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January 18, 2005

Titan update - part of the puzzle comes together 1/17/05

From John Strickland:


Very early on Sunday, Jan 16, someone apparently leaked a bunch of additional Titan photos, and they went out on the web. Immediately, a bunch of amateurs started to fit them together and quickly produced several map-like mosaics. Late on Sunday, ESA released most of the remaining photos on its web site. It is still not clear if the count of 350 photos refers to just the descent photos, or all those taken after landing. These are shown in sets of three. It looks as though one of the downward-pointing cameras has taken close-up pictures of the "soil" under the probe, lit by the 20 watt lamp.

The big news of Sunday is that we now know where the channels go. They drain towards the dark-colored flat terrain after all. If one frame in either direction from the original frame of the dendritic terrain had been shown, we would have seen at least one channel emptying into what now seems more and more like a "dead sea bottom". With the new mosaic maps, the coast-line looks more and more like a real coastline, with capes and bays, many with channels emptying into them. In a few of the photos, very narrow channels can be seen, indicating that there are range of channel sizes. We can see almost 10 places where channels empty into the dark area. Most of the rocks near the probe are rounded, which makes it look like the action of a liquid environment. However, there is no liquid to be seen in any of the photos so far. The mosaic maps do make it quite clear that we landed on the dark, flat terrain. However, we have not yet found the images taken just before landing, which would prove that the light bands are indeed made of loose surface rocks.

This leaves us to wonder where did the ethane go (or whatever once filled the shallow sea)? Indications that the nitrogen in the atmosphere is enhanced in heavy isotopes could mean that most of the regular nitrogen has been lost. If this is true, then the atmospheric pressure might have been much greater in the past, perhaps allowing even ammonia-water seas. However, if the flow of liquids stopped long ago, then we should see considerable cratering across Titan. An unlikely possibility is that the seas have just dried up, and that the cratering process has just begun. Another is that the surface wind blows around enough loose material to fill in any craters. Finally, Titan may go through warm and cold phases, with enough liquid present in a warm phase to allow surface dynamics to continue to erase craters.

Once all the images have been assembled and enhanced, some of these questions may be answered. Eventually, the Cassini probe will be able to get a radar scan across the landing site, and we will be able to match the radar image with the optical ones. Other questions will have to wait for the next Titan mission, perhaps 10 or 20 years in the future. One possibility for a future mission would be a Titan balloon, which would float below the haze layer, giving an excellent close-up optical view of the a large sample of the surface. Another would be a Titan orbiting imaging radar mission, similar to the one sent to Venus. Since Titan is a whole world, larger than Mercury, but cloaked in clouds, it will take a long time to extract all of its secrets. Involvement of the International Science Community, like the ESA, which was largely responsible for this stunning success, will help speed up that process.

Posted by apsmith at 11:09 PM

January 15, 2005

Update on Huygens - Titan - 1/15/05

More science analysis from John Strickland:


The E.S.A. science press conference was held at 5:00 am Eastern Time (1/15/05), and some annoying news was revealed. One of the two main data channels from the Huygens was not received on the Cassini spacecraft. This was caused by a fault in European software commanding the European receiving hardware installed on Cassini. Half of the predicted 700 images were lost, and data from a Doppler experiment that would have helped establish location and wind motion better was lost. A lot of the photos at altitude are redundant, but some of those taken close to the surface are not. After the probe actually hits the surface, images in only 1 direction can be taken, since the probe is no longer spinning. Radio-telescope data may help to locate the probes position to within about 1 km.

The probe came out of the haze layer at about 12-15 miles high, and immediately started to get spectacular images. A temperature profile was produced which clearly shows the troposphere as a distinct temperature layer. Methane abundance rose as the probe neared the surface. Only a few scientific measurements have been released so far. A major revelation seems to be the division of the surface into rough, hard light-colored terrain and smooth, dark-colored terrain. A wind was blowing about 22 miles an hour at altitude, which caused the probe to drift from over the light colored area that was below it when it emerged from the haze deck, and over a dark area further to the east.
"
The basic question you want to ask when first seeing such an alien terrain is "What are we actually looking at? When the probe was still about 8 miles high, it took a spectacular panorama (made of 10-15 smaller images), looking back (possibly west) at the "coast" or edge of the light colored terrain (covered with the dendritic (stream-like) pattern, and in the other direction, with a vivid series of tapering streamers or bands of white material converging apparently toward the east on top of the dark material. The edge of the light terrain appeared to be higher and rough, with dark shadowed cliffs, (but this may be a visual illusion - we need to wait for confirmation with more images from different altitudes.) It turns out that the second image released yesterday, with the tapering geometric markings, is part of that white on dark area with converging streamers. The dark area in the first image is apparently south of the dark area covered with the light bands.

