  Space-based gravitational wave detectors based on the Laser Interferometer
Space Antenna (LISA) design operate by synthesizing one or more interferometers
from fringe velocity measurements generated by changes in the light travel time
between three spacecraft in a special set of drag-free heliocentric orbits.
These orbits determine the inclination of the synthesized interferometer with
respect to the ecliptic plane. Once these spacecraft are placed in their
orbits, the orientation of the interferometers at any future time is fixed by
Kepler's Laws based on the initial orientation of the spacecraft constellation,
which may be freely chosen. Over the course of a full solar orbit, the initial
orientation determines a set of locations on the sky were the detector has
greatest sensitivity to gravitational waves as well as a set of locations where
nulls in the detector response fall. By artful choice of the initial
orientation, we can choose to optimize or suppress the antennas sensitivity to
sources whose location may be known in advance (e.g., the Galactic Center or
globular clusters).
