[meteorite-list] NASA'S Spitzer Observes Gas Emission From Comet ISON

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 23 Jul 2013 13:34:51 -0700 (PDT)
Message-ID: <201307232034.r6NKYp61022978_at_zagami.jpl.nasa.gov>

July 23, 2013

J.D. Harrington
Headquarters, Washington
j.d.harrington at nasa.gov

Whitney Clavin
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin at jpl.nasa.gov

Geoffrey Brown
Johns Hopkins Applied Physics Laboratory
geoffrey.brown at jhuapl.edu

RELEASE 13-229

NASA'S Spitzer Observes Gas Emission From Comet Ison

WASHINGTON -- Astronomers using NASA's Spitzer Space Telescope have observed
what most likely are strong carbon dioxide emissions from Comet ISON ahead of
its anticipated pass through the inner solar system later this year.

Images captured June 13 with Spitzer's Infrared Array Camera indicate carbon
dioxide is slowly and steadily "fizzing" away from the so-called "soda-pop
comet," along with dust, in a tail about 186,400 miles long.

"We estimate ISON is emitting about 2.2 million pounds of what is most likely
carbon dioxide gas and about 120 million pounds of dust every day," said
Carey Lisse, leader of NASA's Comet ISON Observation Campaign and a senior
research scientist at the Johns Hopkins University Applied Physics Laboratory
in Laurel, Md. "Previous observations made by NASA's Hubble Space Telescope
and the Swift Gamma-Ray Burst Mission and Deep Impact spacecraft gave us only
upper limits for any gas emission from ISON. Thanks to Spitzer, we now know
for sure the comet's distant activity has been powered by gas."

Comet ISON was about 312 million miles from the sun, 3.35 times farther than
Earth, when the observations were made.

"These fabulous observations of ISON are unique and set the stage for more
observations and discoveries to follow as part of a comprehensive NASA
campaign to observe the comet," said James L. Green, NASA's director of
planetary science in Washington. "ISON is very exciting. We believe that data
collected from this comet can help explain how and when the solar system
first formed."

Comet ISON (officially known as C/2012 S1) is less than 3 miles in diameter,
about the size of a small mountain, and weighs between 7 billion and 7
trillion pounds. Because the comet is still very far away, its true size and
density have not been determined accurately. Like all comets, ISON is a dirty
snowball made up of dust and frozen gases such as water, ammonia, methane and
carbon dioxide. These are some of the fundamental building blocks which,
scientists believe, led to the formation of the planets 4.5 billion years

Comet ISON is believed to be inbound on its first passage from the distant
Oort Cloud, a roughly spherical collection of comets and comet-like
structures that exists in a space between one-tenth light-year and 1
light-year from the sun. The comet will pass within 724,000 miles of the sun
on Nov. 28.

It is warming up gradually as it gets closer to the sun. In the process,
different gases are heating up to the point of evaporation, revealing
themselves to instruments in space and on the ground. Carbon dioxide is
thought to be the gas that powers emission for most comets between the orbits
of Saturn and the asteroids.

The comet was discovered Sept. 21, roughly between Jupiter and Saturn, by
Vitali Nevski and Artyom Novichonok at the International Scientific Optical
Network (ISON) near Kislovodsk, Russia. This counts as an early detection of
a comet, and the strong carbon dioxide emissions may have made the detection

"This observation gives us a good picture of part of the composition of ISON,
and, by extension, of the proto-planetary disk from which the planets were
formed," said Lisse. "Much of the carbon in the comet appears to be locked up
in carbon dioxide ice. We will know even more in late July and August, when
the comet begins to warm up near the water-ice line outside of the orbit of
Mars, and we can detect the most abundant frozen gas, which is water, as it
boils away from the comet."

NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., manages the
Spitzer Space Telescope mission for NASA's Science Mission Directorate in
Washington. Science operations are conducted at the Spitzer Science Center at
the California Institute of Technology (Caltech) in Pasadena. Data are
archived at the Infrared Science Archive housed at the Infrared Processing
and Analysis Center at Caltech. Caltech manages JPL for NASA.

For more information about Spitzer, visit:


Learn more about NASA's Comet ISON Observing Campaign:


NASA's Comet ISON Toolkit:


Received on Tue 23 Jul 2013 04:34:51 PM PDT

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