[Xastir] An Xastir story

[Craig Anderson]

Hi all,
	I must tell you all how excellent Xastir is.  This
last Friday a student project at Stanford
(http://ssdl.stanford.edu/ssdl/index.php? 
option=com_weblinks&catid=55&Itemid=44)
launched a research balloon and I used Xastir to track
it and recover it.  I work with a group called Stratofox
(http://www.stratofox.org) that tracks and recovers
amateur (and not-so amateur) rockets.

I got to Palo Alto airport (PAO) at 09:30 loading my gear
into a Cessna 182.  The 182 has a 28V electrical system
so I had to bring my own power source.  A 20AH battery
that fed an APRS broadcast setup to allow tracking of the
plane (TH-D7 and eTrex GPS), a radio for ground comm
(an HT and a 50 watt brick amp with mag-mount antenna),
the balloon tracking setup (a 110V Inverter, 110V power
supply, radio, mag-mount antenna, TNC, laptop with
Xastir 1.8.5, and a USB GPS), and binoculars.  The back
seat of the plane was a mass of wires.  I ran the tracking
systems and a really good non-ham grad-student pilot
flew the plane.

We took off about 10:30 and flew to Mt. Hamilton
(Licke Observatory, http://mthamilton.ucolick.org/) and
circled the launch area until the balloon was launched at
11:00.  We could receive the 437.1MHz APRS signal for
only a few thousand feet and then lost it (it was only a
200 miliwatt signal from a BeeLine transmitter).  We
switched to 144.39MHz to the backup transmitter (a 5
watt signal from a TH-D7) and it worked fine.  Xastir
and the Tigerline 2006 maps showed us and the balloon,
altitudes, distances, bearings, and all the landmarks
we needed.  It worked perfectly.

We had over 40 minutes before the balloon reached
altitude so we flew to where the rest of the team was
gathering: the Lodi airport (IO3).

The balloon burst right on schedule at just over 90,000ft.
We took off in the plane intending to climb up to meet it
and track it coming down.  But my laptop kept turning off
the screen and wouldn't turn on, so I had to power-cycle
it (3 times).  When we got to about 12,000 feet we
basically met the balloon on the way down, but we
couldn't see it visually.  The ground teams could see
the APRS packets, but we couldn't because my laptop
was still wedged.  We circled chasing it all the way down
but could never see it.  I finally got the laptop working again
and caught the last few packets before it hit the ground.
Watching the map on my laptop with over-layed position
data we could track the balloon to where it should be but
it still took us 20 minutes of circling before we could see
what we thought was it.

Then the ground crews started showing up.  We finally
saw them and directed them right to the spot in the middle
of a cherry tree orchard and they still couldn't see it until
we told them it was up in the tree above them.  Then they
caught a glimpse of it and could get it down.

Xastir was truly the key to finding that balloon.

Thanks guys.  A *very* nice program.

Craig
n6yxk