There's a new CHARM presentation available:

Huygens Probe: One Year Later
by Dr. Ralph D. Lorenz
(49 pages; ~6Mb PDF)

Astrophysics, abstract
astro-ph/0602512

From: Andrew Prentice [view email]

Date (v1): Thu, 23 Feb 2006 11:04:48 GMT (262kb)
Date (revised v2): Fri, 24 Feb 2006 00:56:14 GMT (262kb)

Titan at the time of the Cassini spacecraft first flyby: a prediction for its origin, bulk chemical composition and internal physical structure

Authors: A.J.R. Prentice

Comments: This paper was submitted to the MNRAS on 27 October 2004 to coincide with the Cassini spacecraft first flyby of Titan. It was assigned the ref. no. ME1249 but was not published.

It is proposed that Titan condensed in a solar orbit, prior to capture by Saturn. Hyperion is the remnant of a Rhea-sized native moon of Saturn that was destroyed by impact with Titan. The Titanian surface should be mostly smooth and crater-free. Titan is predicted to be a 2-zone satellite with a rock-graphite core and water ice mantle. New calculations completed since ME1249 yield an axial moment-of-inertia coefficient C/MR^2 = 0.317 +/- 0.004.

This prediction is to be tested during the first dedicated radio science flypast of Titan on 27 February 2006. Cassini should discover mass anomalies in the upper mantle of Titan that correspond with the burial sites of ~ 2 former native moons of Saturn

I report the results of a new set of calculations for the gravitational contraction of the proto-solar cloud to quantify the idea that Titan may be a captured moon of Saturn (Prentice 1981, 1984).

It is proposed that Titan initially condensed as a secondary embryo in the same proto-solar gas ring from which the central solid core and gaseous envelope of Saturn were acquired. At the orbit of Saturn, the bulk chemical constituents of the condensate are rock (mass fraction 0.494), water ice (0.474), and graphite (0.032). The mean density is 1523 kg/m^3. Structural models for a frozen Titan yield a mean density of 2095 kg/m^3 (chemically homogeneous case) and 1904 kg/m^3 (fully differentiated 2-zone case). The agreement to one percent of the latter value with the observed mean density suggests that Titan is indeed a fully differentiated satellite. The value of C/MR^2 for this model is 0.316.

It is predicted that Titan has no internal ocean or induced magnetic field but it may possess a small native dipole field of magnitude 2 x 10^11 Tesla m^3 due to thermoremanent magnetization fed by the ancient magnetic field of Saturn.

Capture of Titan was achieved by gas drag at the edge of the proto-Saturnian envelope at a time when that cloud had a radius close to the present orbital size of Titan. Collisional drag was also probably an important agent in securing the capture of Titan.

Perhaps Hyperion is the shattered remnant of a pre-existing native moon of Saturn that was destroyed on the arrival of Titan. Titan should thus have much the same appearance as Triton, being nearly smooth, crater-free and streaked with elemental carbon (Prentice 2004a).

http://arxiv.org/abs/astro-ph/0602512

OK, I figured out "CHARM" (Cassini-Huygens Analysis and Results of the Mission )

What does "datation" mean. (See p. 3: “Nitty gritty details like datation of engineering and science data offset by 375 ms.”)

A really interesting presentation, thanks for posting it. I think that Ralph Lorenz has a promising future in presenting planetology results to a wide audiences.

TTT

His book on Titan was excellent.

Saw these pics in the CHARM presentation, and though they would make a good blink (yep, I'm sure its already been done before, but I can't help myself...)

Blink of Huygens DISR mosaic over SAR track

Why two?

The first: The second: ?

A.J.R. Prentice has been publishing abstracts and articles for 20+ years based on his own highly unorthodox solar system cosmogeny. His work is NOT generally accepted, but from what I've seen (and in my own opinion) is very fringe science, but still science. More like Tommy Gold's oddball theories, rather than the people who believe the earth's core is a uranium powered reactor or Hoyle with his Germs from Space ultra-panspermia ideas.

