The Canadian Meteorological Station on NASA's Phoenix Mars Lander tracked some changes in daily weather patterns over the first 61 Martian days of the mission (May 26 to July 22, 2008), a period covering late spring to early summer on northern Mars.
This summary weather report notes that daily temperature ranges have changed only about 4 Celsius degrees (7 Fahrenheit degrees) since the start of the mission. The average daily high has been minus 30 degrees C (minus 22 degrees F), and the average daily low has been minus 79 degrees C (minus 110 degrees F).
The mission has been accumulating enough wind data to recognize daily patterns, such as a change in direction between day and night, and to begin analyzing whether the patterns are driven by local factors or larger-scale movement of the atmosphere.
The air pressure has steadily decreased. Scientists attribute this to a phenomenon on Mars that is not shared by Earth. The south polar cap of carbon dioxide ice grows during the southern winter on Mars, pulling enough carbon dioxide out of the thin atmosphere to cause a seasonal decrease in the amount of atmosphere Mars has. Most of the Martian atmosphere is carbon dioxide. This measurable dip in atmospheric pressure, even near the opposite pole, is a sign of large amounts of carbon dioxide being pulled out of the atmosphere as carbon-dioxide ice accumulates at the south pole.
The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.
Photojournal Note: As planned, the Phoenix lander, which landed May 25, 2008 23:53 UTC, ended communications in November 2008, about six months after landing, when its solar panels ceased operating in the dark Martian winter.