With Curiosity safely landed on Mars, the real work begins. And this is where Canadian expertise comes in.

Designed by a University of Guelph professor, funded by the Canadian Space Agency and built by Canada's MacDonald Dettwiler and Associates Ltd., the Alpha Particle X-ray Spectrometer is a key part of gleaning information on Mars's ancient history, and maybe the secrets to life on other planets.

NASA is hoping its $2.5-billion gambit to send its rover to Mars will yield valuable information on a planet that may likely have once been hospitable to living creatures. Scientists want to know whether that's the case, what conditions supported life and what happened to make Mars the apparently arid, acidic and inhospitable planet it is today.

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So for the next three months, University of Guelph Professor Ralf Gellert will be shuttling between Guelph and the Jet Propulsion Laboratories in Pasadena, Calif. As principal investigator behind the spectrometer, it will be largely his job to ensure the high-tech piece of equipment is working and to see what kind of information it yields.

The APXS is about the size of a pop can and is attached to Curiosity's arm. But its small size is misleading: This device is designed to determine the chemical composition of rocks and soil. If that doesn't sound terribly exciting, consider this: The bits of rock and dirt Curiosity finds in its sojourn on the red planet will tell us whether there was life on Mars, when there was life on Mars and what happened afterwards.

Ultimately, scientists are looking for clay minerals. Clay is formed when the atmosphere is warm and wet enough to support life. Even if those conditions change, as the clay sets underneath multiple layers of rock over millions of years, it retains the same minerals that identified it before.

"That's top on the list," Prof. Gellert said, "to simply find these clay and then put it into context."

Curiosity has both a camera and a laser sensor on the lookout for anything interesting or out of the ordinary. Once the rover ambles over and takes a closer look, its arm is equipped with a drill and shovel to extract bits of whatever catches its attention. The Alpha Particle X-ray Spectrometer does a preliminary analysis: What's in here? Does it differ from other rocks in the area?

If it does, the rover packages the sample and puts it in its belly, where more instruments wait for further analysis.

"All the instruments together put a piece of the puzzle table," Prof. Gellert said. "You put it together, and scientists figure out what happened on this place 3.5 billion years ago."

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The whole process can take several days, Prof. Gellert says. And it's hard work, even for a plutonium- and lithium-power robot.

"So it's a balance: How do you get the biggest scientific bang for your buck? ... You have to watch and look for the interesting spots; you cannot simply take the nearest sample and hope there's something you can see," he said. "These instruments are so complex, and so energy-hungry."

For Curiosity's first few days on Mars, scientists are taking it slow as they check to ensure everything's working as it should. In the spectrometer's case, this means analyzing a rock brought from earth, to check something mundane and ensure its readings are still sound.

Eventually, the rover will head over to Mount Sharp – a 5-kilometre-high crag rising up out of the crater the rover's now in. If all goes well, the mountain will contain layers of rock detailing the planet's geological history.

For the next three months, Prof. Gellert will spend a couple weeks at a time in California, on Mars time, before returning briefly to Guelph and then back again.

It was a thrill to watch the rover land Sunday night, he said. But the fun is just beginning.

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"Being a scientist on such a mission is exciting science. But it's [also] fun to do this detective work on another planet."