#207 CustomRotations give wrong rotations for surface object

open
nobody
5
2008-09-09
2008-09-09
No

The orientation is wrong for objects on the surface of worlds with CustomRotations. This appears to be the result of the fact that the body frame of some planets and moons changed from the default EclipticJ2000 to EquatorJ2000 when they were assigned CustomRotations. There appears to be no bug in the CustomRotation calculations themselves. The issue is whether we should change the CustomRotations so that they work in the EclipticJ2000 (or planet equatorial frames) instead of EquatorJ2000.

There is no problem when a BodyFixed or TwoVector frame is used to fix an object to the surface of a planet. Here's a sample SSC object that is oriented correctly when the rotation of Titan is defined as in 1.5.1, but breaks when the IAU rotational elements are used:

"Huygens on Titan" "Sol/Saturn/Titan"
{
Class "spacecraft"
Mesh "huygens.3ds"
Radius 0.0015

LongLat [-191 -10.6 0.04] # [a b c] 40 meters above the ground
Orientation [-10.6 1 0 0] # [b 1 0 0]
RotationOffset 37.9 # a + Planet_RotationOffset - 90
Albedo 0.3
}

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