Satgen 180  Viva Mexico , UNAMSAT-1      by GM4IHJ       5th September 92

As many readers will have seen, UNAMSAT-1 , a microsat built by the
Autonomous University of Mexico, could be aloft via a piggy back launch on
a CIS Russian Metsat in December 92.

What interests me about this project is not its microsat digital store and
forward capability, which is of the 1980's  FSK up, PSK down type, but ,
its supplementary module featuring a 40 MHz meteor radar.

This meteor radar is a highly ambitious departure. We know  ( from IRAS,
and the Euro,Russian ,Japanese comet probes ) that most meteor trails
are caused by comet dust colliding with the Earth's upper atmosphere.
Anyone who listened to the recent Perseids around 1900 ut on Aug 11th 92,
will know the doppler shift on some meteor echoes can be very pronounced.
Doppler can tell us in an indirect way, the minimum speed at which the
comet dust/meteor was travelling as it hit the ionosphere. In this way we
may be able to get a good answer to a question which has interested Comet
Watchers for centuries.

The question is "Do all comets coming round the Sun at perihelion,
originate in our Solar System" ? 

The general theory that comets formed in the outer "frozen" edges of our
solar system. and perhaps other star systems, calls for disturbance of
these edge of system comets, which now and then sends them tumbling
inwards around the centre of their star/solar system, or , conversely
causes them to leave their star/solar system and perhaps, eventually ,
enter a different star/solar system.

In theory any comet whose orbit is parabolic or hyperbolic ( as opposed to
the closed elliptical orbit of say Comet Halley ), could be a stray from a
star system other than our own. But, orbit determination when eccentricity
is near 1 or greater is notoriously difficult to obtain. If however we get
meteor reflections whose doppler indicates a meteor velocity greater than
the escape velocity from our solar system, then we may just possibly be
able to suggest that it might have an extra solar origin. Hence the
attraction of UNAMSAT-1 which will DSP echoes and report results to earth
by AX25 telemetry.

Please note in addition that one does not need to be a G3IOR, to see two
other possible features of this exciting experiment.
1. You will probably be able to "Ping steal" on this meteor radar, ie
trigger your scope time base on the pulse transmitted by the sat, then
watch the scope trace for echoes. Your own private meteor radar.
2. You will be able to use the 40 MHz pulses from UNAMSAT  as a super
downward  sounding probe of the ionosphere, at all angles of penetration
of the ionosphere.

So whether you want another store and forward bird, or , a stunningly
original experiment. Mexico seems to be the place. Viva Mexico .
73 de GM4IHJ @ GB7SAN