Curiosity rover: all you need to know

On Monday 6 August, NASA will attempt to land its car-sized Curiosity rover on the surface of Mars, the latest mission to look for hints of Martian life. Read on for our comprehensive guide to this revolutionary rover…

What's Curiosity?

Curiosity is NASA’s latest Mars rover, also known as the Mars Science Laboratory. The rover was launched aboard a rocket last November, and it’s scheduled to land on the Martian surface on Monday 6 August. If all goes to plan, Curiosity’s nuclear power source will allow it to roam the rocky surface for at least one Martian year (687 Earth days).

The Curiosity rover during mobility testing inside the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory (credit: NASA/JPL-Caltech)  

Aren’t there already rovers on Mars?

There have been three successful Mars rovers so far, all managed by NASA and the Jet Propulsion Laboratory. Sojourner was the first rover to wander over the Martian surface in 1997, followed by Spirit and Opportunity in 2004. Opportunity is still going today, over 3,000 days after it first woke up on the Red Planet.

How does Curiosity differ from previous rovers?

Curiosity is NASA’s biggest and most advanced rover yet. It’s the size of a Mini Cooper - about twice the length of Spirit and Opportunity, and five times as heavy. Curiosity has to be this big to carry its 10 state-of-the-art science instruments, two of which are located inside the rover’s belly.

Comparing wheel sizes. Left-right: Sojourner, Spirit/Opportunity, and Curiosity (credit: NASA/JPL) 

How will it land?

The rover will enter the Martian atmosphere inside a capsule travelling at around 20,000km/h (over 12,000mph). A heat shield – the largest ever made – will protect the capsule during its initial descent, and then an enormous supersonic parachute will be deployed when the capsule is around 10km off the ground.

Here’s where things get hairy, though. Curiosity is too large and cumbersome to be landed using inflatable airbags like previous rovers, so NASA is going to attempt its most unconventional and audacious landing yet.

At an altitude of around 1.8km, a ‘sky crane’ holding the rover will drop away from the parachute. Then, when just 20m above the surface, the rover will be lowered using three nylon cables.

An artist's impression of the daring sky crane manoeuvre (credit: NASA/JPL-Caltech)    

This automatic landing process – NASA’s ‘seven minutes of terror’ – is likely to be the mission’s make-or-break moment. NASA will be praying that Curiosity doesn’t go the way of the British Beagle 2 lander, which famously disappeared without trace whilst en route to Mars in 2003.

Where will it land?

Curiosity’s target landing site is Gale Crater – a 150km-wide divot in the Martian surface. In the centre of this crater is a giant 5km-high mountain, providing a thick pile of exposed sedimentary rocks. These rocks, deposited over millions of years, will allow the rover to look back in time at the planet’s ancient, watery past.

The target landing site for Curiosity is marked as an ellipse on this image of the Gale Crater. The mountain in the centre of the crater is Aeolis Mons, also known as Mount Sharp (credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS) 

What will Curiosity be doing?

Curiosity is equipped with an onboard laboratory for analysing the Martian rocks, soil and atmosphere. An infrared laser will zap rocks from a distance, allowing a spectrometer to identify their chemical compositions. The rover is also equipped with a ‘Sample Analysis at Mars’ (SAM) system, which heats samples up to about 1000°C in order to look for the chemical signatures of organic molecules and compounds – the carbon-based building blocks of life.

Curiosity uses its ChemCam laser instrument to zap Martian rock (credit: NASA/JPL-Caltech/LANL/J.-L. Lacour/CEA)

Finding organic compounds on Mars would be a major breakthrough - a sign that the planet could have supported microbial life at some point in its past, or even in the present day.

First though, Curiosity has to survive its seven minutes of terror on Sunday night (early Monday morning UK time). Back on Earth, 250 million kilometres away, the mission controllers will only be able to watch and wait.

Curiosity is scheduled to touch down on Mars at 06:31 BST (05:31 GMT) on Monday 6 August. Set your alarm clocks! 

Further reading 

Check out the current issue of Focus for an in-depth article about Curiosity's earthbound twin, Scarecrow.