Configuration

A configuration file named conf.py is required in the same directory in which VLATI is run. It must contain a dictionary with the same name.

###### conf.py ######
conf = {
  ... config options
}

List of configuration options

The options available are found in the conf.py file in the root directory of this repository. Every option in the file is required, and no more and no less can be used (as of now). The conf.py file in this repository is ready for use with the simulator. The following will list each of the configuration options, what they affect, and what units they use.

Variable	Unit	Purpose
frames_to_simulate	frames	Tells VLATI how many iterations it should simulate.
seconds_timestep	seconds	What the Δt of the simulation is; generally, the smaller the more accurate; good to keep it ~1.
meters_spacecraft_start_vec	meters	The starting location vector of the spacecraft.
meters_per_second_spacecraft_start_v_vec	meters per second	The starting velocity vector of the spacecraft.
burn_array	various	Read below for information regarding burn_array.
traj_output_file	file path	Where to save the trajectories of the Sun, Moon, and spacecraft. Should be a file with a .npz extension.
Advanced
ephemeris_file	file path	The file in which the ephemeris is located.
leap_file	file path	The file in which the leap second information is located.

Notes about config options

traj_output_file

Exports an npz file containing trajectories. It’s used as an input in VLATI-VIS.

Usage of burn_array

burn_array is actually a burn tuple. Unfortunately, zero or at least two elements are required in the burn tuple. If you want only one burn, use the following entry in the burn tuple (along with, of course, your chosen burn):

[0, 0, 1]

The structure of the burn_array configuration option is as follows:

( [ burn_time_elapsed_seconds, np.array([ dv vector ]), 0 ] )

The zero indicates to VLATI that the burn hasn’t been performed yet. During each timestep, when iterating through the burn array, it checks this to see whether it should execute the burn, and changes it to 1 when it has.

An example of the Δv vector:

np.array([1000.0, 0.0, 10.412])

At least one of the vector components must contain a .0 (or any other decimal, to your preference) to indicate to NumPy that the vector represents a vector of floating-point numbers, not integers.