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SKY SURFING
RADIO FROM THE OUTER REACHES
Keith Baker, KB1SF / VA3KSF
keithbaker@monitoringtimes.com
A Flock of Other Amateur Radio Satellites
Up to now, I’ve been sharing information
about the mainstays of our Amateur
Radio satellite fleet and how you can receive
their signals or, if properly licensed, actually
work through those that have transponders.
In this installment, I’ll discuss a number
of other amateur satellites that have launched in
the last few years and then bring you up-to-date
on some of the latest happenings in the amateur
satellite world.
❖ An Aging Fleet
In my work as the past president and current
treasurer of AMSAT-North America, I’m
frequently asked, “With all the on-orbit failures
of AMSAT’s satellites lately, what satellites are
left for me to work?”
Clearly, we have recently lost our most
popular so-called “EZ-sats” (AO-51) to battery
failure. Some others (like SumbandillaSat
(SO-67) and Hope OSCAR 68 (HO-68), which
showed great promise soon after their launch, are
now in beacon mode (if that) most of the time.
In addition, satellites like AO-7 (which is now
nearing its fortieth anniversary in orbit) is only
functional while in sunlight, and VO-52’s Indian
ground handlers recently had to switch the satellite
to one of its backup analog transponders as
the primary transponder experienced an on-orbit
failure.
Even the Mode V/U (Mode J) transponder
aboard JAMSAT’s venerable Fuji OSCAR 29
(FO-29) had to be turned off by its handlers for
many months because its orbit progressed into
long periods of darkness.
But, despite all these failures, the good
news is that there are still several fully functioning
Amateur Radio satellites available to listen
to (or work through) most of the time. Satellites
like AO-27 and SO-50 now carry the bulk of
FM traffic and FO-29’s analog transponder has
now come back to life as strong as ever. What’s
more, there’s an emerging class of satellites now
in orbit that are fun to listen to even if they don’t
have transponders aboard. Most are in a satellite
class we call “CubeSats.”
❖ The CubeSats
In a previous column, I briefly described
this whole new class of satellites, based on a
design that now appears poised to become the
future of the Amateur Satellite Service. Measuring
only 4 inches on a side, these tiny satellites
(sometimes also called “nanosatellites”) are now
being built, launched and/or controlled in ever
increasing numbers by numerous organizations
(primarily educational institutions) around the
world.
While some of these organizations have
links to amateur radio, most do not. The bulk
of these satellites have digital downlinks. A few
take pictures. But most are placed in orbit for the
express purpose of conducting various scientific
experiments. And while some of these experiments
are of interest to amateur radio operators,
most are not. Unfortunately, when their original
scientific experiments are complete, many of
them die on orbit or revert to beacon mode…if
they even last that long.
However, despite their shortcomings,
CubeSats are the future of this part of the hobby.
They are reasonably inexpensive to build and
still quite affordable (less than $100K) to launch.
However, they are not without their own built-in
problems.
For example, because these satellites are so
small, they tend to run “cold” on orbit, as they
cannot absorb enough heat when in daylight to
keep their internal parts warm enough during
eclipse to function properly. Batteries, in particular,
usually will not accept a full charge if
their internal temperature falls below freezing.
This issue is further complicated by the fact
that the cross sectional area of these satellites
does not allow for large enough solar panels to
generate enough extra onboard power that could
be used for internal heating. As a result, these
satellites often run in a negative power mode that
eventually “does them in,” sometimes soon after
launch.
But, as I’ve also said, even though most
of these satellites do not contain transponders,
they are still fun to listen for. So, let’s shine the
spotlight on a few of these CubeSats that were
still operational at press time (late June 2012).
Unfortunately, some (or all) of these satellites
could very well be partially or completely defunct
by the time you read this, so “your mileage
may vary.”
❖ PW-Sat
PW-Sat is the first Polish satellite. Its
construction was an initiative of the students
of Warsaw University of Technology (in Polish
- The Politechnika Warszawska, therefore the
“PW” in the satellite’s name) working within
the Students’ Space Association and Student
Space Engineering Scientific Group.
PW-Sat was successfully launched from
Koruou, French Guyana on February 13, 2012.
The satellite is a 1U Cubesat (approximately
The flight model of PW-Sat. (Courtesy: Warsaw
University of Technology)
4 inches square) and its stated mission is to
(eventually) test de-orbiting techniques at the
end of its on-orbit life. At press time its Mode
U/V (Mode J) transponder was still operational.
More information (in Polish) about the
project can be found at: www.pw-sat.pl.
❖ DO-64 (Delfi-C3)
Delfi-C3 is the first nanosatellite built
as a student project at the Delft University of
Technology in the Netherlands. The satellite
is based on the CubeSat concept in a “3U”
design….that is, three single (so-called “1U”)
CubeSat frames stacked on top of one another.
An artist’s concept of how the Delfi-C3 satellite
might appear in orbit. (Courtesy: Delft
University)
66 MONITORING TIMES August 2012