A team of Canadian scientists, led by York University, has discovered snow falling from Martian clouds – a first in observations from the surface of the red planet.
A laser instrument known as the LIDAR, designed to gather knowledge of how the atmosphere and surface interact on Mars, detected snow from clouds approximately four kilometres above the NASA Phoenix spacecraft’s landing site. Data show the snow vaporizing before reaching the ground.
"Nothing like this view has ever been seen on Mars," said York University Professor Jim Whiteway, the principal investigator for the Canadian team and lead scientist for the Canadian-supplied meteorological station on Phoenix.
Left: Professor Jim Whiteway. Photo courtesy of the Canadian Space Agency (CSA)
"We’ll be looking for signs that the snow may even reach the ground,” said Whiteway, who announced the findings during a news briefing Monday at NASA’s Washington headquarters.
The meteorological station gathers crucial information about the climate on Mars, and provides a comprehensive picture of the atmosphere at the landing site, 1,200 km from the planet’s north pole. It consists of temperature, wind, and pressure sensors, as well as a laser-based-light-detecting-and-ranging (lidar) system. The lidar shoots pulses of laser light into the Martian sky, precisely measuring components of the atmosphere such as dust, ground fog, and clouds, from the surface up to a range of 20 km.
Above: The Canadian-built lidar aboard NASA’s Phoenix Mars Lander produced this graphic of a profile of a Martian cloud on the 99th sol, or Martian day, of the mission (Sept. 3, 2008). The vertical streaks at the base of the cloud on the right of the image show ice crystals falling from the cloud, similar to snow. The streaks are curved as the winds are faster around 3 kilometers (almost 2 miles) than at higher altitudes. Scientists are able to determine that the snow is water-based and not carbon-dioxide snow, since temperatures on Mars are currently too warm to support the latter. Image courtesy of NASA/JPL-Caltech/University of Arizona/Canadian Space Agency.
At the briefing, NASA also announced that experiments have provided evidence of past interaction between minerals and liquid water, processes that occur on Earth.
Experiments also yielded clues pointing to calcium carbonate, the main composition of chalk, and particles that could be clay. Most carbonates and clays on Earth form only in the presence of liquid water.
Since landing on May 25, Phoenix confirmed that a hard subsurface layer at its far-northern site contains water-ice. Determining whether that ice ever thaws would help answer whether the environment there has been favorable for life, a key aim of the mission.
The Phoenix mission, originally planned for three months on Mars, has begun its fifth month. However, it faces a decline in solar energy that is expected to curtail and then end the lander’s activities before the end of the year.
Right: The Canadian lidar in action. Photo courtesy of NASA’s Jet Propulsion Laboratory, CSA and the University of Arizona
The lander’s meteorological component is a collaboration led by researchers in the Department of Earth and Space Science & Engineering, Faculty of Science & Engineering, at York University, in partnership with the University of Alberta, Dalhousie University, the University of Aarhus (Denmark), the Finnish Meteorological Institute, MDA Space Missions, and Optech Inc., with $37 million in funding from the Canadian Space Agency. The mission is a joint project of NASA’s Jet Propulsion Laboratories and the University of Arizona.