Enceladus: Hotter Chemical Plume Found

Initial results of Cassini’s March 12 flyby of Enceladus have been published.  You can watch a replay of today’s press briefing, read the blog, and read illustrated bulletins about the organic material, chemical signatures, hot spot locations, the stellar occultation (see also the Quicktime animation).  Another article shows the plume locations.  An astrobiologist (Chris McKay) added his speculations about life.  The encounter preview page contains links to more information, including the flyby details (PDF), and the video page contains an eye-grabbing animation of the flyby sequence as it was programmed with each instrument’s activities.  Here is the rundown on the major findings:

1. The hot spots align predominantly right along the “tiger stripe” fractures at the south pole.
2. The highest temperatures lie at certain points along the tiger stripes where plumes have been seen.
3. Temperatures are hotter than earlier measurements: -135° F. (compared to a background temperature of less than -300° F.).  This indicates a great deal of energy is being transferred from the interior.
4. Some transverse warm areas were detected, oriented perpendicular to the stripes.
5. The material jets out at over 1000 mph and was strong enough to produce a measurable torque on Cassini, 120 miles away.
6. Though most of the jets consist of ice grains 1/10,000 of an inch in diameter, simple organics were detected (methane, carbon monoxide, carbon dioxide, formaldehyde) and some complex organics (propane, propyne, acetylene).
7. No ammonia was found.  Scientists had hoped that ammonia might depress the melting point of water and make the plumes easier to explain.
8. The plumes appear to emerge from localized regions about half a tennis court in area, but extended along narrow strips within the tiger stripes.

Though this brief press flurry did not mention it, Cassini also took a gorgeous mosaic of the north pole of Enceladus – including areas not previously imaged at high resolution.  The mosaic can be seen at the Imaging Team catalog page for March 13.
    Leader of the INMS (Ion and Neutral Mass Spectrometer) instrument Hunter Waite (Southwest Research Institute, San Antonio) was most surprised that the chemical brew emerging from the plumes resembles that of a comet.  Enceladus is obviously not a comet.  He described the cocktail as being “like carbonated water with an essence of natural gas.”
    At this time, no one speculated about the origin of the plumes or how they could be maintained for billions of years.  John Spencer of the CIRS team (Composite Infrared Spectrometer) did say that the temperatures could be hotter further down enough to allow for liquid water.
    Water – that was the magic word.  The astrobiologists kicked into gear.  “Enceladus has got warmth, water and organic chemicals, some of the essential building blocks needed for life,” said Dennis Matson, project scientist (cf. 03/19/2008).  “We have quite a recipe for life on our hands, but we have yet to find the final ingredient, liquid water, but Enceladus is only whetting our appetites for more.”  These thoughts were also echoed on the NASA TV press briefing as if scripted.  Matson and astrobiologist Chris McKay in a related feature talked about the feasibility of exotic life and contrasted the “primordial soup theory” with the “deep sea vent theory.”  Either theory would work on Enceladus, they claimed.  The confidence that life is nearly inevitable contrasted starkly against an admitted background of ignorance and controversy: “We don’t know how long it takes for life to start when the ingredients are there and the environment is suitable, but it appears to have happened quickly on Earth,” the article said.  Then, with a bow to a Darwin metaphor, it continued, “So maybe it was possible that on Enceladus, life started in a ‘warm little pond’ below the icy surface occurring over the last few tens of millions of years.”  More observations will be needed, of course.
    And indeed, more observations are on the way.  A series of close encounters with Enceladus has been planned during Cassini’s extended mission, which begins (pending final approval) on July 1.  The next is in August.  The cameras, which were not the prime instruments for the recent flyby, will have a chance to take extreme high-resolution photos of the tiger stripes, and the Cosmic Dust Analyzer (CDA), which failed to operate, will get one more optimal chance to collect geyser particles.  Seven more close flybys are planned through 2009.    The March 12 encounter dipped 30 miles from the surface at closest approach; some of the daring flybys to come will be even closer – fast, low, and maybe even more thrilling.  The little 300-mile-wide moon Enceladus seems to be a strong contender for Best Actor of the Saturn awards.

Good grief, Enceladus has nothing to do with life.  This is the distracting emotional appeal like the scantily-clad woman beside the truck at the used car lot.  NASA throws in the distraction at every mention of the word water in a vain belief that it will garner public support for the space program.  As could be expected, right on cue, National Geographic News picked up on this theme as the major aspect of the story.  Dave Mosher at Space.com even said “seeds of life found near Saturn.”  Incredible.  All they found was poison gas like methane and acetylene, folks!  Go experiment with your barbecue.  Write us if anything crawls out except the spider that took up residence there over the winter.
    The scientists totally avoided the age issue today.  John Spencer has frankly admitted being completely baffled and embarrassed that the science community has no answer for where this little moon got its energy, or for how it could maintain it over billions of years.  Their plight has only gotten worse since the discovery of the plumes in 2005.  Recall that yesterday (03/25/2008, footnote to main entry) we highlighted a new paper in next month’s Icarus that struck down both tidal heating and radioactivity – the leading theoretical possibilities – as plausible sources of the heat.  That makes the scientists’ focus on exotic life even more distracting, as if the emperor, once exposed, quickly points to the sky and waxes eloquent about how the cloud shapes appear so very lifelike.  Let’s watch instead how his minions are going to robe their little embarrassment now that King Billions-of-Years has mooned the crowd.