ast2000tools.space_mission.SpaceMission¶

class ast2000tools.space_mission.SpaceMission(seed, data_path=None, has_moons=True, verbose=True)¶

Bases: object

Represents a mission to launch a rocket from your home planet and land it safely on another planet.

This class is used to keep track of your mission’s progress and verify your results.

Parameters

seed (int) – The seed to use when generating random solar system and mission properties.
data_path (str, optional) – Specifies the path to the directory where output XML files should be stored (e.g. the MCAst data folder). By default, a folder called “XMLs” is created in the working directory.
has_moons (bool, optional) – Whether the generated planets should be visualized with moons. Setting to False increases performance. Default is True.
verbose (bool, optional) – Whether to print non-essential status messages. Default is True.

Methods

`begin_interplanetary_travel`()	Initiates an interplanetary travel process allowing you to guide your spacecraft to a different planet.
`begin_landing_sequence`([…])	Initiates a landing sequence process allowing you to land on a planet.
`generate_orbit_video`(times, planet_positions)	Calls `generate_orbit_video()` for the `ast2000tools.solar_system.SolarSystem` instance associated with the mission.
`get_sky_image_pixel`(polar_angle, azimuth_angle)	Finds the index of the pixel in the full-sky image correspnding to the given spherical coordinates.
`launch_rocket`([time_step])	Simulates a rocket launch based on the previously specified launch parameters.
`load`(filename[, verbose])	Loads an instance of `SpaceMission` from the specified binary file.
`measure_distances`()	Returns the distances to the bodies of the solar system as measured by your spacecraft directly after launch.
`measure_star_doppler_shifts`()	Returns the Doppler shifts of the two reference stars as measured by your spacecraft directly after launch.
`save`(filename, mission[, verbose])	Saves the given instance of `SpaceMission` as a binary file.
`set_launch_parameters`(thrust, …)	Used to specify various parameters required to perform a launch.
`take_picture`([filename, full_sky_image_path])	Generates a picture of the sky in the direction that the spacecraft is pointing directly after launch.
`verify_launch_result`(position_after_launch)	Verifies that your computation of the final spacecraft position after launch gives a resonable result.
`verify_manual_orientation`(…)	Verifies that your manually inferred values of the position, velocity and pointing angle of the spacecraft directly after launch are reasonable.
`verify_planet_positions`(simulation_duration, …)	Calls `verify_planet_positions()` for the `ast2000tools.solar_system.SolarSystem` instance associated with the mission.

Attributes

`data_path`	The path to the directory where output XML files will be stored.
`destination_planet_idx`	The index of the planet to land on after the interplanetary travel.
`destination_recorded`	Whether the destination state after the interplanetary travel has been recorded.
`estimated_launch_duration`	The estimated duration of the launch (the time required to reach escape velocity) in seconds.
`initial_fuel_mass`	The initial mass of fuel contained in the rocket in kilograms.
`initial_landing_position`	Array of shape (2,) containing the initial x and y-position for the landing sequence, in astronomical units relative to the star.
`initial_landing_time`	The initial time for the landing sequence, in years.
`initial_landing_velocity`	Array of shape (2,) containing the initial x and y-velocity for the landing sequence, in astronomical units per year relative to the star.
`lander_area`	The cross-sectional area of the lander in square meters.
`lander_mass`	The mass of the lander in kilograms.
`landing_completed`	Whether the landing sequence has been successfully completed.
`landing_site_azimuth_angle`	The azimuthal angle of the landing site in degrees.
`landing_site_polar_angle`	The polar angle of the landing site in degrees.
`launch_parameters_set`	Whether the launch parameters have been specified.
`launch_position`	Array of shape (2,) containing the x and y-position of the launch site, in astronomical units relative to the star.
`launch_result_verified`	Whether the launch result has been successfully verified.
`manual_orientation_verified`	Whether the manually inferred orientation data has been successfully verified.
`ongoing_interplanetary_travel`	The object representing the ongoing interplanetary travel.
`ongoing_landing_sequence`	The object representing the ongoing landing sequence.
`reference_wavelength`	The central wavelength of the spectral line (H-alpha) used to measure Doppler shifts, in nanometers.
`rocket_launched`	Whether the rocket has been successfully launched.
`rocket_mass_loss_rate`	The mass loss rate of the rocket engine in kilograms per second.
`rocket_thrust`	The thrust of the rocket engine in Newtons.
`seed`	The seed used to generate random solar system and mission properties.
`spacecraft_area`	The cross-sectional area of the spacecraft in square meters.
`spacecraft_mass`	The mass of the spacecraft in kilograms.
`star_direction_angles`	Tuple (\(\phi_0\), \(\phi_1\)) containing the azimuthal angles of the reference stars relative to the solar system x-axis, in degrees.
`star_doppler_shifts_at_sun`	Tuple (\(\Delta\lambda_0\), \(\Delta\lambda_1\)) containing the Doppler shifts of the stars relative to your sun, in nanometers.
`system`	The randomized solar system where the space mission takes place.
`time_after_launch`	The time of the end of the launch in years.
`time_of_launch`	The time of the start of the launch in years.
`verbose`	Whether non-essential status messages will be printed.

