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WASHINGTON, Sept. 9 (Xinhua) -- The first U.S. asteroid sampling mission took flight on Thursday evening, beginning a seven-year journey that could provide more insight into the early solar system and even the origin of life on Earth.
"Here we go!" principal investigator Dante Lauretta of the University of Arizona tweeted as the spacecraft, OSIRIS-REx, blasted off atop an Atlas V rocket at 7:05 p.m. EDT (2305 GMT) from Cape Canaveral Air Force Station in Florida.
About an hour later, OSIRIS-REx, which stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, successfully separated from the rocket's upper stage, formally embarking on its long trip to chase the asteroid named Bennu.
"You'll all be real glad to know that we got everything just exactly perfect," Lauretta said at a news conference later in the day. "It was an amazing evening for me and for this team."
"Tonight is a night for celebration -- we are on our way to an asteroid," said Ellen Stofan, chief scientist of the U.S. space agency NASA. "We're going to be answering some of the most fundamental questions that NASA really focuses on."
OSIRIS-REx's main goal is to collect a small sample of rocks and surface soil from Bennu, which was selected for the 800-million-U.S.-dollar mission because of its proximity to Earth, its right size, its primitive composition, and its potentially hazardous orbit.
According to NASA, asteroids like Bennu are remnants from the formation of our solar system more than 4.5 billion years ago and may have been a source of the water and organic molecules for the early Earth and other planetary bodies.
Therefore, this is "a journey that could revolutionize our understanding of the early solar system," NASA said in a statement.
"An uncontaminated asteroid sample from a known source would enable precise analyses, providing results far beyond what can be achieved by spacecraft-based instruments or by studying meteorites," it said.
If all goes according to plan, OSIRIS-REx will arrive in August 2018 and spend the next two years photographing and mapping the asteroid's surface to better understand its chemical and mineralogical composition, including selecting the sample site.
Then, in July 2020, the spacecraft will touch the asteroid for only three seconds to collect at least 60 grams of loose rocks and dust using a robotic arm called the Touch-and-Go Sample Acquisition Mechanism and store the material in a sample return capsule.
The spacecraft will depart the asteroid in March 2021 and travel for two-and-a-half years on a trajectory for a return to Earth in September 2023.
But OSIRIS-REx will not land. Instead, it will eject a small capsule containing the asteroid sample, which will land with the help of parachutes at the Utah Test and Training Range, southwest of Salt Lake City.
NASA said at least 75 percent of the sample will be reserved for investigation and analysis by future generations of scientists.
Meanwhile, the main spacecraft will remain in orbit around the Sun after the sample returns.
Also to be explored is how Bennu's orbit is affected by the so-called Yarkovsky effect, the slight push created when the asteroid absorbs sunlight and re-emits that heat as infrared radiation, in the hopes of better understanding the hazards of near-Earth space rocks to Earth.
Bennu, with a diameter of 492 m, is classified as a potentially hazardous object, with a 1 in 2700 chance of impacting Earth sometime between 2175 and 2199. Lauretta said its orbit has changed by over 160 km due to the Yarkovsky effect since it was discovered in 1999.
"We really want to understand this phenomenon, so that we can better understand asteroid Bennu and apply that understanding to all asteroids not only in near-Earth space but throughout our solar system," he said.
OSIRIS-REx was the first U.S. mission to carry samples from an asteroid back to Earth and the largest sample returned from space since the Apollo era.
The world's first asteroid sample-return spacecraft, however, was Japan's Hayabusa 1, which successfully brought back dust grains from the asteroid 25143 Itokawa after a seven-year space trip.
Its successor, Hayabusa-2, which blasted off in 2014, is now on its way to rendezvous with the asteroid 1993 JU3 in 2018.
