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Re: (meteorobs) Radio Meteors
Jim Richardson said:
>Sort of along these same lines, however, I have heard of professionals
>successfully utilizing radio transmitting satellites as the signal source
>for meteor forward scatter (stationary?), although I can't point you to any
>papers. I don't know of any amateurs who have been able to do this also,
>although Dr. Meisel mentioned it as a possibility in the original 1977
>version of AMS Bulletin 203. Most of these satellites today are designed
>for line-of-sight, high-frequency communication and do not give themselves
>over to meteor scatter very easily. It is interesting, but transmitters
>here on the ground are usually more practical.
As a matter of fact, however, radio amateurs HAVE heard reflections from
amateur satellites over the horizon, some of which have had the tell-tale
characteristics of meteor trail reflection while others appeared to be
mainly tropospheric ducting.
Radio amateurs first orbitted their very own satellite, called OSCAR-1
(Orbiting Satellite Carrying Amateur Radio) in 1961; the "bird" was carried
as "piggyback" ballast on a regular satellite launch from the US, and was
built for a total out-of-pocket expenditure of $64 (1961 dollars, of course!
Still...). I am no expert on amateur satellites (had to look up that little
bit of trivia, as a matter of fact!); but I believe that today, there are
about half a dozen funtioning amateur satellites in space from nearly as
many different countries, including Japan and Russia. All-told, I believe
well over three dozen individual amateur radio satellites have been
launched, all carrying only amateur frequency equipment. The latest and
greatest, called Phase IIID, was slated to be launched on a French Ariane 3
rocket this month. However, delays in certifying the rocket itself have
caused unavoidable delays in completion of the satellite and the launch of
Phase IIID has been put off still again (specifically, engineering studies
of the rocket have shown that the amount of vibration imparted on payloads
within the Ariane is much higher than was thought, necessitating redesign
and reconstruction of some satellite mechanical supports).
Most of the amateur satellites have carried, in addition to beacon
transmitters, a special radio receiver-transmitter system called a
transponder; these receive amateur signals on one frequency band and
retransmit the signals on another. There have been many recorded instances
whereby reception of signals retransmitted from the satellite have been
heard on the other side of the earth, beyond line of sight of the satellite
to the receiving station. Several of these instances have had all the
characteristics of meteor scatter, or reflection. I am unaware whether any
two-way communications have been accomplished in this manner, however; but I
would rather doubt it because the satellite's speed through space (and
consequent speed over the earth) would tend to cause it to move out of the
best location to transmit signals that would be reflected from a meteor
trail and then to the same receiving station, all within a few minutes, even
during a major meteor shower. Something like that COULD happen during a
storm, such as what we all are hoping to see from the Leonids over the
coming few years.
Clear skies and bright trails,
Steve Harrison
Amateur Radio Meteor Scatter Station Ko0U
Shrewsbury MA