- 4256 -
ASTEROID - Bennu
sample returned? - After a years-long mission to collect and
retrieve rock samples from the potentially hazardous asteroid Bennu, NASA has
revealed its initial findings and perhaps a clue to life’s origins on Earth.
-
-------------------------
4256 - ASTEROID
- Bennu sample returned?
-
- The sample, between
3.5 to 8.8 ounces of rocky space rubble collected from the asteroid Bennu's
surface contains water and carbon.
(October 11, 2023).
-
- NASA scientists
unveiled the sample two weeks after it hurtled back to Earth at speeds of up to
27,000 mph on September 24. After a
seven-year, 4 billion-mile roundtrip, the capsule deployed its parachute and
safely landed in the Utah desert before being transported to Johnson Space
Center, where scientists have begun analyzing its contents for signs of life
beyond our planet.
-
- Bennu is a
potentially hazardous asteroid that has a 1-in-2,700 chance of striking Earth
in the year 2182, the highest odds of any known space object. But the
scientists are more interested in what's trapped inside the space rock.
-
- This is the biggest
carbon-rich asteroid sample ever returned to Earth. Carbon and water molecules are exactly the
elements we wanted to find. They're crucial elements in the formation of our
own planet, and they're going to help us determine the origins of elements that
could have led to life.
-
- Earth's water is
older than the planet itself and was probably brought here by asteroid and
comet impacts. But water wasn't the only material asteroids brought to Earth:
The building blocks of life likely hitched a ride on a space rock, too. Bennu
is a B-type asteroid, which means it contains high amounts of carbon and,
potentially, many of the primordial molecules present when life emerged on
Earth.
-
- Some of these
building blocks, including uracil, one of the nucleobases for RNA, were
recently found on the asteroid Ryugu by the Japan Aerospace Exploration
Agency's Hayabusa2 spacecraft, which returned to Earth with its rock sample in
2020. OSIRIS-REx mission scientists are hoping to find other potential
precursors for Earth's biology inside the Bennu sample.
-
- As we peer into
the ancient secrets preserved within the dust and rocks of asteroid Bennu, we
are unlocking a time capsule that offers us profound insights into the origins
of our solar system. The bounty of
carbon-rich material and the abundant presence of water-bearing clay minerals
are just the tip of the cosmic iceberg.
-
- The sample was
collected after nearly two years of fraught searching for a landing site on
Bennu's craggy surface. Upon contact with the asteroid, OSIRIS-REx fired a
burst of nitrogen from its Touch-and-Go Sample-Acquisition Mechanism, not only
to stick the landing but to prevent the craft from sinking through the
asteroid.
-
- The blast sent
rocks and dust careening around the craft, and some of that rocky debris landed
in a canister aboard OSIRIS-REx. A
follow-up blast of OSIRIS-REx's thrusters later lifted it from Bennu, and the
spacecraft completed a number of flyovers before leaving the asteroid for Earth
in May 2021.
-
- The tiny particles
of rock gathered from the asteroid Ryugu are some of the most primordial bits
of material ever examined on Earth and could give us a glimpse into the origins
of the solar system.
-
- Asteroid “162173
Ryugu” measures 2,953 feet in diameter and orbits the sun between Earth and
Mars, occasionally crossing Earth's orbit.
The carbonaceous, or C-type, asteroid spins like a top as it hurtles
through space, and like other C-type asteroids, Ryugu likely contains material
from the nebula (giant cloud of dust and gas) that gave birth to the sun and
its planets billions of years ago.
-
- In 2019, the
Japanese spacecraft Hayabusa2 collected samples from the surface of Ryugu, and
on Dec. 6, 2020, those samples were successfully transported to Earth in an
airtight container tucked inside the reentry capsule.
-
- Early results
suggest that these samples are among the most primordial material available in
our laboratories. In total, the
asteroid samples include about 0.2 ounces of material. The largest particles of
rock measure about 0.31 inches across; the smallest have diameters less than
0.04 inch , so they resemble fine dust. To the naked eye, the samples look like
incredibly dark bits of black pepper.
-
- The Ryugu samples
have been handled without exposing them to the Earth's atmosphere. The team
assessed the samples using an optical microscope and various instruments that
measure how the rocks absorb, emit and reflect different wavelengths of light
in the visible and infrared spectra.
-
- The pitch-dark
asteroid bits reflect only about 2% to 3% of the light that hits them. The
samples' bulk density, the mass of the particles divided by the total volume
they occupy, was lower than that of
known carbonaceous meteorites. This finding hints that the rocks are highly
porous, meaning that between the individual grains of materials in the rocks
exist many pockets of empty space that would allow water and gas to seep
through.
-
This finding aligns with preliminary data collected by the
Hayabusa2 spacecraft, which also hinted that the rocks on Ryugu's surface are
highly porous.
-
- A technique known
as hyperspectral microscopy was used to take a closer look at the composition
of the asteroid samples. The hyperspectral microscope works by illuminating the
samples with different wavelengths of light in the visible and infrared spectra
and snapping high-resolution pictures as it does so.
-
- Each snapshot
measures about 0.2 by 0.2 inches, and each individual pixel provides data on
the microscopic scale. In this way, the team revealed fine details of the
rocks' color, structure and chemical composition.
-
- Snapshots of the
Ryugu samples revealed that the rock particles are composed of a "hydrated
matrix," which includes materials such as clay, with carbon-based
compounds embedded throughout. Some of
the material properties were close to those of the carbonaceous chondrites, a
class of carbonous meteorites.
-
- The Ryugu samples
are among the darkest ever examined and we have to understand why and what it
implies regarding the formation and evolution of this material. They discovered traces of ammonia-rich
compounds in the rock, which could have some implications regarding the origin
of Ryugu and our understanding of primordial material.
-
- These initial
analyses represent the first step in figuring out what Ryugu can tell us about
the early solar system, but exposing all of the space rocks' secrets will take
some time.
-
- These additional
techniques will include various chemical analyses, which can reveal the
chronological history of when the asteroid first formed and at what ages it came
into contact with water.
-
- Further
assessments of the organic compounds and minerals in the samples will also
provide key information about how the asteroid and its original body first
formed. Researchers can also examine the volatile compounds, or those that can
be easily vaporized, within the samples; these sorts of tests can reveal how
solar winds shaped the asteroid's surface over time.
-
-
December 6, 2023
4252
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