Nasa is planning to launch a probe to collect rock samples from an asteroid it fears could one day hit the Earth.
The asteroid, named Bennu, can be seen from Earth as it crosses our orbit every six years.
Bennu, which is around 500 metres in diameter at its equator and travels around the sun at 63,000mph, will pass between Earth and the moon in 2135.
"That 2135 fly-by is going to tweak Bennu's orbit, potentially putting it on course for the Earth later that century," Dante Lauretta, professor of planetary science at Arizona University, told The Sunday Times.
"It may be destined to cause immense suffering and death," he added.
Mr Lauretta, Nasa's principal investigator in charge of the Osiris-Rex probe mission to Bennu, launching in September, said the probe will map the asteroid, pick up some rock samples and then head back to Earth.
He said information on the asteroid's size, mass and composition could be vital data for future generations.
Osiris-Rex will arrive at Bennu in 2018 and will spend a year surveying the asteroid's chemical makeup, mineralogy and geologic history. Information gathered during the observation will help scientists understand how its course is affected by absorbing and radiating sunlight as heat.
The probe will then take a sample from the asteroid before heading back to Earth for 2023.
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