decay predictions for 22709 and 23580

From: Mike McCants <mike_at_comshare.com>
Date: Wed, 7 Jun 1995 16:34:51 -0400
Given the following elements, SGP4 generates X,Y,Z values and
velocities (Km and Km/sec):

  22709          95 157.85989037 0.02476110 .73318-5 .53409-3
        65.0141 205.8125 0.0036548 250.3086 109.5744 16.28101334
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
157.859890 -5925.5 -2874.7    16.6  6586.0  1.43212 -2.95429  7.05056

  22709          95 157.92128463 0.02569199 .73350-5 .53500-3
        65.0130 205.5839 0.0036649 249.1160 110.6650 16.28443845
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
157.921285 -5938.7 -2846.3     5.8  6585.6  1.40777 -2.96613  7.05049

  22709          95 157.92127324 0.02886197 .73326-5 .59299-3
        65.0176 205.5874 0.0035650 248.7398 111.0506 16.28689871
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
157.921273 -5937.9 -2846.2     5.5  6584.8  1.40824 -2.96552  7.05120

  22709          95 158.22809823 0.03133175 .73649-5 .54611-3
        65.0110 204.4374 0.0032595 246.9286 112.8465 16.30641515
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
158.228098 -5990.0 -2721.9     0.1  6579.5  1.34514 -2.99706  7.05375

Given these X,Y,Z values, a numerical integration program generates
a decay time of about 159.43 = June 8 at 10Hrs 19Min UT.

    X      Y      Z     Xdot   Ydot   Zdot   Time        R        Hght   Pgee
 -5926. -2875.    17.  1.432 -2.954  7.051  157.85989  6586.0250  207.9
 -5990. -2719.     0.  1.343 -2.998  7.055  158.22818  6578.6980  200.5  183.9
  4544.  -580.  4446.  4.863  4.009 -4.600  159.47031  6383.5587   15.8   15.8

 -5939. -2846.     6.  1.408 -2.966  7.050  157.92129  6585.5611  207.4
 -5991. -2720.     0.  1.343 -2.998  7.054  158.22817  6579.2368  201.1  183.3
   973. -2516.  5782.  7.317  2.707 -0.186  159.46365  6380.4933   20.0   20.0

 -5938. -2846.     6.  1.408 -2.966  7.051  157.92127  6584.7962  206.6
 -5990. -2720.     0.  1.344 -2.997  7.055  158.22811  6578.3218  200.2  182.9
  3549.  3329. -4135. -6.080  0.208 -4.847  159.42525  6385.4761   16.3   16.3

 -5990. -2722.     0.  1.345 -2.997  7.054  158.22810  6579.4255  201.3
 -6000. -2697.     0.  1.333 -3.003  7.055  158.28942  6577.9391  199.8  181.5
 -1593.  2272. -5740. -7.123 -3.021  0.923  159.43389  6375.3359   14.6   14.6

But there is still quite a bit of uncertainty.

------------

Here is the same stuff for 23580:

  23580          95 157.22490726 0.01237469 .12039-4 .30868-3
        51.6588 207.1839 0.0024004 145.9985 214.2602 16.27393220
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
157.224907 -5863.4 -3011.5     0.2  6591.5  2.21733 -4.27874  6.09770

  23580          95 157.47047454 0.01389866 .12055-4 .32337-3
        51.6599 205.8151 0.0023708 147.1420 213.2089 16.28152194
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
157.470475 -5928.7 -2875.9     9.0  6589.5  2.12639 -4.32542  6.09872

  23580          95 157.89990513 0.01678244 .12086-4 .34783-3
        51.6601 203.4283 0.0021018 151.1701 209.1609 16.29550653
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
157.899905 -6038.7 -2625.4    10.1  6584.7  1.94472 -4.41235  6.10140

  23580          95 157.89988602 0.01574487 .12090-4 .32375-3
        51.6603 203.4318 0.0021641 148.9873 211.2530 16.29588713
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
157.899886 -6041.4 -2619.1     0.9  6584.7  1.93297 -4.41740  6.10140

  23580          95 158.34794757 0.02121481 .12123-4 .37138-3
        51.6566 200.9357 0.0019913 154.7863 317.2322 16.31327149
      TDAY       X       Y       Z       R   XDOT   YDOT   ZDOT
158.347948  3630.0 -2650.6  4765.9  6551.1  6.11726  4.27742 -2.28904

    X      Y      Z     Xdot   Ydot   Zdot   Time        R        Hght   Pgee
 -5863. -3012.     0.  2.217 -4.279  6.098  157.22491  6591.5546  213.4
 -5898. -2941.     0.  2.166 -4.306  6.098  157.34770  6590.3088  212.1  183.4
  1181. -3796.  4992.  7.596  1.869 -0.496  160.11118  6382.0794   17.1   17.1

 -5929. -2876.     9.  2.126 -4.325  6.099  157.47048  6589.4131  211.2
 -4867.  1981. -3638. -4.889 -4.401  4.277  160.08729  6390.4855   19.3   19.3

 -6039. -2625.    10.  1.945 -4.412  6.101  157.89991  6584.7342  206.6
 -2744. -3921.  4228.  7.020 -1.274  3.225  160.16633  6385.8549   17.1   17.1

 -6041. -2619.     1.  1.933 -4.417  6.101  157.89989  6584.6943  206.5
 -6153. -2325.     0.  1.718 -4.509  6.105  158.39013  6577.5948  199.4  175.5
  2348.  3992. -4397. -7.226  0.930 -2.872  160.13635  6385.9680   18.0   18.0

  3630. -2651.  4766.  6.117  4.277 -2.289  158.34795  6551.0597  184.3
 -6154. -2325.     0.  1.718 -4.508  6.104  158.39017  6578.8404  200.7  175.5
 -6167. -2288.     0.  1.691 -4.519  6.105  158.45141  6577.8346  199.7  175.0
  5231. -1662.  3276.  4.308  4.579 -4.695  160.18026  6392.2599   19.7   19.7

The prediction is 160.18 = June 9 at 4Hrs 19Min UT.

But I will get more elsets from OIG tomorrow and come up with a new estimate.

Mike
Received on Wed Jun 07 1995 - 18:33:54 UTC

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