Attitude

Library for simulating space-based VLBI missions (spacevlbi)

Copyright 2024 Ben Hudson

Licensed under the GNU General Public License, Version 3.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

spacevlbi.Attitude.AttitudePropagation(spaceTelescopes, rSun, rMoon, sourceRa, sourceDec, i, timeStep)

Propagate space telescope’s attitude state. This function calculates the attitude matrix required to point the antenna at the target source. The constraint axis is pointed in a direction perpendicular to the antenna direction, defined by the rollAngle parameter of a SpaceTelescope.

Parameters:

  • spaceTelescopes (list) – Array of SpaceTelescope objects, defaults to None

  • rSun (numpy.ndarray) – Sun position vector in ECI frame in metres, defaults to None

  • rMoon (numpy.ndarray) – Moon position vector in ECI frame in metres, defaults to None

  • sourceRa (float) – Right ascension of target source in degrees, defaults to None

  • sourceDec (float) – Declination of target source in degrees, defaults to None

  • i (int) – Current time step, defaults to None

  • timeStep (int) – simulation time step in seconds, defaults to None

Returns:

Array of SpaceTelescope objects

Return type:

list

spacevlbi.Attitude.TRIAD(r1, r2, b1, b2)

TRIAD algorithm to calculate the attitude matrix from two pairs of body and inertial constraint vectors.

Parameters:

  • r1 (numpy.ndarray) – Inertial pointing vector, defaults to None

  • r2 (numpy.ndarray) – Inertial constraint vector, defaults to None

  • b1 (numpy.ndarray) – Body pointing vector, defaults to None

  • b2 (numpy.ndarray) – Body constraint vector, defaults to None

Returns:

Attitude Matrix

Return type:

numpy.ndarray