MONTREAL - The iconic Canadarm is expected to play a key role in the coming days in what's being described as another historic step in space exploration.

But the mission is not without risks.

The giant arm on the International Space Station will be used to grab the so-called "Dragon" capsule -- the first privately built spacecraft to visit the orbiting space lab.

The unmanned Dragon launched at 3:44 a.m. ET Tuesday from Florida atop a Falcon 9 rocket built by California-based Space Exploration Technologies, better known as "SpaceX". The Dragon is expected to dock with the station in a few days.

Canadarm2 will perform a "cosmic catch" when the space capsule comes within eight to 10 metres of the station.

MacDonald, Dettwiler and Associates (MDA) built the space station's Canadarm2, and vice-president Paul Cooper welcomed the private-sector involvement.

"I think the test flight of SpaceX actually is one of the first steps toward having good old-fashioned competition to create value in space activities," he told The Canadian Press

Cooper stressed the space station, which is the size of a football field, must keep its distance from any remotely controlled vessels that bring up supplies.

"You wouldn't want to have any opportunity for there to be a collision," he said.

"So the easiest way for that to be avoided is to have a plan in which the approach vehicle actually stops before it even touches the space station."

MDA's Dextre, a two-armed, $200-million robot that is also on the space station, will be hooked up to the robotic arm and its cameras will be used to inspect the capsule.

The space capsule will then be docked to the station and the food and supplies on board will be unloaded.

The cargo also reportedly includes the ashes of 308 space enthusiasts, including those of James Doohan of Star Trek fame.

The Vancouver native who portrayed chief engineer Montgomery "Scotty" Scott on the original Star Trek television series died in 2005 at the age of 85.

The families of 308 people have paid about $3,000 for the privilege of having the remains of their loved ones sent into space. The ashes also include those of Mercury astronaut Gordon Cooper, who died in 2004.

The Dragon capsule will remain docked for 18 days in the first of many planned commercial space trips to resupply astronauts now living on the station.

Pierre Jean, the director of space exploration operations at the Canadian Space Agency, says the agency has been working closely with SpaceX.

"The Canadarm2 will be capturing its third free-flying vehicle, (but) it's a brand new vehicle for us," he said.

"We're optimistic that the mission will be smooth.

"SpaceX had put a lot of energy and a lot of money into this development and they've done everything they feel is necessary for their vehicle to be safe."

Jean added that the docking operation could be aborted if there are any safety issues.

In the past, the robotic arm has been used successfully twice to capture a Japanese supply vehicle.

Jean also pointed out that the Dragon is unique compared with previous Japanese as well as Russian supply vehicles which burned up in the atmosphere once released by the Canadarm.

"The SpaceX Dragon will have the ability to return back to Earth and to take cargo back down with it," he said. "That's introducing a new capability to the space station."

The goal is to eventually use a more advanced version of the Dragon to ferry up -- not just supplies -- but astronauts as well.

Since the retirement of the American shuttle fleet last year, NASA has turned to the private sector to develop space transportation systems.

The U.S. and other space agencies have been switching their focus on space travel beyond low Earth orbit. They are now studying ways of travelling to asteroids and to Mars.

In the meantime, astronauts continue to hitch a ride up to the space station on Russian Soyuz capsules where one seat costs a hefty US$62 million.

Among them is astronaut Chris Hadfield, who is scheduled to begin a six-month visit in late 2012.

He will also become the first Canadian to take command of the space station during his stay.

Canada has bartered its way up to the space station and hasn't had to pay anything to get seats on the American and Russian shuttles.

Meantime, Orbital Sciences, another U.S. company based in Virginia, is continuing to develop a supply vessel. Ottawa-based Neptec is working with the firm to provide docking sensors on its "Cygnus" space capsule.

Neptec made the laser-camera system used to inspect for damage on the exterior of the U.S. space shuttles while in flight.

CEO Iain Christie says he isn't jealous that SpaceX will beat Orbital to the space station.

"We are excited, as everyone in the space exploration community is, to see the inauguration of commercial resupply of the ISS," he said in a statement.

"But unfortunately, we are just spectators on this one."