Cape Town - A year before the word “selfie” was somewhat belatedly added to the Oxford Dictionaries, perhaps the most outlandish selfie had already been snapped – taken by Nasa’s rover Curiosity on the red planet of Mars.
The selfie – or in the words of Nasa scientists a “high-resolution self-portrait” – was beamed back to Earth in late October 2012, about two months after the rover touched down on the planet.
Mars, depending on where it and the Earth are positioned in their orbits, can be anywhere from 60 to 400 million kilometres away from Cape Canaveral Air Force Station in Florida, from where, in November 2011, a spacecraft carrying Curiosity launched on its mission of exploration.
On August 6, 2012, two years ago to the month, the exploration rover touched down successfully on the floor of what scientists have baptised the Gale Crater. Its landing was a delicate operation, to say the least.
The Mars Science Laboratory spacecraft, carrying the rover, had entered into the Martian atmosphere at a screaming 20 000km/h, six times as fast as the top speed of the Lockheed SR-71 “Blackbird”, the world’s fastest jet.
After breaching the atmosphere about 130km above Mars’s surface, it had 10 minutes to deposit its rover on the planet’s surface.
The spacecraft slowed itself by flying to the left and right in what are called S-curves, while a heat shield protected it from burning up from the more than 2 000ºC heat. This, together with atmospheric friction, slowed it down, but not enough.
Three minutes before touchdown and 11km above the surface, a parachute unfolded to put the brakes on.
Then, like something from a Neill Blomkamp sci-fi film, eight steerable “retrorockets” fired downwards to bring the craft to a near halt, positioning it above the Mars desert. Its descent had now slowed to just over a metre per second.
Next, like a rescue helicopter lowering someone on to a lifeboat, the hovering spacecraft gently let down the 900kg rover – about the weight of a smallish female adult black rhino – on to the surface attached to nylon cords.
At about 3pm (Martian time), the rover’s computer switched to “surface mode” after it felt ground beneath its wheels. The cords were severed and its mother craft blasted away to crash-land far from the rover.
Since landing, the rover has been exploring, roving the landscape at about 30m/h. The world’s slowest mammal, the three-toed sloth, would easily beat it in a 100m race.
The rover has studied the geology and environment in the Gale Crater by analysing samples it drilled from rocks or scooped from the ground with a mechanical arm.
Curiosity not only takes selfies, and does science. It also has its own twitter feed @MarsCuriosity, with 1.6 million followers.
It also has a cheeky sense of humour. It, or rather colleagues on Earth, tweeted recently: “Laser zapped this rock to see what was inside. (Hint: not nougat.)”
Nasa says the rover has already made significant discoveries.
Among these, it has found that ancient Mars could have had the right chemistry to support living microbes, after it found carbon, hydrogen, oxygen, phosphorus and sulphur, all ingredients necessary for life.
It has also photographed smooth and rounded rocks, which indicate they may have been formed in an ancient river bed.
The rover has been searching for signs of life by checking for methane, or as the folks as Nasa put it: “Curiosity has sniffed the Martian air.”
As living organisms produce methane, scientists believe the finding could hint at life, but Curiosity has found none yet.
The search continues.
The rover, which is powered by plutonium-238, was expected to last for at least one Mars year, or 687 earth days, on the red planet.
But if it doesn’t break down or get stuck, it could last far longer.