ANISE (Attitude, Navigation, Instrument, Spacecraft, Ephemeris)

ANISE is a rewrite of the core functionalities of the NAIF SPICE toolkit with enhanced performance, and ease of use, while leveraging Rust's safety and speed.

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Introduction

In the realm of space exploration, navigation, and astrophysics, precise and efficient computation of spacecraft position, orientation, and time is critical. ANISE, standing for "Attitude, Navigation, Instrument, Spacecraft, Ephemeris," offers a Rust-native approach to these challenges. This toolkit provides a suite of functionalities including but not limited to:

• Loading SPK, BPC, PCK, FK, and TPC files.
• High-precision translations, rotations, and their combination (rigid body transformations).
• Comprehensive time system conversions using the hifitime library (including TT, TAI, ET, TDB, UTC, GPS time, and more).

ANISE stands validated against the traditional SPICE toolkit, ensuring accuracy and reliability, with translations achieving machine precision (2e-16) and rotations presenting minimal error (less than two arcseconds in the pointing of the rotation axis and less than one arcsecond in the angle about this rotation axis).

Features

• High Precision: Matches SPICE to machine precision in translations and minimal errors in rotations.
• Time System Conversions: Extensive support for various time systems crucial in astrodynamics.
• Rust Efficiency: Harnesses the speed and safety of Rust for space computations.
• Multi-threaded: Yup! Forget about mutexes and race conditions you're used to in SPICE, ANISE guarantees that you won't have any race conditions.
• Frame safety: ANISE checks all frames translations or rotations are physically valid before performing any computation, even internally.
• Auto-downloading capability: ANISE simplifies your workflow by automatically downloading the latest Earth orientation parameters, or any other SPICE or ANISE file from a remote location, seamlessly integrating them into the Almanac for immediate use.

Usage

Start using it by adding to your Rust project:

cargo add anise

Frame Transformation of an Orbit

ANISE provides the ability to create Cartesian states (also simply called Orbits), calculate orbital elements from them in an error free way (computations that may fail return a Result type), and transform these states into other frames via the loaded context, called Almanac, which stores all of the SPICE and ANISE files you need.

use anise::prelude::*;
// ANISE provides pre-built frames, but examples below show how to build them from their NAIF IDs.
use anise::constants::frames::{EARTH_ITRF93, EARTH_J2000};

// Initialize an empty Almanac
let ctx = Almanac::default();

// Load a SPK/BSP file
let spk = SPK::load("../data/de440.bsp").unwrap();
// Load the high precision ITRF93 kernel
let bpc = BPC::load("../data/earth_latest_high_prec.bpc").unwrap();
// Build the planetary constants file, which includes the gravitational parameters and the IAU low fidelity rotations
use anise::naif::kpl::parser::convert_tpc;
// Note that the PCK variable can also be serialized to disk to avoid having to rebuild it next time.
let pck = convert_tpc("../data/pck00008.tpc", "../data/gm_de431.tpc").unwrap();

// And add all of these to the Almanac context
let almanac = ctx
    .with_spk(spk)
    .unwrap()
    .with_bpc(bpc)
    .unwrap()
    .with_planetary_data(pck);

// Let's build an orbit
// Start by grabbing a copy of the frame.
let eme2k = almanac.frame_from_uid(EARTH_J2000).unwrap();

// Define an epoch, in TDB, but you may specify UTC, TT, TAI, GPST, and more.
let epoch = Epoch::from_str("2021-10-29 12:34:56 TDB").unwrap();

// Define the orbit from its Keplerian orbital elements.
// Note that we must specify the frame of this orbit: ANISE checks all frames are valid before any translation or rotation, even internally.
let orig_state = Orbit::keplerian(
    8_191.93, 1e-6, 12.85, 306.614, 314.19, 99.887_7, epoch, eme2k,
);

// Transform that orbit into another frame.
let state_itrf93 = almanac
    .transform_to(orig_state, EARTH_ITRF93, None)
    .unwrap();

// The `:x` prints this orbit's Keplerian elements
println!("{orig_state:x}");
// The `:X` prints the prints the range, altitude, latitude, and longitude with respect to the planetocentric frame in floating point with units if frame is celestial,
println!("{state_itrf93:X}");

// Convert back
let from_state_itrf93_to_eme2k = almanac
    .transform_to(state_itrf93, EARTH_J2000, Aberration::NONE)
    .unwrap();

println!("{from_state_itrf93_to_eme2k}");

// Check that our return data matches the original one exactly
assert_eq!(orig_state, from_state_itrf93_to_eme2k);

Load and query a PCK/BPC file (high fidelity rotation)

use anise::prelude::*;
use anise::constants::frames::{EARTH_ITRF93, EME2000};

let pck = "../data/earth_latest_high_prec.bpc";

let bpc = BPC::load(pck).unwrap();
let almanac = Almanac::from_bpc(bpc).unwrap();

