NASA asteroid mission hopes to learn origins of life on Earth

NASA will send a spacecraft barrelling towards an asteroid, in a seven-year round trip launching Thursday to scoop up and bring back samples from the rock's surface.

This will be the organization's first send-and-return mission to an asteroid, and it has an ambitious goal: to discover the origins of life on Earth.

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The OSIRIS-REx — or the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer — takes off Thursday night from Cape Canaveral in Florida.

It will take two years to get to its destination: the asteroid Bennu.

The spherical asteroid is about 500 metres in diameter and has an orbit similar to Earth's. Its rotation makes its day last about four hours, which is slow enough for the craft to execute its mission.

The asteroid is chock full of carbon, one of the key components of life on Earth, and NASA says it hasn't changed much over the past 4.5 billion years that it's been around.

"We're going to Bennu because it's a time capsule from the earliest stages of solar system formation," said Dante Lauretta, who is leading the mission.

When our solar system was beginning to form, small rocky bodies swirling around were studded with water and organic materials, "key compounds that we believe may have led to the habitability of our planet and even to the origin of life on Earth."

Another of the $1-billion US mission's goal is to study whether the asteroid could ever collide with Earth. Bennu has been deemed a Potentially Hazardous Asteroid, but the risk is low: scientists estimate there is a one-in-2,700 chance that it could hit Earth sometime between the years 2175 and 2199.

'Touch and go'

Once it gets to Bennu, OSIRIS-REx will extend a robotic arm to do a "touch and go." It will touch down for a few seconds on the surface of the asteroid, release a blast of nitrogen gas, and then collect the material that gets stirred up.

The team has three chances to collect at least two ounces, or 60 grams, of material.

But why such a short visit?

Early on, Lauretta said the team had considered landing for a longer period of time, but they quickly decided against that idea.

"There's just so much unknown about the surface of the asteroid that the idea that you could develop a harpoon or anchoring system or use hold-down thrusters to keep you on the surface was deemed too high a risk for the program," he said.

Lauretta added he feels confident about this decision, especially after seeing what happened with the European Space Agency's Philae lander. The Philae landed on a comet, but bounced twice, making it difficult for the team behind it to establish a connection to the probe.

"It just shows me that that was the right design solution," he said.

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'Darker than charcoal'

The asteroid is basically unknown territory, and it's "darker than charcoal," said Dr. Ed Cloutis of the University of Winnipeg.

Cloutis is part of the Canadian science team working on the mission, to help NASA decide where to touch down.

By using various instruments on board, including a special laser made by the Canadian Space Agency and Michael Daly of Toronto's York University, they'll scan the asteroid to see where it's safe to land, and where there might be "rubble" to pick up, said Cloutis.

"The main thing we're interested in looking for are organic molecules or carbon-bearing compounds because there's a thought that these kinds of materials were required for life to have originated on the Earth."

Jitters from SpaceX explosion?

Any mission to space is expensive and fraught with complications. Just last week, a SpaceX rocket exploded during a routine test firing.

But it doesn't seem to have rattled the OSIRIS-REx team.

"It was a stark reminder to me and this whole team about the risks that we face in this business," said Lauretta.

He said because of that, they checked all their equipment to ensure everything was in order.

If all goes as planned, the capsule containing samples from Bennu will be jettisoned from the returning Osiris-Rex spacecraft on Sept. 24, 2023, for a parachute descent and landing at the U.S. Air Force Utah Test and Training Range.

"It really is a great adventure ... we are bringing back scientific treasure," Lauretta said.