Probe to Fetch Rocks From Ancient Asteroid

Organic compounds and other materials collected from Asteroid Bennu may provide clues about how Earth became a haven for life.

Image: Artist's impression of NASA's Osiris-Rex spacecraft on the job at Asteroid Bennu. Credit: NASA Goddard Space Flight Center.

A NASA spacecraft is being prepared for launch on Thursday to visit a small asteroid, collect a few ounces of soil from its surface and fly the precious cargo back to Earth.

Scientists hope their atomic-level analysis of the materials will shed light on why Earth -- and perhaps other planets in the solar system -- became habitats for life and perhaps even reveal the origins of life itself.

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The asteroid, known as Bennu, dates back to the early days of the solar system's formation, said the mission's lead scientist Dante Lauretta, with the University of Arizona in Tucson.

"It's a time capsule ... from back when our planetary system was spread across as dust grains in a swirling cloud around our growing protostar," Lauretta said.

Discovered in 1999 by Lincoln Near-Earth Asteroid Research (LINEAR) project, Bennu is a small, dark world just one-third of a mile in diameter that is orbiting the sun at roughly the same distance as Earth.

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Bennu is among the thousands of so-called Near-Earth Asteroids, one or more of which may prove to be hazardous to Earth in the future. Scientists with the upcoming Osiris-Rex mission hope to learn more about how heating and pressure from sunlight impart motions into an asteroid. The information one day may be critical for diverting an asteroid that is on a collision course with Earth.

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The $800 million Osiris-Rex spacecraft is expected to spend between 18 months and two years slowly circling Bennu so its science instruments and cameras can collect data for global, three-dimensional surface maps and catalog chemicals and minerals on the asteroid's surface.

Scientists expect to find Bennu rich with chondrules, which likely formed when bits of dust in the solar nebula were flash-heated to become molten rock that later solidified. Over time, chondrules clumped together to become the building blocks of asteroids and planets.

"On planets like Earth, the original materials have been profoundly altered by geologic activity and chemical reactions with our atmosphere and water. We think Bennu may be relatively unchanged," mission deputy scientist Edward Beshore, also with University of Arizona, said in a NASA interview.

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Scientists suspect Bennu also contains organic material from the solar system's early years. Carbon-rich organics are key to life on Earth, and perhaps elsewhere as well.

NASA says an analysis of any organic material found on Bennu will give scientists an inventory of the materials present at the beginning of the solar system that may have had a role in the origin of life.

"By bringing this material back to Earth, we can do a far more thorough analysis than we can with instruments on a spacecraft, because of practical limits on the size, mass, and energy consumption of what can be flown," Beshore said.

Osiris-Rex is designed to collect a minimum of 60 grams – 2 ounces -- of soil and crushed rock from Bennu's surface. However, preflight tests of the probe's sample collection system have scientists optimistic the spacecraft can collect as much as 70 ounces, or 4 pounds.

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Osiris-Rex will descend to the asteroid's surface for only the briefest of time and come only as close as what is need to place its 11-foot long robot arm on the ground. The arm is designed to fire off a burst of nitrogen gas and then collect small rocks and soil that have been stirred up.

Once scientists confirm they have at least 60 grams of material aboard, Osiris-Rex has just one task left: Get home.

If all goes as planned the spacecraft will put itself into orbit around Bennu in 2018, collect the sample in 2020 and fly back to Earth in September 2023.

Launch aboard a United Launch Alliance Atlas 5 rocket is scheduled for at 7:05 p.m. EDT Thursday at Cape Canaveral Air Force Station in Florida.

GALLERY: Check Out NASA's Future Asteroid-Grabbing Mission

On April 10, 2013, the White House and NASA released details of the US space agency's budget for the 2014 fiscal year. Included in the budget was a request for over $100 million to begin work on the Asteroid Retrieval and Utilization Mission. The mission would see a robotic spacecraft rendezvous with a small asteroid, which would then steer the space rock to the Earth-moon libration point (EML2) -- a region of gravitational stability beyond the far side of the moon. A manned mission would then meet the "tamed" asteroid to carry out science in-situ. It has been determined that such a mission would optimize the scientific gains while reducing risk and cost. On Wednesday, NASA released an animation detailing the stages of asteroid capture, here are the highlights.

Although its exact configuration has yet to be established, the robotic asteroid capture spacecraft will likely be solar powered and be propelled by an advanced ion drive. Optimistic estimates put a 2017 launch window on the first phase of the mission.

When approaching the asteroid, the spacecraft will jettison the hatch covering the folded asteroid "capture bag." According to the Keck Institute study that the mission is based on, the asteroid will be approximately 7 meters wide and have a mass of 550 tons.

During approach, the capture bag expands.

The capture bag will expand like an accordion's bellows in preparation for asteroid capture.

The spacecraft will likely carry out an automated docking maneuver with the asteroid. Seen here, a laser is emitted by the spacecraft, guiding it in.

When fully expanded, and centered, the capture bag will envelop the space rock.

A draw-string-like mechanism will allow the capture bag's opening to be closed around the asteroid, securely mating spacecraft with asteroid.

Once secured, the spacecraft will "de-spin" the asteroid and begin steering it toward the Earth-moon system. This will mark the first time in human history that we have ever changed the trajectory of a natural object in space.

Meanwhile, preparations will be underway for a manned expedition to the captured asteroid. Seen here, NASA's future Space Launch System (SLS) rocket blasts off.

NASA's Orion space capsule will take a team of astronauts to the asteroid's parking orbit at EML2.

The Orion capsule will perform a docking maneuver with the robotic asteroid capture spacecraft after several days transit.

With the asteroid secure, astronauts will have the freedom (and time) to carry out extensive studies during extravehicular activity (EVA).

With the science done and samples collected, the Orion capsule returns to Earth.

The entire mission will culminate in the spashdown of the Orion capsule with astronauts on board. The asteroid will remain parked at EML2 for further study by followup missions to the lunar farside. You can watch the whole video on the NASA website: