Hi, I thought that adding support for 6DOF devices like SpaceMouse, would be of a great benefit for a true 3D application like Celestia.
6DOF = 6 Degrees Of Freedom, that means that movement in space, goes along X,Y,Z axis + rotation around these (A,B,C) simultaniously, like moving objects in real world. I have worked with these 6DOF devices as a CAD-consultant for some years and this is out of comparison with use a traditional mouse, which only have 2 DOF (X,Y axis movement)
More info here:
http://www.spacemouse.com/products.htm
http://www.spacemouse.com/documentation.htm
Regards Lars