[meteorite-list] New Clues From the Dawn of the Solar System

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 18 Mar 2015 17:15:24 -0700 (PDT)
Message-ID: <201503190015.t2J0FOPq000478_at_zagami.jpl.nasa.gov>

NEWS RELEASE

March 17, 2015

New Clues From the Dawn of the Solar System
University of Arizona

TUCSON, Arizona - A research group in the University of Arizona Lunar
and Planetary Lab has found evidence in meteorites that hint at the discovery
of a previously unknown region within the swirling disk of dust and gas
known as the protoplanetary disk - which gave rise to the planets in our
solar system.

Led by Kelly Miller, a doctoral student in the lab of Dante Lauretta,
the principal investigator of NASA's OSIRIS-REx mission, the team has
found evidence of minerals within meteorites that formed in an environment
that was enhanced in oxygen and sulfur and date from a time before the
particles stuck together, or "accreted," to form larger bodies such as
asteroids and planets.

Miller will present the data at the 46th Lunar and Planetary Science Conference,
being held this week in The Woodlands, Texas. The results are in preparation
for publication in a journal, but have not been peer-reviewed yet.

The elements that later went on to constitute the major ingredients in
life on Earth - such as carbon, oxygen, nitrogen and hydrogen - originated
as volatile gases in the protoplanetary disk when the solar system was
less than 10 million years old, Miller said.

"If we want to understand how those elements contributed to life, we have
to understand where they occurred at the time the solar system formed,"
she said.

Miller and her team study meteorites called chondrites, which are thought
to be the most primitive leftovers from the birth and infancy of the solar
system about 4.6 billion years ago. They derive their name from their
main component - chondrules, which formed as molten droplets floating
in space.

"We think that chondrites represent the earliest building blocks of rocky
planets such as Earth, Mars or Venus," Miller said.

Specifically, Miller and her co-workers studied sections about half as
thin as a human hair that were cut from R chondrites, a rare type of meteorite
so named after the location where the type specimen fell: Rumuruti in
Kenya. R chondrites are thought to have formed somewhere between Earth
and Jupiter. In one specimen, found in Antarctica, they discovered a new
type of building block called sulfide chondrules. The samples were obtained
from the U.S. collection of Antarctic meteorites - a cooperative effort
among NASA, the National Science Foundation (NSF) and the Smithsonian
Institution.

"Generally, chondrules are made up of minerals rich in silicon, but the
chondrules we found in this meteorite are completely different in that
they are composed of sulfide minerals," she explained. "This suggests
that they formed in a region that was rich in sulfur, and provides evidence
for a previously unknown type of environment in the early solar system."

"Our discovery of the sulfide chondrules will help us put a quantifiable
number on how much sulfide was enhanced in that region of the protoplanetary
disk," Miller added.

Obtaining a better understanding of the distribution of gases in the early
solar system has been identified by the Planetary Science Decadal Survey
as a primary objective for the study of primitive bodies. Published by
the National Research Council for NASA and other government agencies such
as the National Science Foundation, the document identifies key questions
in planetary science and outlines plans for space- and ground-based exploration
ten years into the future.

"What is exciting about this sample is that it has not been heated to
high temperatures and thereby altered in its composition," Miller said.
"We know it's a fragment of a larger asteroid, and some of that asteroid
heated up to higher temperatures, erasing the signature of the original
building blocks of the asteroid, but our piece retains the original building
blocks."

"These sulfide chondrules help us pin down when and where that sulfur
enhancement occurred and help us better understand the process," she added.

To learn more about the early stages of the solar system including the
origin of the building blocks of life and water, the UA-led OSIRIS-REx
mission is getting ready to launch a robotic spacecraft to asteroid Bennu
in 2016 and bring a sample of at least 60 grams of pristine material back
to Earth for study. The mission will provide ample amounts of sample material
and, most importantly, from a known context.

"Unlike with meteorites that came to us serendipitously and we're lacking
the context of where the material formed, with OSIRIS-REx we will know
exactly where that piece came from, and we will know the travel history
of Bennu ? where it has been in the past," Miller said.

To learn more about Bennu's past and the OSIRIS-REx sample return mission,
visit the OSIRIS-REx Website (www.asteroidmission.org)
and watch the short documentary, "History of Bennu" (www.asteroidmission.org/movie)

###

Images are available to the press. Please contact Doug Carroll (contact
details below).

Meeting info:
The findings of this research will be presented on Thursday, March 19,
2015, 1:30 p.m., Waterway Ballroom 6.

Miller K. E. * Lauretta D. S. Nagashima K. Domanik K.
The Nature of Primitive R Chondrite Material: Characterization of an R3.2
Clast in Mount
Prestrud 95404 [#2402]

Research Contact:
Kelly Miller
Lunar and Planetary Laboratory
The University of Arizona
kemiller115 at gmail.com<mailto:kemiller115 at gmail.com>
Cell phone: 520-288-2599

Media Contacts:
LPSC:
Mary Ann Hager
Lunar and Planetary Institute
281-486-2136
mhager at hou.usra.edu<mailto:mhager at hou.usra.edu>

University of Arizona:
Doug Carroll
University Relations, Communications
520-621-9017
dougcarroll at email.arizona.edu<mailto:dougcarroll at email.arizona.edu>
UANews.org
Received on Wed 18 Mar 2015 08:15:24 PM PDT