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)
Bodies can be created by making a list of strings with the bodies that is to be included in the simulation.
The default body settings (such as atmosphere, body shape, rotation model) are taken from `SPICE`.
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.
### Create the bodies
"""
Bodies can be created by making a list of strings with the bodies that is to be included in the simulation.
The default body settings (such as atmosphere, body shape, rotation model) are taken from `SPICE`.
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`.
"""
# Define bodies in simulation
bodies_to_create = ["Sun", "Earth", "Moon"]
# Create bodies in simulation
body_settings = environment_setup.get_default_body_settings(bodies_to_create)
system_of_bodies = environment_setup.create_system_of_bodies(body_settings)
### Create the vehicle
"""
Let's now create the 5000kg Vehicle for which the trajectory bewteen the Earth and the Moon will be propagated.
"""
# Create the vehicle body in the environment
system_of_bodies.create_empty_body("Vehicle")
system_of_bodies.get_body("Vehicle").set_constant_mass(5e3)
## Propagation setup
"""
Now that the environment is created, the propagation setup is defined.