by Jeff Foust — February 18, 2022
A simulation of the Russian ASAT demonstration
in November 2021. Much of the debris from that event is in an orbit that
periodically lines up with satellites in sun-synchronous orbits. Credit:
WASHINGTON — Debris from a Russian
antisatellite weapon demonstration in November are creating surges of close
approaches, in some cases tens of thousands in a week, with active satellites
in low Earth orbit.
Such events, dubbed “conjunction
squalls” by space situational awareness company COMSPOC, were first noticed in
January and stem from the unique circumstances of the Nov. 15 Russian ASAT test
that destroyed the Cosmos 1408 satellite and created thousands of pieces of
The squalls can result in
thousands of close approaches, or conjunctions, over just a few days. “In the
first week of April, in that week alone, there will be 40,000 conjunctions that
we predict purely from that one event,” said Travis Langster, vice president
and general manager of COMSPOC, during a panel at the 24th annual FAA Commercial
Space Transportation Conference Feb. 17.
Those surges come from the
interaction of the Cosmos 1408 debris with constellations of remote sensing
satellites. Cosmos 1408 was in an orbit at an inclination of 82.3 degrees,
while many remote sensing satellites are in sun-synchronous orbits with
inclinations of about 97 degrees. As the orbits precess, the debris overlaps
the orbits of remote sensing satellites — but going in the opposite direction.
“When they sync up, you have the
perfect storm: they’re in the same orbit plane but counter rotating, crossing
each other twice an orbit, again and again,” said Dan Oltrogge, director of
integrated operations and research at COMSPOC, in an interview. Those squalls
last for several days until the orbits precess out of sync.
COMSPOC first noticed a surge on
conjunctions at the beginning of the year, linked to a group or “Flock” of Dove
imaging cubesats operated by Planet. That first surge peaked at about 4,000
daily conjunctions, defined as approaches within 10 kilometers, on Jan. 2. A
second conjunction squall, peaking at about 2,000 conjunctions a day Jan. 25,
linked to another set of Planet satellites.
COMSPOC is predicting an even
stronger conjunction squall in early April as the debris encounters several
Flocks of Planet cubesats, including a peak of more than 14,000 conjunctions on
a single day, April 5. Another squall is predicted with those same cubesats
about six months later, but with a peak only about half as strong as debris
spreads out and reenters.
Planet feels some of the strongest
effects of the Russian ASAT debris because of the size of its constellation,
but it is not alone. “This is no different for any Earth observing system that
uses sun-synchronous orbits at this altitude,” Oltrogge said. “We expect that a
lot will be affected.”
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