Curryer

A library for SPICE extensions and geospatial data product generation.

• Github: https://github.com/lasp/curryer
• PyPi: https://pypi.org/project/lasp-curryer/
• Documentation: https://lasp-curryer.readthedocs.io/

Core Features

• Extensions and wrappers for SPICE routines and common data patterns.
• Automation of SPICE kernel creation from JSON definition files and modern data file formats and third-party data structures.
• Level-1 geospatial data processing routines (e.g., geolocation).

Install

pip install lasp-curryer

Data / Binary Files

NOTE: Data files and precompiled binaries are not currently automated and thus require manual downloading. This will be addressed in the next major release.

Download from the Curryer repo:

• data/generic - Generic spice kernels (e.g., leapsecond kernel)
  • Download
• data/<mission> - Mission specific kernels and/or kernel definitions.

Define the top-level directory using the environment variable CURRYER_DATA_DIR or pass the path to routines which require data files.

Download Third-party Files:

• SPICE Utilities: https://naif.jpl.nasa.gov/naif/utilities.html
  • At minimum: mkspk, msopck, brief, ckbreif
• SPICE Generic Kernels (large):
  • de430.bsp, place in data/generic.
• PyProj Data:
  • Data directory: import pyproj; print(pyproj.datadir.get_user_data_dir())
  • EGM96 TIFF
• (OPTIONAL, USED FOR TESTING) data/gmted - Digital Elevation Model (DEMs) with global coverage at 15-arc-second.
  • Alternatively, use the script download_dem.py to download different types and/or resolutions from the USGS.

Examples

SPICE Extensions

Time conversion:

from curryer import spicetime

print(spicetime.adapt(0, from_='ugps', to='iso'))
# 1980-01-06 00:00:00.000000

print(spicetime.adapt('2024-11-13', 'iso'))
# 1415491218000000

print(spicetime.adapt(1415491218000000, to='et'))
# 784728069.1827033

import numpy as np

print(repr(spicetime.adapt(np.arange(4) * 60e6 + 1415491218000000, to='dt64')))
# array(['2024-11-13T00:00:00.000000', '2024-11-13T00:01:00.000000',
#        '2024-11-13T00:02:00.000000', '2024-11-13T00:03:00.000000'],
#       dtype='datetime64[us]')

Abstractions:

from curryer import spicierpy

spicierpy.ext.infer_ids('ISS', 25544, from_norad=True)
# {'mission': 'ISS',
#  'spacecraft': -125544,
#  'clock': -125544,
#  'ephemeris': -125544,
#  'attitude': -125544000,
#  'instruments': {}}

earth = spicierpy.obj.Body('Earth')
print(earth, earth.id)
# Body(EARTH) 399

import curryer

mkrn = curryer.meta.MetaKernel.from_json(
    'data/tsis1/tsis_v01.kernels.tm.json', sds_dir='data/generic', relative=True
)
print(mkrn)
# MetaKernel(Spacecraft(ISS_SC), Body(ISS_ELC3), Body(ISS_EXPA35), Body(TSIS_TADS),
#   Body(TSIS_AZEL), Body(TSIS_TIM), Body(TSIS_TIM_GLINT))

with spicierpy.ext.load_kernel([mkrn.sds_kernels, mkrn.mission_kernels]):
    print(spicierpy.ext.instrument_boresight('TSIS_TIM'))
# [0. 0. 1.]

mkrn = curryer.meta.MetaKernel.from_json(
    'tests/data/clarreo/cprs_v01.kernels.tm.json', sds_dir='data/generic', relative=True
)
print(mkrn)
# MetaKernel(Spacecraft(ISS_SC), Body(CPRS_BASE), Body(CPRS_PEDE),
#   Body(CPRS_AZ), Body(CPRS_YOKE), Body(CPRS_EL), Body(CPRS_HYSICS))

with spicierpy.ext.load_kernel([mkrn.sds_kernels, mkrn.mission_kernels]):
    print(curryer.compute.spatial.get_instrument_kernel_pointing_vectors('CPRS_HYSICS'))
# (480,
#  array([[ 0.00173869, -0.08715574,  0.99619318],
#         [ 0.0017315 , -0.08679351,  0.99622482],
#         [ 0.00172431, -0.08643127,  0.99625632],
#         ...,
#         [-0.00171712,  0.08606901,  0.9962877 ],
#         [-0.00172431,  0.08643127,  0.99625632],
#         [-0.0017315 ,  0.08679351,  0.99622482]]))

