Lewis decay prediction

Alan Pickup (alan@wingar.demon.co.uk)
Fri, 26 Sep 1997 19:46:08 +0100

The latest elset for Lewis is:
Lewis                                            222 x 207 km
1 24909U 97044A   97269.60253286  .02192090  25336-5  99705-3 0  1445
2 24909  97.5549 167.7974 0011296 157.6698 202.5752 16.21871313  5479
showing a fall from a 232 x 216 km orbit during the past day.

My SatEvo analysis suggests that decay may occur about September 28.8.
The evolution gives a mean error of 0.1 seconds for the satellite's
motion over the preceding 1.4 days (max error 0.3 sec), in comparison
with the ten equator crossings during this time for which I have OIG
elsets.

Geomagnetic conditions have been quiet over the past few days, but could
become disturbed on the 27th if the Earth catches the effect of a solar
coronal mass ejection following a major solar flare on the 24th. If this
happens, the atmospheric density at Lewis's height is likely to increase
and its decay be brought forward by a several hours (depending on the
duration and intensity of the disturbance).

The following SatEvo-predicted elsets do *not* include any geomagnetic
allowance...
Lewis                                            214 x 203 km
1 24909U 97044A   97270.03410995  .02745155  41324-2  10530-2 0 91339
2 24909  97.5530 168.3021 0008493 147.3501 212.7024 16.24072959  5548
Lewis                                            205 x 196 km
1 24909U 97044A   97270.52659607  .03558080  73884-2  10552-2 0 91338
2 24909  97.5519 168.8792 0007230 145.3442 214.7029 16.27138415  5624
Lewis                                            193 x 185 km
1 24909U 97044A   97271.01800512  .05227047  17483-1  10603-2 0 91333
2 24909  97.5504 169.4580 0005696 143.3324 216.7065 16.31338190  5709
Lewis                                            184 x 178 km
1 24909U 97044A   97271.26316240  .07011419  34310-1  10653-2 0 91339
2 24909  97.5493 169.7481 0004749 142.3234 217.7098 16.34290729  5745
Lewis                                            172 x 167 km
1 24909U 97044A   97271.50779246  .11170271  95901-1  10756-2 0 91339
2 24909  97.5478 170.0391 0003561 141.3116 218.7139 16.38563199  5781
Lewis                                            147 x 145 km
1 24909U 97044A   97271.75153348  .36840304  12677+1  70258-3 0 91335
2 24909  97.5450 170.3314 0001687 140.2947 219.7176 16.47632897  5825
Lewis                                            123 x 123 km
1 24909U 97044A   97271.81215071 1.77121937  26481+2  88145-3 0 91337
2 24909  97.5434 170.4049 0000632 140.0387 219.9660 16.56224840  5834

Current elsets for this and other selected objects are updated throught
the day in the file select.tle, available via my SatEvo WWW page.

Alan
-- 
 Alan Pickup | COSPAR site 2707:   55d53m48.7s N   3d11m51.2s W    156m asl
 Edinburgh   | Home:      alan@wingar.demon.co.uk       +44 (0)131 477 9144
 Scotland    | SatEvo satellite page: http://www.wingar.demon.co.uk/satevo/