Page 82 - Intro to Space Sciences Spacecraft Applications

Propulsion @

ignoring the component of velocity imparted to our launch vehicle due to
the rotation of the earth). However, if we launch directly east (90"
azimuth), we find that the resulting orbit has an inclination of 28.5" cor-
responding to the launch site latitude (refer to Figure 3-7). Launching a
little northerly or even a little southerly (greater or less than 90" launch
azimuth) from this location results in an orbital inclination greater than
28.5", meaning that 28.5" is the minimum inclination orbit into which we
can launch directly from this site.
The conclusion one should draw from this discussion is that the incli-
nation into which a spacecraft can be launched directly is limited by the
geographical location (latitude) of the launch site. If an orbit of lower
inclination than the launch site latitude is desired, then an orbital adjust-
ment (plane change) must be performed requiring additional fuel andor
propulsion systems, which generally means increased weight and cost.
The 28.5" latitude example used in the above discussion corresponds to
the latitude of the Kennedy Space Center. Figure 3-8 shows the relation-

NORTH
LATITUDE
DEGREES

Flgure 3-8. United States launch sites. This figure shows the relationships
between launch azimuths and orbital inclinations for U.S. launch sites.