Star Tracker Orientation
The star trackers don't really have to be at 90-degree angles to each
other. Mathematically, any set of angles will do as long as none of them
are parallel. But to place 3 of them at mutual right angles, imagine a
pyramid formed by 3 vectors coming together at right angles. Then balance
it on its point. Then the three telescopes could be looking out the same
side of the Lunar Transfer Vehicle service
module. None of the star trackers have to point
precisely along the major axes of the vehicle. If need be, we can rotate
the vehicle to several different attitudes to update the inertial platform,
picking up stars hither and yon around the sky. Or even have a single star
tracker with a wide enough field of view to see at least three guide stars.
==== === === ==== Vehicle skin, with holes for star trackers
\ | /
Star Tracker \ | / Image this is a right-angle, 3-sided pyramid;
Cones \|/ a regular tetrahedron
It's hard to do a 3-D drawing in text graphics, but that's sort of
what it would look like. Incidentally, the star trackers need not all be
in the same location in the service module, and probably should not be.
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