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ESA CryoSat 2
Theory_Execution
I was flicking through the Sci/Tech news on googel and happened upon an actual science article!!!!

Now, I did have to check that it wasnt really an underhanded, sudoscience shrouded press release for some new game by Nintendo, those who make Call of Duty or a new piece of i-crap from apple - it checks out.


The idea was to measure the thickness of the sea ice of the arctic by repeated pass over using a satellite and some ingenious imaging equipment.


Here's a link top the website that came up with the program.[url]http://www.esa.int/esaLP/SEMAAW0T1PG_LPcryosat_1.html[/url]
 
catman
I'd like to know how it does the measuring, if my tired little brain could comprehend it.

"i-crap" - ROFL!
"If I owned both Hell and Texas, I'd live in Hell and rent out Texas." - General Sheridan
 
Theory_Execution
I believe its a similar principle to throwing a wave at it and seeing what comes back. Then depending on how long it takes, or the change made to the initial wave they can work out what they have just 'looked' at.

I think it is less involved than determining the atmosphere of a distant planet as it passes between us and its star.

I have not really looked into it though.
 
Photon
catman wrote:
I'd like to know how it does the measuring, if my tired little brain could comprehend it.



CryoSat uses an interferometric radar technique, where it sends a coherent signal of short pulsed radio waves, receives reflected radio signals at multiple antenna positions, looks at the phase of the signal and time elapsed, and can construct a range to the target with high accuracy. It's very much like combining laser interferometry, with an array of phase detectors, I think. It makes multiple passes of the same area over time in order to get time variation in the landscape, gets down to cm resolution, if I recall correctly. The device is specifically designed for ice, whereas other similar instruments are designed for land. Basically it constructs a topographic map of sea and land ice.

I think it gets measurement of ice thickness and changes to ice thickness at the periphery of the ice.

What I don't understand is how they use an array of antennas to create what is known as a "synthetic aperture" - if they use an array of real antennas, like on a ground-based radar system, that makes sense to me. I'm guessing they use Fourier analysis of the reflected signal from multiple locations simultaneously to kind of get a multiple element array effect, but I have no clue if that's right, or how it's done.
Edited by Photon on 06/23/2011 02:41
 
Theory_Execution
Ye Photon, like I said.Smile
 
catman
Thanks, y'all!
"If I owned both Hell and Texas, I'd live in Hell and rent out Texas." - General Sheridan
 
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