Low-thrust maneuver validation in GMAT

Question

I'm working on a LEO-to-LEO transfer with low-thrust propulsion. I've generated a control sequence with a direct optimization implemented by me and I would like to use GMAT to validate the maneuver. I tried to model an object Electric Thruster with all the burns, but this approach seems a bit too complex with respect to my problem. I'm wondering if it's possible to insert just the acceleration acting on the center of the S/C in LVLH reference frame. Is there a way to load from file the control history in terms of accelerations acting on the center of the S/C in each time instant and use it directly in GMAT? Or is it mandatory to add an Electric Thruster object with several burns?

Answer 1

One option is to build a "ThrustHistoryFile" to model your maneuver. That file contains a time history (in seconds) of either the thrust (in N) or the acceleration (km/s), and, optionally. mass flow rate (kg/s).

There is a sample script, Ex_R2020a_Propagate_ThrustHistoryFile.script, that intended to help you get started with this approach. The GMAT User's guide provides documentation for the options for this feature.

(Addressing the comment) GMAT has a pretty flexible coordinate system definition system. You can define your LVLH system, something like this:

Create CoordinateSystem SatLVLH;
SatLVLH.Origin = Earth;
SatLVLH.Axes = ObjectReferenced;
SatLVLH.XAxis = R;
SatLVLH.ZAxis = N;
SatLVLH.Primary = Earth;
SatLVLH.Secondary = TheSat;

and then use it in the thrust history file:

BeginThrust {ThrustLVLH}
Start_Epoch = 01 Jan 2000 11:59:28.000
Thrust_Vector_Coordinate_System = SatLVLH 
...

(You may need to tweak the LVLH definitions - e.g., setting an axis nadir pointing rather than zenith, etc...)