NASA’s “COSmIC” Simulator Helps Fingerprint Unknown Matter in Sp
Who are we? Where do we come from? These are questions that scientists hope to find clues to by better understanding the composition and evolution of ...
Who are we? Where do we come from? These are questions that scientists
hope to find clues to by better understanding the composition and
evolution of the universe.
NASA flies sophisticated space missions that can probe vast
regions of space to detect spectral signatures, or fingerprints, of
unknown materials.
Through the years, scientists have found that these materials are much
more complicated than originally anticipated. Because conditions in
space are vastly different from conditions on Earth, identifying
extraterrestrial materials is extremely difficult. Recently,
researchers have achieved a major milestone by adding a new capability
to one of the world’s unique laboratory facilities.
Located at NASA’s Ames Research Center, Moffett Field, Calif.,
this specialized facility, called the Cosmic Simulation Chamber
(COSmIC), integrates a variety of state-of-the-art instruments to allow
scientists to form, process and monitor simulated space conditions for
planetary and interstellar materials in the laboratory.
The chamber is the heart of the system. It recreates the
extreme conditions that reign in space where average temperatures can
be as low as 100 Kelvin (less than -170 degree Celsius!), densities are
billionths of Earth's (of the order of 10-16 - 10-17) and interstellar
molecules and ions are bathed in stellar ultraviolet and visible
radiation.
"The harsh conditions of space are extremely difficult to reproduce in
the laboratory, and have long hindered efforts to interpret and analyze
observations from space," said Farid Salama, a space science researcher
in the Astrophysics Branch at Ames.
The idea of building the COSmIC facility started as a Director’s
Discretionary Fund (DDF) project initiated by Salama in 1996, and its
realization represents a true success story for Ames’ DDF
program. The facility resulted from collaboration between Ames space
science researchers and Los Gatos research scientists as a Small
Business Innovative Research (SBIR) contract awarded by NASA.
The team of space scientists and engineers, lead by Salama, designed
and built this unique laboratory facility to gain a deeper
understanding of the composition of our universe and of the evolution
of galaxies, both major objectives of NASA’s space research
program.
In 2003, Ames scientists delivered their first major milestone by
coupling COSmIC with a cavity ringdown spectrometer, an extremely
sensitive device that can detect the spectral fingerprint of matter at
the molecular level.
Now, another major milestone has been achieved by coupling COSmIC with
a time-of-flight mass spectrometer, an ultra-sensitive device that
detects the mass of matter at the molecular level.
In the past, part of the problem that prevented scientists from
identifying unknown matter was the inability to simulate space
conditions in the gaseous state. Today, researchers can successfully
simulate gas-phase environments similar to interstellar clouds, stellar
envelopes or planetary atmospheres environments by expanding solids
using a free jet spray.
“By doing this, we now can measure large carbon molecules, like
polycyclic aromatic hydrocarbons (PAHs) and similar carbon species.
This is a major accomplishment,” said Salama. “This type of
new research truly pushes the frontiers of science toward new horizons,
and illustrates NASA's important contribution to science,” he
added.
Scientists will use this “far out” facility to
address two key problems: First, they want to identify the nature of
big aerosol particles that have been detected by Cassini in the
atmosphere of Saturn's moon, Titan. The second problem they will study
is the formation of interstellar grains in the outflow of carbon stars.
“We can now truly simulate in the laboratory the formation of
carbon grains in the envelope of stars, a major problem in
today’s astrophysics,” said Cesar Contreras a NASA
Postdoctoral Program (NPP) fellow and a member of the research team.
“We begin with small carbon molecules, expose these molecules to
high energy processing in COSmIC, expand them in a cold jet spray and
detect them with our highly sensitive detectors,” added
Contreras, who studies interstellar grains.
Funded by NASA’s Science Mission Directorate Astronomy and
Physics Research and Analysis, Planetary Atmospheres and Cosmochemistry
programs, this new facility will also study the very large aerosol
particles that were seen by the Cassini spacecraft in the upper
atmosphere of Titan.
“In the Cassini data we see evidence for large aerosols in the
upper atmosphere of Titan that we plan to explain with COSmIC”
said Claire Ricketts, another NASA NPP fellow and member of the team,
who studies the composition of the atmosphere of Titan.
“Titan is an important body in our solar system because it helps
us understand the conditions that existed on early Earth” added
Ricketts. “Organic haze in the atmosphere of Titan is similar to
haze in early Earth's air.”
To understand Cassini’s data, scientists need this very
powerful, very sensitive new tool. They will begin their analysis by
forming molecules and species in the lab, measuring them in situ
(inside their environment without disturbing them), and then trying to
match their identity to Titan’s unknown aerosol molecules.
“Titan’s upper atmosphere data shows a rich
spectrum. We will recreate those data in the lab and compare them to
Cassini’s data. If they fit, great. If not, we will try something
else. We will know when we are coming close to understanding them. We
now have the right tool to do this,” said Salama.
“One day we will talk about the details and the implications of
the data, but today we are celebrating the new milestone in the
completion of this unique tool,” concluded Salama.
The Astrophysics and Astrochemistry Laboratory is part of the
Astrophysics Branch in the Space Science and Astrobiology Division.
Scientists in the Astrophysics Branch perform a wide range of astronomy
and astrophysics research focusing on the development of new space,
airborne and ground-based laboratory instrumentation such as COSmIC and
SOFIA, as well as laboratory simulation experiments. The Ames team
includes Farid Salama (POC), Claire Ricketts (NPP), Cesar Contreras
(NPP) and Robert Walker.
For more information about the NASA Ames Astrophysics and Astrochemistry Laboratory, visit:
To learn more about the coupling of a reflectron time-of-flight mass spectrometer with a cosmic simulation chamber, see: International Journal of Mass Spectrometry, 300, 26, 2011 (doi:10.1016/j.ijms.2010.11.017
For more information about NASA Ames, visit:
