Update user guide for multiple gravity assist trajectory design with low-thrust + create new examples

[MiguelAvillez]

The code for trajectory design using multiple gravity assists was refactored to allow the inclusion of low-thrust legs (relevant pull requests: https://github.com/tudat-team/tudat/pull/93 and https://github.com/tudat-team/tudatpy/pull/69).

The user guide for the transfer trajectory design module should be updated to reflect the new leg types (hodographic shaping and spherical shaping). Additionally, it might be worth mentioning that it is possible to create transfers by mixing different types of legs; that was already possible before the refactor, but not mentioned in the user guide.

Also, it would be cool to create some new examples: (1) example with low-thrust legs, and/or (2) example with a mix of high- and low-thrust legs. The attached code includes examples of: (1) transfer with just spherical-shaping legs ( mga_with_spherical_shaping function ); (2) transfer with just hodographic-shaping legs ( mga_with_hodographic_shaping function); (3) transfer with high-thrust leg, low-thrust leg and another high-thrust leg ( mga_with_mixed_legs function). The spherical and hodographic shaping examples show different ways (that can be changed using the creation_mode variable) to create the transfer leg and node settings: either by manually calling the factory function for each leg and node constituting the transfer, or by calling the factory function associated with the transfer trajectory for a specific leg type. Note that the values used for setting up these transfers are not necessarily realistic. The other two functions included in the file ( mga_without_dsm and mga_with_dsm) are the examples with high-thrust legs already present on the tudat website.

mga_dsm_analysis.py.zip Edit: updated example

[MiguelAvillez]

Tasks:

• [x] Rewrite user guide
• [x] High thrust example
• [x] Low thrust example
• [ ] Hybrid thrust example
• [x] High-thrust optimization example
• [x] Low-thrust optimization example

Branches: User guide + examples: https://github.com/MiguelAvillez/tudat-space/tree/feature/mga_docs_ht_lt API (just small corrections/additions): https://github.com/MiguelAvillez/tudat-multidoc/tree/feature/mga_docs_ht_lt

[MiguelAvillez]

@DominicDirkx, the updated user guide for the MGA code is available at https://github.com/MiguelAvillez/tudat-space/blob/feature/mga_docs_ht_lt/docs/source/_src_user_guide/astrodynamics/trajectory_design.rst Feel free to have a look :)

[DominicDirkx]

@MiguelAvillez, all these changes have been made and merged right?

[MiguelAvillez]

Yep:

• https://github.com/tudat-team/tudat-space/pull/81
• https://github.com/tudat-team/tudatpy-examples/pull/12

Closing issue.