It now seems that the atmosphere on Mars is thinner than on Earth, and therefore unable to support life as we know , the planet does share many characteristics with our own. Its surface is rocky like ours, days are almost the same length, and it has four distinct seasons. It also has winds, clouds and high mountains with volcanoes, one of is three times as high as Everest. Huge cracks on the planets surface suggest there once channels, hundreds of miles wide and hundreds of feet deep, and water is thought to lie under the planet's crust.

However, there are some notable differences in Mars is smaller than Earth, much further from the Sun, and as a consequence, has far lower temperatures. Also, years are twice as long, and it. has two moons. Probably the most significant difference is that spacesuits it is impossible to breathe, but scientists are now developing schemes to give the planet a breathable atmosphere.

Scientists believe that Mars was not always like it is today. It is thought that several thousand million years ago it was warm and lush, probably with a thick atmosphere. Today. Mars appears to be a lifeless desert with nothing red sand, rock and rubble. However, its crust contains the six elements essential to life: hydrogen, oxygen, carbon, nitrogen, phosphorous and sulphur.