Decaying C*2293 94-72A (page plug)
bjorn@tt-tech.se
Wed, 24 Apr 1996 9:45:19 +0100
Cosmos 2293 will decay around 17.May -96
---------------------------------------------------------------------
This is the justified but unedited header and text of the root
(http://algonet.se/~b_gimle/eorsat.htm) of a new tree of
articles and charts about the EORSATs during operation
and decay, and a comparison to photo recon satellites.
The links start from the #23336 line in the home (index.htm)
and decayers.htm pages. As usual with Netscape, you can follow
the links before the miniature charts are completed, but if you
only want to pick a few charts, you may want to disable 'Images'
before you load the root page. The charts are also linked in an
(almost) circular wheel, with eorsat.htm as the hub, but the
order is at the moment not the same as in the following text.
---------------------------------------------------------------------
Cosmos 2293 6.0 0.0 0.0 4.5
1 23336U 94072 A 96114.40186927 +.00440256 +68709-5 +53284-3 0 01787
2 23336 064.9950 067.0026 0108389 254.9591 103.9629 15.96982904083652
NASA's (USSPACECOM's?) latest 60-decay prediction (Apr.18) does not
yet list this object.
Cosmos 2293 is one of the Russian 'EORSAT's ( Electronic Ocean
Reconnaisance Satellites ). The operational orbits of the current
generation of these satellites has always been a circular orbit with
Mean Motion of 15.520 anomalistic orbits per day. Usually there are
two or more satellites operating at any given time, and their orbits
are controlled so that they pass at about 30 minutes intervals. This
is maintained with a very high precision, (See below.) unlike photo
reconnaisance satellites, whose orbits are adjusted with large
impulsive delta-V's, when atmospheric drag has lowered the orbit too
much.
Since Cosmos 2293 was commanded out of its operation orbit, about
960326, it appears to follow a normal decay curve. An earlier EORSAT
that decayed normally after being brought down from the operational
orbits is Cosmos 2244.
Some EORSATs appear to have had their orbit correction systems
running in the initial decay phase (Two-phase EORSAT decays)
and, finally, some decayed so slowly that the orbit correction
systems appears to have been operating during the entire decay (Slow
EORSAT decays)
The screen snapshot below shows Mean Motion values for EORSAT Cosmos
2293 from elsets.
To EORSAT Cosmos 2293 graph.
Operational EORSATs :
Cosmos 2326 is still operational. The screen snapshots below shows
Mean Motion values from elsets.
You can see many cycles of decreasing MM, with intervals of about 12
days and amplitude of about 0.0015. This is very different from the
normal operation of the KeyHoles and the Russian photo-reconnaissance
spacecraft, that increase their MM by about a hundred times this
amplitude by atmospheric drag over periods of nine days to many
months, and then reclaim that by single (or double) rocket impulses.
The smooth decreases seem to indicate a continuous low-thrust orbit
correction system - but there are lots of data points between and
during these periods. They could indicate inaccurate orbital
elements, or a correction system that is working by small impulses -
not always exact.
To EORSAT Cosmos 2326 graph. See also "Novosti
Kosmonavtiki" article in seesat-l/2182.
Cosmos 2313 is operational, in the same orbital plane as 2326 (and 2293).
To EORSAT Cosmos 2313 graph.
Reconnaisance satellites :
Cosmos 2320 is a typical Russian reconnaisance satellite.
The size of MM adjustments vary between about 0.2 and 0.02, the
intervals between 9 and 45 days ! This is very different from the
normal operation of the EORSATs, that decrease their MM by about one
percent of this amplitude over a period of 12 days, then quickly lose
that decrease by atmospheric drag (or rocket impulses).
The screen snapshot below shows Mean Motion values from elsets.
To Recon sat Cosmos 2320 graph.
Cosmos 2305 was another typical photo reconnaisance satellite,
deorbited 951218:
To Recon sat Cosmos 2305 graph.
Other EORSATs that decayed normally :
To EORSAT Cosmos 2244 graph.
EORSATs that decayed slowly at first :
Note that, approximately midway through the decay, ndot2 (the time
derivative of Mean Motion) suddenly multiplies by a factor of 4-5 !
To EORSAT Cosmos 2258 graph.
To EORSAT Cosmos 2238 graph.
EORSATs that decayed slowly all the time :
Note that because the orbit correction system apparantly was
operating during the entire decay phase, my normal approximation
function does not work (the shape of the curve is different, not only
the slope)!
To EORSAT Cosmos 2264 graph.
Back to my Home Page.