RE: Cosmos 100 payload and booster exchanged identities (was: ISS near-collision with Cosmos)

Ted Molczan (molczan@home.com)
Fri, 16 Jul 1999 09:44:14 -0400

Russell Eberst wrote:

> The object that ISS nearly hit was Cosmos 100.
> The payload and booster exchanged identities back in 1966.

The switch seems to have occurred on 18 July 1970, based on the orbital
history of 65106A, on Jonathan McDowell's site:

http://hea-www.harvard.edu/QEDT/jcm/space/elements/sats/01800/S01843

it appears that it occurred on day 70199, between bulletins 127 and 128.
Here is the relevant excerpt from the file:

txt/ALLEN10.TXT
1 01843U 65106  A 70191.89870134  .00001368 +00000-0 +00000-0 0 01262
2 01843 065.0068 174.5601 0020282 264.3066 095.5682 14.78668916246157
txt/ALLEN10.TXT
1 01843U 65106  A 70199.27068820  .00001290 +00000-0 +00000-0 0 01278
2 01843 065.0272 152.2997 0019989 261.4991 098.3804 14.78688112247240
txt/ALLEN10.TXT
1 01843U 65106  A 70199.38703500  .00000787 +00000-0 +00000-0 0 01282
2 01843 065.0083 168.3842 0140098 249.1468 109.4541 14.76670153246903
txt/ALLEN10.TXT
1 01843U 65106  A 70220.65242946  .00000722 +00000-0 +00000-0 0 01301
2 01843 064.9957 104.3031 0139353 242.2344 116.4529 14.76701176250044

The file for the B object confirms the switch:

http://hea-www.harvard.edu/QEDT/jcm/space/elements/sats/01800/S01844

1 01844U 65106  B 70187.46738532  .00001067 +00000-0 +00000-0 0 01138
2 01844 065.0113 204.2962 0140629 252.8872 105.6747 14.76649887245142
ga/G980123A.TXT
1 01844U 65106  B 70218.07242321  .00001021 +00000-0 +00000-0 0 01181
2 01844 065.0039 095.4691 0020719 268.8467 091.0220 14.78713199250029

Their orbital planes were far apart on the date of the switch, so it does
not seem to have been a case of the radar/analysts having to decide between
two nearly co-orbital objects.

The pre-switch elements were consistent with the orbits stated in the RAE
Table of Satellites.


Another possible switch that I have studied, was 71120A and B. The RAE Table
lists their initial orbital dimensions as:

A: 878 X 889, e = 0.001

B: 845 X 927, e = 0.006

But the earliest elements available from NASA/OIG's archive disagree:

1 05731U 71120  A 72005.29074670  .00002217 +00000-0 +00000-0   00090
2 05731 081.2674 277.2781 0058990 160.0228 200.3217 14.02575552000966

1 05732U 71120  B 71363.58485295  .00001920 +00000-0 +00000-0 0 00021
2 05732 081.2667 283.7106 0009799 233.5201 126.5015 14.03473663000025

NORAD's orbital dimensions:

A: 849 X 934, e = 0.006

B: 882 X 896, e = 0.001

NORAD has continued with these designations to the present.

Initially, based on RCS values (SL-3 rocket bodies are about 25 percent
larger than the Meteor 1's), I was inclined to believe that NORAD's
designations were incorrect, but Rainer Kracht's 1995 analysis of Russell
Eberst's magnitude observations of 71120A indicates that it is very close to
the mean magnitude of other Meteor 1 sats:

http://www2.satellite.eu.org/seesat/Jan-1996/0014.html

Rainer found that the SL-3 rocket bodies are about 0.8 mag fainter than the
Meteor 1's:

http://www2.satellite.eu.org/seesat/Dec-1995/0016.html


Returning to Cosmos 100, it was Rainer's analysis of Russell's magnitude obs
of 65106B (see the above URL), that convinced me of the correctness of
Russell's claim (in an Oct'96 e-mail to me) that NORAD had swapped the A and
B objects. Its magnitude is very close to that of other SL-3 rocket bodies.

That was another case where the RCS values seemed to suggest otherwise,
causing me to initially doubt Russell's claim. Perhaps NORAD swapped the
objects on the basis of their RCS.

Besides magnitude and RCS, there are other possible checks of these object's
identities. For example, correlation of records of radio monitoring of the
payloads' transmissions (perhaps the Kettering Group has records) against
the archived orbital elements. Or, perhaps Ron Dantowitz could image them.

Ted Molczan