I have never seen a systematic review of Prentice's ideas, with an "honest accounting" of his hits and misses. He certainly makes a LOT of predictions, and later pats himself on the back a lot about things he correctly predicted. I'm inclined to think his "hits" are more on the order of "I.E.D. Sharpshooting" than real marksmanship. Let enough shrapnel fragments fly and you're bound to get a lot of hits. But whether he's had some solidly based predictions that came out correct, I just don't know.

EXCELLENT idea! Notice that Lorenz gives "an amateur blogger" credit for first noticing the correspondence between the SAR cat scratches and the dark streaks in Huygens' photos? I believe he's referring to Jason.

In this connection, though, the DISR team has a startling new EGU abstract out ( http://www.cosis.net/abstracts/EGU06/08846/EGU06-J-08846.pdf ) which claims that, properly analyzed, the dark arroyos in the Huygens photos look dark not because they actually have a residue of dark goo on their floors, but just because they're steep-walled enough to be seriously shadowed even in the blurry illumination of Titan's sky:

"While DISR images of the riverbed area originally exhibit a contrast of a few per cent, the corrected contrast of true surface brightness is 10–20 %. Based on the surface illumination implied by the modelled radiance, we render various digital terrain models to investigate the contribution of topographic shading to the observed contrast. We find that a moderate terrain with slopes of up to 20 degrees yields surface brightness variations which are comparable in magnitude to the observations. We present models for the elevation profile of Titan river beds that can reproduce the observed brightness profiles without assuming local variations in surface albedo, i. e., without any 'dark stuff' in the river beds."

I don't know how to mesh this with the unquestionable darkness of the playa's mud.

I think he's actually referring to Rene Pascal who had done a fair bit of amateur processing of the Huygens' raw images.

Yeah, the photo mosaic is Pascal's, but I think it was Jason who first noticed the correlation between the dark Huygens streaks and the cat scratches.

I think 'amateur blogger' hardly expresses the level of commitment, expertise or professionalism of both of these guys!

There must be a better way to put it - 'independent researcher' sounds like one of the anti-gravity green ink brigade. The Victorians had gentleman scientists, after all...

Bob Shaw

Well, whatever you call them, they noticed something important that probably couldn't have been caught any other way, since the spatial resolution of Cassini's own near-IR photos was too fuzzed up by the haze to allow determination of the actual visual albedo of the Cat Scratches.

I remain puzzled, though, by the apparent belief of the DISR team that the dark appearance of the arroyos in the Huygens photos can be entirely explained by topographic shadows -- since clearly Cassini is seeing similar dark linear marks (albeit of a much larger size) that can't possibly be due to topographic shadowing.

I think he is crediting both, and really crediting the forum. This is a good sign of unjealous cooperation, and as I have said before, Cassini herself will ultimately sit on the textbook credit for the discoveries. Cudo's to everyone.

That said, I don't think the agreement between the radar and Huygens images is tight enough to declare victory.

I have a LOT to say about this presentation, but let me start with page 28, "Periodic Spin modulation of AGC allows diagnosis of spin rate and direction".

This caught my eye because, as one who has a lot of experience with analogue to digital signal processesing, these clipped waveforms are highly indicative of aliasing due to inadequate high frequency filtering. I can't conclude this is true from these brief waveforms, (especially since the two images have diffferent point mean counts(??!)), but the entire field signal should tell the story: Basically, if the pattern changes are coincidental with duty cycle changes in the Huygens computer data aquisition program, the patterns featured here are more likely due to signal aliasing than antenna cycling. This can be easily checked by a real-time comparison between the signal signature and the various duty cycles.

Likewise the noise in the AGC voltage record on page 27 - the noise reduction at the time of the 'landing' IS coincidental with a change in the duty cycle broadcasting images (the rate was much slower after landing.).
Since images were not broadcast in the early moments of the descent, this correlates somewhat with the lower noise levels in the first ~20 minutes as well.

http://www.spaceref.com/news/viewpr.html?pid=19162

An international team of planetary scientists may have solved the mystery of why the atmosphere of Saturn's moon, Titan, is rich in methane.

There's another new CHARM presentation posted. Not very science-y, but it does have an update on propellant remaining (chart 3).

http://saturn.jpl.nasa.gov/multimedia/prod...ARM_Webster.pdf

Bart