[meteorite-list] Researchers Brew Up Organics on Ice

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 18 Sep 2012 13:34:37 -0700 (PDT)
Message-ID: <201209182034.q8IKYb8x001149_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2012-293

Researchers Brew Up Organics on Ice
Jet Propulsion Laboratory
September 18, 2012

Would you like icy organics with that? Maybe not in your coffee, but
researchers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., are
creating concoctions of organics, or carbon-bearing molecules, on ice in
the lab, then zapping them with lasers. Their goal: to better understand
how life arose on Earth.

In a new study published in the Astrophysical Journal Letters, the
research team provides the first direct look at the organic chemistry
that takes place on icy particles in the frigid reaches of our solar
system, and in the even chillier places between stars. Scientists think
that the basic ingredients of life, including water and organics, began
their journey to Earth on these lonesome ice particles. The ice and
organics would have found their way into comets and asteroids, which
then fell to Earth, delivering "prebiotic" ingredients that could have
jump-started life.

The various steps needed to go from icy organics to slime molds are not
clear, but the new findings help explain how the process works. The lab
experiments show that organic material can begin the processing it needs
to become prebiotic -- while still frozen in ice.

"The very basic steps needed for the evolution of life may have started
in the coldest regions of our universe," said Murthy Gudipati, lead
author of the new study at JPL. "We were surprised to see organic
chemistry brewing up on ice, at these very cold temperatures in our lab."

The organics looked at in the study are called polycyclic aromatic
hydrocarbons, or PAHs for short. These carbon-rich molecules can be
found on Earth as combustion products: for example, in barbecue pits,
candle soot and even streaming out of the tail pipe of your car. They
have also been spotted throughout space in comets, asteroids and more
distant objects. NASA's Spitzer Space Telescope has detected PAHs in the
swirling planet-forming disks around stars, in the spaces between stars
and in remote galaxies.

Murthy and his colleague Rui Yang of JPL used their lab setup to mimic
the environment of icy PAH molecules in the quiet cold of space, at
temperatures as low as 5 Kelvin (minus 450 degrees Fahrenheit, or minus
268 degrees Celsius). First, they bombarded the particles with
ultraviolet radiation similar to that from stars. Then, to determine the
products of the chemical reaction, they used a type of laser system
known as MALDI (for Matrix Assisted Laser Desorption and Ionization),
which involves zapping the ice with both infrared and ultraviolet lasers.

The results revealed that the PAHs had transformed: they had
incorporated hydrogen atoms into their structure and lost their
circular, aromatic bonds, becoming more complex organics. According to
Gudipati, this is the type of change that would need to occur if the
material were to eventually become amino acids and nucleotides -- bits
and pieces of protein and DNA, respectively.

"PAHs are strong, stubborn molecules, so we were surprised to see them
undergoing these chemical changes at such freezing-cold temperatures,"
said Gudipati.

Another bonus for the research is that it might explain the mystery of
why PAHs have not yet been identified on ice grains in space. While the
hardy organics are pervasive in the cosmos as gases and hot dust,
researchers have remained puzzled that their signatures do not show up
on ice. The new findings show that PAHs, once they stick to the ice
surface, are chemically transformed into other complex organics,
explaining why they might not be seen.

While the new results teach us that life's journey could have already
begun in the very cold regions of the universe, another question
remains: Did it arise elsewhere beyond our sun, too? Researchers don't
know, but studies like this one help the ongoing search for life beyond
Earth.

The journal article is online at
http://iopscience.iop.org/2041-8205/756/1/L24 .

The California Institute of Technology in Pasadena manages JPL for NASA.

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin at jpl.nasa.gov

2012-293
Received on Tue 18 Sep 2012 04:34:37 PM PDT