Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NASA Research Estimates How Long Titan's Chemical Factory Has Been in Business

25.04.2012
Saturn's giant moon Titan hides within a thick, smoggy atmosphere that's well-known to scientists as one of the most complex chemical environments in the solar system. It's a productive "factory" cranking out hydrocarbons that rain down on Titan's icy surface, cloaking it in soot and, with a brutally cold surface temperature of around minus 270 degrees Fahrenheit, forming lakes of liquid methane and ethane.

However the most important raw ingredient in this chemical factory - methane gas, a molecule made up of one carbon atom joined to four hydrogen atoms – should not last for long because it's being continuously destroyed by sunlight and converted to more complex molecules and particles.


Titan's dense atmosphere shrouds the moon beneath a tan haze in this image. Saturn's third-largest moon Dione can be seen through the Titan haze in this view of the two posing before the planet and its rings from NASA's Cassini spacecraft. The rings, viewed nearly edge-on, appear as a horizontal line through the image. The rings cast shadows on Saturn, which appear as dark lines at the bottom of the image. The Cassini spacecraft narrow-angle camera made this image on May 21, 2011 at a distance of approximately 1.4 million miles (2.3 million kilometers) from Titan. Credit: NASA/JPL-Caltech/Space Science Institute

New research from NASA-funded scientists attempts to estimate how long this factory has been operating. The results are presented as two papers appearing in the April 20 issue of the Astrophysical Journal.

These papers used data from two instruments onboard NASA's Cassini spacecraft in orbit around Saturn and one instrument on the European Space Agency's Huygens probe that landed on Titan’s surface in January, 2005. All three instruments were built at NASA's Goddard Space Flight Center in Greenbelt, Md. A paper led by Conor Nixon of the University of Maryland, College Park uses infrared signatures (spectra) of methane from Cassini's composite infrared spectrometer to estimate how much "heavy" methane containing rare isotopes is present in Titan's atmosphere.

Isotopes are versions of an element with different weights, or masses. For example, carbon 13 is a heavier (and rare) version of the most common type of carbon, called carbon 12. Occasionally, a carbon-13 atom replaces a carbon-12 atom in a methane molecule. Because methane made with carbon 12 is slightly lighter, the chemical reactions that convert it to more complex hydrocarbons happen a bit faster. This means carbon-12 methane gets used up at a slightly faster rate than heavy carbon-13 methane, so the concentration of heavy methane in Titan's atmosphere increases slowly.

By modeling how the concentration of heavy methane changes over time, the scientists predicted how long Titan's chemical factory has been running.

"Under our baseline model assumptions, the methane age is capped at 1.6 billion years, or about a third the age of Titan itself," said Nixon, who is stationed at NASA Goddard. "However, if methane is also allowed to escape from the top of the atmosphere, as some previous work has suggested, the age must be much shorter - perhaps only 10 million years - to be compatible with observations." Both of these scenarios assume that methane entered the atmosphere in one burst of outgassing, probably from the restructuring of Titan's interior as heavier materials sank towards the center and lighter ones rose toward the surface.

"However, if the methane has been continuously replenished from a source then its isotopes would always appear 'fresh' and we can't restrict the age in our model," adds Nixon. Possible sources include methane clathrates, basically a methane molecule inside a "cage" or lattice of ice molecules. Methane clathrates are found in the frigid depths of Earth's oceans, and some scientists think there could be an ocean of liquid water mixed with ammonia (acting as antifreeze) beneath Titan's water-ice crust. If this is so, methane might be released from its clathrate cages during the eruptions of proposed 'cryovolcanoes' of water-ammonia slurry, or more simply could slowly seep out through fractures in the crust.

The second paper by Kathleen Mandt of the Southwest Research Institute, San Antonio, Texas, and colleagues also models the time-evolution of methane. In this work, the concentration of the heavy methane is determined from measurements by Cassini's ion and neutral mass spectrometer, which counts molecules in the atmosphere of different masses (weights). Measurements made by the Huygens gas chromatograph mass spectrometer, which also counts molecules of different masses, were used to constrain the impact of escape on the heavy methane in the atmosphere.

"We compute that, even if methane has been replenished from the interior over time to match or exceed the amounts fed into the atmospheric chemical factory, the process must have been running for a maximum of one billion years," said Mandt. "If the process had started any earlier, we would see a build-up of methane in the lakes on the surface and in the atmosphere beyond what is observed today."

Together these papers add important new perspectives and constraints on the history of Titan's methane atmosphere, confirming that it must have formed long after Titan itself. Previous work considering the evolution of Titan's interior has predicted the last major methane eruption occurred 350 million to 1.35 billion years ago, while crater counting has put the age of the current surface at 200 million to one billion years. (Crater counting works on the principle that an older surface has more craters, just as the longer you're in a paintball game, the more hits you'll get.)

The present work for the first time estimates the methane age from the atmosphere itself, at less than one billion years, considering both papers.

This research was supported by the NASA Cassini Mission and the NASA Cassini Data Analysis Program grant NNX09AK55G. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington.

All of Cassini's raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/ .

For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

Bill Steigerwald
NASA's Goddard Space Flight Center, Greenbelt, Md.
William.A.Steigerwald@nasa.gov

Bill Steigerwald | EurekAlert!
Further information:
http://www.nasa.gov
http://www.nasa.gov/mission_pages/cassini/whycassini/factory20120420.html

More articles from Physics and Astronomy:

nachricht When helium behaves like a black hole
22.03.2017 | University of Vermont

nachricht Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars
22.03.2017 | International Centre for Radio Astronomy Research

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>