The fact that the probe landed on very flat terrain with rocks that are whiter than the surface they rest on could indicate that the rocks are made of the same material as the light-colored terrain. If the rocks are water ice, the light colored terrain may also be water ice. Therefor, the tapering light-colored areas on the dark areas may be bands of the same rocks seen by the surface image. This means they are too heavy to be moved by the wind into the streamer-like patterns. Dr. Ingersoll (Principal Investigator for the Descent Imager - Spectro-radiometer) suggested that the dark area may be a wide flood channel and the rock bands may be gravel banks left behind by a ancient flood.

We can also possibly regard the light terrain as "bedrock" (made of ice?) and the dark terrain as a wide channel filled with alluvial material. (Last year they thought that the light areas were organic and the dark areas were ice. This is now thought to be wrong.) The probe showed that it landed on a surface with the consistency of mud or clay. Could the alluvial deposit be made of "sand" grains of ice mixed with the organic goop? The narrow dendritic channels on the light colored terrain may also be draining the organic goop, along with pieces of the "bedrock", but to where?. One problem with this argument is that none of those channels seemed to be draining towards the dark, flat, and presumably lower terrain.

The wide panorama was obviously taken at a much lower altitude than the earlier images, since the features on the light, rough terrain are very strongly foreshortened. However, in the panorama, a white band (of possible ethane fog droplets) can be seen right along the now distant edge of the light terrain. This does not show up in the higher image shown yesterday, and is presumably visible due to the low angle of sight along the distant surface. The panorama image also shows both terrain types as being more similar in brightness, indicating that most of the dark area may be covered with a very thin layer of the same fog.

We will have to wait for more of the science data to be released in order to verify any of these speculations. The images are not sharp enough to see all the details we need to see to tell all of what we are looking at. It also would have been far more interesting if the probe had landed on the "bedrock" area near one of the channels, but you cannot be lucky, like Opportunity, every time you land on a strange planet. Computer software will soon be able to integrate all of the descent imagery and produce an accurate 3-D model of the whole area, up to the resolution limits of the camera, similar to what was done for Endurance and Eagle Craters at the Opportunity site on Mars. All of the other data should eventually give us a much better picture of surface conditions at the landing site.

John

Posted by apsmith at 11:48 PM

January 14, 2005

NSS members awed by images of Titan's shores

January 14, 2005 -
The members of the National Space Society have been waiting for
this very moment for a long time, and now it is here. After 20 years
of effort and seven years of waiting, the Huygens probe has landed
on Titan, 900 million miles away, rewarding scientists with spectacular
pictures of a bizarre terrain. This is the very first truly
cryogenic world with a solid surface that a probe from
earth has landed on. The images of potential shores are astounding.
The "rocks" here may be made out of ice, and any volcanoes might
release water. All those who worked on and then waited for results
from Cassini and Huygens for so many years should now be truly
congratulated. This is one of the most significant collaborations
by international science ever undertaken. Our horizons, minds and
hearts have been widened again.

John Strickland, an NSS board member from Austin Texas,
provided the following analysis of results so far:

No Science Results have yet been released to my knowledge. At the
very brief 5:00 EST press conference, 2 more images were released
at the conference and to the ESA Cassini Web site. A couple of
poorer quality additional raw images are available on Space.com.
No more images may be released today. The web site:

http://www.esa.int/SPECIALS/Cassini-Huygens/
, has image 3 at the top,
image 1 in the middle, and image 2 at the bottom.


The first image, taken at 10 miles, shows the drainage channels
previously mentioned. (This image may or may not be much higher
resolution than the second one taken at 5 miles. The web site gives
conflicting info.) The totally different scene leads us to think
the latter is true, or that wind has carried the probe over a
different area as it descended. The dark area at the right of the
image is probably not liquid, but simply the darker part of the
landscape surface. (The surface of the whole planet seems to be
divided into bright and dark areas.) Note that the channels are
NOT draining towards the dark area, but at 90 degrees or parallel
to it. It is clear that an area in the middle of the frame and
next to the dark region is a higher elevation area, since the
channels are draining away from it. No channel in the image seems
to be crossing or touching the dark area, so we cannot say if it
is higher or lower than the bright, channeled area. There are some
lighter channels closer to the dark area. The dark area seems to
have some texture on it, which could be more image compression
artifacts, or maybe frozen ethane or methane slush floating in a
shallow puddle of ethane. The areas most likely to have liquid are
those which are darkest. We seemed to see some channels in the
radar images, which indicates that a channel network could extend
over large areas of the surface. Next Question: What is the liquid,
where does the liquid come from and where does it end up? Why are
the channels dark? How wide and deep are they?

These bright and dark areas have fairly well defined sharp edges,
and often somewhat geometric (triangular or curving, as shown in
the second image, taken at 5 miles. These sharp edges are what
give the impression of a coastline or shoreline. In this image,
none of the drainage channels show at all. Perhaps, part of one
of the somewhat triangular bright areas is the area with the
channels. These may be similar to the same kind of shapes shown
on the radar. However, the current image are optical, not radar,
and rough areas would not necessarily be brighter.

