Cassini spacecraft finds plastic ingredient on Saturn's moon Titan

September 30, 2013
NASA's Cassini spacecraft looks toward the night side of Saturn's largest moon and sees sunlight scattering through the periphery of Titan's atmosphere and forming a ring of color. Credit: NASA/JPL-Caltech/Space Science Institute

( —NASA's Cassini spacecraft has detected propylene, a chemical used to make food-storage containers, car bumpers and other consumer products, on Saturn's moon Titan.

This is the first definitive detection of the plastic ingredient on any moon or planet, other than Earth.

A small amount of propylene was identified in Titan's lower by Cassini's composite infrared spectrometer (CIRS). This instrument measures the infrared light, or heat radiation, emitted from Saturn and its moons in much the same way our hands feel the warmth of a fire.

Propylene is the first molecule to be discovered on Titan using CIRS. By isolating the same signal at various altitudes within the lower atmosphere, researchers identified the chemical with a high degree of confidence. Details are presented in a paper in the Sept. 30 edition of the Astrophysical Journal Letters.

"This chemical is all around us in everyday life, strung together in long chains to form a plastic called polypropylene," said Conor Nixon, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., and lead author of the paper. "That plastic container at the grocery store with the recycling code 5 on the bottom—that's polypropylene."

CIRS can identify a particular gas glowing in the lower layers of the atmosphere from its unique thermal fingerprint. The challenge is to isolate this one signature from the signals of all other gases around it.

The detection of the chemical fills in a mysterious gap in Titan observations that dates back to NASA's Voyager 1 spacecraft and the first-ever close flyby of this moon in 1980.

Credit: NASA's Goddard Space Flight Center

Voyager identified many of the gases in Titan's hazy brownish atmosphere as hydrocarbons, the chemicals that primarily make up petroleum and other fossil fuels on Earth.

On Titan, hydrocarbons form after sunlight breaks apart methane, the second-most plentiful gas in that atmosphere. The newly freed fragments can link up to form chains with two, three or more carbons. The family of chemicals with two carbons includes the flammable gas ethane. Propane, a common fuel for portable stoves, belongs to the three-carbon family.

Previously, Voyager found propane, the heaviest member of the three-carbon family, and propyne, one of the lightest members. But the middle chemicals, one of which is propylene, were missing.

As researchers continued to discover more and more chemicals in Titan's atmosphere using ground- and space-based instruments, propylene was one that remained elusive. It was finally found as a result of more detailed analysis of the CIRS data.

"This measurement was very difficult to make because propylene's weak signature is crowded by related chemicals with much stronger signals," said Michael Flasar, Goddard scientist and principal investigator for CIRS. "This success boosts our confidence that we will find still more chemicals long hidden in Titan's atmosphere."

Cassini's mass spectrometer, a device that looks at the composition of Titan's atmosphere, had hinted earlier that propylene might be present in the upper atmosphere. However, a positive identification had not been made.

"I am always excited when scientists discover a molecule that has never been observed before in an atmosphere," said Scott Edgington, Cassini's deputy project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This new piece of the puzzle will provide an additional test of how well we understand the chemical zoo that makes up Titan's atmosphere."

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5 / 5 (3) Sep 30, 2013
May be the aliens use PP bags to pack their lunch!! Ha Ha !!
2.2 / 5 (10) Oct 01, 2013
May be the aliens use PP bags to pack their lunch!! Ha Ha !!

That, or they have some aging celebrities. ;)
1.9 / 5 (9) Oct 01, 2013
"Cassini's mass spectrometer, a device that looks at the composition of Titan's atmosphere, had hinted earlier that propylene might be present in the upper atmosphere."

I assume that Cassini needs to fly through Titan's upper atmosphere to make use of the mass spectrometer, or am I mistaken?

1.4 / 5 (9) Oct 01, 2013
Not really. The spectrometer simply analyses the light reflected from Titan's upper atmosphere for spectral lines. Cassini is not aerodynamic and cannot fly through any atmosphere.
1 / 5 (10) Oct 01, 2013
Voyager identified many of the gases in Titan's hazy brownish atmosphere as hydrocarbons, the chemicals that primarily make up petroleum and other fossil fuels on Earth.

You'd think the detection of hydrocarbons on other worlds would falsify the silly belief in "fossil fuels", sadly more epicycles are added.
5 / 5 (3) Oct 01, 2013
Actually restrider was correct. The mass spectrometer on cassini is a direct measurement instrument that examines particles around the spacecraft as it passes through the ionosphere and magnetosphere of the planet and moons.

Here's an official page on Cassini:

Here's a quote:

The fields and particles instruments take in-situ direct sensing measurements of the environment around the spacecraft measuring magnetic fields, neutral and charged particle composition, the composition of dust particles and the properties of plasma waves

The INMS instrument is a quadrupole mass analyzer, in which particles must actually pass between the sensor rods inside the machine.

The orbiter did not go very far into Titan's atmosphere though. The measurements were taken 950 km above Titan's surface, basically measuring the outer fringe of Titan's atmosphere.
4.8 / 5 (4) Oct 01, 2013
The infra-red instrument used to make the above discovery is standard remote sensing light wave spectrometer, that looks at the spectrum of light from a distance.

The terms "spectrometer" and "mass spectrometer" refer to very different types of instruments.

The mass spectrometer actually filters massive particles according to their mass, rather than looking at wavelengths of light.

Cantdrive, you should go check out the pages related to mass spectrometers. You would learn a lot about the modern study of plasma and ions in space. Nobody was able to directly measure space plasma in Alfven's time, which led to some of his misconceptions.
1 / 5 (8) Oct 01, 2013
What misconceptions are you referring?
Also, Alfven worked and wrote into the 1990's, what do you mean "Alfven's time"?
5 / 5 (2) Oct 02, 2013
Alfven's misconceptions are well known, and I know you know them. Most of them deal with "alfven-klein cosmology". See that section of the following wiki page for more details. Specifically note the criticisms of Jim Peebles:


Alfven just didn't like the new (at that time it was new) theory of General Relativity and he didn't accept it, despite growing evidence to support it. We have now demonstrated through experiment many predictions of GR, which rule out the Alfven-Klein model in several indisputable ways.

I would be more inclined to accept AWT than PC, since AWT doesn't make any testable claims, and therefore can't be disputed any more than Christianity can. PC makes enough specific claims which can be physically disproven through observations to completely invalidate it. You can only continue to believe in PC if you ignore all observations since 1960.
1 / 5 (6) Oct 07, 2013
Yep, but don't forget to read the next section;
"In the 1980s and 1990s, Alfvén and Anthony Peratt...."
Talked about outdated. Am I relegated to accept every notion a man suggests? I repeatedly refer to how the plasma is modeled, whether theoretical of the "standard" theory, or more laboratory and in situ based that Alfven supported. Where PC gets more theoretical I tend to drift toward EU, a bit of WT and other more classical approaches. As far as the metaphysics of GR and the BB with all their ridiculousness, it's a shame to science they're held in such regard.

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