From: Hal <hfinney@shell.portal.com>
Date: Tue, 26 Apr 94 09:06:47 PDT
To: cypherpunks@toad.com
Subject: spy satellites
Message-ID: <199404261607.JAA03345@jobe.shell.portal.com>
MIME-Version: 1.0
Content-Type: text/plain


Two points re the spy satellite thread.

First, spy satellites want to be close to what they are looking at, so
they can see it better.  That means they are generally in low orbits, and
low orbits are fast orbits.  Typical speeds are on the order of 10,000 mph.
This means that any given spot is in view of a particular satellite for only
a few minutes on each pass, and due to the earth's rotation it is hard to
pass repeatedly over the same spot frequently.  This means you need a large
number of satellites in order to provide much coverage, and even then you will
probably get snapshots at an interval of hours at best (I don't know how many
satellites are flying).  This is OK for military bases where you are looking
at construction, ships, and other large equipment, but it is not at all
adequate for tracking the movement of terrorists.

Secondly, any technology which did allow the government to surveil us well
enough to track the physical movements and meetings of terrorists would be
far more of a threat than any Clipper chip!  Offering satellite surveillance
as an alternative to Clipper jumps from the frying pan into the fire, IMO.

Hal