We know what Mars looks like from Earth. When the sky is clear of light, clouds and pollution, it can be seen with the naked eye. It’s the red one, a lonely ruby among scattered diamonds, and often appears close to Jupiter even though their orbits are 550 million kilometres apart.
Zoom in, and Mars becomes more beautiful and more terrifying. It is not, as writers have imagined in the past, criss-crossed with canals and the deep canyons are unlikely to hide fleets of flying saucers primed to swarm down on humanity at a moment’s notice. Instead, it’s a desolate place of rocks, craters and giant mountains, one of which is a 27-kilometre high volcano. Most of the mountains are in the southern hemisphere, and a massive impact millions of years ago left much of the north a dusty basin. It’s a downhill walk to the north pole, should anyone get the chance.
The planet is red not because it is the angry eye of the god of war. Rather, it’s rusting: the dust that is everywhere on the surface is full of oxidised iron. Dry, dead and forbidding are common descriptions of Mars. The thin atmosphere is high in carbon dioxide and strong winds blow sand into dunes with incredible patterns. For a desert, it’s cold.
With an average temperature of -55C it had long been thought all the water was frozen at the poles, although there is abundant evidence Mars was once much wetter. Billions of years ago it might have resembled a planet closer to the one in visionary author Ray Bradbury’s imagination, with a thicker atmosphere, higher temperatures and flowing rivers and oceans. Some suspect there is a chance life began on Mars even before Earth’s amino acids got their act together.
Nasa announced last week water still flows in places, which comes after the discovery of organic material. Martian life may be microbes or algae instead of little green men, but after the curious case of space plankton growing outside the International Space Station, it would be foolish to underestimate life’s persistence. What awaits could be exciting for all mankind, or may only arouse the curiosity of a select group of boffins — we will only know from exploration.
Nothing has galvanised humanity’s interest in the universe in quite the same way as Neil Armstrong’s small step on the moon, but there have been other giant leaps in the decades since. Last week’s announcement of liquid water on Mars was soon followed by spectacular photographs of Pluto’s moon Charon, a lumpy and colourful rock with a violent past and a 1,600km-long canyon stretching like a belt to the north of the equator. These images are the latest from the New Horizons probe that has already redefined our understanding of Pluto and will venture further into the outer reaches of the solar system. Astronomers have discovered thousands of planets in systems near and far, and our knowledge of stars’ life cycles, nebulae and the quirks of quasars and pulsars is becoming incredibly complex.
But since landing on the moon in 1969, Mars has held the greatest appeal. Standing on the red planet is the next giant leap to make: it is the next closest and most conquerable part of space for whoever wants to invest the time and money. Nasa has a plan for the 2030s; SpaceX’s Elon Musk wants to go sooner.
There is already an earthly presence on Mars. The Curiosity rover continues its exploration 1,154 days after landing, long beyond its primary mission of lasting one Martian year. Like Pixar’s Wall-E, the car-sized robot will continue to work indefinitely and recently sent home a selfie for humanity to geek out over. It has also sent pictures of us.
We know what Earth looks like from Mars. The sky is clear of pollution, and when the sun sets our planet would look to the naked eye like an evening star. From 60 million kilometres away, Earth is a gentle blue, a sapphire twinned with the smaller gem of the moon.
Zoom in, and the familiar oceans and continents become clear. Look close enough and deserts, mountains and forests can be seen. There is enough fresh heat, water, carbon and oxygen for life, and from the rock of Mars or the vacuum of space this blue-green marble must seem like a marvel.
At night, the lights of cities glow but you have to be quite close before signs of humanity become visible.
Earth also has us: a curious species capable of great ingenuity, art, violence and compassion. Humans shoot, stab and bomb each other, yet we dedicate lifetimes to music and literature, to medicine and science. For all our petty squabbles, we are a species that dares to dream. Earth is a world of terror and beauty, unlike any other, but we were always meant to reach further.