VBar Approach RPO Sequence

The VBar Approach RPO sequence causes the chase satellite to approach a target satellite along the VBar. It uses an in-track maneuver to initiate an in-track rate toward the target. It then performs small radial maneuvers when either the radial position or radial rate errors exceed a threshold. This keeps the satellite within a small tolerance of being on the VBar during the approach.

An alternative is to use FMWaypoints with the initial state on the VBar and the final relative position also on the VBar.

This sequence does not allow going through zero meters along the VBar. If it detects this condition, the sequence issues an error message and terminates. Also, if the initial condition is not on the VBar, the sequence issues an error message and terminates.

The following picture shows a VBar approach from -1000 meters on the VBar to a final stopping position of -50 meters on the VBar in six hours.

Watch the following video to learn more about the RPO sequence on this page.

Sequence parameters

Option	Description
Final_InTrack_Offset	Enter, in distance units, the stopping in-track offset relative to the target.
Transfer_Time	Enter the duration of the VBar transfer time.
Max_Radial_Error	Enter, in distance units, the maximum allowed radial error.
Max_RadialRate_Error	Enter the maximum allowed radial rate error.
Engine_Name	Enter, as a string, the name of the finite maneuver engine model.
Maneuver_Type	Select the type of maneuver, "Impulsive" or "Finite," from the drop-down list.
WhoAmI	Enter, as a string, the name of the current satellite.
ThisSequence	Enter, as a string, the name of this sequence. This is nominally VBar_Approach but if you insert the sequence multiple times in the MCS, Astrogator adds a monotonically increasing number to the end of the name (VBar_Approach1, VBar_Approach2, etc.).