Problems refer to appendix b for coordinate system definitions and to appendix b section 3.10 for satellite orbit equations. 2.1 which of the following coordinate systems is not rotating? (a) north-east-down (ned) (b) enu (c) ecef (d) earth-centered inertial (eci) (e) moon-centered, moon fixed

correct option is (d) Earth-centered inertial (ECI)

Explanation:

we know that in ECI The Earth-centered inertial frame use the Earth orbit plane

and the orientation of Earth rotation axis in  the space

as we know ECI frames is the origin at the center of mass of the  earth

and it is not rotating with respect to the star

and ECI Earth-centered inertial frame use for NORAD that is called here true equator

so here correct option is d  Earth-centered inertial (ECI)

answer called a epicycle;

the answer is the last option or letter d)