// Load the useful frame constants
use anise::constants::frames::*;

// Define an Epoch in the dynamical barycentric time scale
let epoch = Epoch::from_str("2020-11-15 12:34:56.789 TDB").unwrap();

// Query for the DCM
let dcm = almanac.rotate_from_to(EARTH_ITRF93, EME2000, epoch).unwrap();

println!("{dcm}");

Load and query a text PCK/KPL file (low fidelity rotation)

use anise::prelude::*;
// Load the TPC converter, which will create the ANISE representation too, in ASN1 format, that you may reuse.
use anise::naif::kpl::parser::convert_tpc;

// Note that the ASN1 ANISE format for planetary data also stores the gravity parameters, so we must convert both at once into a single ANISE file.
let planetary_data = convert_tpc("../data/pck00008.tpc", "../data/gm_de431.tpc").unwrap();

let almanac = Almanac {
    planetary_data,
    ..Default::default()
};

// Load the useful frame constants
use anise::constants::frames::*;

// Define an Epoch in the dynamical barycentric time scale
let epoch = Epoch::from_str("2020-11-15 12:34:56.789 TDB").unwrap();

// Query for the DCM to the immediate parent
let dcm = almanac.rotation_to_parent(IAU_VENUS_FRAME, epoch).unwrap();

println!("{dcm}");

Load and query an SPK/BSP file (ephemeris)

use anise::prelude::*;
use anise::constants::frames::*;

let spk = SPK::load("../data/de440s.bsp").unwrap();
let ctx = Almanac::from_spk(spk).unwrap();

// Define an Epoch in the dynamical barycentric time scale
let epoch = Epoch::from_str("2020-11-15 12:34:56.789 TDB").unwrap();

let state = ctx
    .translate(
        VENUS_J2000, // Target
        EARTH_MOON_BARYCENTER_J2000, // Observer
        epoch,
        None,
    )
    .unwrap();

println!("{state}");

Validation

ANISE is validated by running the same queries in ANISE and in SPICE (single threaded) in the Validation step linked above. This workflow validates 101,000 BSP queries in the DE440.BSP file, and 7305 queries each frame in the PCK08 file (every day for 20 years), along with thousands of rotations from Earth high precision BPC file.

Note: The PCK data comes from the IAU Reports, which publishes angle, angle rate, and angle acceleration data, expressed in centuries past the J2000 reference epoch. ANISE uses Hifitime for time conversions. Hifitime's reliance solely on integers for all time computations eliminates the risk of rounding errors. In contrast, SPICE utilizes floating-point values, which introduces rounding errors in calculations like centuries past J2000. Consequently, you might observe a discrepancy of up to 1 millidegree in rotation angles between SPICE and ANISE. However, this difference is a testament to ANISE's superior precision.

Resources / Assets

For convenience, Nyx Space provides a few important SPICE files on a public bucket:

• de440s.bsp: JPL's latest ephemeris dataset from 1900 until 20250
• de440.bsp: JPL's latest long-term ephemeris dataset
• pck08.pca: planetary constants ANISE (pca) kernel, built from the JPL gravitational data gm_de431.tpc and JPL's plantary constants file pck00008.tpc
• pck11.pca: planetary constants ANISE (pca) kernel, built from the JPL gravitational data gm_de431.tpc and JPL's plantary constants file pck00011.tpc
• moon_fk.epa: Euler Parameter ANISE (epa) kernel, built from the JPL Moon Frame Kernel moon_080317.txt

You may load any of these using the load() shortcut that will determine the file type upon loading, e.g. let almanac = Almanac::new("pck08.pca").unwrap(); or in Python almanac = Almanac("pck08.pca"). To automatically download remote assets, from the Nyx Cloud or elsewhere, use the MetaAlmanac: almanac = MetaAlmanac("ci_config.dhall").process() in Python.

Contributing

Contributions to ANISE are welcome! Whether it's in the form of feature requests, bug reports, code contributions, or documentation improvements, every bit of help is greatly appreciated.

License

ANISE is distributed under the Mozilla Public License 2.0 (MPL-2.0), offering a balanced approach to open-source by allowing the use of source code within both open and proprietary software. MPL-2.0 requires that modifications to the covered code be released under the same license, thus ensuring improvements remain open-source. However, it allows the combining of the covered software with proprietary parts, providing flexibility for both academic and commercial integrations.

For more details, please see the full text of the license or read a summary by Github.

Acknowledgements

ANISE is heavily inspired by the NAIF SPICE toolkit and its excellent documentation.

Contact

For any inquiries, feedback, or discussions, please open an issue here or contact the maintainer at christopher.rabotin@gmail.com.