Kete

The repository for Kete, Solar System Survey Simulation Software. 'Kete' comes from ancient greek mythology, meaning sea monsters, and is the root word for Cetaceans (Whales).

Introduction

The kete tools are intended to enable the simulation of all-sky surveys of minor planets. This includes multi-body physics orbital dynamics, thermal and optical modeling of the objects, as well as field of view and light delay corrections. These tools in conjunction with the Minor Planet Centers (MPC) database of known asteroids can be used to not only plan surveys but can also be used to predict what objects are visible for existing or past surveys.

The primary goal for kete is to enable a set of tools that can operate on the entire MPC catalog at once, without having to do queries on specific objects. It has been used to simulate over 10 years of survey time for the NEO Surveyor mission using 10 million main-belt and near-Earth asteroids.

Documentation

• Examples
• Tutorials

ztf_2023.mp4

Here is a simulation of what the ZTF survey would observe during the entirety of 2023. This is every position of every numbered asteroid, along with a calculation of the expected V-band magnitudes. If the expected magnitude is less than ZTF's reported magnitude limit for the specific frame, then the object will flash light grey.

This took about 50 minutes on a desktop computer to compute, and about 40 minutes to generate the movie.

Installation

Kete may be installed using pip:

pip install kete

Installation - From Source

If kete is built from source, the rust compiler must be installed. Installation instructions may be found here:

https://www.rust-lang.org/learn/get-started

Ensure that your Python is up to date, this code runs on Python 3.9+.

python --version

Ensure that your pip is up to date, this should be at least version 22.0.0.

pip --version

This can be updated using:

python -m pip install "pip>=22.0.0" --upgrade
pip install setuptools --upgrade

Units and Reference Frame

Kete uses the ICRF Reference frame as the base coordinate frame, with units of AU, with time in JD with Barycentric Dynamical Time (TDB) scaling. Internally this frame converted to an Ecliptic coordinate system which is defined by the Obliquity Angle definition used by JPL Horizons, which is the defined IAU76/80 model in the J2000 frame.

  - https://en.wikipedia.org/wiki/Axial_tilt#Short_term
  - https://ssd.jpl.nasa.gov/horizons/manual.html#defs

Both JPL Horizons and the Minor Planet Center (MPC) use this coordinate frame, which is essentially equivalent to J2000 Ecliptic coordinates. Conversion tools are available in kete which enable conversion to the Equatorial frame and to various flavors of time.

Cache directory

Many operations in kete result in downloading various files. These files are cached automatically, the directory where this cache is stored may be set by setting the environment variable KETE_CACHE_DIR. The default directory is ~/.kete/.

export KETE_CACHE_DIR="~/.kete/"

Development

If you plan on doing development, it is recommended to install with the following:

pip install '.[dev]'

The [dev] in that line has pip install a number of optional dependencies which are useful for development. Including pytest and documentation tools.

Building Documentation

In order for documentation to be built, some additional Python libraries are needed. These can be installed with:

pip install sphinx sphinx_gallery autodoc

After this has been installed, the documentation can be built by running inside the kete directory.

(cd docs && make html && open html/index.html&)

Once this has completed running, open the file kete/docs/html/index.html for access to the HTML documentation.

To clean the previous docs build:

(cd docs && make clean)

Documentation tests may be run with:

(cd docs && make doctest)

Running tests

Running tests require that the pytest and pytest-cov packages be installed.

Open a terminal in the base of this folder and run the following command:

pytest --cov-report term-missing --cov=kete   

Another coverage report type is HTML, this will generate a folder called htmlcov in the directory where the command was run, then you can open the htmlcov/index.html file. This is a user-friendly website representation of the code coverage.

pytest --cov-report html --cov=kete   

Running Tutorials

Tutorials are computationally expensive examples which are more indicative of typical expected use. Since these examples are so expensive to run, they are not run unless manually performed. A convenience python script has been provided to do just this.

cd docs
python utils.py

Running Benchmarks

There are a test suite of micro-benchmarks in the rust backend of kete. These require gnuplot to be installed, and may be run using the following command:

cargo bench
open target/criterion/report/index.html

Additionally, Flamegraphs may be produced using the following:

cargo bench --bench propagation -- --profile-time=5
cargo bench --bench spice -- --profile-time=5
cargo bench --bench thermal -- --profile-time=5

These flamegraphs will be put in target/criterion/*/profile/flamegraph.svg. Opening these files in a web browser will show what functions are being used during the bench.