A group of Canadian scientists is awaiting delivery of an outer space postcard from the past.

On Sept. 24, seven years after it blasted off from its Florida launch pad, NASAB次元官网网址檚 OSIRIS-REx spacecraft is expected to drop a capsule into the EarthB次元官网网址檚 atmosphere containing matter plucked from the surface of an asteroid dating from the early history of the solar system.

B次元官网网址淚B次元官网网址檝e never worked with extraterrestrial material,B次元官网网址� said Dominique Weis, a geoscientist at the University of British Columbia, whoB次元官网网址檚 in line to get a tiny sample.

B次元官网网址淚B次元官网网址檓 perfectly excited.B次元官网网址�

The material comes from Bennu, previously known as near-Earth object 101955, a frozen chunk of rock about 500 metres across and roughly 450,000 kilometres from Earth. OSIRIS-REx has orbited within a couple hundred metres of its surface, scooped up a shovelful of it and is on its way home to drop off the package of whatever it found.

A Canadian-built set of lasers helped guide OSIRIS to its destination and produced a relief map of Bennu accurate to within a couple centimetres of height.

B次元官网网址淚n six weeks, we took data that provided the most detailed asteroid model ever,B次元官网网址� said Michael Daly of York UniversityB次元官网网址檚 Centre for Research in Earth and Space Science, who headed the team that designed the lasers. B次元官网网址淵ou could see fractures and details in the rocks.

B次元官网网址淲eB次元官网网址檙e very proud of that.B次元官网网址�

Bennu was chosen for several reasons.

ItB次元官网网址檚 a doable distance. ItB次元官网网址檚 large enough for a spacecraft to orbit B次元官网网址� although OSIRIS set a record for the smallest orbit yet. And itB次元官网网址檚 considered B次元官网网址減rimitive,B次元官网网址� relatively unmodified since its origin billions of years ago.

That makes it a window into the early history of the solar system, said Weis.

B次元官网网址淭he idea is to go as far back in time as possible,B次元官网网址� she said.

Alan Hildebrand, a University of Calgary geoscientist, who is also to receive a Bennu bit, said that sheds light on EarthB次元官网网址檚 history as well.

B次元官网网址淭he Earth was formed by asteroids getting together,B次元官网网址� he said. B次元官网网址淪tudying asteroids helps you understand the origins of our planet.B次元官网网址�

Bennu can help answer questions such as how the early crust of the Earth formed, he said.

As well, Bennu is from an area of space that cooled off well before the central part of what became the solar system, B次元官网网址渇reezingB次元官网网址� those materials before they were altered by heat. And grabbing samples directly from the asteroidB次元官网网址檚 surface means scientists donB次元官网网址檛 have to account for the effects that flying through EarthB次元官网网址檚 atmosphere has on meteorites.

B次元官网网址淭he rocks comprising Bennu are from an older part of the solar system,B次元官网网址� Hildebrand said. B次元官网网址淲e get to see the whole suite (of constituents) without the atmospheric filter.B次元官网网址�

Finally, Bennu is thought to be rich in carbon. That could mean it contains organic compounds B次元官网网址� those composed of carbon, hydrogen, oxygen and nitrogen.

Some scientists think those compounds could offer clues to how life began on Earth B次元官网网址� although Hildebrand points out planets such as Mars and Venus are also showered with such material and donB次元官网网址檛 appear to host life.

BennuB次元官网网址檚 bits wonB次元官网网址檛 be the first asteroid pieces brought to Earth. Two previous Japanese missions have brought back samples.

But the yield from OSIRIS is expected to be much larger. The Hayabusa missions brought back about five grams of asteroid B次元官网网址� OSIRISB次元官网网址檚 yield is estimated at anywhere between 60 grams and two kilograms.

B次元官网网址淲eB次元官网网址檒l have more material to do more things,B次元官网网址� Hildebrand said.

Canadian scientists are getting samples of Bennu because of CanadaB次元官网网址檚 $61-million investment in OSIRIS. But before any lab starts to warm up its mass spectrometer, NASA makes sure recipients know how to handle the precious grains, practising protocols on fragments of meteorites.

B次元官网网址淲e rehearse and rehearse and rehearse and rehearse some more,B次元官网网址� said Weis. B次元官网网址淲e are working on the methods to be as sensitive and precise as possible.B次元官网网址�

OSIRIS has already led to the publication of dozens of research papers. The arrival of its Bennu samples is expected to lead to many more.

The spacecraft also has enough fuel in its tank to take on more work after its return.

OSIRIS-REx, renamed OSIRIS-APEX, is to head off to study Apophis, an asteroid roughly 370 metres in diameter that will come within 32,000 kilometres of Earth in 2029. The spacecraft will then use its thrusters to try to dislodge dust and small rocks on and below that asteroidB次元官网网址檚 surface.

OSIRIS will then send information on the rockB次元官网网址檚behaviour back to Earth B次元官网网址� its last assignment.

Bob Weber, The Canadian Press

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