Installation

SpiceyPy is currently supported on Mac, Linux, FreeBSD, and Windows systems.

If you are new to python, it is a good idea to read a bit about it first https://docs.python-guide.org. For new installations of python, it is encouraged to install and or update: pip, setuptools, wheel, and numpy first before installing SpiceyPy

pip install -U pip setuptools
pip install -U numpy

Then to install SpiceyPy, simply run:

pip install spiceypy

If you use anaconda/miniconda/conda/mamba/micromamba run:

conda config --add channels conda-forge
conda install spiceypy

Using the appropriate "conda" or "mamba" or "micromamba" command.

If no error was returned you have successfully installed SpiceyPy. To verify this you can list the installed packages via this pip command:

pip list

You should see spiceypy in the output of this command. Or you can start a python interpreter and try importing SpiceyPy like so:

import spiceypy

# print out the toolkit version installed
print(spiceypy.tkvrsn('TOOLKIT'))

This should print out the toolkit version without any errors. You have now verified that SpiceyPy is installed.

Using a system or custom CSPICE (source builds)

Since version 7.0.0 SpiceyPy is built with CMake (scikit-build-core). When building from source (pip install . in a clone of the repository), CSPICE is located in this order:

1. SPICEYPY_CSPICE_PREFIX (environment variable or CMake define): an install prefix containing a CSPICE built with cspice-cmake-spiceypy. The shared library is bundled into the built package.

2. A system or conda CSPICE found via find_library, with headers (SpiceUsr.h) findable on the default paths (e.g. include/cspice/). Used as-is, not bundled.

3. Otherwise CSPICE is downloaded and compiled from source automatically via the cspice-cmake-spiceypy recipe, and the shared library is bundled into the package.

To build a reusable CSPICE prefix (option 1) from a SpiceyPy clone:

cmake -S . -B build-cspice -DSPICEYPY_CSPICE_ONLY=ON -DCMAKE_BUILD_TYPE=Release
cmake --build build-cspice
cmake --install build-cspice --prefix /tmp/cspice-prefix
SPICEYPY_CSPICE_PREFIX=/tmp/cspice-prefix pip install .

CMake options can be passed through pip in several equivalent ways:

# scikit-build-core config-setting
pip install . -C cmake.define.SPICEYPY_CSPICE_PREFIX=/tmp/cspice-prefix
# environment variable form of the same (";"-separated NAME=VALUE list)
SKBUILD_CMAKE_DEFINE="SPICEYPY_CSPICE_PREFIX=/tmp/cspice-prefix" pip install .
# raw CMake arguments (space-separated), also reaches recipe options
CMAKE_ARGS="-DCSPICE_PATCH_SOURCE=OFF" pip install .

CMAKE_PREFIX_PATH is honored as well: a CSPICE installed under a non-standard prefix (e.g. CMAKE_PREFIX_PATH=/tmp/mycspice) is found by the system search (option 2 above) — and, unlike SPICEYPY_CSPICE_PREFIX, used in place without being bundled into the package.

The cspice-cmake-spiceypy recipe (used by options 1 and 3) exposes a few options of its own, which flow through a pip install .:

• CSPICE_SRC (environment variable): path to a local extracted CSPICE toolkit source tree to use instead of downloading from NAIF. It is copied into the build tree before patching; your copy is never modified.

• CSPICE_PATCH_SOURCE (CMake option or environment variable, default ON): apply SpiceyPy-specific patches to the working copy. Set to OFF if supplying an already-patched CSPICE_SRC.

• BUILD_EXECUTABLES / BUILD_TESTING (default OFF): additionally build the CSPICE utility executables / the recipe's C test.

Offline installation

A from-source build normally downloads two things: the cspice-cmake-spiceypy recipe (via git) and the CSPICE toolkit archive (from NAIF). To install without a network, either use a system CSPICE or a prebuilt SPICEYPY_CSPICE_PREFIX prefix (see above), so that neither download occurs, or point the build at local copies of both:

export CSPICE_SRC="/tmp/cspice"  # extracted CSPICE toolkit source tree
pip install . -C cmake.args=-DFETCHCONTENT_SOURCE_DIR_CSPICE=/path/to/cspice-cmake-spiceypy

Note

The build-time CSPICE_SRC_DIR and CSPICE_SHARED_LIB environment variables from the pre-7.0.0 build system are no longer used.