property seed¶

The seed used to generate random solar system and mission properties.

Type: int

property data_path¶

The path to the directory where output XML files will be stored.

Type: str

property verbose¶

Whether non-essential status messages will be printed.

Type: bool

property system¶

The randomized solar system where the space mission takes place.

Type: ast2000tools.solar_system.SolarSystem

property spacecraft_mass¶

The mass of the spacecraft in kilograms.

Type: float

property spacecraft_area¶

The cross-sectional area of the spacecraft in square meters.

Type: float

property lander_mass¶

The mass of the lander in kilograms.

Type: float

property lander_area¶

The cross-sectional area of the lander in square meters.

Type: float

property rocket_thrust¶

The thrust of the rocket engine in Newtons. Only available after calling set_launch_parameters().

Type: float

property rocket_mass_loss_rate¶

The mass loss rate of the rocket engine in kilograms per second. Only available after calling set_launch_parameters().

Type: float

property initial_fuel_mass¶

The initial mass of fuel contained in the rocket in kilograms. Only available after calling set_launch_parameters().

Type: float

property estimated_launch_duration¶

The estimated duration of the launch (the time required to reach escape velocity) in seconds. Only available after calling set_launch_parameters().

Type: float

property launch_position¶

Array of shape (2,) containing the x and y-position of the launch site, in astronomical units relative to the star. Only available after calling set_launch_parameters().

Type: 1-D numpy.ndarray

property time_of_launch¶

The time of the start of the launch in years. Only available after calling set_launch_parameters().

Type: float

property time_after_launch¶

The time of the end of the launch in years. Only available after calling launch_rocket().

Type: float

property reference_wavelength¶

The central wavelength of the spectral line (H-alpha) used to measure Doppler shifts, in nanometers.

Type: float

property star_direction_angles¶

Tuple (\(\phi_0\), \(\phi_1\)) containing the azimuthal angles of the reference stars relative to the solar system x-axis, in degrees.

Type: tuple

property star_doppler_shifts_at_sun¶

Tuple (\(\Delta\lambda_0\), \(\Delta\lambda_1\)) containing the Doppler shifts of the stars relative to your sun, in nanometers.

Type: tuple

property ongoing_interplanetary_travel¶

The object representing the ongoing interplanetary travel. Only available after calling begin_interplanetary_travel().

Type: InterplanetaryTravel

property ongoing_landing_sequence¶

The object representing the ongoing landing sequence. Only available after calling begin_landing_sequence().

Type: LandingSequence

property destination_planet_idx¶

The index of the planet to land on after the interplanetary travel. Only available after calling record_destination().

Type: int

property initial_landing_time¶

The initial time for the landing sequence, in years. Only available after calling record_destination().

Type: float

property initial_landing_position¶

Array of shape (2,) containing the initial x and y-position for the landing sequence, in astronomical units relative to the star. Only available after calling record_destination().