In both of these images, there are specks which look like huge
boulders. These are camera artifacts caused by the fiber-optics
of the camera and lens system used in the Huygens probe, and will
be removed when the images are cleaned up more. The surface image
(3) seems to show none of them.

The third image gives us our first glimpse of the surface of Titan
from near or on the surface. Well, sorry, but I do not see any
cryogenic plants or animals in the picture! This does not rule out
microscopic cryogenic life, but it sure makes it a lot less likely.
What we do see are some rocks or large boulders. These are probably
made out of ice, which at minus 290 degrees F are as hard and tough
as granite. The foreground rocks are lighter in color than the
ones in the background, and also seem to be much more rounded, as
if they were large beach boulders. There is a smooth rock-free
zone between the two groups of rocks. There are very few if any
angular rocks, like pieces of limestone flagstones, with straight
edges. We have no idea how these rocks were formed and why they
are scattered on the surface. I see no sign of any body of water
in the direction the camera is pointed. (We should get a complete
panoramic view around the lander, since it apparently survived for
an extended time on the surface.) They have not said if it would
keep on taking images after it landed. It is also not clear if
this image is actually taken on the surface or about 10-20 feet
above it.

More later this evening

John

Posted by apsmith at 11:04 PM

EXPEDITION TO A NEW WORLD

HUYGENS DESCENT JANUARY 14, 2005

(from John Strickland, NSS board member from Austin, TX)

Descent Timeline: Jan 14, 2005 (All times E.S.T.)

All times are when signals arrive at Earth.

Huygens carrier signal only may be able to be tracked by radio-telescopes, proving probe is still functioning and providing position and speed of probe. Huygens transmits as fast as it takes images. Cassini will not transmit to earth until after it has captured all the Huygens data. Images are taken by 3 camera lenses making a spiral pattern, looking out and down. These can then be combined into panoramas. We already know that Huygens is spinning at the correct rate.


Huygens signal (arrival times)


4:51 am
- probe turns on transmitters.

5:13 - 5:18 am
- Re-entry, shields released, chutes opened and cameras start taking pictures during descent.

~7:34 am
- touchdown on surface (probe motion should stop).

~9:50 am
- batteries on Huygens run out of power.



Cassini Signal - (arrival times)


9:44 am
- Cassini flys below Huygens Horizon, Loss of Signal

9:46 – 10:07 am
Cassini turns towards Earth to begin transmitting data

10:14 am
First post-landing data from Cassini sent to Earth (proof Cassini is working).

10:17 am
Playback of Huygens Data begins (This is when we will know whether data is good).

2:24 – 3:15 pm
Presentation of First Titan Images from ESA/JPL.

5:07 pm
First Playback of data completed.

5:00 – 6_00 pm
Additional Images from Titan from ESA/JPL.

Jan 15

12:00 – 1:00 pm
Early Look at Science Results from Huygens ESA/JPL.

WHAT TO LOOK FOR:


So far, we still have no idea what the radar and infra-red images are showing us, since we have no sample of “ground truth” and since we see very few if any recognizable shapes. There are no shadows sharp enough to reveal surface shapes. The radar shows mainly smooth and rough areas only as light and dark color. Based on the high amount of texture seen in both the radar and near-infra-red images, this seems to be a very young and dynamic surface.


We do not see many if any craters. We see what might be results of a very dynamic surface environment, with possible rivers and streams (but not of water!) Bright areas could be alluvial fans of debris, or the results of tectonics, wind and sand or unknown forces. There should be ice and frozen organic material on the surface. However, the organics might make up a hard, dry soil or sand-like surface material instead of being a sticky goop. There could be small lakes or pools of liquid ethane, and dissolved in it could be methane and liquid nitrogen. There should be a “water table” with the hydrocarbons taking the place of water. Surface conditions: 1.5 atmospheres of pressure at -290 deg F. There should be enough light to take good pictures if there are recognizable shapes. There may be a lot of wind.


We know so little about what a cryogenic environment would be like after billions of years, that we cannot rule out less likely discoveries such as cryogenic life, until we see the surface. The probability of such a discovery may be extremely unlikely, however. No one wants to discuss such unlikely things to the media, especially. There is a good chance that the surface, surface materials and whatever features are formed there may be unlike anything we have ever seen before.

RISKS TO WATCH:

Since the number of critical mission events is much smaller than for a lander, the chances of success are high. Assuming there is no failure of the mission electronics, the most critical events are mechanical ones:


Timers to start the mission sequence


Detection of end of re-entry period

Deployment of Pilot chute

Deployment of Main chute

Release of Front Heat Shield cover

Deployment of main instruments

Deployment of small chute

Surface proximity sensor on

Descent Imager light turned on

Touchdown

Posted by apsmith at 10:58 AM

 

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