Mars Express frame definition

In irfpy.aspera modules, the frame definition follows that of SPICE.

Note

There are confusion in the SPICE definition and ASPERA-team internal definition of the IMA frame name. Internal definition of “IMA” frame is equivalent to “IMAS” frame in SPICE (MEX_ASPERA_IMAS). “IMA” frame in SPICE is not used in the internal ASPERA document.

In irfpy.aspera.mima module, all the definition of “IMA frame” should follow the internal-“IMA” frame which is identical to “IMAS” frame in SPICE. Therefore, if I state “IMA frame”, this means internal-IMA. In some modules, the frame name is explicitly says imas, but this is again the same as internal-IMA frame.

Frame and numbering

irfpy.mima.fov for the field of view and frame definition and implementation.

../_images/mex_frame_definition.png

Note

Definition for VEX differs.

IMA angles

For IMA, sometimes the numbering is expressed by the angles.

Conversion

High level operation can be supported in irfpy.mima.fov.SimpleFOV.

Convert from numbering to IMA frame

For IMAS frame, the azimuth and polar angle between az=0 and az=1 and between po=7 and 8 points x direction. irfpy.mima.fov.SimpleFOV.viewvector_imasframe() supports this. irfpy.mima.fov.SimpleFOV.velocityvector_imasframe() method returns the corresponding (unit) velocity vector in IMAS frame.

Samples are in the docstring in the above method.

IMA frame conversion to numbering

You may use irfpy.mima.fov.SimpleFOV.numbering_imasframe().

Samples are in the docstring in the above method.