Starship Asterisk*

Wow, look at ALL those crater chains on Enceladus, esp. in the 'tiger stripe' region. Fragmented meteor impacts? Nah!!!! Nessy? Maybe...

"Tiger stripe" is a colorful but useless term.

The prominent feature in this photo is a rift valley.

To the right side of the picture it passes into a triangular region and thence into two symmetrical deformed belts at approximately 120 degrees to the rift trend. Although the symmetry of these features suggest they formed as a rift-rift-rift "triple junction", the rumpled appearance of the junction and other two arms rather suggests they are now undergoing folding (contraction). This is at right angles to the tensional axis, which is what one would expect in regional deformation.

So nothing to do with tigers, everything to do with some sort of plate tectonics.

The caption explains: "This newly released raw image shows at least one type of false artifact, however, as seeming chains of craters are not so evident in other concurrently released images of the same region." How are they false artifacts? They are all different lengths and slightly curved in different ways - not what you'd expect from a photographic artifact anyway.

http://apod.nasa.gov/apod/ap081014.html
Looks like something made those dents on the surface.

Orin

Looks to me like the same sort of "Noise" one might expect to see looking at linear features through a screen that is angled slightly different than the linear angles

Is that really a shadow in the main rift? (Down with tiger stripes!) It looks like liquid may have oozed out and froze in place, but it looks too dark for ice. Or is it indeed just pure black shadow with digital noise?

BMAONE23 wrote:Looks to me like the same sort of "Noise" one might expect to see looking at linear features through a screen that is angled slightly different than the linear angles

would you mind explaining your logic here.

Hello all!

I am very happy to be a new member and know I will enjoy the experience imensely.

I have been retired for some time but have just recently discovered the joy of astronomy and the overwhelming expanse and mystery of space.

A rank amature, I have plunked APOD on the desktop of my PC and find it not only beautiful and awesome, but a fantastic source of new knowledge and learning.

At my age a preplanned, strategic learning course might be too disciplined and boring for my temperment but, the many links in APOD provide many surprises and considerable learning.

Hence my first comment - What I think on this image are being called "crater chains" appear to be lines of dimples that seem very uniform and equidistant. This leads me to doubt that they were formed by the impact of objects from space but rather that they may have been formed (each instance) by such an object entering ata low angle and skipping on impact. Much as a child might skip a flat stone over the surface of a pond.

This is probably a silly idea and in no way helps explain why these "dimples" appear so uniform insize. - Perhaps we are looking at whale or other blowholes (A vent to permit the escape of air or other gas.) rather than tiger stripes.

Anyway this is a great site and the mysteries of space sure beat Agatha Christie and Ruth Rendell and their "Golden Oldies"by being forever refreshed.

Best regards,

Coolbear

http://antwrp.gsfc.nasa.gov/apod/ap081014.html

Yep, it's a shadow.

I don't think I see any significant digital noise, but it looks like the APOD was stretched from a slightly smaller image (try viewing the "full size" version). This creates some artifacts.

It's interesting how the highlight of the Cassini tour was supposed to be Titan, but lately it seems like Encelaus has been stealing the show.

By the way, in the next few months NASA will select the next "flagship" mission. It is likely to be either a Jupiter or a Saturn orbiter, designed in particular for detailed observations of either Europa or Titan. Galileo and Cassini both were more general purpose probes.

The neatest proposal so far includes an orbiter and a balloon for exploring Titan from within the atmosphere, as well as a lander that could potentially set down in a methane/ethane lake.

Welcome to the site Coolbear. I agree, it's a fantastic way to learn about astronomy in bite-size chunks.

The normal way crater chains form is for an object to break up into several large pieces that then separate into a train of objects due to tidal forces. The comet Shoemaker-Levy 9, which hit Jupiter several years ago in several large chunks is a great example.

As these chunks fall towards the surface, the hit in successively different locations due to the motion and/or rotation of the planet or moon, forming a nice straight line.

However, that doesn't seem to be what happened here. Take a look at these successive pictures, in full size:

The APOD:


Over lapping frame:


Comparing these frames, it does look like the apparent circles are an artifact of some kind from processing small features. I'd guess from sharpening, as there's clear sharpening "jaggies" in other parts of the images.

I vote for artefact.
Note that the apparent chains are all at right angles to each other. These orientations on the processed pic emphasise this distortion.
Also, see the top edge of the major stripe, where it is high lighted by the sun. Several runs of jagged edges, simulating a crater chain, where none could be, along a line that is parallel to one orientation of the apparent chains.

John

This Link shows some more images from the fly by and in my opinion indicateds that the "Chains" are artifact in nature and not realy crater chains

If you magnify the picture enough; the dents look more like bumps; so I'm agreeing that they are probably artifacts.

Orin