[amsat-bb] Re: JUBILEE and other frustrations

[Bruce Robertson]

On Wed, May 28, 2008 at 8:17 PM, John Wright <ham at g4dmf.co.uk> wrote:
>  >>SNIP
>
>
>> > Honestly, if somebody has put a 45 kg amateur satellite into a 1,500 km
>>plus orbit and has NOT included a
>> > transponder,
>
> <<SNIP
>
> There seems to be a proliferation of satellites using the Amateur
> bands as cheap down link frequencies,  and using Radio Amateurs as a
> cheap way of collecting their data. It is MY personal belief that a
> satellite should only use our hard-earned and much coveted
> frequencies if they REALLY do carry an Amateur Radio payload... I.E.
> a Transponder! , or, at the end of their commercial life, should be
> put to real amateur use, I.E. a Transponder, promised several times
> but not often delivered.
>
> OK there are many out there who get satisfaction from getting signals
> from anything that is orbiting, to them, I raise my hat
> BUT.. if it is in an amateur band, it should be a REAL amateur satellite.
>
> This is my view, and I stand here to be shot down.....
>

John:

I'm not going to shoot you down. With some moderation, your views
represent many of us. But I want to suggest another way forward, one
that is audible on our radios right now. Delfi C3 is a project that
makes a fair trade between the college projects' desire for data from
our unequaled network of receiving stations and the amateurs' desire
for a transponder. Even if a few other cubesats go up at the same time
-- and I have to confess that as a university professor (though in the
humanities), I love to collect telemetry from these, because I can
imagine the enthusiastic young people behind them -- even if these
others without a transponder go up at the same time, we stand to
benefit greatly (admittedly, in LEO) from this sort of trade-off.

I understand William PE1RAH is working on a transponder design that
will fit within the cubesat format, too.

Here's my optimistic summary (again, apropos LEO). Cubesats have
created a low-cost, frequent ride to space. The experimenters have
developed a standard ejection system, and a well-known set of
parameters for power, etc. We know a linear transponder can ride on
one of these. At the same time, I'd say that on the whole our
groundstations are improving (with antenna design and low-noise
preamps) that we can compensate slightly for lower power in space. We
should get behind these cubesat projects and be in the position to
offer a SDX transponder that can, during their science phase, be used
as a data downlink. Here: it's yours. Just let us turn on the
transponder in a year or so.

I'll end with a challenge to continue this thread. Cubesats tend to be
launched into low LEO orbits. What experimental schemes could be put
on board to boost their orbits, say to the height of FO-29? The ION
cubesat was meant to look into alternate propulsion. These probably
should not be tried-and-true systems, since such would not be of
interest to the cubesat research teams. We offer the comms, we cheer
on the science, and even if the boost engine doesn't work, we have
another low LEO transponder.


73, Bruce
VE9QRP