There is one place in the universe that grips the public imagination more than any other – our close neighbour Mars.
That is hardly surprising. For the so-called Red Planet resembles our own Earth in many ways. It is made of rock, it has an atmosphere and weather systems. Mars is much smaller, with a diameter of around 4,222 miles (6,795 km), but its day is just 40 minutes longer than ours and its axis is tilted by 25 degrees – a similar amount to Earth’s – giving it seasons like those we experience.
There is growing evidence, too, that reservoirs of water exist as ice at the martian south pole and that the planet was once covered with oceans. With all these ingredients, it is natural to wonder whether life ever existed on Mars – and if it might be found there even today!
The human race is determined to find out. Mars has been put under greater scrutiny than any other planet. A large flotilla of spaceships have traversed the gulf of space to reach it, some with more success than others. But a number of probes have gone into orbit, robot rovers have landed to explore the surface and still more missions are on their way or are being prepared.
Most excitingly of all, the world’s space agencies have set goals of putting men on Mars within the next few decades.
Animation of NASA’s latest Curiosity mission to Mars
Thanks to spaceprobes, we are learning more and more about what a dramatic world awaits the first explorers. They include the biggest volcano in solar system, the 16 mile (26 km) high Olympus Mons, plus Valles Marineris, a vast chasm 2,500 miles (4,000km long) that dwarfs the Earth’s own Grand Canyon.
We have known since 1965 that Mars is covered with craters from asteroid impacts. Surprisingly, recent monitoring of the surface shows that impacts are still happening today. But surface features are gradually eroded by the winds or covered by desert dust whipped up by martian whirlwinds. Bigger dust storms, caused by seasonal changes in temperature, can occasionally envelop the whole planet.
Mars represented the god of war for the Vikings, the Greeks and the Romans. In Assyria, it was known as the “Shedder of Blood”.
The surface area of Mars is around the same as the land area of Earth. Its red colour is due to oxidised iron minerals in the surface rocks – in other words rust!