RE: [HearSat] Titan IVA/K-18 launch

Ted Molczan (
Mon, 6 Oct 1997 01:19:56 -0400


Thank you for posting the Titan IV launch information. I have only one=20
problem with it: the inclination should be 68 deg, not 57 deg as stated.
Is the Air Force playing games with us?

At VAFB's latitude of 34.7 deg N, the 153 deg launch azimuth would =
the following orbital inclination:

inc =3D acos(sin(AZ) * cos(lat))

    =3D acos(sin(153) * cos(34.7))

    =3D 68 deg

Obviously, this is Lacrosse 3. The parking orbit dimensions are
reminiscent of Lacrosse 2's parking orbit - that will be the final orbit =

of the Titan 2nd stage. The apogee of the parking orbit approximates the =

standard Lacrosse altitude.=20

I cannot see any reason to use the 57 deg inclination of Lacrosse 1, =
since that was simply the maximum available inclination for a Shuttle =
launch of this payload.=20

Also, through the many launch delays, the launch period appears to have
maintained about the same relationship to the orbital plane of Lacrosse =
There would be little point in doing so if the payload was destined for
57 deg, since the planes would rapidly drift apart.
I firmly believe that there is an optimal plane-spacing between the two. =

At the stated launch time, it appears that Lacrosse 3 would be nearly=20
30 deg west of Lacrosse 2. I had predicted a 49.4 deg spacing, but we'll =

see when the launch actually occurs.=20

It will be easy to construct accurate 68 deg search orbits with the data =
you provided.

Ted Molczan