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MET Station Sensors

Measuring Local Weather Conditions on Mars

There are three types of sensors on the mast of the Canadian weather station:

1. Temperature
2. Pressure
3. Wind speed

1. Cold and colder

When Phoenix lands near the north polar ice cap of Mars, the Sun will be close to its highest point in the sky, providing almost 24 hours of sunshine. Local temperatures are expected to vary between highs of -33ºC to lows of -73ºC or -100ºC degrees.

The weather station has three temperature sensors. Fixed to the mast at different levels, the top sensor is about 2.3 metres above the ground.

The sensors measure temperature by its effect on the flow of an electrical current through a closed circuit. They were built by MDA Space Missions in Brampton.

2. Pressure helps forecast weather on Mars

About the size of a deck of cards, the pressure sensor can take air pressure readings at the Phoenix landing site throughout the day. It is mounted on the side of an electronics box on the deck of the lander.

The air pressure is expected to be about 1% of Earth's. Researchers hope to be able to correlate the pressure data with observations from the other sensors so they can develop a daily weather forecast for the landing site.

The pressure sensor was provided by the Finnish Meteorological Institute.

3. Who has seen the wind?

Near the top of the mast by a temperature sensor, the wind monitor measures the direction and strength of winds at the landing site. Researchers had to create a small, light device for the lander. Their innovative solution is made of a small tube and a ball. As the wind lifts and moves the ball, onboard stereoscopic cameras capture the movement. The deflection of the ball tells wind speed and direction.

Mars has light winds most of the time, about four kilometres an hour. These may pick up to around 15 to 40 kilometres an hour during the day. But visible effects from ferocious winds, up to 150 kilometres an hour, have been recorded. Windstorms have cleared crater-scarred plains, and swept soil into giant dunes six-stories high.

Martian storms carry lots of dust. The Red Planet experiences dozens of dust storms every year. And every five or six years, a storm develops into a monstrous tempest that can cover the entire planet.

The wind monitor, also known as a "telltale," was provided by Denmark's Aarhus University with support from Canadian science team members.