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.
