A slightly slower answer

Mike McCants (mike@comshare.com)
Sat, 9 Dec 1995 02:02:37 -0600

Jim Varney's reply:

>Out of 4,248 elements in Allen Thomson's TLE set, this satellite has
>the least eccentric orbit:

>1 19671U 88106  B 95334.24686766  .00000060  00000-0  97511-5 0    03
>2 19671  56.9760 110.1146 0000010 288.0998  71.9002 14.70781741    07

>This is Lacrosse 1.

Lacrosse 1 makes small orbit changes every few months.  I generated
an element set with a non-zero eccentricity from Russell Eberst's
observations in October and November.

1 19671U 88106  B 95308.75846419  .00000060  00000-0  97490-5 0    09
2 19671  56.9760 208.1897 0002000 244.6889 115.3110 14.70789681    00

But when Russell made an observation of Lacrosse 1 on November 30,
it did not agree with the previous orbit.  So, I assumed that a
small change in the orbit had occurred in the intervening 26 days
and I arbitrarily set the eccentricity to (very nearly) zero.

In general, the eccentricity of a satellite orbit normally varies a
little bit because of lunar and solar perturbations.  And when the
eccenticity of a satellite orbit is close to zero, NORAD is likely
to issue elements that have small variances in the mean motion
because the mean motion is the reciprocal of the anomalistic period
(perigee to perigee) and the location of perigee for a nearly circular
orbit is not well defined.  I believe this explains the Mir elset

Mike McCants