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Fraser
2006-May-08, 11:09 PM
SUMMARY: Researchers from NASA, ESA and the University of Arizona have put together a new animation that shows what the Huygens probe saw as it landed on Titan on January 14, 2005. The 5-minute video was put together with data collected by Huygen's Descent Imager/Spectral Radiometer instrument. The scene below the lander is a mosaic, updated piece by piece as the instrument captured new images.

View full article (http://www.universetoday.com/am/publish/new_titan_movies.html)
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Grand_Lunar
2006-May-09, 12:36 AM
I saw these videos. Well worth a look.

One thing with the 'bells and whistles' video brings up an interesting detail; I saw that when Huygens is on the surface, the signal to Cassini gradually gets weaker. That I expect, as the batteries use up power.
But then, near the end, it increases for a bit. What causes that?

I wonder if such a video could be made applicaple to other space probes; i.e, make similar videos that do the same for other space probes, like Galileo, the Voyagers, Pioneers, ect.

antoniseb
2006-May-09, 12:06 PM
I saw these videos. Well worth a look.

It was very fun to watch this. I remember being a little frustrated trying to correlate the images when they first came out. This did a great job of putting it in context, and really giving a feeling of the depth of field.

If you're interested in Titan, and haven't already seen this. Take a look.

astro-orange
2006-May-09, 12:12 PM
Hi, Grand Lunar!

I would expect some animations of Galileo etc. to be around there somewhere. Unfortunately I don´t know where, but a search on those projects´website could bring about a movie, if they have any!

May our journeys be at light speed (Sorry Tammy :-) ).

Oliver

Jerry
2006-May-09, 01:55 PM
I saw these videos. Well worth a look.

One thing with the 'bells and whistles' video brings up an interesting detail; I saw that when Huygens is on the surface, the signal to Cassini gradually gets weaker. That I expect, as the batteries use up power.
But then, near the end, it increases for a bit. What causes that?

I wonder if such a video could be made applicaple to other space probes; i.e, make similar videos that do the same for other space probes, like Galileo, the Voyagers, Pioneers, ect.
Great question, and the answer is even better. The signal faded when Huygens was on or near the surface and as Cassini was approaching the horizon. A pattern of distructive interference started to occur when the signal from Huygens antenna and the signal reflected from the surface of Titan approached a phase shift of 180 degrees. As the reflective path shortened, the phases were again out-of-sinc and finally complimented each other near the end of signal reception. This means the surface of Titan close to the landing site was mostly flat and reflective in the radio bandlengths.

I have seen a web presentation of this, but I don't have time to chase it down.

One caution about this NASA reconstruction: The coloring is based upon the spectral signature, not the color of individual objects. So while the composite color is quite accurate, individual features should show more contrast and color detail - the tops of the rocks, for example, might have a thin layer of white ice on them that is adversely tinted by the coloring.

Also, I can't find any documentation on how the descent altitude and images were coordinated. It is unclear whether this is a best guess, or truly time sychronized data.

bigbluestar
2006-May-09, 04:14 PM
I would say that it was a time synched as they showed the spacecraft taking images and where with its funnly lil bleeps. I was quite fasinated about the very long descent I thought it would have been faster. And it hit pretty hard poor lil probe. its almost like it got jolted too as it took a few seconds to start taking pictures of the ground when landed. By far one of my favourite movies. Im definatly linking it on my astro site

Jakenorrish
2006-May-10, 11:14 AM
It goes to show what an astonishing achievement this was. I was mesmerised.

GBendt
2006-May-10, 02:34 PM
It was not easy to perform the landing of the Huygens probe such that Huygens was already on the ground on Titan, while Cassini had not yet sunk below the horizon of Huygens´landing site: As soon as Cassini was to sink below the horizon, it were unable to receive any data from Huygens.

On its descend through Titans´s atmosphere, Huygens met different conditions than was expected when that descend was planned. The plans expected calm weather in which Huygens would descend, spinning gently and slowly under its parachute. The automatic program was set up such that it would take various overlapping pictures in one revolution of the probe. However, instead of the expected "calm weather", Huygens met strong gushes of wind which caused the probe to toss, swing and rotate frequently. Therefore the revolutions of the probe were too fast to get a sequence of overlapping pictures, and so it turned out difficult to put the pictures together, in order to get a comprehensive and detailed overview.

Huygens landed on something with the properties of wet sand, so the landing shock on the surface was not too hard. The batteries worked fine, and the data transmission to Cassini worked fine, at least on the Huygens´side. Unfortunately, there was a fault in Cassini´s control program for its Huygens data receiver, so one of the two data transmission channels of the receiver was disabled, thus Cassini did not receive 50% of the data and pictures sent by Huygens, they are lost. The lost data seem to have been essential for the precise evaluation of the set of pictures received.
The position of Huygens with relation to Titan was evaluted by analyzing the red shift of the bearer signal sent from Huygens and received by Cassini. There were other specific data sent by Huygens, but these data were sent via the comminications channel that was not received.

I think that the video represents a "best guess", but the result of this "best guess" is really very impressive. I don´t think that something better can be generated from the raw data we have got.

On the videos, the dark areas on the surface that were once interpreted as "lakes" look like areas of dark sand, shaped by strong winds. This fits the recent findings of sand dune systems detected by Cassini´s radar. Other worlds are strange!

Regards,

Günther

Jerry
2006-May-10, 05:08 PM
"These movies really demonstrate that the Huygens camera was very well designed for the job," said Jean-Pierre Lebreton,

That's a bit of a stretch. Time stamps on the images would have been a simple addition, and only required a few bits. Likewise, some way to look in more than one direction after landing, even a simple mirror could have muliplied the images returned, rather than hoping the probe would be bobbing around in an ocean.

The imaging system worked well, even perfectly. But it was not a perfect design.