Type: 1-D numpy.ndarray

property initial_landing_velocity¶

Array of shape (2,) containing the initial x and y-velocity for the landing sequence, in astronomical units per year relative to the star. Only available after calling record_destination().

Type: 1-D numpy.ndarray

property landing_site_polar_angle¶

The polar angle of the landing site in degrees. Only available after completing a successful landing with LandingSequence.

Type: float

property landing_site_azimuth_angle¶

The azimuthal angle of the landing site in degrees. Only available after completing a successful landing with LandingSequence.

Type: float

property launch_parameters_set¶

Whether the launch parameters have been specified.

Type: bool

property rocket_launched¶

Whether the rocket has been successfully launched.

Type: bool

property launch_result_verified¶

Whether the launch result has been successfully verified.

Type: bool

property manual_orientation_verified¶

Whether the manually inferred orientation data has been successfully verified.

Type: bool

property destination_recorded¶

Whether the destination state after the interplanetary travel has been recorded.

Type: bool

property landing_completed¶

Whether the landing sequence has been successfully completed.

Type: bool

static save(filename, mission, verbose=True)¶

Saves the given instance of SpaceMission as a binary file.

Parameters

filename (str) – The name/path to use for the written binary file. Warning: If there exists a file with the same name it will be overwritten.
mission (SpaceMission) – The instance of SpaceMission to save.
verbose (bool, optional) – Set to False to mute the message saying that the file was successfully saved.

static load(filename, verbose=True)¶

Loads an instance of SpaceMission from the specified binary file.

Parameters

filename (str) – The name/path of the binary file to read.
verbose (bool, optional) – Set to False to mute the message saying that the file was successfully loaded.

Returns

The loaded SpaceMission instance.

Return type

SpaceMission

Raises

ValueError – When filename does not point to a valid file.

set_launch_parameters(thrust, mass_loss_rate, initial_fuel_mass, estimated_launch_duration, launch_position, time_of_launch)¶

Used to specify various parameters required to perform a launch.

Note

Any existing launch results will be cleared.

Parameters

thrust (float) – The total thrust of the rocket engine in Newtons.
mass_loss_rate (float) – The total rate of mass loss of the rocket engine in kilograms per second.
initial_fuel_mass (float) – The total mass of rocket fuel contained in the rocket before launch, in kilograms.
estimated_launch_duration (float) – The estimated duration of the launch, i.e. the time required to reach escape velocity, in seconds.
launch_position (1-D array_like) – Array of shape (2,) containing the x and y-position of the launch site, in astronomical units relative to the star. Must be close to the surface of your home planet (maximum 1% deviation).
time_of_launch (float) – The time of the start of the launch in years.

launch_rocket(time_step=0.01)¶

Simulates a rocket launch based on the previously specified launch parameters.

Note

Any existing launch result verification will be cleared.

Parameters

time_step (float, optional) – The time step duration to use for the simulation, in seconds. Not allowed to exceed the default of 0.01. Decrease if you suspect that higher accuracy is needed.

Raises

RuntimeError – When called before set_launch_parameters().
RuntimeError – When the rocket runs out of fuel.
RuntimeError – When the rocket is unable to overcome gravity.
RuntimeError – When the rocket reaches escape velocity too quickly.
RuntimeError – When the rocket hasn’t reached escape velocity at the time the simulation is completed.

verify_launch_result(position_after_launch)¶

Verifies that your computation of the final spacecraft position after launch gives a resonable result.

Parameters

position_after_launch (1-D array_like) – Array of shape (2,) containing your values for the x and y-position of the spacecraft after launch, in astronomical units relative to the star.

Raises

RuntimeError – When called before launch_rocket().
RuntimeError – When the input position is too far from the correct position.

verify_planet_positions(simulation_duration, planet_positions, filename='planet_trajectories.npz')¶

Calls verify_planet_positions() for the ast2000tools.solar_system.SolarSystem instance associated with the mission.

