From: Mary Shafer <shafer@orville.dfrc.nasa.gov>
Newsgroups: sci.space.shuttle
Subject: Re: SCA countermeasures...
Date: 06 Jun 2000 11:42:12 -0700

kodostheexecutioner@my-deja.com writes:

> Remember when SCA 905 was fitted with IR flares and detectors for
> the Paris Air Show when they showed off Enterprise?

Not flares and detectors but dummy IR sources, hotter than the engines
to lure IR-tracking missiles and expendable if hit.  The concern
wasn't an interceptor armed with Sidewinders/Crotales/A-somethings,
but someone on the ground with Stingers.

No detectors were needed, as the SCA wasn't going to be firing at
anyone (IR-tracking missiles can't be detected in the air, as they
don't radiate anything that can be detected in the airplane they're
fired at).

> Anyone know the package carried?

As the plane taxied out of the blocks I was told by an ops engineer
that we'd borrowed the system from the USAF.  More particularly, it
was the same as that used for Air Force 1 and the Airborne Command
Post.

--
Mary Shafer    http://www.dfrc.nasa.gov/People/Shafer/mary.html
shafer@orville.dfrc.nasa.gov Of course I don't speak for NASA
Senior Handling Qualities Research Engineer
NASA Dryden Flight Research Center, Edwards, CA
For non-aerospace mail, use shafer@spdcc.com please

Newsgroups: sci.space.shuttle
From: henry@spsystems.net (Henry Spencer)
Subject: Re: SCA countermeasures...
Date: Wed, 7 Jun 2000 02:59:26 GMT

In article <u0u2f6648r.fsf@orville.dfrc.nasa.gov>,
Mary Shafer  <shafer@orville.dfrc.nasa.gov> wrote:
>Not flares and detectors but dummy IR sources, hotter than the engines
>to lure IR-tracking missiles and expendable if hit...

Also, probably pulsed to confuse the guidance system.  A lot of the early,
simple IR-homing missiles used a rotating mask over the sensor to simplify
the sensor and control electronics, and the price of the simplicity was a
very firm assumption that the IR source is more or less steady.  Such a
guidance system goes berserk if the IR source blinks at roughly the
rotation rate of the mask.  This is thought to be a common tactic of the
older IR-countermeasures systems.  Fooling modern sensors is harder...

>No detectors were needed, as the SCA wasn't going to be firing at
>anyone (IR-tracking missiles can't be detected in the air, as they
>don't radiate anything that can be detected in the airplane they're
>fired at).

There has been work done on detecting the launch of a short-range missile
by sensing IR or UV emission from its exhaust plume, to trigger expendable
countermeasures like flares only when they are needed.  However, that's
the leading edge of today's countermeasures technology, and I doubt it
was available back then...
--
Microsoft shouldn't be broken up.       |  Henry Spencer   henry@spsystems.net
It should be shut down.  -- Phil Agre   |      (aka henry@zoo.toronto.edu)