Saturday, May 05, 2012

An update on IGS 1B - a spy satellite about to reenter this summer

(updated reentry prediction at the end of this post)

Last year I wrote extensively about the malfunctioned Japanese spy satellite IGS 1B (2003-009B) which is about to reenter, uncontrolled, into the atmosphere soon. The above footage of the object was shot by me last April 13 and 14 and shows two passes over Leiden.

This radar satellite, launched to keep an eye on North-Korea in 2003, malfunctioned in March 2007, halfway though its mission. Since then, it has been steadily coming down (see diagrams below) in a way that clearly shows that the satellite operators do no longer have control over it.

Last year, I pointed to the fact that the 1.2 tons  satellite will reenter in 2012 (so this year), and likely still has some remnant fuel onboard. A subsequent assessment by high-end amateur satellite tracker Ted Molczan showed that this amount of fuel is limited - probably about 14 to 50 kg, an order of a magnitude less than the infamous case of USA 193 in 2008. This assessment is important, as an uncontrolled reentry of a satellite with fuel onboard is a potential hazard (reason why I wrote about it last year) and authorities were (and are) very quiet about it. Ted's assessment, the only public one to date, helped to put the potential risks involved into proper context.

In the autumn of 2011 we temporarily lost track of IGS 1B because it entered winter invisibility for the Northern hemisphere (where most of our observers are located). Early April this year, it emerged from this winter blackout again. I did a failed attempt to recover it on the evening of April 2, and then Russell Eberst successfully recovered it a day later on the evening of April 3. Since then, I observed it on April 13, 14 and 22 (see video footage above of the April 13 and 14 passes) and other amateurs have observed it as well.

Below is a 35-second integration of video frames from the April 13 video (upper right are tail stars of the Big Dipper):

click image to enlarge

Orbital evolution over the winter blackout

When IGS 1B was lost in the winter blackout in the autumn of 2011, it was in a 453 x 455 km orbit. Since then, it has come down considerably: as of 2012 May 1 it is in a 366 x 368 km orbit, almost 100 km lower (and now below the orbital altitude of the ISS). It is coming down at an increasingly fast speed, as the diagrams below show (based on orbital calculations by Mike McCants, derived from amateur observations which include my observations):

click diagrams to enlarge

Current Decay Prediction

Using Alan Pickup's SatEvo software with the current orbit and solar activity, I expect the reentry of IGS 1B to occur somewhere during a window that spans from June until August. As the orbit is evolving fast, it is pertinent that we keep close track of the object in order not to lose it (a few days old elements already results in several minutes uncertainty in pass time).

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