According to findings from the Phoenix Mars Lander mission, snow and water-ice clouds play a crucial role in the exchange of water between the atmosphere and surface of Mars, which suggests that Mars is even more like Earth than previously thought.
The surprise discovery of Martian snow in 2008 by the Canadian-built weather station on NASA’s Phoenix Mars lander helps explain how the water cycle on Mars behaves, especially the seasonal increase of the Martian polar caps in winter and their consequent shrinking in summer. The Canadian science team’s paper, entitled “Mars Water-Ice Clouds and Precipitation,” describes how water vapour is lofted upwards during the daytime, forming clouds of ice-crystals low in the atmosphere that resemble cirrus clouds on Earth. Water then precipitates through the atmosphere at night in the form of snow.
“It’s similar to the phenomenon known as ‘diamond dust’ in the Arctic. If you look up into the Arctic night sky, you see fine ice crystals falling softly towards you,” said Jim Whiteway, of York University, lead scientist for Phoenix’s Meteorological Station. “You can still see the stars but it is like a continuous, light snowfall in the form of ice crystals.”
Prior to the Phoenix mission, scientists had not anticipated precipitation on Mars, nor had they predicted that clouds would form as low as they did. “We knew that the polar ice cap advanced as far south as the Phoenix site in winter, but we didn’t know how the water vapor moved from the atmosphere to ice on the ground,” said Whiteway. “Now we know that it does snow, and that this is part of the hydrological cycle on Mars.”
Canada’s participation in the Phoenix mission brought together expertise from the Canadian Space Agency, private industry and researchers from across the country. “Phoenix’s weather station is a tribute to the talent and strength of Canada’s space community,” said Alain Berinstain, Director of Planetary Exploration and Space Astronomy at the Canadian Space Agency. “It is no small feat to build a suite of sophisticated science instruments that must be delicate enough to take very precise measurements, but robust enough to survive the trip to Mars. Canada’s weather station functioned beautifully throughout the mission in spite of the hostile conditions on the Red Planet, and produced high-quality data that has allowed Canadian scientists to solve one more piece of the Martian puzzle.”
York University led the Canadian science team with the participation of the University of Alberta, Dalhousie University, Optech and Natural Resources Canada (Geological Survey of Canada), with international collaboration from the Finnish Meteorological Institute. MDA Space Missions was the prime contractor for the meteorological station, in partnership with Optech. The Canadian Space Agency invested $37 million for the design, development, operations and scientific support of the Meteorological Station.
Within hours of landing, Phoenix’s Meteorological Station began beaming back data on the temperature and pressure at the landing site, and measured dust, clouds and fog in the lower atmosphere. The warmest temperature recorded during the mission was minus 19.6 degrees Celsius, with the coldest at minus 97.7 degrees Celsius. Canada’s lidar instrument on Phoenix (a shoe-boxed sized laser instrument) probed the Martian atmosphere daily throughout the mission for a total of approximately 137 hours of operating time (about 1 hour each Martian day), emitting 49 423 600 laser shots. Perched at the top of the meteorological station’s mast, the wind indicator (known as the “telltale”), contributed by Aarhus University in Denmark, measured wind speed and direction and detected the presence of several dust devils at the landing site. Winds at the Phoenix landing site were typically between 3-5 metres/second (11-18 km/h), which increased to an average of about 10 m/s (36 km/h) during the last 50 sols of the mission, when winter weather started to set in. The highest recorded wind speed was 16 m/s (58 km/h).
The Canadian science team’s paper is available to registered journalists through Science’s SciPak web page, within EurekAlert!’s password protected section. Visit: http://www.eurekalert.org/jrnls/sci/ . Reporters can also request a copy through the SciPak team at 202-326-6440.
The Phoenix Mission is led by Principal Investigator Peter H. Smith of the University of Arizona, supported by a science team of co-investigators, with project management at NASA’s Jet Propulsion Laboratory and development partnership with Lockheed Martin Space Systems. International contributions are provided by the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus Denmark; the Max Planck Institute, Germany; and the Finnish Meteorological Institute.
About the Canadian Space Agency
Established in 1989, the CSA coordinates all civil space-related policies and programs on behalf of the Government of Canada. The CSA directs its resources and activities through four key thrusts: earth observation, space science and exploration, satellite communications, and space awareness and learning. By leveraging international cooperation, the CSA generates world-class scientific research and industrial development for the benefit of humanity.
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