def create_simulation_bodies(itokawa_radius):
### CELESTIAL BODIES ###
# Define Itokawa body frame name
itokawa_body_frame_name = "Itokawa_Frame"
# Create default body settings for selected celestial bodies
bodies_to_create = ["Sun", "Earth", "Jupiter", "Saturn", "Mars"]
# Create default body settings for bodies_to_create, with "Earth"/"J2000" as
# global frame origin and orientation. This environment will only be valid
# in the indicated time range [simulation_start_epoch --- simulation_end_epoch]
body_settings = environment_setup.get_default_body_settings(
bodies_to_create,
"SSB",
"ECLIPJ2000")
# Add Itokawa body
body_settings.add_empty_settings("Itokawa")
# Adds Itokawa settings
# Gravity field
body_settings.get("Itokawa").gravity_field_settings = get_itokawa_gravity_field_settings(itokawa_body_frame_name,
itokawa_radius)
# Rotational model
body_settings.get("Itokawa").rotation_model_settings = get_itokawa_rotation_settings(itokawa_body_frame_name)
# Ephemeris
body_settings.get("Itokawa").ephemeris_settings = get_itokawa_ephemeris_settings(
spice.get_body_gravitational_parameter( 'Sun') )
# Shape (spherical)
body_settings.get("Itokawa").shape_settings = get_itokawa_shape_settings(itokawa_radius)
# Create system of selected bodies
bodies = environment_setup.create_system_of_bodies(body_settings)
### VEHICLE BODY ###
# Create vehicle object
bodies.create_empty_body("Spacecraft")
bodies.get("Spacecraft").set_constant_mass(400.0)
# Create radiation pressure settings, and add to vehicle
reference_area_radiation = 4.0
radiation_pressure_coefficient = 1.2
radiation_pressure_settings = environment_setup.radiation_pressure.cannonball(
"Sun",
reference_area_radiation,
radiation_pressure_coefficient)
environment_setup.add_radiation_pressure_interface(
bodies,
"Spacecraft",
radiation_pressure_settings)
return bodies
def create_bodies():
# Define string names for bodies to be created from default.
bodies_to_create = ["Mars"]
# Use "Earth"/"J2000" as global frame origin and orientation.
global_frame_origin = "Mars"
global_frame_orientation = "J2000"
# Create default body settings, usually from `spice`.
body_settings = environment_setup.get_default_body_settings(
bodies_to_create, global_frame_origin, global_frame_orientation)
# Add a predefined exponential atmosphere model for Mars
body_settings.get(
"Mars"
).atmosphere_settings = environment_setup.atmosphere.exponential_predefined(
"Mars")
# Return the system of selected celestial bodies
return environment_setup.create_system_of_bodies(body_settings)
These settings can be adjusted. Please refere to the [Available Environment Models](https://tudat-space.readthedocs.io/en/latest/_src_user_guide/state_propagation/environment_setup/create_models/available.html#available-environment-models) in the user guide for more details.
Finally, the system of bodies is created using the settings. This system of bodies is stored into the variable `bodies`.
"""
# Create default body settings for "Earth"
bodies_to_create = ["Earth"]
# Create default body settings for bodies_to_create, with "Earth"/"J2000" as the global frame origin and orientation
global_frame_origin = "Earth"
global_frame_orientation = "J2000"
body_settings = environment_setup.get_default_body_settings(
bodies_to_create, global_frame_origin, global_frame_orientation)
# Create system of bodies (in this case only Earth)
bodies = environment_setup.create_system_of_bodies(body_settings)
### Create the vehicle
"""
Let's now create the massless satellite for which the orbit around Earth will be propagated.
"""
# Add vehicle object to system of bodies
bodies.create_empty_body("Delfi-C3")
## Propagation setup
"""
Now that the environment is created, the propagation setup is defined.
First, the bodies to be propagated and the central bodies will be defined.
Central bodies are the bodies with respect to which the state of the respective propagated bodies is defined.