Jonathan’s Space Report No. 523 2004 Apr 7
Kosmos-2406
===========
Russia launched Kosmos-2406 on Mar 27 into geostationary orbit. The
launch vehicle was a Proton-K with a Blok DM-2 upper stage, in contrast
to the Mar 15 launch of the more modern Proton-M and Briz-M combination.
Kosmos-2406 is a Globus military communications satellite. The first
orbital data show the satellite in an unusual subsynchronous 1329.92
minute, 32307 x 35056 km x 0.0 deg drift orbit, with a perigee over 3000
km lower than normal Russian GEO insertions. (As of April 7, no further
orbital data was available). The previous Globus satellite, launched in
Oct 2001, also was tracked in such an orbit the day after launch, and
then found again in a normal GEO orbit two weeks later. The reason for
this new launch profile is not obvious.
WDC-A and Space Command are reporting the satellite as Kosmos-2407,
presumably because the original Russian launch schedule stated the
now-delayed Zenit-2 launch would be Kosmos-2406. However, after launch
Novosti called the new satellite Kosmos-2406, implying that the Kosmos
numbers will continue to be assigned in launch order, and so provisional
numbers released before launch may change. This makes sense since the
Kosmos numbers are used purely for public consumption, with internal
classified military names used in all technical documentation, so
changing the Kosmos number at a late date doesn’t break anything.
TASS reported the launch as a `four tonne satellite’ which is simply an
error, as the Proton does not have the capacity to put such a heavy
satellite in the orbit achieved. The Kommersant story says 2 tonnes,
which is correct.
The Blok-DM final stage from Kosmos-2406 has not yet been cataloged;
neither has the Briz-M stage from the Eutelsat launch two weeks ago.
There were two kinds of Kosmos satellite launched in the recent past to
GEO – the Lavochkin US-KMO Prognoz early warning series, and the NPO-PM
Geizer military communications satellites. The last Geizer launch was
Kosmos-2371 in Feb 2000; the last US-KMO launch was Kosmos-2397 in Apr
2003. The US-KMO series has been plagued with failures, with only the
2001-launched Kosmos-2379 still operating, and Kosmos-2371 is the last
operating Geizer, so originally I suspected Kosmos-2406 could be a
replacement in either series. David Todd suggested to me that instead it
might be a Globus military communications satellite and this has now
been confirmed by a story in the Kommersant newspaper. Earlier Globus
launches were given the Raduga-1 cover name, but it looks like the
Russian Defense Ministry may be consolidating all its launches under the
Kosmos cover name now (as for last month’s Kosmos-2405 launch).
Navstar 59
==========
A new Navstar GPS (Global Positioning System) satellite was launched on
Mar 20. SVN 59, the 11th Block IIR launch, rode to space on a Boeing
Delta 2 from Cape Canaveral’s Space Launch Complex 17B. The Delta
second stage reached a 174 x 200 km orbit at 1803 UTC; after its second
burn the third stage separated at 1857 UTC and fired to enter an
elliptical transfer orbit. The GPS satellite separated from the third
stage at 1901 UTC, followed two seconds later by a `yo weight’, a small
weight attached to a 1-meter cable which unwinds from the spinning PAM-D
stage and whose departing angular momentum is used to tumble the stage
and make sure that residual thrust doesn’t cause it to hit the payload.
I’ve been obssessing about these yo weights recently. Humour me, Gentle
Reader – it’s harmless and keeps me off the street where I might be
fomenting revolution instead. Here’s the problem: solid propellant upper
stages are usually fired while spinning rapidly to keep them stabilized.
After separation of the stage, you usually don’t want your payload
spinning fast. One way of fixing this, invented independently by JPL and
APL in the early years of the space age, is the despin weight or `yo-yo
device’, in which a pair of long wires with masses on the ends are
wrapped around the vehicle. When the masses are unclamped from the
satellite, the spin unwinds the wires, and angular momentum is
transferred from the satellite to the masses. When the wires have fully
unwound they are released and each wire-plus-mass pair becomes a piece
of space debris. For early satellites the despin weights were wrapped
around the satellite itself, but for modern Delta launches the weights
are attached to the third stage and are released after third stage
burnout but about 5 seconds before third stage/satellite separation.
