(Lou Scheffer) wrote:

(Derek Lyons) wrote in message ...
h (Rand Simberg) wrote:

"But that doesn't explain why similar systems designed for marine use
(the ocean has extremely high positive pressures, and seawater is an
extremely corrosive environment) can be built for orders of magnitude
less."

Please provide a cite of a marine system of the equivalent complexity
and mission of the weather sat with a design lifetime of years or
decades. (Or any marine system with those kinds of lifetime
requirements.)

Transatlantic cables come close. Before fiber optics, these had
repeaters every few km. Since they were in series, ALL of the
repeaters must work. If I remember correctly, they were designed so
the cable as a whole had a 20 year lifetime. Using good old
conservative engineering, the even made this work with vacuum
tubes(!). Needless to say this was one of the first applications of
transistors.

Indeed. And they were *extremely* expensive. Somewhere I have a
telco manual from the early 70's that cites the costs of a repeater as
being in excess of a million dollars a pop. It goes to great lengths
to explain and stress the engineering, qualification, and component
testing required.

Transoceanic cable repeaters and SOSUS arrays are about the only
things marine I can think of that are designed for decades of
unmaintained service, and both are extremely expensive. Most other
things marine seem to be designed for shorter lifetimes and hence
don't meet the similarity requirements Rand specifies, or are far less
complex than a weather sat, and equally fail to meet the similarity
requirement.

FWIW, when pressed Rand declined to supply marine example at all.

D.
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