Mile-High Dust Devils Prepared to Meet the Incoming Phoenix
“The sand in the lower part of a Martian dust devil would be the biggest hazard,” says Mark T. Lemmon, associate research scientist in the Department of Atmospheric Sciences at Texas A & M University. “The atmospheric pressure on Mars is only 1 percent that at sea level [on Earth], so you wouldn’t feel much wind against you. But you’d still be pinged by high-speed material.”
The dust devils on Mars are known to be about 10 times larger than any Earth tornado, with a typical one twirling about 70 miles per hour with zero visibility. Their high-moving particles of dust and sand have the ability to become electrically charged when the twirling particles rub against each, which can “arc” to an astronaut’s vehicle or what they are wearing.
Compared to those on Earth where dust storm charges measure on the order of 20 thousand volts per meter, electric fields on Mars or terrestrial thunderstorms build to 100 times greater before lighting will flash—enough to cause air molecules to ionize. Scientists have made studies on this to recognize that these 20 thousand volts per meter will be pretty close to breaking down the think Martian atmosphere, according to William M. Farrell of NASA’s Goddard Space Flight Center. They also found out that these electrical fields are exceptionally strong around corner area.
Beside the corner areas, another concern for NASA scientists is radio static whenever the charged grains hit the antennas that show bare wires and accumulated dust adhesing to many areas—vehicles and spacesuits for example. All of this NASA is aware of as two mile high dust devils are waiting patiently for the landing of the Phoenix Mars lander on May 25th in an oval-shaped region called “Green Valley” of northern Mars.
Monitoring the sight is NASA’s Mars Reconnaisance Orbitor (MRO), already located on Mars. The dust devils were spotted on April 20th by the MRO, measuring 20 by 100 kilometres across at that time—with researchers estimated one at 920 metres high with the other one 790 metres high. This height was achieved because of the low gravity on Mars, “It’s the low gravity and the fact that the surface gets warm and the energy is transferred into turbulence and uplift within the atmosphere,” says Phoenix team member Ray Arvidson of Washington University in St Louis, Missouri, US.
This entry was posted on Friday, May 9th, 2008 at 2:35 am and is filed under Mission Objectives, Space Agency News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
