Goals: Mission Results

Goal 2: Characterize the Climate of Mars

Today, liquid water is not found on the surface of Mars because the planet is too cold and the atmospheric pressure too low. Yet, not only the Mars rovers, but earlier missions such as NASA's Mars Global Surveyor orbiter and the Pathfinder lander and Sojourner rover, found evidence suggesting that Mars was once a wetter place. Some scientists think Mars used to be warmer. Others think Mars has always been a cold place by Earth standards, but that frozen water melts periodically when the planet's poles are tilted more directly toward the Sun. Some think volcanic activity may occasionally melt polar ice or ice buried beneath the surface.

Wind-Swept Planet Modern Mars is a vast desert of sand dunes, ripples, dust devils, and streaks of materials deposited by wind. Dust even covers icy deposits at the poles. But the surface of the Red Planet has been wet at times. Both Mars rovers as well as orbiters have found plenty of evidence for water in the past. Opportunity used the 13-filter panoramic camera to acquire this color image of dunes marching across the floor of Endurance Crater. Credit: NASA/JPL-Caltech/Cornell Full Image

If life could ever have existed on the surface of Mars, it would have had to be able to survive the planet's climate. Both Mars Exploration Rovers have collected a treasure trove of data about the Martian atmosphere to help characterize the modern climate on the red planet. This information is important because atmospheric conditions affect the amount of sunlight reaching the surface and the amount of heat reflected back into space.

Frost on Mars In October 2004, the Opportunity rover documented a thin veneer of frost coating a black peg that serves as a calibration target for the panoramic camera. Credit: NASA/JPL-Caltech/Cornell Full Image

Spirit and Opportunity surveyed the amount and distribution of dust and water ice in the Martian atmosphere, using cameras and spectrometers that measured the absorption of different wavelengths of light. As the seasons changed from summer to fall to winter to spring, the rovers monitored changes in temperature at different heights above the surface and at different times of day.

Clouds Accompany Martian Winter In November, 2004, Opportunity observed clouds at the onset of Martian winter. Similar in appearance to cirrus clouds on Earth, these clouds are believed to be composed of water-ice particles on the order of several micrometers (a few ten-thousandths of an inch) in length. Credit: NASA/JPL-Caltech Larger Image

The rovers have provided daily weather reports from Mars. Spirit documented dozens of daily dust devils during the Martian spring. On the opposite side of Mars, Opportunity took images of clouds in the Martian sky and frost on the rover deck. These observations are giving researchers a better understanding of current climate conditions on Mars, an important step in determining how they may or may not be different from those in the past.

Dust Devils on Mars During spring and summer of 2005 on Earth, Spirit often observed dozens of dust devils each day at around lunchtime local solar time on Mars. Credit: NASA/JPL-Caltech Full-Res (NASA's Planetary Photojournal)