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Artist’s impression of Rosetta as it flies by asteroid Steins. (ESA, image by C.Carreau)
Artist’s impression of Rosetta as it flies by asteroid Steins. (ESA, image by C.Carreau)

SPACE

New solar system missions will go where we’ve never gone before Add to ...

When astronauts set foot on the moon 45 years ago this week, those who watched on live television witnessed not just a spectacular feat of engineering but a landscape utterly unlike anything on Earth. Chasing that thrill – of seeing other worlds for the first time – has been a key part of space exploration ever since.

“People love it when we go somewhere new,” says Alan Stern, a planetary scientist at Boulder’s Southwest Research Institute.

That can be a challenge, however, as there are fewer “firsts” left to explore. The International Space Station is just a short step from home, and places like the moon and Mars have been visited multiple times by robot explorers. But Dr. Stern is about to change that: He’s the lead scientist on a mission called New Horizons, which is set to unveil the biggest piece of unexplored real estate in the solar system – Pluto. And his is just one of several upcoming efforts that promise to show us new terrain, off the well-beaten path and out of Earth’s orbit.

The impact on science will be significant: Every new mission tells its own story about the origins of the solar system, and, in doing so, reveals something about our own place in the cosmos. But these missions will also revive a previous era in space history, showing us what we’ve never seen before.

The Pluto encounter is set for July, 2015, but first up on the view screen is another mission called Rosetta. Launched by the European Space Agency in 2004, the spacecraft is less than three weeks from reaching comet Churyumov-Gerasimenko, a four-kilometre-wide pile of ice and dust named after the two Soviet-era astronomers who discovered it.

Other spacecraft have approached comets before and captured fleeting glimpses, but Rosetta will be the first mission to orbit one. In November, it will also drop a 100-kilogram lander onto the comet’s frozen crust.

It’s a tall order. The comet is steadily vapourizing, so the lander will have to find a spot to latch onto that’s not disintegrating under it. Once on the surface the probe may even see the comet changing in real time, says Dr. Stern, who is also on the science team for Rosetta.“It’s much more rapidly evolving than any object we’ve ever been to.”

This week, photos from Rosetta revealed the mission’s first big surprise: The comet looks like it’s made of two distinct sections, one rounder and one flatter, stuck together in a way that one scientist on Twitter compared to a rubber duckie. The weird shape could pose an additional challenge for the lander, which will have to cope with the comet’s small but complex gravitational field as it tries to touch down.

The payoff is a better understanding of the raw material that larger planets are made of, and a first “in situ” look at what happens on a comet’s surface as it warms in the sun.

Other journeys to small places have a similar goal, including OSIRIS-Rex, a NASA-led mission to bring back a piece of a nearby asteroid called Bennu. This week, the Canadian Space Agency awarded the contract to build Canada’s share of the mission, a laser altimeter (a.k.a. lidar) that will map the asteroid in three dimensions and help scientists assess where to move in and grab a piece once the spacecraft arrives in late 2018. In exchange, a share of whatever OSIRIS-Rex returns in 2023 will end up in Canadian labs.

It’s not the first time such a mission has been attempted. Japan did it in 2005. But they only managed to retrieve a few grains. The mission to Bennu will mark the first time a spacecraft has made contact with a carbon-rich asteroid – precisely the kind of object that may have once carried the building blocks of life throughout the solar system.

“It will give us insights into what kinds of organic molecules might have seeded Earth before life evolved,” says Ed Cloutis, a planetary scientist at the University of Winnipeg who will be among the researchers trying to find the most interesting spot to grab a sample on the asteroid.

Collectively, asteroids like Bennu – of which there are hundreds of thousands – form a part of the solar system that Canada is especially well-qualified to explore: The lidar that will be used on OSIRIS-REx is a spinoff of one previously built for a Mars lander; the technology that went into the Canadarm could be repurposed for grappling with small asteroids.

But there’s limited support from the federal government, so Canadian researchers have to find other ways to leverage their expertise and get a piece of the action. For example, Dr. Cloutis is gearing up for some big revelations next February as an outside collaborator on NASA’s Dawn mission, which will make the first visit to Ceres, the largest asteroid.

With a diameter of 950 kilometres Ceres is comparable in size to Quebec, but it remains too distant for astronomers to see in any detail from Earth. It’s physical nature is a mystery. Especially tantalizing are recent hints that Ceres is releasing trace amounts of water vapour from a hidden, internal source.

But Pluto remains the big prize in this latest exploration boom.

With its own atmosphere, one large and four smaller moons, Pluto presents a rich trove of new information. Its complex formational history will likely have something to say about our own Earth-Moon system. And with the possibility of internal heat and a subterranean ocean, Pluto cannot be ruled out as a haven for alien life.

Pluto was the solar system’s ninth planet until its demotion by the International Astronomical Union into a new class known as “dwarf planet.” But whether it is an “official” planet or not, it’s a novel world and the gateway to an entirely different part of the solar system, full of thousands of small icy bodies.

After it leaves Pluto, New Horizons is meant to be directed at another of these bodies. The trouble is that a suitable target has not yet been found and time is tight.

This month astronomers have turned to the Hubble Space Telescope in a final attempt to sift out some appropriate targets for New Horizons. “It’s a real challenge … you’re looking at the gaps between the stars for these faint moving things,” says JJ Kavelaars, an astronomer with the National Research Council, based in Victoria, B.C., who is participating in the Hubble search.

Meanwhile, excitement continues to build around the Pluto visit. By early next year, the probe will have crossed to the point where it can see Pluto better than any telescope – a thrill we should do our best to savour, says Dr. Stern.

“It’s rare that we get a chance to go somewhere and expect to be nothing but surprised.”

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