Polyus/Skif, part 2

A few months ago, in a discussion of the somewhat-mysterious Polyus/Skif
payload of the first Energia launch, I posted a brief summary of the paper
on it in the then-latest issue of Quest (vol. 14 no. 1). The next issue
has appeared, and with it part 2 of the paper, so here's a summary of the
rest of it...

(Brief recap of part 1: Concepts for orbital laser ABM systems produced
an interim goal of an orbital laser antisatellite system, Skif. The
prototype, Skif-D, would use a CO2 laser already designed for an aircraft
testbed, and various other systems including a variant of the TKS service
module for attitude control and general support services. Skif-DM was an
attempt to assemble as much of a test article as could be built quickly --
in particular, no laser -- as a payload for the first Energia. The top
third of it, under a big launch fairing, was the TKS service module. Much
of the rest was an empty shell, although there were a few real subsystems,
like the nonpropulsive-vent system for the laser -- with provisions to
expel gas through it for testing -- and the target dispensers at the tail.
It was painted black to help with thermal control, its internal heat
output being far less than an operational version.)

Skif-DM was put together in great haste, with much of the assembly and
testing done at Baikonur. Even final testing was somewhat compressed.
In the end, Skif-DM, Energia, and the launch pad (modified from the
static-test stand, because the definitive Energia launch complex was
running very late) were all behind schedule and none were ready for the
original Sept 1986 launch date.

Skif-DM was originally labeled "Polyus". While waiting at Baikonur, it
acquired another label: "Mir-2". The latter appears to have been partly
KB Salyut politicking for their Mir-2 concept (based somewhat on Skif, and
in competition with NPO Energiya's concept), and partly an attempt to give
Skif-DM a cover story as a prototype space-station module.

Around this time, politics started scaling back the Skif-DM test plans.
Gorbachev was highly critical of SDI, and there was some sentiment that
this was not a good time for a Soviet space-weapon prototype to be tested,
with or without plausible deniability. Target deployment and testing of
the vent system were both canceled. And when Gorbachev visited Baikonur,
partly to see Energia/Skif-DM, he was quite firm: "We are categorically
against the shift of the arms race into space." Launch was approved, for
15 May 1987, but the program had no future after that.

On the 15th, after some hours of delays due to Energia problems, launch
occurred in late evening. Energia did its job, the service-module fairing
was jettisoned properly during ascent, and Skif-DM separated cleanly, in a
barely-suborbital trajectory. The TKS service module having been launched
on top (to match its launch environment to that of Proton, for which it
had been built, as closely as possible), Skif-DM would have to turn 180deg
before the first of the two orbit-insertion burns.

Attitude control and the RCS system were activated, and the turn started.
Several equipment covers were jettisoned... and when the RCS system should
have fired to stop the turn at 180deg, nothing happened and the rotation
continued. Various other cover jettisons and deployments happened as
programmed, and the OMS engines were started for the first burn, but the
rotation continued unchecked, and the OMS burn (lasting roughly two full
turns) accomplished nothing. Skif-DM reentered and fell into the same
area where the Energia core fell.

The problem was identified quickly: the RCS engines had been disabled
because a command had shut down their "power amplifiers" [drive circuits
for their valves, I would guess] just before the cover jettison. The
cover jettison used a timing signal which, on the original TKS, deployed
the service module's solar arrays... and RCS operation was inhibited
during solar-array deployment.

This would have been caught if normal development testing had been done at
the factory, but the test setup at Baikonur didn't permit the full range
of tests. Even so, the RCS shutoff command did show up in the recorded
test results, but there had been no time for a full data analysis and
nobody had noticed.

Work continued for a little while on Skif-D1, a more complete Skif
prototype (although without the laser), but resources started to dwindle
since the government was no longer very interested, delays multiplied, and
technical problems did not get solved. Skif prototype work was stopped in
late 1987, and the combination of the weakening Cold War and growing
Soviet economic problems ended all military "heavy orbital station"
funding in 1989.

One minor surviving element is the big carbon-composite launch fairing
that covered the TKS service module. The Mir add-on modules and the Zarya
ISS module were all variants of the same service-module design, and all
were launched under the fairing developed by the Skif program.

(Oh yes, credits: the two-part article is "The 'Star Wars' That Never
Happened", original by Konstantin Lantratov, translation by Asif Siddiqi.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. | henry@xxxxxxxxxxxxx
.

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