Re: 80-008B tumbling? plus a couple of other items

Bjoern Gimle (b_gimle@algonet.se)
Sat, 22 Mar 1997 11:39:02 +0100

Ed Cannon <ecannon@mail.utexas.edu> wrote:
>
>Just wondering -- How much longer will Cosmos 2053 (20389, 89-100A) stay in
>orbit?
>
>SATNO = 20389
>Element set number = 1
>1 20389U 89100A   97078.04713189  .00045189  00000-0  18790-3 0  5209
>2 20389  73.4996 273.6702 0001708 177.6725 182.4510 15.85521550408145
>Element set number = 2
>1 20389U 89100A   97078.99358446 +.00044494 +00000-0 +18430-3 0 05258
>2 20389 073.5012 271.4113 0001453 187.4865 172.6266 15.85604166408298
>Element set number = 3
>1 20389U 89100A   97079.56143592  .00042933  00000-0  17751-3 0  5213
>2 20389  73.5018 270.0550 0001578 187.2994 172.8134 15.85648668408384
>Element set number = 4
>1 20389U 89100A   97080.00308593 +.00043140 +00000-0 +17803-3 0 05239
>2 20389 073.5016 269.0003 0001567 185.5160 174.6041 15.85687040408459
>Element set number = 5
>1 20389U 89100A   97080.57090983  .00040938  00000-0  16869-3 0  5224
>2 20389  73.5027 267.6439 0001372 180.7518 179.3613 15.85727331408541
>
With these elsets, SatEvo gives 1997 Aug.22,25,31,31 and Sep.9 as decay
prediction, reflecting the decreasing ndot2 values.

For a near-circular orbit like this, you can estimate the remaining
lifetime as Q/ndot2,  where Q is about 0.10 days (actually days^-1,
since ndot2 is in orbits/day^2). This leads to a much longer lifetime
than SatEvo, which puzzles me.

Q decreases at higher MM. For elliptic orbits, Q is much higher,
but seldom more than 2*(16.6-MM)



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