Posted: Fri, Oct 12, 2001, 12:19 AM ET (0419 GMT)
Two NASA spacecraft have tracked the largest dust storm seen on Mars in 30 years, scientists announced Thursday. The giant dust storm developed in late June, first in the Hellas impact basin in the planet's southern hemisphere but soon spreading across the planet. For weeks nearly the entire surface was obscured by dust injected in the planet's upper atmosphere, and only recently has the storm started to subside. Planetary scientists are using observations by the Hubble Space Telescope and Mars Global Surveyor spacecraft to monitor the storm and try to understand what caused the storm to spread across the planet when in other years dust storms remain localized. Such storms are a cause of concern because the 2001 Mars Odyssey spacecraft, scheduled to enter orbit around Mars on October 23, will use the atmosphere to aerobrake into a circular orbit: dust storms elevate the temperature and pressure of the atmosphere and thus could throw off aerobraking calculations. Scientists said there is a strong possibility that another dust storm will form, but NASA officials said they will use MGS to monitor the Martian atmosphere and adjust Mars Odyssey's aerobraking regime accordingly.

Related Links:

•  NASA press release
•  SPACE.com article