Iridium status...
A month ago or so, there was a post indicating that Iridium deorbit operations had begun. I've done some checking and can't find any evidence of this.
Sources I looked at include NASA's Orbital Information Group
oig1.gsfc.nasa.gov@app01?tdac=NKOB4PDFG9N4H3KZV15R
which will provide orbital elements for each spacecraft
and this interesting site
www2.satellite.eu.org
which details the status of Iridium's various satellites for the benefit of "flare watchers."
From these two sites, it's possible to confirm that at least 67 spacecraft are still in their operational orbit, and that each of the six planes has at least the as-designed complement of 11 operational (or at least non-tumbling) satellites. In addition, there appear to be 10 functional spares.
Iridium had 20 successful launches of a total of 88 spacecraft between May'97 and June'99. Of the 88, Space News reported that two satellites failed before reaching their designated orbits. Of the remaining 86 that made it to orbit, eight are reported as "tumbling" and presumably unrecoverable. That leaves 78 operable spacecraft of which 10 are spares (in a significantly lower than operational orbit) and two are at operational altitude but reported as non-operating. One of these last two (S/N 9) is apparently being deorbited, which may have led to the rumor that the entire constellation was being taken down.
"*A forwarded message on SeeSat-L provides information that Iridium 9 is in the process of being de-orbited ALONE due to an imminent failure
of a secondary backup attitude control system. This is NOT the beginning for de-orbiting the constellation. Future manuvers should see the
perigee lowered to 250 km to accelerate decay of the satellite within a year. "
It will be very easy to observe the status of any deorbiting that does take place, btw. Enter "Iridium" in the box located here:
oig1.gsfc.nasa.gov@app01?tdac=QC4Z0JLU6J61A8FXM7KT
and the website returns simple orbital parameters like period, apogee and perigee. All the Iridium satellites in their operational orbits are in an orbit with period 100.4 minutes, apogee 779km, perigee 776km.
I'm happy to report that a similar query run for Globalstar shows 48 satellites operating in a 114.1 minute orbit, at a 1414 km near circular orbit. Our four spares are idling at about 900 km.
Iridium's web site has been taken off line, RIP
www.iridium.com
but rumors abound, and the last filing by the debtors seemed to confirm, that negotiations toward a new owner taking over the constellation continue. |