Runtime library selection

At import time SpiceyPy loads the first CSPICE shared library found from:

1. The CSPICE_SHARED_LIB environment variable (full path to the library).

2. A system or conda library found by ctypes.util.find_library("cspice") — note this takes precedence over the library bundled in the wheel. On Linux, directories on LD_LIBRARY_PATH (set before launching Python) are searched here too, though CSPICE_SHARED_LIB is the more reliable override.

3. The bundled library next to the package (spiceypy/utils/).

Set SPICEYPY_LOGLEVEL=INFO before importing spiceypy to log which library was loaded.

A simple example program

This script calls the spiceypy function 'tkvrsn' and outputs the return value.

File tkvrsn.py

   import spiceypy

   def print_ver():
           """
           Prints the TOOLKIT version
           """
           print(spiceypy.tkvrsn('TOOLKIT'))

   if __name__ == '__main__':
          print_ver()

From the command line, execute the function:

$ python tkvrsn.py
CSPICE_N0067

From Python, execute the function:

$ python
>>> import tkvrsn
>>> tkvrsn.print_ver()
CSPICE_N0067

SpiceyPy Documentation

The current version of SpiceyPy does not provide extensive documentation, but there are several ways to navigate your way through the Python version of the toolkit. One simple way is to use the standard Python mechanisms. All interfaces implemented in SpiceyPy can be listed using the standard built-in function dir(), which returns an alphabetized list of names comprising (among) other things, the API names. If you need to get additional information about an API parameters, the standard built-in function help() could be used:

>>> import spiceypy
>>> help(spiceypy.tkvrsn)

which produces

Help on function tkvrsn in module spiceypy.spiceypy:

tkvrsn(item: str) -> str
    Given an item such as the Toolkit or an entry point name, return
    the latest version string.

    https://naif.jpl.nasa.gov/pub/naif/misc/toolkit_docs_N0067/C/cspice/tkvrsn_c.html

    :param item: Item for which a version string is desired.
    :return: the latest version string.

As indicated in the help on the function, the complete documentation is available on the CSPICE toolkit version. Therefore it is recommended to have the CSPICE toolkit version installed locally in order to access its documentation offline.

Common Issues

SSL Alert Handshake Issue

Attention

As of 2020, users are not likely to experience this issue with python version 3.7 and above, and for newer 3.6.X releases. Users running older operating systems are encouraged to update to newer versions of python if they are attempting to install version 3.0.0 or above. See other sections of this document for more information.

In early 2017, JPL updated to a TLS1.2 certificate and enforced https connections causing installation issues for users, in particular for macOS users, with OpenSSL versions older than 1.0.1g. This is because older versions of OpenSSL still distributed in some environments which are incompatible with TLS1.2. As of late 2017 SpiceyPy has been updated with a strategy that can mitigate this issue on some systems, but it may not be totally reliable due to known deficiencies in setuptools and pip.

Another solution is to configure a new python installation that is linked against a newer version of OpenSSL, the easiest way to do this is to install python using homebrew, once this is done spiceypy can be installed to this new installation of python (IMHO this is the best option).

If your python 3.6 distribution was installed from the packages available at python.org an included command "Install Certificates.command" should be run before attempting to install SpiceyPy again. That command installs the certifi package that can also be install using pip.

Alternatively, installing an anaconda or miniconda python distribution and installing SpiceyPy using the conda command above is another possible work around.

Users continuing to have issues should report an issue to the github repository.

Supporting links:

• https://bugs.python.org/issue29065

• https://github.com/psf/requests/issues/2022

• https://pyfound.blogspot.com/2017/01/time-to-upgrade-your-python-tls-v12.html

• https://www.python.org/dev/peps/pep-0518

• https://github.com/AndrewAnnex/SpiceyPy/pull/202

How to install from source (for bleeding edge updates)

Attention

If you have used the pip or conda install commands above you do not need to do any of the following commands. Installing from source is intended for advanced users. Users on machines running Windows should take note that attempting to install from source will require software such as visual studio, CMake, and additional environment configuration. Given the complexity of this Windows users are highly encouraged to stick with the releases made available through PyPi/Conda-Forge.

If you wish to install from source, first simply clone the repository by running the following in your favorite shell:

git clone https://github.com/AndrewAnnex/SpiceyPy.git

If you do not have git, you can also directly download the source code from the GitHub repo for SpiceyPy at https://github.com/AndrewAnnex/SpiceyPy

To install the library, simply change into the root directory of the project and then run:

pip install .

The build will locate or build CSPICE as described in Using a system or custom CSPICE (source builds) above (downloading and compiling it from source if none is found) and install SpiceyPy into your site-packages directory. Building from source requires CMake and a C compiler; Cython and NumPy are handled automatically by build isolation.