Probe to Fetch Rocks From Ancient Asteroid

Artist's impression of NASA's Osiris-Rex spacecraft on the job at Asteroid Bennu.

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.

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.

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.

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.

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.

Read more at Discovery News