The despin weight idea is a one-use-only solution and some satellites
have more sophisticated forms of spin control, using magnets or gas jets
– for instance, the GPS satellite has its own solid motor for orbit
circularization, and so it needs to be still spinning for that burn. In
those cases a single weight is used by Delta third stages, and is
released 2 seconds after third stage separation instead of 5 seconds
before. The asymmetric transfer of angular momentum to the weight causes
the third stage to tumble, so that if rocket exhaust is still escaping
from the embers in the thrust chamber it won’t go in the direction of
the payload but will average out to zero net thrust. In the early days,
there were several cases of a rocket stage bumping into its payload
again after separation and causing damage, because of this residual
thrust problem. The despin weight analogy with a yo-yo is a bit
strained, and to the extent that it holds a single weight+wire is really
the equivalent of a yo-yo, but nevertheless not only has the name stuck
but the single-weight tumbler case has become known as a `yo’ (half a
yo-yo)!
Every three-stage Delta 2 variant uses either a yo or a yo-yo, and so
leaves one or two pieces of debris in orbit each with a mass of 1 kg and
a cable length of 1.0m. In 1994 Space Command started cataloging
some of these debris pieces, and it was a while before I figured out
what they were. Not all the pieces have been cataloged; I present here
a list of recent three-stage Delta 2 launches and their despin type.
Date Delta Model Payload Despin type Catalog1998 Dec 11 7425-9.5 Mars Climate Orbiter Yo-Yo No 1999 Jan 3 7425-9.5 Mars Polar Lander Yo-Yo No 1999 Feb 7 7426-9.5 Stardust Yo No 1999 Oct 7 7925-9.5 GPS IIR-3 Yo 26789 2000 Mar 25 7326-9.5 IMAGE Yo-Yo No 2000 May 11 7925-9.5 GPS IIR-4 Yo 27764 2000 Jul 16 7925-9.5 GPS IIR-5 Yo 27765 2000 Nov 10 7925-9.5 GPS IIR-6 Yo No 2001 Jan 30 7925-9.5 GPS IIR-7 Yo 27766 2001 Apr 7 7925-9.5 2001 Mars Odyssey Yo-Yo No 2001 May 18 7925-9.5 GeoLITE Yo-Yo No 2001 Jun 30 7425-10 MAP Yo-Yo No 2001 Aug 8 7326-9.5 Genesis Yo-Yo No 2002 Jul 3 7425-9.5 CONTOUR Yo No 2003 Jan 29 7925-9.5 GPS IIR-8 Yo 27773 2003 Mar 31 7925-9.5 GPS IIR-9 Yo No 2003 Jun 10 7925-9.5 MER-A Yo-Yo No 2003 Jul 8 7925H MER-B Yo-Yo No 2003 Dec 21 7925-9.5 GPS IIR-10 Yo 28189 2004 Mar 20 7925-9.5 GPS IIR-11 Yo 28193
Table of Recent Launches
———————–
Date UT Name Launch Vehicle Site Mission INTL.DES. Feb 5 2346 AMC-10 Atlas IIAS Canaveral SLC36A Comms 03A Feb 14 1850 DSP 22 Titan 4B/IUS Canaveral SLC40 Early Warn 04A Feb 18 0705 Kosmos-2405 Molniya-M Plesetsk Comms 05A Mar 2 0717 Rosetta Ariane 5G+ Kourou ELA3 Comet probe 06A Mar 13 0540 MBSAT Atlas IIIA Canaveral SLC36B Comms 07A Mar 15 2306 Eutelsat W3A Proton-M/Briz-M Baykonur PL81 Comms 08A Mar 20 1753 Navstar SVN 59 Delta 7925 Canaveral SLC17B Navigation 09A Mar 27 0330 Kosmos-2406 Proton-K/DM-2? Baykonur PL81 Comms 10A
.-------------------------------------------------------------------------. | Jonathan McDowell | phone : (617) 495-7176 | | Somerville MA 02143 | inter : jcm@host.planet4589.org | | USA | jcm@cfa.harvard.edu | | | | JSR: http://www.planet4589.org/jsr.html---------------------------
