stronomers using the Hubble Space Telescope provide updated planetary weather reports to help plan NASA's two mid-year missions to Mars.

Hubble images taken barely three weeks apart show that the Mars Pathfinder that landed on July 4 and the Mars Global Surveyor that will land September will experience considerably cloudier and colder conditions than seen by Viking, the last U.S. spacecraft to land on Mars 21 years ago.

"Understanding the state of the atmosphere prior to landing is important," said Dr. Matthew Golombek, Pathfinder project scientist at NASA's Jet Propulsion Laboratory. Hubble images of Mars are helping us to adjust our flight path for landing and effectively plan surface operations," said Golombek.

NASA's Mars Global Surveyor will skim across the upper martian atmosphere to slow down by friction and enter orbit around the red planet. Atmospheric density is a key factor in precisely executing this complex and delicate aerobraking maneuver. Hubble is ideal for tracking dust storms which could threaten Surveyor by drastically changing the planet's air density.

Hubble's "weather satellite" view is complementary to close-up views provided by Pathfinder and Surveyor.

For more information, contact Donald Savage at NASA Headquarters
Call 202/358-1547.

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