Dubai impound ships suspected in cable damage

Wed Apr 9 12:14:03 UTC 2008

On Tue, 08 Apr 2008 22:16:57 -0700
Joel Jaeggli <joelja at bogus.com> wrote:

> 
> 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.
> 
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