[meteorite-list] Dawn Discovers Evidence for Organic Material on Ceres
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 17 Feb 2017 13:36:55 -0800 (PST)
Dawn Discovers Evidence for Organic Material on Ceres
Jet Propulsion Laboratory
February 16, 2017
NASA's Dawn mission has found evidence for organic material on Ceres,
a dwarf planet and the largest body in the main asteroid belt between
Mars and Jupiter. Scientists using the spacecraft's visible and infrared
mapping spectrometer (VIR) detected the material in and around a northern-hemisphere
crater called Ernutet. Organic molecules are interesting to scientists
because they are necessary, though not sufficient, components of life
The discovery adds to the growing list of bodies in the solar system where
organics have been found. Organic compounds have been found in certain
meteorites as well as inferred from telescopic observations of several
asteroids. Ceres shares many commonalities with meteorites rich in water
and organics -- in particular, a meteorite group called carbonaceous chondrites.
This discovery further strengthens the connection between Ceres, these
meteorites and their parent bodies.
"This is the first clear detection of organic molecules from orbit on
a main belt body," said Maria Cristina De Sanctis, lead author of the
study, based at the National Institute of Astrophysics, Rome. The discovery
is reported in the journal Science.
Data presented in the Science paper support the idea that the organic
materials are native to Ceres. The carbonates and clays previously identified
on Ceres provide evidence for chemical activity in the presence of water
and heat. This raises the possibility that the organics were similarly
processed in a warm water-rich environment.
Significance of organics
The organics discovery adds to Ceres' attributes associated with ingredients
and conditions for life in the distant past. Previous studies have found
hydrated minerals, carbonates, water ice, and ammoniated clays that must
have been altered by water. Salts and sodium carbonate, such as those
found in the bright areas of Occator Crater, are also thought to have
been carried to the surface by liquid.
"This discovery adds to our understanding of the possible origins of water
and organics on Earth," said Julie Castillo-Rogez, Dawn project scientist
based at NASA's Jet Propulsion Laboratory in Pasadena, California.
Where are the organics?
The VIR instrument was able to detect and map the locations of this material
because of its special signature in near-infrared light.
The organic materials on Ceres are mainly located in an area covering
approximately 400 square miles (about 1,000 square kilometers). The signature
of organics is very clear on the floor of Ernutet Crater, on its southern
rim and in an area just outside the crater to the southwest. Another large
area with well-defined signatures is found across the northwest part of
the crater rim and ejecta. There are other smaller organic-rich areas
several miles (kilometers) west and east of the crater. Organics also
were found in a very small area in Inamahari Crater, about 250 miles (400
kilometers) away from Ernutet.
In enhanced visible color images from Dawn's framing camera, the organic
material is associated with areas that appear redder with respect to the
rest of Ceres. The distinct nature of these regions stands out even in
low-resolution image data from the visible and infrared mapping spectrometer.
"We're still working on understanding the geological context for these
materials," said study co-author Carle Pieters, professor of geological
sciences at Brown University, Providence, Rhode Island.
Next steps for Dawn
Having completed nearly two years of observations in orbit at Ceres, Dawn
is now in a highly elliptical orbit at Ceres, going from an altitude of
4,670 miles (7,520 kilometers) up to almost 5,810 miles (9,350 kilometers).
On Feb. 23, it will make its way to a new altitude of around 12,400 miles
(20,000 kilometers), about the height of GPS satellites above Earth, and
to a different orbital plane. This will put Dawn in a position to study
Ceres in a new geometry. In late spring, Dawn will view Ceres with the
sun directly behind the spacecraft, such that Ceres will appear brighter
than before, and perhaps reveal more clues about its nature.
The Dawn mission is managed by JPL for NASA's Science Mission Directorate
in Washington. Dawn is a project of the directorate's Discovery Program,
managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.
UCLA is responsible for overall Dawn mission science. Orbital ATK Inc.,
in Dulles, Virginia, designed and built the spacecraft. The German Aerospace
Center, Max Planck Institute for Solar System Research, Italian Space
Agency and Italian National Astrophysical Institute are international
partners on the mission team. For a complete list of mission participants,
More information about Dawn is available at the following sites:
News Media Contact
Jet Propulsion Laboratory, Pasadena, CA
elizabeth.landau at jpl.nasa.gov
Received on Fri 17 Feb 2017 04:36:55 PM PST