[X] My Assistant

[Steffen]

Which device made the Huygens probe spin underneath its satellite?
I read that's the way how 360° images were made during descent...

[Big_Gazza]

These sections of Huygens descent imaging triads (from the near-vertical camera) look like a droplet in the process of settling under gravity and draining away. Could it be either moisture (liquid methane) from the surface thrown up from the probes impact, or maybe condensation on the inside of the lens caused by cooling effect of low ambient temperature?

If the former, surely this proves that liquid does indeed lie just under the surface on the "dry lakebeds".

I'm sure these images have caused debate before, but I can't find mention anywhere.



P.S I've looked long and hard for anything that looks like an aquatic lifeform gasping for its life as its moisture drains away, but no luck i'm afraid!!

[edstrick]

Big Gazza: "I'm sure these images have caused debate before, but I can't find mention anywhere. "

I'm pretty sure those images are highly out-of-focus data taken after landing.

The lower-left portion of the image is the out of focus surface. The upper right portion of the image expands from frame to frame and appears to show the structure of the fiber-optic bundle that routed the image from the focal plane of the downward looking lens to the CCD. It is entirely confined to the brightest part of each frame, and I think is the negative image of a flat-field calibration frame subtracted from the raw data. Where the raw data is within the dynamic range of the camera, the texture of the fiber-optic bundle in the raw data and in the calibration data cancel out. The brightest portions of the image appear to have been saturated in the raw data. There, the fiber-optic texture is not present and in the decalibrated image, the texture is put into what should be featureless saturated data.

[The Messenger]

Big Gazza: "I'm sure these images have caused debate before, but I can't find mention anywhere. "

I'm pretty sure those images are highly out-of-focus data taken after landing.

The lower-left portion of the image is the out of focus surface. The upper right portion of the image expands from frame to frame and appears to show the structure of the fiber-optic bundle that routed the image from the focal plane of the downward looking lens to the CCD. It is entirely confined to the brightest part of each frame, and I think is the negative image of a flat-field calibration frame subtracted from the raw data. Where the raw data is within the dynamic range of the camera, the texture of the fiber-optic bundle in the raw data and in the calibration data cancel out. The brightest portions of the image appear to have been saturated in the raw data. There, the fiber-optic texture is not present and in the decalibrated image, the texture is put into what should be featureless saturated data.

We thought this might be the parachute, being blown or wrapped about the imaging system after the landing, but this is a better explanation.

From the articles they have written, the ESA seems to have a good handle on the imaging sequence. I wish they would clarify this for us. Even so, there are two features - the "arrow" and the 'round kiva' that provide unambiguous evidence that the asimuth of the platform was changing significantly. The probe had to be bouncing or swinging, either of which should have been recorfed by the accelerometers.

Let me put things in prospective a little. While I was pouring over the Huygens data, my wife, who is a detail artist, was assembling mosiacs from the images, ala Rene Pascal. She kept saying, "Look at this, these are images of the heat shield."

I kept nodding my head but not really paying attention, because I knew they could not be: The heat shield was long-gone before the images were recorded. But she didn't know that, and eventually I had to agree with her analysis, especially after I saw the Doppler indicating there was much more acceleration during the first twenty minutes of the descent than expected.

There was a light spring that was supposed to push the heat shield away as the parachute tugged at the other other end of the probe. The Doppler data indicates that the probe continued to accelerate after the parachute deployed, which would have kept an effective load on the bottom of the probe, holding the heat shield in place. The heat shield falling away as the images were taken, explains a lot of otherwise very weird images.

[djellison]

unambiguous evidence that ..

You don't know the order of the images - so you don't know what the evidence is. You're so desperate to find an out-of-the-ordinary situation where ever possible that you're jumping to conclusions.I don't see a single image that is clearly the heatshield - not a single one. At best there is a "it might be"

How about, before jumping to such extraordinary conclusions that are so off-nominal that they WOULD have said something about it, we wait for the PDS release of the imaging, accelerometer and other data this summer? Then we can look at the best possible quality of images, in the right order, combined with accelerometer data and have a sensible, valid debate about this? Until then, it's nothing more than idle speculation. There is nothing that is unambiguous yet.

Doug

[Bob Shaw]

Doug:

There *is* unambiguous evidence that the released images are strangely disordered, though!

As ever, ESA's outreach is without peer. I hope.

Bob Shaw