments on Curiosity to assess whether areas inside Gale
Crater ever offered a habitable environment for microbes.

JPL manages the Mars Science Laboratory Project for NASA's Science
Mission Directorate in Washington. JPL also built Curiosity.

For more about the mission, visit:

http://www.nasa.gov/msl

You can follow the mission on Facebook and Twitter at:

http://www.facebook.com/marscuriosity

and

http://www.twitter.com/marscuriosity


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