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NASA headed to asteroid Bennu

A seven-year robotic mission to a near-Earth asteroid will launch in September, NASA scientists and project managers said Wednesday.

The space agency plans to launch a spacecraft the size of a sport-utility vehicle Sept. 8, with the goal of mapping the asteroid Bennu, scooping up a surface sample, and bringing it back home.

Following a nighttime launch from Cape Canaveral, Florida, the craft will take a trip around the sun and eventually encounter the asteroid, which travels close to the orbit of the Earth and has a diameter of about one-third of a mile.

The robotic craft will eventually collect up to 4.4 pounds of material in what will be the largest space sample brought back to Earth since the Apollo missions.

One of the key goals of the asteroid encounter is to better understand the complex orbital movements of small bodies in space in order to better predict when one of these space rocks is on a collision course with the Earth.

“In 150 years, some of our models do show it could rendezvous with the Earth,” Morton said of the Bennu asteroid. But she stressed that the chance of such a catastrophe is less than one-tenth of 1 percent.

Morton said the mission will allow scientists to study something called the Yarkovsky Effect, which refers to a propulsion force that’s created when an asteroid absorbs heat from the sun and then emits it back into space later on. This creates a kind of thrust that can alter the trajectory of the asteroid in space.

“One of the reasons we are studying Bennu is we are looking to more precisely track the orbits of small bodies,” she said. 

The mission’s focus on mapping the asteroid’s resources will also provide insights for future missions engaged in space mining ventures, NASA officials said.

NASA officials praised the $800-million long-range project as on time and under budget during a briefing at NASA headquarters in Washington, D.C. That contrasts with another NASA project, the Asteroid Redirect Mission, whose goal will be to grab a chunk of another near-Earth asteroid and guide it into orbit around the moon. The cost of that delayed mission, which will begin in late 2021, has increased from $1.25 billion to $1.4 billion, NASA announced this week.

The mission to Bennu, which carries the name OSIRIS-REx, will allow scientists to examine a pristine asteroid sample in ways that may provide information about the origin of the solar system and the sources of water and organic molecules on Earth.

The spacecraft contains a long mechanical arm with a 12-inch-diameter soil collector. Once the craft completes its laser-guided mapping of the asteroid, scientists will choose a suitable sample-selection site, and the craft will maneuver down toward the asteroid’s surface at a speed of 10 centimeters per second, or a quarter-mile per hour, according to Rich Kuhns, a program manager with Lockheed Martin Space Systems in Denver.

“It takes three to five seconds to give the asteroid the gentle high-five,” Kuhns said during Wednesday’s briefing.

Dante Lauretta of the University of Arizona, the project’s principal investigator, said the sample will eventually be subject to a battery of tests that could not be done anywhere else but on Earth. Those tests will be a boon to meteorite science because the 4-billion-year-old sample will be pristine material, as opposed to meteorite samples found on Earth, which are subject to contamination and extreme heat when plunging through the atmosphere. 

“The sample return is the gift that keeps on giving,” Lauretta said.

Such sample returns from space have only been done a few times in human history, according to project scientist Jeff Grossman. These include the moon landings as well as NASA’s Stardust mission, which captured dust from the trail of a comet and brought it back to Earth in 2006.

The asteroid sample will be placed in a 100-pound detachable capsule and will be guided back through Earth’s atmosphere to NASA’s test range in Utah after the spacecraft completes its return trip, NASA officials said. The spacecraft will then be placed in a “parking orbit” around the sun and can be summoned back into service for a future mission, they said.

The mission is part of NASA’s New Frontiers program, which included last year’s flyby of the dwarf planet Pluto and the Juno spacecraft’s arrival into orbit around Jupiter on July 4 this year.