Saturnian Moon Shows Evidence of Ammonia

Feature

July 22, 2009

Saturnian Moon Shows Evidence of Ammonia

Data collected during two close flybys of Saturn's moon Enceladus by NASA's
Cassini spacecraft add more fuel to the fire about the Saturnian ice world
containing sub-surface liquid water. The data collected by Cassini's Ion and
Neutral Mass Spectrometer during Enceladus flybys in July and Oct. 2008, were
released in the July 23 issue of the journal Nature.

"When Cassini flew through the plume erupting from Enceladus on October 8
of last year, our spectrometer was able to sniff out many complex chemicals,
including organic ones, in the vapor and icy particles," said Hunter Waite, the
Cassini Ion and Neutral Mass Spectrometer Lead Scientist from the Southwest
Research Institute in San Antonio, Texas. "One of the chemicals definitively
identified was ammonia."

On Earth, the presence of ammonia means the potential for sparkling clean
floors and counter tops. In space, the presence of ammonia provides strong
evidence for the existence of at least some liquid water.

How could ammonia equate to liquid water inside an ice-covered moon in one
of the chillier neighborhoods of our solar system? As many a homeowner
interested in keeping their abodes spick and span know, ammonia promptly
dissolves in water. But what many people do not realize is that ammonia acts as
antifreeze, keeping water liquid at lower temperatures than would otherwise be
possible. With the presence of ammonia, water can exist in a liquid state to
temperatures as low as 176 degrees Kelvin (-143 degrees Fahrenheit).

"Given that temperatures in excess of 180 Kelvin (-136 degrees Fahrenheit)
have been measured near the fractures on Enceladus where the jets emanate,
we think we have an excellent argument for a liquid water interior," said Waite.

Cassini discovered water vapor and particles spewing from Enceladus in 2005.
Since then, scientists have been trying to determine if the plume originates from
a liquid source inside the moon or is due to other causes.

"Ammonia is sort of a holy grail for icy volcanism," said William McKinnon,
a scientist from Washington University in Saint Louis, Missouri. "This is the first
time we've found it for sure on an icy satellite of a giant planet. It is probably
everywhere in the Saturn system."

Just how much water is contained within Enceladus' icy interior is still up for
debate. So far, Cassini has made five flybys of Enceladus, one of the chief
targets for Cassini's extended mission. Two close flybys are scheduled for
November of this year, and two more close flybys are scheduled for April and
May or 2010. Data collected during these future flybys may help settle the
debate.

"Where liquid water and organics exist, is there life?" asked Jonathan Lunine a
Cassini scientist from the University of Arizona, Tucson. "Such is the case for
Earth; what was found on Enceladus bolsters this moon's promise for
containing potential habitable environments."

The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Cassini orbiter was designed,
developed and assembled at JPL. JPL manages the mission for the Science
Mission Directorate at NASA Headquarters in Washington.
More information about the Cassini mission is available at
http://www.nasa.gov/cassini or http://saturn.jpl.nasa.gov .

Media Contacts:
DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

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