This section provides an in-depth explanation of the below Mission Control Sequence (MCS).

 

As one can see above, the MCS contains three targeter sequences: Arrive at Periselene Sequence, Orbit Insertion Sequence, and Adjust Inclination to Overfly Target Sequence. Each targeter sequence involves anywhere from one to three iterative differential corrector schemes that shape the trajectory based on defined mission constraints.

 

Arrive at Periselene Sequence

This targeter sequences uses three iterative schemes to place the spacecraft in a desired lunar orbit.

Scheme 1: Delta Right Ascension and Declination
This iteration varies the launch time and end time of the coast period to achieve a zero right ascension and declination of the spacecraft with respect to the Moon. That is, at a certain cutoff distance, the vehicle should be headed directly at the Moon. The purpose of this iteration is to place the spacecraft in the general vicinity of the Moon.

Scheme 2: B-Plane Targeting
This iteration varies launch time, end time of the coast period, and the translunar injection delta-V to place the spacecraft at desired location on the lunar B-Plane. The B-Plane is a planar coordinate system that normally allows for targeting during a gravity assist maneuver, but can also simply be used to target a certain location with respect to the Moon. The purpose of this iteration is to orient the spacecraft’s arrival location with respect to the Moon.

Scheme 3: Altitude and Inclination
This iteration varies launch time, end time of coast period, and the translunar injection delta-V to achieve place the spacecraft at 100 km altitude and 172° inclination at periselene. The purpose of this iteration is to specifically constrain the spacecraft’s arrival location with respect to the Moon.

 

Orbit Insertion Sequence

Scheme 1: Insertion
This iteration varies orbit insertion delta-V to capture the spacecraft into a circular orbit around the Moon (i.e. zero eccentricity). The purpose of this iteration is to achieve a circular parking orbit.

 

Adjust Inclination to Overfly Target Sequence

Scheme 1: Adjust Inclination
This iteration adjusts the plane change delta-V (magnitude and direction) to place the spacecraft into an orbit that directly over flies the longitude and latitude of the landing site. The purpose of this iteration is to place the spacecraft in the same orbital plane with the landing site.