SPICE Kernel Creation

Create CLARREO Dynamic Kernels:

import curryer

meta_kernel = 'tests/data/clarreo/cprs_v01.kernels.tm.json'
generic_dir = 'data/generic'
kernel_configs = [
    'data/clarreo/iss_sc_v01.ephemeris.spk.json',
    'data/clarreo/iss_sc_v01.attitude.ck.json',
    'data/clarreo/cprs_az_v01.attitude.ck.json',
    'data/clarreo/cprs_el_v01.attitude.ck.json',
]
output_dir = '/tmp'
input_file_or_obj = 'tests/data/demo/cprs_geolocation_tlm_20230101_20240430.nc'

# Load meta kernel details. Includes existing static kernels.
mkrn = curryer.meta.MetaKernel.from_json(meta_kernel, relative=True, sds_dir=generic_dir)

# Create the dynamic kernels from the JSONs alone. Note that they
# contain the reference to the input_data netcdf4 file to read.
generated_kernels = []
creator = curryer.kernels.create.KernelCreator(overwrite=False, append=False)

# Generate the kernels from the config and input data (file or object).
for kernel_config in kernel_configs:
    generated_kernels.append(creator.write_from_json(
        kernel_config, output_kernel=output_dir, input_data=input_file_or_obj,
    ))

Level-1 Geospatial Processing

Geolocate CLARREO HYSICS Instrument:

import pandas as pd
import curryer

meta_kernel = 'tests/data/clarreo/cprs_v01.kernels.tm.json'
generic_dir = 'data/generic'

time_range = ('2023-01-01', '2023-01-01T00:05:00')
ugps_times = curryer.spicetime.adapt(pd.date_range(*time_range, freq='67ms', inclusive='left'), 'iso')

# Load meta kernel details. Includes existing static kernels.
mkrn = curryer.meta.MetaKernel.from_json(meta_kernel, relative=True, sds_dir=generic_dir)

# Geolocate all the individual pixels and create the L1A data product!
with curryer.spicierpy.ext.load_kernel([mkrn.sds_kernels, mkrn.mission_kernels]):
    geoloc_inst = curryer.compute.spatial.Geolocate('CPRS_HYSICS')
    l1a_dataset = geoloc_inst(ugps_times)
    l1a_dataset.to_netcdf('cprs_geolocation_l1a_20230101.nc')

Assumes dynamic kernels have been created and their file names defined within the metakernel JSON file.

---

SPICE Path Length Handling

Curryer automatically handles SPICE's 80-character path limit using a simple two-strategy approach:

1. Symlink (always tried first—zero overhead, no copying)
2. File copy to temp directory (bulletproof fallback if symlink fails)

No configuration needed for most users. Temp files are automatically cleaned up after kernel generation.

Configuration Options

# Custom temp directory (default: /tmp on Unix, auto-detected on Windows)
export CURRYER_TEMP_DIR="/tmp"

# AWS/Cloud: Disable file copying to avoid storage costs
export CURRYER_DISABLE_COPY="true"

How It Works

When kernel paths exceed 80 characters:

INFO: Path exceeds 80 chars (102 chars): /very/long/path.../naif0012.tls
INFO:   → Using symlink: /tmp/curryer_naif0012.tls

Or if symlinks fail:

INFO: Path exceeds 80 chars (102 chars): naif0012.tls
INFO:   → Using copy: /tmp/curryer_abc12345.tls

See SPICE Path Handling Documentation for more details.