APOD: Soaring over Titan (2014 Nov 24)

Comments and questions about the APOD on the main view screen.
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APOD: Soaring over Titan (2014 Nov 24)

Post by APOD Robot » Mon Nov 24, 2014 5:06 am

Image Soaring over Titan

Explanation: What would it look like to fly over Titan? Radar images from NASA's robotic Cassini satellite in orbit around Saturn have been digitally compiled to simulate such a flight. Cassini has swooped past Saturn's cloudiest moon several times since it arrived at the ringed planet in 2004. The virtual flight featured here shows numerous lakes colored black and mountainous terrain colored tan. Surface regions without detailed vertical information appear more flat, while sufficiently mapped regions have their heights digitally stretched. Among the basins visualized is Kraken Mare, Titan's largest lake which spans over 1,000 kilometers long. Titan's lakes are different from Earth's lakes in that they are composed of hydrocarbons with similarities to liquid natural gas. How Titan's lakes were created and why they survive continues to be a topic of research.

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CharlesE

Re: APOD: Soaring over Titan (2014 Nov 24)

Post by CharlesE » Mon Nov 24, 2014 5:21 am

Many of the lakes appear to go extend up the sides of a hill. Typically, water lakes on earth have a level liquid surface. Is this simply the result of minimal data used to generate the movie, or is the sloped lakes indicating a "watershed" area flowing into a valley?

Thanks.

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Nitpicker » Mon Nov 24, 2014 5:27 am

Lovely video.

http://en.wikipedia.org/wiki/Atmosphere ... n#Overview
The atmosphere is so thick and the gravity so low that humans could fly through it by flapping "wings" attached to their arms.
Hopefully, the noise of our flapping arms wouldn't interfere with the sound of the lovely music. But unless we had radar eyes, I'm not so sure we'd see much of anything on our flight.

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Nitpicker » Mon Nov 24, 2014 5:35 am

CharlesE wrote:Many of the lakes appear to go extend up the sides of a hill. Typically, water lakes on earth have a level liquid surface. Is this simply the result of minimal data used to generate the movie, or is the sloped lakes indicating a "watershed" area flowing into a valley?

Thanks.
My guess is that it could be an artefact of the way the radar images are mapped into a 3-D model and exaggerated vertically and/or the radar could have penetrated some distance into the lakes, showing the lake floors.

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by rwlott » Mon Nov 24, 2014 2:08 pm

Intriguing video. However, I was surprised and put off by the statement at the end saying that "heights of the features have been exaggerated 10 times." For what purpose was that necessary?

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Chris Peterson » Mon Nov 24, 2014 2:45 pm

CharlesE wrote:Many of the lakes appear to go extend up the sides of a hill. Typically, water lakes on earth have a level liquid surface. Is this simply the result of minimal data used to generate the movie, or is the sloped lakes indicating a "watershed" area flowing into a valley?
The same thing happens with these sorts of reconstructions on Earth. The image data is much higher resolution than the digital elevation data. So small bodies of liquid aren't resolved in elevation, and end up lying on interpolated surfaces.
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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by FloridaMike » Mon Nov 24, 2014 3:28 pm

rwlott wrote:Intriguing video. However, I was surprised and put off by the statement at the end saying that "heights of the features have been exaggerated 10 times." For what purpose was that necessary?
Without the exaggeration you would not be able to make out the different elevations. It would appear essentially flat from the height of the camera in this visualization. This is a common tactic for visualizing topographical features right here on earth..
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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Ron-Astro Pharmacist » Mon Nov 24, 2014 4:39 pm

If we have mapped the surface of Titan to detect mountains is the mapping technique able to note the level of the surface of the hydrocarbon lakes? I was curious as it might shed light on the "Mysterious Changing feature on Titan".

http://apod.nasa.gov/apod/ap141015.html

It was interesting to read that the lakes lack evidence of waves that makes me think surface levels may be detectable. Also how much do hydrocarbons expand with heat compared to water? Titan's goo sounds closer to a blob than the water of our lakes which may throw off many of our likely comparisons.

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by MountainJim » Mon Nov 24, 2014 5:42 pm

Anyone know the source of the music?

