From January 2002 issue of Orbital Debris Quarterly News, NASA JSC

Two major satellite breakups, the worst in 20
months, occurred just four weeks apart in the fourth quarter of 2001, both
producing in excess of 300 large fragments. Two other lesser breakup events
brought the total number of satellite fragmentations to nine for the year,
a rate not matched since 1998.

On 21 November a Russian satellite,
Cosmos 2367 (International Designator 1999-072A, US Sat. No. 26040),
experienced a significant fragmentation while in an orbit just 30 km above
the International Space Station (ISS), i.e., 411 km mean altitude for Cosmos
2367 and 382 km for ISS. Approximately 200 debris were detected by normal
US Space Surveillance Network (SSN) operations, while special
sensor observations several days after the event indicated that
another 100 or more smaller debris were also in orbit. These debris
were concentrated in the orbital regime of 200-500 km, but some were
thrown into orbits with apogees above 1000 km.

Approximately 40% of
the debris were immediately thrown into orbits which crossed the orbit of
ISS. Immediately upon notification of the breakup, the Orbital Debris Program
Office undertook an effort to characterize the probable debris cloud and to
assess the risks posed by it not only to the ISS but also to the imminent
STS-108 mission. Naval Space Command, headquartered in Dahlgren, Virginia,
spearheaded the effort to identify the individual debris and to develop
initial orbital parameters for each. Throughout Thanksgiving and the
following weekend, NASA and Naval Space Command personnel worked to gain
a better insight into the extent of the newly created debris cloud.

The STS-108 mission, then planned for launch on 29 November,
raised new safety issues. The Space Shuttle is not as well protected
from small debris impacts as ISS. Specific concerns were STS-108
overall mission risks, EVA risks, risks associated with boosting ISS
during the mission, and risks associated with special Space Shuttle
attitudes planned during independent flight. Fortunately, these new risks
were assessed to be within NASA guidelines.

Cosmos 2367 was the
latest in the Cosmos 699 series of 3-metric-ton spacecraft which began in
1974. To date 20 of these spacecraft have undergone one or more fragmentation
episodes with the number of debris generated usually on the order of 100 or
more. Most of the events have occurred at relatively low altitudes, resulting
in relatively rapid decay of the debris. In the case of Cosmos 2367 some of
the debris should remain in orbit for many months.

About three weeks
after the Cosmos 2367 breakup, the 12-year-old Molniya 3-35 spacecraft
(International Designator 1989-043A, US Sat. No. 20052) fragmented during
catastrophic orbital decay on 14 December while passing over the Southern
Hemisphere. About two dozen pieces were detected with most reentering
immediately. Some debris appear to have remained in orbit for a few more
revolutions before falling back to Earth.

On 19 December the eighth
breakup of the year resulted in a severe fragmentation of an Indian PSLV
fourth stage (2001-049D, US Sat. No. 26960), which had been in orbit for only
two months. Within two days of the event approximately 200 debris with orbits
stretching from 200 to 1100 km had been identified. By 27 December the number
of tracked debris surpassed 300. The event marked the first breakup of an
Indian satellite.

This was the sixth flight of the PSLV (Polar
Satellite Launch Vehicle) which had successfully inserted the main payload,
the Indian TES (Technology Experiment Satellite) spacecraft, into a
sun-synchronous orbit along with a small German satellite called BIRD. A
second piggyback satellite from Belgium, PROBA, was placed into a
slightly elliptical orbit after the deployment of TES and BIRD. The 900
kg stage was in an orbit of 550 km by 675 km with an inclination of 97.9
deg at the time of the event.

The cause of the PSLV breakup is under
investigation. A potential energy source for the fragmentation may be
residual hypergolic propellants. The release of all residual propellants and
compressed fluids at the end of launch vehicle stage and spacecraft
operations is highly recommended by US Government agencies as well as
many space-faring nations around the world. To date no satellite which has
been successfully passivated in this manner is known to have suffered a

The final fragmentation of the year appears to have occurred
late on 24 December when a 10-year-old Ariane 4 orbital stage
generated several pieces of debris. The stage (1991-075B, US Sat. No.
21766) had placed the Intelsat 601 spacecraft into a geosynchronous
transfer orbit on 29 October 1991. The orbit of the stage at the time of
the event was 230 km by 28,505 km with an inclination of 7.2 deg.
The extent of the fragmentation was still being evaluated at the close of