Curiosity: The Complete Mission in Real-Time 3D
August 6, 2012
Experience the Curiosity mission of August 6, 2012: follow the spacecraft's real journey from Earth to Mars, down to the Gale Crater landing, in a real-time 3D reconstruction.
It's November 26, 2011.
At Cape Canaveral, Florida, an Atlas V rocket is about to leave for Mars.
It carries Curiosity, a 900-kilo rover the size of a small car.
Its mission: to find out whether Mars could ever have hosted life.
Total cost of the mission: 2.5 billion dollars.
Mars comes within reach only every 26 months. The 2011 window has just opened.
Liftoff. A Russian engine and four solid boosters lift 530 tonnes.
All that for 3.9 tonnes: the rover, its capsule and the stage that will fly it to Mars.
At 48 kilometres up, the four spent boosters fall away.
The fairing opens: a 4.5-metre capsule needed the widest one the Atlas has.
The first stage drops away. The Centaur upper stage lights for seven minutes.
Engine off: in orbit at 28,000 km/h, it will coast for twenty minutes.
It is not aiming at Mars, but at where Mars will be in eight months.
Earth already races around the Sun at 107,000 km/h, and Curiosity with it.
To climb out to the orbit of Mars, it only needs to add 12,000 km/h.
Over Africa, the Centaur relights for eight minutes.
Engine off at 40,000 km/h: Earth can no longer hold it back.
Curiosity parts from the Centaur and carries on alone.
To reach Mars, it goes almost halfway round the Sun: 567 million km.
As it climbs away from the Sun, it slows, from 121,000 to 76,000 km/h.
Mars, moving faster, catches it up at the point aimed for eight months ago.
Mars is still only a small red disc, 240,000 kilometres away.
No solar panels: the rover lives off the heat of 4.8 kilos of plutonium oxide.
On board, ten instruments, including a laser that vaporises rock seven metres away.
On the way, it measured the radiation an astronaut would take on this trip.
Its target: Gale Crater, 154 kilometres wide, perhaps an ancient lake.
At its centre, Mount Sharp, 5 km high: its layers tell the story of Mars.
Mars pulls it in: it is falling at 13,000 km/h, and speeding up.
A radio signal takes 14 minutes to get from here to Earth.
When word of entry reaches Earth, the rover will have been down, or lost, for seven minutes.
The cruise stage is cast off. Only the capsule and its heat shield remain.
Atmospheric entry at 21,000 km/h. Seven minutes left to stop.
In front of the heat shield, compressed air turns into glowing plasma.
Its thrusters roll it from one side to the other: it is correcting its course.
An off-centre weight makes it fly tilted: the air lifts it like a wing.
A first at Mars: the capsule steers itself toward a zone 20 km by 7.
Parachute! It opens at 1,500 km/h: the air has already taken 93% of the speed.
Even under the parachute, it is still falling at over 300 km/h: the air of Mars is too thin.
The heat shield drops away: inside the shell, the rover appears, folded under its descent stage.
In 1997, Pathfinder landed wrapped in airbags, bouncing some fifteen times.
Spirit and Opportunity did the same in 2004. But each of those rovers weighed only 185 kilos.
Curiosity weighs 900: it would have needed giant airbags, far too heavy to carry.
That left a platform on legs, like Viking in 1976, with ramps to drive down.
But with so heavy a rover perched so high, it would tip over on the slightest rock.
And its engines, firing close to the ground, would blast dust and stones onto the rover.
Hence the idea they chose: keep the engines up high, and set the rover down on its own wheels.
The rover and its descent stage drop from the capsule and light eight engines.
First move: get clear, so the shell and the parachute do not fall back on top of it.
In half a minute, the engines brake it from 280 km/h to a walking pace.
Twenty metres up, the rover lets go and descends on the end of three 7.5-metre cables.
Touchdown, 6 August 2012. Cables cut, the descent stage flies off to crash further away.
It crashes 600 metres away: far enough for its debris to spare the rover.
Its first drilled rock reveals it: this crater once held a freshwater lake.
It will also find organic molecules here, building blocks of the chemistry of life.
So Mars could have hosted life. What remains to learn is whether it did.
Planned for two years, it is still driving, climbing Mount Sharp layer by layer.