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Illustration of OSIRIS-REx spacecraft at Bennu.Lockheed Martin

A Canadian laser system destined to explore a distant asteroid that could one day threaten Earth has begun its long journey to deep space.

The system, proposed by researchers at York University and built by a collaboration of Toronto-area companies, is Canada's contribution to a NASA-led mission called OSIRIS-REx that will try to snatch a piece of a small Earth-crossing asteroid.

Scientists hope the mission will reveal clues to the early history of the solar system, as well as inform strategies for how to divert objects that end up on a collision course with our planet.

The Canadian component of the mission is known as OLA (short for OSIRIS-REx Laser Altimeter). Once in action, it will be essential for mapping the asteroid's irregular surface and helping mission scientists select a spot where the spacecraft can swoop down and grab a sample for analysis back on Earth.

Researchers working on OLA confirmed this week that their device has left Canada and is now at a Lockheed Martin facility in Denver, where the main OSIRIS-REx spacecraft is in the final stages of assembly and testing. The completed spacecraft is slated for launch next September. It is expected to rendezvous with Bennu, a half-kilometre-wide asteroid named after a mythical Egyptian bird, in August, 2018.

The integration of OLA into the OSIRIS-REx spacecraft marks a milestone in what has at times seemed a harrowing voyage through the vagaries of Canada's cash-strapped space program.

"There were many times when the challenges looked insurmountable," said Mike Daly, an associate professor at York and lead scientist on OLA.

Although Dr. Daly first envisioned OLA in 2008, it would take many years before the Harper government approved funding for it through the Canadian Space Agency. The final tranche that enabled OLA's construction was not released until July, 2014, leaving team members with less than 18 months and little margin for error to get the one-of-a-kind device built and tested.

Along the way, there was pressure to scale back the instrument, Dr. Daly said.

Ordinarily, a laser altimeter is a stationary device that uses laser light to measure the distance from an orbiting spacecraft to the surface below. After many orbits, this data can be assembled into a topographical map. What makes OLA different, and more ambitious, is the addition of a scanning mirror that allows the laser beam – pulsing at 10,000 times a per second – to create an accurate three-dimensional representation of an asteroid's surface with near-photographic speed.

This is important for OSIRIS-REx in two ways. First, it will provide detailed information on the overall size and shape of the asteroid to help scientists understand its history and structure. It will also help guide the spacecraft when it closes in to capture a precious sample.

While the sample will constitute only a handful of material – about 60 grams in total – its successful return to Earth, scheduled for 2023, would make it the largest single acquisition of extraterrestrial material since the moon landings of the 1970s.

Scientists are interested in asteroids such as Bennu because they were never incorporated into larger bodies and so are more representative of the raw material that was present billions of years ago, just when Earth and the other rocky planets were just forming.

"You're peering back to the very beginning of the solar system," said Christopher Herd, a professor at the University of Alberta who specializes in the analysis of meteorites.

Although Bennu does not pose an immediate threat, it has about a one-in-2,700 chance of colliding with Earth late in the next century, and it is representative of the kinds of objects that have peppered our planet over geologic time, sometimes with devastating consequences. Canada has significant expertise in meteorites, craters and other areas related to asteroid impacts, which makes it "absolutely crucial" for Canadian scientists to participate in missions such as like OSIRIS-REx, Dr. Herd added.

In this case, the cost of participation amounts to about $61-million over 15 years, the space agency said, including the cost of developing OLA, which was built in Brampton, Ont., by MacDonald, Dettwiler and Associates and Optech.

In exchange, about 4 per cent of the asteroid sample will belong to Canada.

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