Comparing Martian Dust Storms to Earth's Cyclones

Grade Levels: 3 - 6

Background Information

In 1975, two Viking spacecraft landed on Mars and returned with samples of soil – red Martian soil. The Mariner flybys led the way to our early investigations of Mars, which will continue in the future.

Mariner 9 was launched on May 30, 1971 and took 5 1/2 months to reach Mars. Previous Mariner flights had photographed Mars from as close as 6,000 miles. When Mariner 9 arrived at its destination on November 13, 1971, Mars was experiencing a terrible dust storm that postponed any photography of the planet for weeks. When Mariner 9 was finally able to photograph the red planet, it took a total of 7,000 photographs. These photos revealed exciting new information – that rivers and perhaps seas once existed on Mars.

The Viking project, which followed the Mariner projects, successfully landed spacecraft on Mars, another milestone for the U.S. space program.

During a dust storm such as the one witnessed on Mars, winds may speed at hurricane-like force. Although Martian air has 0.001 as much water as Earth's air, it can condense and form clouds and fog. In its past, the , Martian atmosphere may have been denser and water may have flowed on the planet.

Ask students to think and compare a Martian dust storm to a storm on planet Earth. On November 13, 1970, a terrible cyclone swept through Bangladesh, creating massive tidal waves and high winds.

Cyclones are storms of wind that encircle a center of low atmospheric pressure. If they occur north of our equator, they move in a counter-clockwise direction. If they are south, they move in a clockwise direction.

In the Southern Hemisphere where there is less land and continental resistance, cyclones can be much stronger and more damaging. Although Bangladesh is in the Northern Hemisphere, the cyclone formed in the Southern Hemisphere and caused more than 300,000 deaths. (In May of 1991, Bangladesh again suffered a devastating cyclone.)

The following activity will help your students understand the principles of air pressure. They can also read about storms and atmospheric pressure both on Earth and on Mars. The atmosphere on Mars is similar to the atmosphere on Venus, consisting mostly of carbon dioxide, with some oxygen, nitrogen, and argon.

What features do a Martian dust storm, as witnessed by Mariner 9, and a violent cyclone have in common? Read and find out about both of these storms. How fast can the wind blow?

What is "atmospheric pressure" and how can it affect the storm?

What is a cyclone? In what direction does the wind move – clockwise, counterclockwise, or both? What forms of precipitation do cyclones bring? Where are they generally found geographically in relation to the equator? You will find that there are variations in cyclones depending on their movement and location.

Here is an investigation that will help you understand some principles about air pressure. After completing the investigation, write a Mini Report about violent storms such as the dust and cyclone storm, based upon your readings and other sources.

Objectives

• Students will learn about Earth's cyclones and Martian dust storms.
• Students will compare and contrast these types of storms.
• Students will learn some principles about air pressure.