Index Home About Blog
From: (Allen Thomson)
Subject: Nuking LEO (yet again)
Date: Thu, 15 Oct 1998 17:45:27 GMT

Last week's Space News contained an interesting letter on the
consequences of a high-altitude nuclear burst, a topic that has
occasionally been discussed here. The author is the former Lt. Col.
Glenn Kweder of the Radiation Sciences Directorate of the Defense Nuclear
Agency (now incorporated into the Defense Threat Reduction Agency).  In
1994-1995 he was responsible for briefing "Third World Threat to Low Earth
Orbit Satellites" to a number of US government agencies.  He was also a
member of the team briefing "The Role of Radiation Tolerant Micro-
electronics in Support of the U.S. Satellite Industrial Base."

Both Space News and Mr. Kweder have given permission to reproduce the
letter in its entirety.


Nuclear Threat
Space News, Oct. 5-11, 1998, p.14

I would like to comment on the article urging protective measures for
U.S. satellites ["Report Urges Use of  Stealth, Deployment Alternatives
to Protect U.S. Satellites," Sept. 7-13, page 41].  I was surprised to
see no mention of a nuclear weapon detonated at high altitude, over 100
kilometers, which would have a devastating effect on hundreds of low-
Earth-orbit (LEO) satellites.

A high-altitude nuclear detonation releases a tremendous number of high-
energy electrons. These electrons, trapped in Earth's magnetosphere,
rapidly populate all LEO orbital space.  As a result, hundreds of LEO
satellites are exposed to electron levels up to 10,000 times higher than
the natural LEO space environment . This enhanced electron radiation
damages critical electronic circuits in satellites, leading to the
demise of LEO constellations in weeks or a few months.

Furthermore, most of the protection solutions mentioned in the report
detailed in the article would be ineffective against this threat. On-
orbit spares would suffer the same fate as the primary satellites, while
launching replacement satellites also would be ineffective since the
enhanced radiation levels can persist for several months to a year.

This ultimate anti-satellite weapon also is extremely low-tech. All that
is required is a small nuclear weapon and a launch vehicle with a timer.
Because the effect is global, no fancy guidance system and no homing
sensors are required.  No satellite needs to be directly attacked since
the damaging electrons rapidly move out from the point of explosion. This
leads to another attractive feature of this nuclear approach:

An aggressor country could launch an attack near its own territory and
claim it was only doing a test and had no knowledge or intent to harm
satellites. Sanctions could be imposed on the country, but it is
unlikely that a direct military response would be aimed at it since the
high-altitude explosion killed no one and no cities were destroyed.

The primary means of defeating this threat is to make sure that
satellites [are equipped with] a combination of shielding and radiation-
hardened electronics. Such an approach, if implemented in the beginning
of a satellite program, would only add a small percentage to development

Remember the problems caused when Galaxy 4 failed earlier this year?
Imagine if hundreds of satellites failed in the timespan of a few weeks
and replacements could not be launched for a year. It would be a

Glenn Kweder
Space systems analyst
Logicon RDA
Alexandria, VA

Index Home About Blog