Wow, civilian satellite images are getting very sharp.
http://www.hindu.com/2008/04/07/stories/2008040759181200.htm
Using satellite images of ship movements in the area, Reliance
Globalcom identified two ships in the area at the time which
may have damaged the cable.
Reliance also confirmed the cable was damaged because of "jerks and force of the ship."
There is no reason to assume these are civilian satellites. Any one of a number of affected or interested countries could have provided the imagery (or ship information) to Reliance. Its not saying *who* analyzed the images. 
Then again, how are ship's captains supposed to know *where* they are allowed to drop anchor? Is there a "Call before you drop" anchor service similar to "call before you dig?"
Deepak
Sean Donelan wrote:
Deepak Jain wrote:
There is no reason to assume these are civilian satellites. Any one of a number of affected or interested countries could have provided the imagery (or ship information) to Reliance. Its not saying *who* analyzed the images.
Then again, how are ship's captains supposed to know *where* they are allowed to drop anchor? Is there a "Call before you drop" anchor service similar to "call before you dig?"
Deepak
Anchorages are normally VERY clearly marked on maritime navigation charts.
There is no reason to assume these are civilian satellites. Any one of a number of affected or interested countries could have provided the imagery (or ship information) to Reliance. Its not saying *who* analyzed the images.
Then again, how are ship's captains supposed to know *where* they are allowed to drop anchor? Is there a "Call before you drop" anchor service similar to "call before you dig?"
That's what maritime pilots are for (every commercial harbor has them) and my understanding is that they are generally required
by law and that there can be criminal penalties for not following their advice.
Regards
Marshall
There is no reason to assume these are civilian satellites. Any one of a
number of affected or interested countries could have provided the imagery
(or ship information) to Reliance. Its not saying *who* analyzed the images.
You can purchase these things from sattelite image services these days
as well as get them from intelligence services.
Then again, how are ship's captains supposed to know *where* they are
allowed to drop anchor? Is there a "Call before you drop" anchor service
similar to "call before you dig?"
The Captain has a responsibility to know where proper anchorages are.
That, and they are required to know where oil pipelines, utilities,
and other types of cables are run including communications cables.
There is a lot of stuff under the water. Cable operators also provide
specific locating data so that Captains do have information available
to avoid these issues.
If it was the result of the specific ships that they've surveilled,
it's likely that they were off anchorage and "slipping" their anchor.
The anchor catches the cable and then the cable snaps under it's own
weight from the pulling.
-M<
Thanks. I wish, though, the article had said *which* cable cuts those
ships were responsible for -- remember that Egyptian authorities had
said that their videos showed no ships off Alexandria.
There's a bit more at
http://web20.telecomtv.com/pages/?newsid=42942&id=e9381817-0593-417a-8639-c4c53e2a2a10&view=news
--Steve Bellovin, http://www.cs.columbia.edu/~smb
Awesome, so could anyone buy a copy of the same images? Which satellite
do you think happened to be taking images of the area with these ships near the time the cables were broken? Which company is selling that set of images?
Sean Donelan wrote:
Awesome, so could anyone buy a copy of the same images? Which satellite
do you think happened to be taking images of the area with these ships near the time the cables were broken? Which company is selling that set of images?
Wouldn't it be reasonable that, when the break occurred, they used their optical time domain reflectometer to compute the approximate location of the break, and then just called around for whoever had the best images, or who could quickly task the satellite to get an image?
--Patrick
Patrick Giagnocavo wrote:
Sean Donelan wrote:
Awesome, so could anyone buy a copy of the same images? Which satellite
do you think happened to be taking images of the area with these ships near the time the cables were broken? Which company is selling that set of images?Wouldn't it be reasonable that, when the break occurred, they used their optical time domain reflectometer to compute the approximate location of the break, and then just called around for whoever had the best images, or who could quickly task the satellite to get an image?
spot can generally deliver an image within 1 day in 60kmx60km blocks assuming no contention for the slot. 20m resolution is more than adequate to pick up ships underway at sea. ikonos can deliver 11x11km swaths.
Hank Nussbacher wrote:
You can purchase these things from sattelite image services these days
as well as get them from intelligence services.Awesome, so could anyone buy a copy of the same images? Which satellite
do you think happened to be taking images of the area with these ships near the time the cables were broken? Which company is selling that set of images?
