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NASA Jet Propulsion Laboratory California Institute of Technology

If the Mars rover Curiosity ever brushed up against its space-exploring cousins, Spirit and Opportunity, on the Red Planet, it would loom over its smaller six-wheeled relations.

Curiosity is five times heavier, twice as long and has twice the number of scientific tools. It will carry a payload 10 times as massive as its planet-cruising forebears.

Curiosity

Mass: 899 kilograms

Height: 2.2 metres

Width: 2.7 metres

Length: 3 metres

Program cost: $2.5 billion

"It’s not your father’s rover," Doug McCuistion, director of NASA's Mars program, said in a media briefing earlier this month.

"It’s truly the largest and most complex piece of equipment ever placed on the surface of another planet, truly a wonder in engineering."

Curiosity, otherwise known as the Mars Science Laboratory (MSL), is due to blast off from Cape Canaveral, Fla., on Saturday aboard an Atlas rocket on an 8½-month flight.

Along with carrying 10 very high-tech scientific instruments (one made in Canada), Curiosity takes with it the hopes and dreams of scientists trying to make a giant leap in the understanding of Mars.

"It bridges the gap from the past decade scientifically to the next decade, from understanding the planet as being warmer and wetter than we had previously believed, to the next decade to try to understand if it was ever habitable," McCuistion said.

'Not a life-detection mission'

That’s not to say anyone is expecting to find definitive evidence of little green men or any other type of creature — "it’s not a life-detection mission," McCuistion cautioned.

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Technicians at Kennedy's Payload Hazardous Servicing Facility at Cape Canaveral, Fla., put the instrument mast and science boom on Curiosity through a series of deployment tests. (Courtesy NASA/Frankie Martin)

But maybe, just maybe, there are signs that the planet could have supported microbial life, and Curiosity is decked out to try to find evidence of that.

"What really dominates this rover is that it has the ability to sample rocks and soils on Mars for the first time," Ashwin Vasavada, NASA deputy project scientist for MSL, told the media briefing.

When Spirit and Opportunity landed on Mars in 2004, each carried with it five scientific instruments weighing a total of five kilograms. Curiosity has 10 instruments weighing a total of 75 kilograms.

"We have ever-increasing payloads. We've got more accurate landing capabilities. We've got longer live systems on the surface with nuclear power and we have state-of-the-art instruments aboard," McCuistion said.

"These are also techniques that are necessary as we move towards the ultimate goal of putting humans on the surface of Mars."

But first, Curiosity has to get there.

And that meant finding a new way to get a rover about the size of small car — sort of like a Mini Cooper — off the launch pad for a 570-million-kilometre flight that ends with landing safely in Gale Crater.

Airbags, as were used to lower the lighter Spirit and Opportunity onto the Martian surface, just wouldn't do the trick.

Skycrane and tethers

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This artist's concept shows the sky crane manoeuvre during the descent of NASA's Curiosity rover to the Martian surface. (Courtesy NASA/JPL-Caltech)

Reverse rockets will slow Curiosity down during its descent and the rover will be lowered from a skycrane and a series of tethers attached to an ejection capsule.

On the surface of Mars, Curiosity will have features that will give it a considerable leg-up on the abilities of Spirit, which last communicated with Earth on March 22, 2010, and Opportunity, which is still sending back data.

Because Curiosity is taller (2.2 metres vs. the 1.5-metre height for Spirit and Opportunity ), a camera mounted on top will provide the opportunity for scientists to see further ahead and make for better navigation. Curiosity’s aluminum wheels are twice as big, and have curving titanium spokes that offer springy support.

As well, its robotic arm is 2.1 metres long, more than twice the 0.8-metre length of the arm on the older rovers.

The computing power on Curiosity has also been given a considerable boost. It has has two main computers and will use one at a time, with the other as backup. There is eight times as much flash memory on Curiosity as on Spirit and Opportunity.

Curiosity also has a radiation detector that is designed to give scientists a better sense of radiation levels on the Red Planet, something that has never been fully assessed and is considered important in planning for possible human exploration.

Canada's contribution — the alpha particle X-ray spectrometer — is also a new and improved version of the APXS used on the older rovers to identify chemical elements in rock and soil.

While all Curiosity’s instruments and procedures have been subjected to as much testing as possible, scientists still know there are risks with such a mission.

"There are always going to be surprises," Pete Theisinger, MSL project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif., told the media briefing.

Those same scientists will just be hoping the ingenuity that helped design Curiosity will be equally able to get them out of any difficulty that might arise.