Of all the planets in the solar system, none have intrigued the people more than Mars. Mars is easy to observe and changing surface markings can be seen with even a small telescope. It was the changing variegated surface markings that led to the speculation of life on the red planet.
Mars has a diameter of 6796 km, about half the size of the Earth. A day on Mars is 24 hours 37 minutes almost exactly the same as Earth’s. The Martian year is 687 days slightly less than twice the length of a year on Earth.
In some ways, Mars is quite similar to Earth. The red planet’s axial tilt is 25.2 degrees, very close to the Earth’s. Mars also displays seasons, polar caps geological features of the grandest scale. Mars is a fascinating planet.
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Mars has been explored by numerous spacecraft, most of them belonging to NASA. As early as 1965, the Mariner 4 spacecraft flew by the red planet. At long last we had our first glimpses of 3 World we were so sure was much like our own.
Unfortunately, we found no Martians and saw no traces of irrigation canals or signs of life at all. But the more we saw of Mars, the more we wanted to know.
Mariner 4 flew by Mars in July 1965. This was followed by Mariner 6 and 7 in 1969. The images sent back showed what appeared to be a geologically dead world. There was an abundance of craters much like the moon. It was also from these spacecraft that we learned that Mars’ polar caps were made of Carbon Dioxide ice instead of water ice.
In 1971, Mariner 9 flew by Mars and mapped the entire planet down to 1 km. These images brought a wealth of information and it soon become clear that Mars was indeed a complex planet. It was not, in fact, like the moon and merely composed of a crater strewn rocky surface. Mariner 9 revealed plains, canyons, drainage channels and even volcanoes. Mariner 9 evoked such enthusiasm that plans were begun for Mars Landers.
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In 1976, Viking 1 and 2 landed on the Martian surface. Viking orbiters mapped the planet down to 100 meters and refined landing site locations for the Landers. The Landers used a heat shield to leave orbit, then parachuted to the surface, using retro- rockets to further slow descent.
Viking 1 landed on an ancient lava flow Viking 2 landed 6 weeks later about 5000 km away The orbiters and Landers returned over 55,000 images. Over the next four years, over 4 million weather reports from the Martian surface were transmitted to Earth. The Landers studied the Martian rocks, which were found to be basaltic lava in composition.
Once the rover is deployed it will move along at about 2 inches per hour, controlled by ground crews. Messages to and from Mars take 10 minutes each way so there is always a lag in commands given and action taken. Rover will explore about a football field sized area within the next week.
After diet, if all is still well, Sojourner may expand its horizons and venture farther away- The Lander will act as a weather station and communications relay for the rover. The spacecraft still in orbit will image the Martian surface with a resolution of about 5 feet. Attempts will be made to locate the Viking landing sites of 21 years ago.