RE: 2015FEB8-9.OBS

From: Ted Molczan via Seesat-l <>
Date: Mon, 9 Feb 2015 10:45:20 -0500
Russell Eberst wrote:

> Notes: 13-43A not seen on two passes.
>         95-15A seems to have exploded and is in a slightly higher orbit.

According to this source, DMSP F-13 (95015A / 23533) remained operational as of 2015 Jan 09:

Russell observed it five times between 2015 Jan 03-24, in the following orbit determined by Mike McCants:

                                                         832 X 842 km
1 23533U 95015A   15024.21375644  .00000250  00000-0  12751-3 0    09
2 23533  98.7536  28.2203 0007000 169.7000 190.2999 14.15741333    04

Its brightness was steady during those observations.

On Feb 9 at 06:42:44.51 UTC, Russell observed it 33 s late relative the above elements, and varying regularly in
brightness between mag 5.1 and 6.8 over an approximately 10 s period.

According to NASA's History of On-Orbit Satellite Fragmentations, 14th Ed., on 2004 Apr 15 UTC, DMSP F-11 (91082A /
21798) underwent a partial fragmentation that resulted in 56 pieces of debris catalogued within 6 weeks of the event.
The assessed cause was "propulsion", and the following comments were made:

"The spacecraft was non-operational at the time of the event. The electrical power generation system had been
passivated by discharging the batteries and disconnecting them from the charging circuit. Virtually no nitrogen
remained on board due to a leak detected early in the mission. The only energy source assessed to be on the spacecraft
at the time of the event was approximately 6 kg of hydrazine."

The effect on the orbit of 91082A was minor (the exact change is difficult to estimate with certainty because the orbit
was not visible to our observers at the time and for several months afterward). When Russell resumed observations in the
fall of 2004, he found that sometimes it was steady in brightness and sometimes it varied over a period of 5 s.

Exactly what has happened to 95015A remains to be determined.

Ted Molczan

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Received on Mon Feb 09 2015 - 09:46:38 UTC

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