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by JohnD » Mon Nov 24, 2014 6:11 pm

By serendipitous coincidence, today's EPOD (Earth science Picture Of the Day) may explain, a little.
http://epod.usra.edu/ (24/11/2014, OR 11/24/2014, you choose)
It shows South Eastern Greenland from 32,000 ft up, from a commercial passenger jet, taken by the Captain! (What, me worry?)

And it shows relatively flat areas of ice between mountain peaks. The flat areas are glaciers, and they seem to creep up the valleys between the mountians, well above the flat, lake like surface further from the mountains. So perhaps some of the apparently sloped 'lakes' on Titan are semi-liquid glaciers of methane? As if I knew anything about the properties of methane at minus whatever it is.

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by BillBixby » Mon Nov 24, 2014 7:00 pm

Hydrocarbon Lakes - Now to develop a twentieth century style spacecraft using hydrocarbon power which will refuel at the gas stations set up around Titan by our current petrochemical corporations. EPA can regulate the emissions as different planet peoples search for alternative energy forms. :idea:

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Ron-Astro Pharmacist » Mon Nov 24, 2014 7:45 pm

BillBixby wrote:Hydrocarbon Lakes - Now to develop a twentieth century style spacecraft using hydrocarbon power which will refuel at the gas stations set up around Titan by our current petrochemical corporations. EPA can regulate the emissions as different planet peoples search for alternative energy forms. :idea:
I guess to fix the next fuel crisis NASA, et al will be heading to Titan. Like in the days of the 49er's - it'll be the next "Gas Rush?" Phew, some names are better than others. :thumb_down:
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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Boomer12k » Mon Nov 24, 2014 9:34 pm

Dibs on the Northern Hemisphere!!!

Nice video, but could have been a better flyover of the larger lake area....missed allot.

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Nitpicker » Tue Nov 25, 2014 12:26 am

Chris Peterson wrote:
CharlesE wrote:Many of the lakes appear to go extend up the sides of a hill. Typically, water lakes on earth have a level liquid surface. Is this simply the result of minimal data used to generate the movie, or is the sloped lakes indicating a "watershed" area flowing into a valley?
The same thing happens with these sorts of reconstructions on Earth. The image data is much higher resolution than the digital elevation data. So small bodies of liquid aren't resolved in elevation, and end up lying on interpolated surfaces.
According to this:
http://saturn.jpl.nasa.gov/spacecraft/c ... ardetails/

The two active radar instruments are:
Synthetic Aperture Radar Imager [SAR] (13.78 GHz Ku-band; 0.35 to 1.7 km resolution)
Altimeter (13.78 GHz Ku-band; 24 to 27 km horizontal, 90 to 150 m vertical resolution)
I wonder if the elevation data has been purely derived from the much lower resolution altimeter, or whether the elevation data has been augmented with relative levels inferred from the SAR images.

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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Chris Peterson » Tue Nov 25, 2014 12:39 am

Nitpicker wrote:I wonder if the elevation data has been purely derived from the much lower resolution altimeter, or whether the elevation data has been augmented with relative levels inferred from the SAR images.
I would assume they'd use some complex filtering tools to combine the data to achieve the best possible resolution. But these numbers are pretty typical for space-based SAR, on the order of 1km resolution, compared with typical space-based imaging on the order of perhaps 10m resolution.
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Re: APOD: Soaring over Titan (2014 Nov 24)

Post by Nitpicker » Tue Nov 25, 2014 12:47 am

Chris Peterson wrote:
Nitpicker wrote:I wonder if the elevation data has been purely derived from the much lower resolution altimeter, or whether the elevation data has been augmented with relative levels inferred from the SAR images.
I would assume they'd use some complex filtering tools to combine the data to achieve the best possible resolution. But these numbers are pretty typical for space-based SAR, on the order of 1km resolution, compared with typical space-based imaging on the order of perhaps 10m resolution.
Oh I'm not complaining!

CharlesE

Re: APOD: Soaring over Titan (2014 Nov 24)

Post by CharlesE » Fri Nov 28, 2014 4:43 pm

Thanks to all for the replys. It is appreciated.

CharlesE