Iridium 24 elsets getting old

Ed Cannon (ecannon@mail.utexas.edu)
Mon, 30 Mar 1998 22:05:31 -0600

I'm not sure if this is unusual or not, and I know that for objects
in near-800 km (500-mile) circular orbits it's not usually anything
to mind, but as of a few moments ago (about 3:50 UTC 31 March 1998), 
the elements for Iridium 24 (below) have not been updated for over
five days.  I believe we're now at day 98090.1666.

SATNO = 24905
Element set number = 1
1 24905U 97043C   98084.69500837 -.00006280  00000-0 -22974-2 0  1581
2 24905  86.3971 310.1893 0001391 177.1665 182.9976 14.33207912 31141
Element set number = 2
1 24905U 97043C   98084.13648030 -.00004397  00000-0 -16100-2 0  1567
2 24905  86.3973 310.4223 0002009  80.4630 279.6848 14.33212441 31064
Element set number = 3
1 24905U 97043C   98083.15904621 -.00006016  00000-0 -22008-2 0  1552
2 24905  86.3965 310.8305 0002700  92.4199 267.7307 14.33213066 30927
Element set number = 4
1 24905U 97043C   98082.67034253 -.00009047  00000-0 -33081-2 0  1542
2 24905  86.4014 311.0374 0002481 121.0454 239.1232 14.33203297 30858
Element set number = 5
1 24905U 97043C   98082.18162301 -.00010930  00000-0 -39962-2 0  1530
2 24905  86.4009 311.2412 0002633 117.3243 242.8236 14.33202924 30783

Mike McCants pointed out to me that the changes in argument of perigee 
of the above elements are unexpected.  We've had more reports of non-
flares from Iridium 24.  Are the failures due to old elements or to it
having gone awry?

Speaking of elements, here's a very nice page that I had not seen
before explaining TLEs:

http://liftoff.msfc.nasa.gov/academy/rocket_sci/orbmech/state/2line.html

It's part of a set of pages on orbital mechanics.

Cloudy here tonight.

Ed Cannon
ecannon@mail.utexas.edu
Austin, Texas, USA