Satgen449  Ariane/P3D Prospects   by GM4IHJ  (BID SGEN449)  1 Nov 97

In examining the prospects for Amsat Phase 3D satellite , the major
factors are expense - purely an Amsat problem , and , launch
opportunities - which are outside Amsats control.

Whether Amsat board can persuade Radio Amateurs to continue to fund
P3D, long after they expected it to be in orbit , and , after they had
already contributed a large sum , which may have exhausted many donors
resources, remains in doubt. But perhaps , more alarming is the
problem faced by the European Space Agency (ESA), which has provided
Amsat launches for so long.

For the past 20 years or so, all launches of amateur satellites, have
been European, Russian , or Japanese. There have been no launches on
American rockets since 1978 , apart from Uo9 and Uo11, which did not
carry transponders. ESA has provided all the launches since then ,
excepting those from Russia and Japan. But ESA has recently been
experiencing an unprecedented and undeserved series of problems.

The ESA way forward , as seen in 1996, was via the new, much more
powerful, Ariane 500 series. Replacing the extremely successful Ariane
400 series. But Ariane 501 had a disastrous launch, when its new
configuration produced acceleration rates , which had not been allowed
for in the software of the onboard control equipment. Whereby, it is
suggested that, a reliable 400 series stabilization feature , simply
failed to accomodate the thrust and acceleration of the new 500 series
rocket assembly.

When the consequences of this became clear. Amsat were asked to ensure
that Phase 3D could itself accept this new acceleration regime.
Unfortunately there was nowhere near enough time to carry out the
necessary modifications to Phase 3D that this required. So P3D was not
aboard Ariane 502 as it awaited launch this week.

Indeed Ariane 502 has been further delayed a number of times since the
opportunity to fly P3D was lost. Several major tests and simulations
of 502 being necessary, to examine uncertainties regarding fuel system
resonances and other engine problems. Naturally this has had effects
far beyond Amsat. Whereby commercial firms planning launches on the
500 series have got cold feet , and have instead begun to reconsider
whether or not to order launches on the proven Ariane 400

As a consequence of the above . Arianespace , the commercial operator
of the rocket, has announced that it is buying 20 of the Ariane 400
series , what ever the outcome of the 502 launch. This order for 400
series rockets is worth 1.5 billion dollars, and it has reportedly
been placed because European space industry executives want to see
several successful launches of 500 series Arianes ( ie a wait of
perhaps 18 months or so), before they will use it for their
satellites. A situation which leaves ESA, with a lot to worry about
but hopefully ,enormously relieved, that 502 launched successfully