The rocket carrying Nasa’s Osiris-Rex spacecraft on the launchpad at Cape Canaveral (Nasa/AP)
A Nasa spacecraft has blasted off on a seven-year mission to explore an asteroid.
The Osiris-Rex explorer rocketed away from Cape Canaveral, Florida, just before sunset for a seven-year quest to the big, black, unexplored space rock named Bennu.
Once there, the spacecraft will gather a few handfuls of gravel for return to Earth.
The bite-size bits of ancient space rock – due beck on Earth in 2023, if all goes well – could hold clues to the origin of life.
Thousands gathered to witness the evening launch of Osiris-Rex, a robotic hunter resembling a bird. It took flight atop an Atlas V rocket.
Among the well-wishers was Mike Puzio, a 12-year-old North Carolina boy who won a contest to name the asteroid.
Principal scientist Dante Lauretta, of the University of Arizona at Tucson, said: “It’s a dream come true. I have to keep pinching myself to make sure this is all real.”
The SUV-sized explorer will travel more than four billion miles by the mission’s end in 2023.
It will take two years to reach Bennu, which is circling the sun in a slightly wider orbit than Earth’s. The boxy spacecraft will go into orbit around the asteroid, seeking out the best spot before going in for a quick bite.
Nasa has gone after comet dust and solar wind particles before, but never anything from an asteroid. It promises to be the biggest cosmic haul since the Apollo moon rocks.
The roundish rock – about 1,600ft across and taller than the Empire State Building – is believed to harbour carbon dating back 4.5 billion years, to the beginning of our solar system. That makes it a time capsule and a scientific prize.
“We will make discoveries on this mission that we have not anticipated. It’s exciting,” said Bill Nye, chief executive officer of the Planetary Society.
The launch came 50 years to the day after the first Star Trek episode aired on TV. Nasa launch commentator Mike Curie referenced the anniversary, urging the spacecraft at lift-off “to boldly go” to the asteroid and back.
Osiris-Rex may lead to asteroid-mining missions, according to scientists, and could help protect the planet one day from menacing space rocks.
Japan has already visited an asteroid and returned some specks, and is chasing another space rock for more samples. Osiris-Rex’s bounty should surpass that – Mr Lauretta and his team want at least 60 grammes of dust and gravel when the big day comes in 2020. Ground tests have yielded eight times that in a single scoop, so hopes are high for four to five handfuls.
Osiris-Rex will hover like a hummingbird over Bennu, according to Mr Lauretta, as the spacecraft’s 10ft mechanical arm touches down like a pogo stick on the surface for three to five seconds. Thrusters will shoot out nitrogen gas to stir up the surface, and the loose particles will be sucked up into the device. Spacecraft managers call it “the gentle high five”. They get just three shots at this before the nitrogen gas runs out and the effort is abandoned.
The team opted for this touch-and-go procedure instead of landing to increase the odds of success. Despite extensive observations of Bennu from ground and space telescopes, no-one knows exactly what to expect there, and it could be difficult if not impossible to anchor a spacecraft on the surface, Mr Lauretta said.
Osiris-Rex’s freed sample container – the same kind used for the comet dust retrieval – will parachute down with the asteroid treasure in Utah. The mother spacecraft will continue its orbit of the sun.
The name Bennu comes from a heron of Egyptian mythology. Mike Puzio thought Osiris-Rex looked like a bird, with its twin solar wings and long arm outstretched for a sample grab, and with the spacecraft named after the Egyptian god Osiris, Bennu was an obvious choice, he said.
Osiris-Rex is also a Nasa acronym for origins, spectral interpretation, resource identification, security-regolith explorer. The estimated cost of the mission is more than 800 million dollars (£600 million).
“Space exploration brings out the best in us,” Mr Nye said shortly before Osiris-Rex began its journey. “It is an extraordinary use of our intellect and treasure to elevate humankind, to help us know our place in the cosmos.”
It may also one day save the home planet.
Bennu swings by Earth every six years, and 150 years from now, could hit us. The odds are less than a 10th of 1%, according to Mr Lauretta. While this particular rock would not destroy Earth – just carve out a huge crater – other asteroids could cause more trouble.
Osiris-Rex will help scientists better understand the ever-changing paths of asteroids, and that could prove its biggest payoff.