dark green organic material

If we saw this on Mars, we would just call it the mineral “ olivine ”

But because it is on Enceladus, NASA allows them to call it “ organic ”

Science 10 March 2006:
Vol. 311. no. 5766, p. 1388
DOI: 10.1126/science.311.5766.1388
Introduction to special issue
Tiger, Tiger, Burning Bright
Joanne Baker

“Earlier Earth-based and Voyager space probe images revealed that Enceladus' surface is icy and complex. Old cratered terrains butt up against newly resurfaced smooth ice flows. So Cassini scientists hoped to see signs of recent activity and possibly ice volcanism. As the papers in this special issue show, their anticipation was rewarded. In three flybys, in February, March, and July 2005, Cassini trained its instruments on Enceladus. The first two cruises descended to about 1000 and 500 km above the moon's equator. Onboard cameras snapped images of lines of folded mountain ridges and cracked white ice plains streaked with dark green organic material. The magnetometer saw signs of ions leaking out from Enceladus'atmosphere, and it localized, in the second flyby, a strong outflow from the south pole. The trajectory of the third flyby on 14 July 2005 was then adjusted to fly through the emergent gas just 168 km above the south pole.”

http://www.sciencemag.org/cgi/content/summary/sci;311/5766/1388

A challenge to the imagination.

Consistent use of the term, without reservation.

"a parallel set of linear trenches stained with dark organic material. From these warm vents, water vapor, ice, and dust particles are lofted in a spectacular plume,"

Common use of the term perhaps. Such a tiny satellite for a spectacular display.

Hi Henry

I totally agree with your comments above.

Winston

Enceladus' polar hot spot combined with the organic compounds are a strong indicator for biology. At 500km wide, it is quite small, yet seems to have everything needed for life.

Josh

The article got it wrong according to Jason Perry, who ran the former Titan Today blog and is part of the Cassini team. The dark green streaks referred to are actually the dark blue-green water ice deposits in the tiger stripes. The fourth paragraph in that article makes that a bit more clear also though, referring specifically to the deposits being in the tiger stripes as opposed to being other separate streaks of some kind.

http://www.unmannedspaceflight.com/index.php?showtopic=2379&st=30#

Oh well, that said, there are still the other organics found in the plumes themselves, which is still a significant discovery, of course.

The article got it wrong according to Jason Perry, who ran the former Titan Today blog and is part of the Cassini team.

Some som blogger, not an author of one of the several papers, says the article got it wrong. Whoopie-do, case solved. I'll just wait for the official correction from Science.

http://www.blogger.com/profile/2996844

I'm just saying that, according to Jason, the article itself apparently got it wrong, simply getting the results of two instruments mixed up.

Jason is a well-known and highly respected member of the Cassini team, I've followed his work for a long time. He's not just "some blogger," far from it.

The article is not an original paper itself, it is only an intro to the special issue of the magazine.

One of the original papers linked to after the article does mention "light organics" on the surface in the abstract I found, so I'm not quite sure now actually just what is what. I can try to check some of the other original papers again also however. But, the tiger stripes having blue or blue-green coloured ice deposits in them was already well-known also, as reported by the Cassini team and discussed previously here and elsewhere.

Paul, Jason is a 22 year-old undergraduate geology student, who works part-time in the graphics art department at Cassini (Arizona State). His word should not be taken over those of the lead Scientists, who are PhD's of many years experience. These papers have suffered many revisions and approvals from many levels during the refreeing process.

Consider the source.

Ok, but the article you quoted from is just an intro written by another Science magazine writer, it is not one of the papers themselves, or written by any of the lead scientists, just a summary of them, and perhaps prone to some mistakes, that's all.

I asked Jason about this again. His responses:

"The simple organics seen by VIMS are found only within the tiger stripes in Enceladus' south polar region, and at no other location. This identification is based on two small absorption bands at 3.44 and 3.52 microns, attributed to short-chain organics. Again, the blue-green color of the tiger stripes is due to coarse-grained water ice, NOT these short-chain organics. The author of the special section intro did not interpret our results correctly."

"I should point out that Cassini ISS and VIMS have found other examples of blue-green material on the surface, identified as coarse-grained ice. VIMS found NO evidence for the 3.44 and 3.52 micron absorption bands at these locations. Images of these blue-green areas indicate that these areas correspond with outcrops along canyon and fracture walls as well as at the tops of ridges, likely areas where the downslope movement of Enceladus' fine-grained regolith has exposed the coarser-grained bed ice."

So the organics are (only) within the tiger stripes, but the blue-green colouring in the tiger stripes and elsewhere is from the ice deposits. This still suggests to me though that abundant organics are present in the subsurface water, and being expelled from the vents, being deposited on the surface within the tiger stripes. That itself is very interesting I think.

It does seem like there are subsurface organics, one way or the other, on Enceladus. They aren't as obvious as the burnt-red colored ejecta from Europa's "stripes". Those are long cracks in the ice that are full of obvious organics. Enceladus is amazing and deserves more research, but I still think we need a lander/sampler for Europa.

I just read about the Phoenix Lander, due for launch next year

[link]

I like the soft landing, but I hate that it won’t be able to move around: it will be stuck right where it happens to land.

I too want a soft landing on Europa. From what I have seen, it will be hard to find a nice spot to land on Europa. But on Europa, I think that a rover will be absolutely necessary. We need to be able to crawl over to one of those suspicious organic-looking structures, and really see what’s up.

Maybe by the time the Europa probe is built, the micro rovers will be ready to go, too. Be nice to turn ten tiny robotic spiders loose on Europa, to scout out the landing zone.