Those are geostationary.
hybrid in this case implies wide medium and narrow beam applications, like voice tv and internet...
Cable systems have these capabilities built in. In fact, before the
full break occurred they were highly likely to be receiving event data
indicating that there were problems occurring based on the movement of
the cable.
-M<
Right, but those images would be after the fact.
Assume the ship is moving at 10 knots, which is 18.5 km/hr. In 24
hours, it can go about 450 km. You can't go south from Alexandria by
ship, except into the Suez canal, but you can go about that far east
(eyeballing Google Maps...) before you reach Israel or
Israeli-controlled waters. A semicircle of that radius has an area of
about 320,000 km^2. You'd need about 100 images (88 by sheer area, but
you won't get an exact match); the pictures alone would cost a
minium of $100K, according to
http://www.spotimage.fr/automne_modules_files/standard/public/p425_ba582c667a21f3b7d1108ad9773629fdSPOT_Commercial_Price_List_-_Jan_2008_without_EULA.pdf
and quite possibly considerably more. *Plus* there are a lot of ships
to consider -- that area includes the northern terminus of the Suez
Canal, and you want good enough evidence to take to a maritime court
somewhere.
It might be possible. You can rule out some ships because they're too
close, or because you know their historical rate of movement. There's a
lot of data to crunch; maybe that's why it took two months. Or maybe
they just wanted to wait until both ships were accessible to the forces
of a country friendly to FLAG. But I'd have to think there would be
considerable uncertainty. I'd hate to go to court with no better
evidence than day-old pictures. Perhaps, though, that would be good
enough to get a look at the ships' logs (I almost wrote "logfiles"...).
--Steve Bellovin, http://www.cs.columbia.edu/~smb
There are a number of unique characteristics of ships including
profile and radar fingerprint. I'd like to see the images from the
article that was forwarded to the list.
-M<
There are lots of ways to identify ships. The question is which were
trained on the right area at the right time -- and if the scanning was
done somewhat later, how can you tell which ships had been at that spot
then.
I'm not saying it can't be done; I'm just wondering how.
--Steve Bellovin, http://www.cs.columbia.edu/~smb
I'm not saying it was done. The image alone is probably out of
context. I'd venture to believe that someone was able to provide
additional evidence to cause the impound of the ships. As you say,
it's "possible" that the satellite snapped them as they were dragging
their anchor specifically in the area of the cable, but perhaps they
acquired correlating evidence such as a fingerprint from a friendly
military in the area? Military platforms record radar fingerprints and
compile them in databases after visual identification to use as
'unique identifiers'.
My original point was that it's a fairly unimpressive story. I've been
using satellite to do terrestrial surveys for networks and it's not
incomprehensible that someone could take a longshot and call a
company, find out anothers telemetry, call them, and get images
covering a specific time period as you mention. With correlating data
points, it's a compelling case.
-M<
And ikonos can do a lot better than 20m resolution. We had ikonos target
the campus for a special event a few months ago:
http://glovis.geog.vt.edu/hokiesthanktheworld/
"The full extent of the satellite image is approximately 100-square kilometers,
stretching from Brush Mountain (upper left) across Blacksburg (center) to
Ellett Valley (lower right). The Virginia Tech Drillfield is located near the
center of this November 17, 2007 scene from the GeoEye IKONOS satellite. This
true color rendering by Peter Sforza combines red, green, and blue wavelengths
(3.7-meter pixels) into a RGB color image, and sharpened using the panchromatic
band (0.92-meter pixels). Note the sun's angle of elevation was 32 degrees and
the azimuth was 164.1 degrees (north being zero)."
1-meter pixels sounds about right - if you look at the right place on the
full-scale image, you can find (and tell the difference between) my dark green
Camry, and the immediately adjacent dark grey Nissan my neighbor drives, and
still see 3 feet worth of parking lot pavement in between them too...
Not bad for 423 miles up and moving at 4.7 miles per second....
Lots - for values of lots including “practically all” - of ships use the AIS (Automatic Identification System), which broadcasts various details on radio. For an example application, try www.aisliverpool.org.uk
