An ambitious mission to collect dust from an asteroid and return it to Earth for scientific analysis has blasted off from Cape Canaveral in Florida.

NASA's Osiris-REx spacecraft will take 23 months to reach Bennu, a 500m-wide asteroid which scientists believe contains perfectly preserved material from 4.5 billion years ago when it and the rest of the solar system was formed.

Professor Dante Lauretta, the mission's principle investigator, said similar material on Earth has long since been erased.

NASA To Probe 'Armageddon' Asteroid

He said: "We are going to asteroid Bennu because it's a time capsule from the earlier stages of solar system formation, back when our planetary system was spread across as dust grains in a swirling cloud around our growing proto star.

"Inside this region of the proto planetary disk there were bodies that were cumulating - many of them were getting water, ice and organic material.


"These are really critical because our Earth went through a major period of geological upheaval during the late heavy bombardment when millions of asteroids collided with the surface, sterilising our planet."

Osiris-REx - a handy shortening of the Origins, Spectral, Interpretation, Resource Identification, Security, Regolith Explorer - will spend two years mapping the surface of Bennu at a resolution so high that scientists would be able to spot a penny.

In July 2020 it will descend towards the asteroid at a speed of less than 10cm a second.

NASA Animation: Osiris-REx

As it briefly touches down it will blow high pressure nitrogen gas into the surface, dislodging dust and rock which it will suck up and store in a sterile capsule.

NASA hopes to collect between 60g and 2kg of material, which should return to Earth in 2023.

Osiris-REx will return the largest amount of extra-terrestrial material since the Apollo moon landings.

Dr Jim Garvin, chief scientist at the NASA Goddard Space Flight Centre, told Sky News: "This particular asteroid contains molecules that include carbon.

"Those carbon-forming molecules are really important ingredients for what many scientists believe could be the building blocks, the origins for life on our planet and perhaps other worlds.

"So getting to those elusive and sometimes fragile molecules where they are preserved back to Earth is a special engineering project with an incredible science potential."

NASA also wants to understand the effects of the sun's heat on the asteroid's orbit.

In 2035, Bennu is due to pass the Earth closer than the moon.

The combination of the heat effect and the Earth's gravitational pull means there is a one in 2,700 chance that it will smash into the planet 150 or so years later, creating a crater 5km wide and 500 metres deep.

Image: The craft arriving at the asteroid - as imagined in a NASA animation

Meanwhile, the European Space Agency is working with Airbus in Stevenage to develop a "road-sweeper" type device to retrieve a sample of dust and rock from the Martian moon Phobos in a mission due to launch in 8-10 years.

Ralph Cordey, head of science at Airbus Defence and Space said: "The difference between a meteorite that falls from space and something that you bring back from an asteroid is context.

"You know where it has come form, the processes it has gone through and you can do a lot more science about the object."