A mission to land Nasa’s Curiosity rover on Mars will hinge on just seven minutes of terror as it descends to the red planet’s surface.
It has taken nine years and more than £1.5 billion to set it on its journey to Mars, but the fate of the most advanced space exploration rover ever built will be determined in just seven minutes when it finally reaches the red planet.
Engineers and scientists will face a tense wait in little over a week’s time when Nasa’s Mars Science Laboratory rover, called Curiosity, begins its descent towards the surface of Mars at 13,200 miles per hour in a landing that has been nicknamed “seven minutes of terror”.
Nasa has developed an entirely new landing system to get the van-sized wheeled robot, the largest ever sent to another planet, on to the Martian surface – it will be lowered the last 20 feet to the ground from a hovering spacecraft known as a “sky crane”.
If that fails, the exploration of the Mars and the search for signs that the planet once supported life will come to a stop for at least five years and – in the current financial climate – could permanently set back Nasa’s ambitions to send humans to the red planet.
Hanging in the balance are the careers of thousands of scientists from around the world who have been anticipating at least two years of new data to pour over as the rover explores the Martian surface searching for signs of life.
Dr Stephen Lewis, a senior lecturer at the Open University who is a member of the entry, descent and landing team for the Curiosity mission, said: “A mission like this probably only comes along once in a lifetime; there are going to be a lot of nervous people keeping their fingers crossed next Sunday.”
With an atmosphere up to 200 times thinner than the Earth’s and with just a third of its gravity, landing a one ton rover on Mars presents unique challenges as a parachute will not slow the spacecraft down enough to land safely.
Over the next week Dr Lewis and his fellow scientists will be intently studying the atmosphere and weather above the landing site in the hope of predicting the conditions the lander will face when it arrives, so it can be prepared for the final descent.
Curiosity will have travelled 352 million miles since it was launched in November last year by the time it reaches the edge of the Martian atmosphere. From there it will take just seven minutes to reach the ground.
The entry capsule will enter Mars’ atmosphere 81 miles above the surface, slowing down as air resistance builds, causing its heat shield to reach temperatures of more than 3,800 degrees F as it descends.
Around seven miles above the surface, a 51 feet wide parachute will deploy, slowing it to 180 miles per hour until it is just mile above, when the parachute and outer capsule will be detached entirely from the sky crane inside.
Booster rockets on the sky crane will then fire, slowing it to just 1.7 miles per hour while on board radar and computers will steer it towards the landing zone.
The rover will finally be lowered 20 feet from the crane on nylon cords to set it down gently on the surface. The sky crane will then detach and fly away.
However, with more than 154 million miles of space separating Mars from the Earth, it will take 14 minutes for signals from the spacecraft to reach the scientists back on Earth. It would take another 14 to send any instructions to the rover.
It means the rover will have to control the landing by itself using on-board computers. By the time Nasa’s mission control hears that it has entered the Martian atmosphere, the rover will either be safely on the ground, or it will have been smashed to pieces in the descent.
Tom Rivellini, an engineer at Nasa’s Jet Propulsion Laboratory who worked on the new landing system, said: “The entry, descent and landing is also known as seven minutes of terror.
“We have to get from the top of the atmosphere to the surface of Mars, going from 13,000 miles per hour to zero, in perfect sequence, perfect choreography, and perfect timing. If any one thing does not go right, it is game over.”
Although it has never used a “sky crane” system to land a vehicle on another planet before, Nasa chose to use it to touch down its most expensive ever planetary rover on Mars, to enable it to land with greater accuracy in areas never before explored.
It is a big gamble. Of the 17 missions that have aimed to land on Mars since the first by the USSR in 1971, 10 have ended in failure.
If successful, Curiosity has a suite of advanced scientific instruments on board to analysing the planet’s rock, soil and atmosphere for clues about how wet the planet was in the past, whether it supported life, and what led to it becoming the barren red desert it now is.
A robotic arm on the rover with a drill and scoop will allow it to delve down into the rock and soil further than ever before.
Dr John Grunsfeld, associate administrator for Nasa’s science mission directorate, said: “The Curiosity landing is the hardest robotic mission ever attempted by Nasa.
“But it holds the potential to look for evidence of habitable environments if they existed on Mars in the distant past. It has the capacity to discover the building blocks of life if it ever existed on Mars.
“It is phenomenal that we have a rover that is this close to helping us answer these questions.”
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