PSN-L Email List Message

Subject: Re: Satellite re-entry to Seismic record
From: Ed Thelen ethelen@........
Date: Tue, 01 Feb 2000 12:12:27 -0800

I knew  a guy who lived under the landing pattern for Los Angles
International air port.  He ran a garden gate type seismograph
adjusted to about 20 seconds natural period.  He said that
even though it was in a little shed in the back yard,
the seismograph had to be carefully covered with a good box
or he would be affected by planes flying low overhead.

Could there have been an non-audible pressure wave from the 
fireball that pushed the boom  of the seismometer a tiny bit?

I don't know if a shock wave from say 50 Km high event
(presumably a very audible sharp step in pressure) 
gets converted to a slow rising pressure wave that
humans don't hear at ground level.

(I do know that a supersonic Hustler bomber flying at
 say 30,000 feet makes a very audible window rattling
 "BOOM" at ground level.)

"Grasping at straws"
  Ed Thelen

ajbv@............ wrote:
> Hi,  I asked around and nobody heard any sounds except an observer
> in the north of the state who claimed to hear a "hissing sound".  This
> type of comment does occur on some Fireball sightings.  But no rattling
> of windows or the like.  So alas,  I'll just have to say the measured "noise"
> at the time of satellite entry will be put in the Hmmmm basket.  I do agree
> that the magnet effect is not really possible given the 1/r^3 decline in the
> magnet strength with distance.  Anyhow  unit the next event.
> Thanks to John Hernlund and Ken Navarre.
> Arie
> Ken Navarre wrote:
> > On Sat, 29 Jan 2000 ajbv@............ wrote:
> > > Apparently the object disintegrated in "mid-air" over the sea
> > > approximately north of Kunnunura (near the border with the Northern
> > > Territory). It was seen by people spread out about 2,000km across the
> > > state. This is very unusual for a meteor as it suggests a 'grazing'
> > > trajectory. We believe it was the entry of the  Molniya 1-67, a Russian
> > > communications satellite that was launched in 1986.
> >
> > Was there a sonic boom associated with the reentry event?  If so, the
> > "noise" you described could be related to that.  Several years ago when
> > "AREA 51" in Nevada was an active source of classified aerial activity
> > southern California seismometers tracked several events that
> > seemed to be associated with high altitude sonic booms headed from
> > out over the Pacific and flying toward the Nellis Test facility in
> > the Nevada desert.  The booms left a "seismic footprint" across the
> > seismic network.  I recall some work being done to determine the altitude
> > and direction of travel of the aircraft that produced the sonic booms.
> > There were several events like this that occurred over several months.
> > No one stepped forward to claim responsibility and it was assumed that
> > the booms resulted from the operation of some classified project at the
> > test site.
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Larry Cochrane <cochrane@..............>