Repeatable Weather Patterns

Each day the Mars Global Surveyor camera operated, it collected images that were used to build a daily global map. These maps formed a record of changing meteorological conditions, revealing some dust storm patterns. Some such storms repeated in the same location within a week or two of the time they occurred in the previous year. In addition, local disturbances and dust devils may start up at any time in spring and continue until Martian autumn.

An overhead view of a dull, medium-to-light-gray landscape shows mostly smooth terrain interrupted by several freckle-like bumps, slightly raised but in the same color as the sorrounding terrain. Taking up the right one-third of the image is a depression in the land, uniformly deep but wider at its upper section and narrowing toward the bottom of the frame, like a jalapeno pepper pressed into dough. The left wall of the depression is much brighter than the rest of the area, almost white, and about a half-dozen dagger-shaped marks – much darker gray than anything else in the image – scar the walls of the depression, pointing toward its bottom.
Slope-Streaked Knob: This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark slope streaks coming down the slopes of a knob in western Amazonis Planitia. All of the surfaces in this image are mantled by dust. On the slopes, mass movement of dry dust has created the streaks. May 28, 2005

Water Features

A panoply of high-resolution images showed gullies and debris flows. These images suggest that occasional sources of liquid water, similar to an aquifer, were present at or near the Martian surface – even in relatively recent times.

This overhead view of a Martian crater shows the upper-left quarter of the crater – its rim and the walls descending to the floor below. The rim and floor appear as a bright yellow-orange, while the wall is in various darker shades culminating in a deep rust color at the bottom where it meets the wall. The rim is fairly smooth while the walls are grooved with straight and slightly curved lines until they meet the crater floor, making the scene look like the underside of a mushroom. The crater floor is somewhat uneven, highlighted by a ribbon of bright yellowish-orange terrain, undulating from the middle of the bottom frame of the image toward the right edge of the frame, where it ends at in the lower quarter.
Newton Crater is a large basin on Mars, about 178 miles (287 kilometers) across, formed by an asteroid impact more than 3 billion years ago. This picture shows the north wall of a specific, smaller crater within Newton Crater. About 4.4 miles (7 kilometers) across, this smaller crater is still about seven times bigger than the famous Meteor Crater in northern Arizona. The image shows many narrow gullies eroded into the smaller crater’s north wall – thought to have been formed by flowing water and debris. Small channels in many of the finger-like deposits at the base of the crater indicate that a liquid – most likely water – flowed in these areas, with possibly hundreds of individual events carving these features. If the deposits shown in this image are like debris flows on Earth, researchers estimate that each event carried about 660,000 gallons (2.5 million liters) of flowing water, or enough to fill about seven community-sized swimming pools. This picture is a mosaic of three images captured by the Mars Global Surveyor’s high-resolution Mars Orbiter Camera from January-May 2000.

Mars is Dynamic

Numerous observations over several years showed that Mars' history includes seasonal and long-term change. The spacecraft viewed gully formation, new boulder tracks, recently formed impact craters, and diminishing amounts of carbon-dioxide ice within the south polar cap.

Magnetic Discoveries

Magnetometer readings showed that while Mars has no global magnetic field, it does have localized magnetic fields in areas of its crust.

Meteoroid History

Temperature data and closeup images of the Martian moon Phobos determined that the moon is covered by powdery material at least 3 feet (1 meter) thick – the pulverized output of millions of years of meteoroid impacts.

Other Science

The mission yielded the first 3D views of Mars' north polar ice cap. Radio transmissions refracted by the Martian atmosphere enabled scientists to create vertical profiles of atmospheric temperature and pressure. Spacecraft accelerations due to gravity helped scientists better understand the Mars interior.