Note

The exact trajectories will be needed in later stages of the mission. By default, this wrapper causes the trajectories to be stored in the file “planet_trajectories.npz” in the working directory. The syntax for loading the data is:

with np.load('planet_trajectories.npz') as f:
    times = f['times']
    exact_planet_positions = f['planet_positions']

generate_orbit_video(times, planet_positions, number_of_frames=None, reduce_other_periods=True, filename='orbit_video.xml')¶: Calls generate_orbit_video() for the ast2000tools.solar_system.SolarSystem instance associated with the mission.

static get_sky_image_pixel(polar_angle, azimuth_angle)¶

Finds the index of the pixel in the full-sky image correspnding to the given spherical coordinates.

Parameters

polar_angle (float) – The polar angle of the point in radians. Must be in the range [0, pi].
azimuth_angle (float) – The azimuthal angle of the point in radians.

Returns

The index of the pixel.

Return type

int

take_picture(filename='sky_picture.png', full_sky_image_path='himmelkule.npy')¶

Generates a picture of the sky in the direction that the spacecraft is pointing directly after launch.

Note

You can safely assume that the spacecraft is looking along the solar system plane.

Parameters

filename (str, optional) – The name/path to use for the generated image. By default the image is stored as “sky_picture.png” in the working directory.
full_sky_image_path (str, optional) – The name/path to use when looking for the sky data file. This file must be downloaded from the course website. By default the file is assumed to be named “himmelkule.npy” and reside in the working directory.

Raises

RuntimeError – When called before verify_launch_result().
ValueError – When full_sky_image_path does not point to a valid file.

measure_star_doppler_shifts()¶

Returns the Doppler shifts of the two reference stars as measured by your spacecraft directly after launch.

Note

The Doppler shifts are computed for the H-alpha spectral line, which has a central wavelength of 656.3 nm.

Returns: Tuple (\(\Delta\lambda_0\), \(\Delta\lambda_1\)) containing the Doppler shifts of the stars relative to your spacecraft, in nanometers.
Return type: tuple(float)
Raises: RuntimeError – When called before verify_launch_result().

measure_distances()¶

Returns the distances to the bodies of the solar system as measured by your spacecraft directly after launch.

Returns: Array of shape (number_of_planets+1,) containing the distances to the planets and sun (last entry) in your system, in astronomical units.
Return type: 1-D numpy.ndarray
Raises: RuntimeError – When called before verify_launch_result().

verify_manual_orientation(position_after_launch, velocity_after_launch, angle_after_launch)¶

Verifies that your manually inferred values of the position, velocity and pointing angle of the spacecraft directly after launch are reasonable.

Parameters

position_after_launch (1-D array_like) – Array of shape (2,) containing your inferred values for the x and y-position of the spacecraft, in astronomical units relative to the star.
velocity_after_launch (1-D array_like) – Array of shape (2,) containing your inferred values for the x and y-velocity of the spacecraft, in astronomical units per year relative to the star.
angle_after_launch (float) – Your inferred value for the azimuthal angle of the spacecraft’s pointing, in degrees.

Raises

RuntimeError – When called before verify_launch_result().
RuntimeError – When any of the inputted values are too far from the correct values.

begin_interplanetary_travel()¶

Initiates an interplanetary travel process allowing you to guide your spacecraft to a different planet.

Note

Any ongoing interplanetary travel or landing sequence will be terminated. Any recorded destination state will be cleared.

Returns: A new instance of InterplanetaryTravel associated with your system.
Return type: InterplanetaryTravel

begin_landing_sequence(assume_uniform_gravity_atmosphere=True)¶

Initiates a landing sequence process allowing you to land on a planet.

Note

Any ongoing interplanetary travel or landing sequence will be terminated. Any recorded landing site coordinates will be cleared.

Parameters: assume_uniform_gravity_atmosphere (bool, optional) – Whether to neglect the change of gravitational force with height when modelling the atmosphere. Default is True.
Returns: A new instance of LandingSequence associated with your system.
Return type: LandingSequence