Even in the vacuum of outer space, it's hard to keep the sound of a secret quiet.
The U.S. Air Force apparently has a malfunctioning Defense Support Program satellite on its hands. DSP-23 is one piece of a constellation of such Earth-staring satellites designed to detect missile launchings and nuclear detonations, and gather other technical intelligence.
DSP-23 seems to be drifting out of its high-altitude slot — and might prove troublesome to other high-value satellites in that populated area.
One person who has flagged the problem to a U.S. satellite tracking expert is a Russian space analyst — a project partner of the International Scientific Optical Network, or ISON for short.
Vladimir Agapov is a senior scientist for the Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences. He told Space.com that ISON is a global network of scientific optical facilities for observation of high-altitude geocentric orbits. They keep an eye on what's going on in order to better understand the real population of artificial objects — mainly space debris — in that part of outer space.
Agapov said ISON is monitoring the entire ring of objects in geostationary Earth orbit, or GEO. The network tracks all operational satellites, as well as space debris, spent rocket bodies, dead spacecraft, operational fragments and objects originating from satellite fragmentations that have appeared in geostationary orbit.
"We have continuously tracked an object we have identified as DSP F23 since January 10, 2008," Agapov said. "Identification is made on the base of initial orbital information obtained by amateur astronomers using their own measurements."
Slideshow: Month in Space Processing of optical measurements obtained by ISON confirmed that DSP-23, after making three stationkeeping maneuvers, has not performed any follow-on movements during the course of some two months, he said.
The spacecraft has strayed from its spot in space — moving along in geostationary orbit as a passive object.
It's not clear from optical data alone just what the operational status of the satellite truly is at present, Agapov added. "You need other kind of observations, radio-monitoring data, photometry, etc., to come to more definitive conclusion," he said.
Asked about the possibility of DSP-23 smacking into others satellites in GEO, Agapov said that "it exists." Sauntering willy-nilly through space, the classified satellite could have close encounters with many operational satellites, he said.
As of the beginning of 2008, the ISON network consists of 18 scientific institutions, 18 observatories and observation facilities, 25 optical instruments, and more than 50 observers and researchers in various nations.
In the big picture, Agapov noted that ISON has discovered 152 "unknown" objects that have no public orbital information as distributed by the U.S. Air Force Space Surveillance Network through its Space-Track database.
In addition, ISON has discovered and is tracking 192 previously unknown, faint debris objects in geostationary orbit, using a variety of instruments.
"Thus, our ISON effort resulted in increasing the number of known — for the public — and continuously tracked objects in GEO region by more than 35 percent, compared to published Space-Track data," Agapov concluded.
Leonard David has been reporting on the space industry for more than four decades. He is past editor-in-chief of the National Space Society's Ad Astra and Space World magazines and has written for Space.com since 1999.
An earlier version of this report misidentified the International Scientific Optical Network.
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