Astronomical and Spacecraft Toolkit Written in Zig

Featuring the fastest open-source SGP4 propagator.

Orbital Mechanics	Spacecraft Ops	Astronomy
SGP4 propagation	CCSDS packets	FITS parsing
TLE parsing	VITA49 packets	WCS coordinates
Orbital maneuvers	Attitude determination	Star precession
Monte Carlo sims		Celestial bodies

Performance

Sub-meter accuracy validated against reference implementations. Uses SIMD (AVX2/SSE) to process 4 satellites simultaneously.

Single Satellite (Python)

Scenario	astroz	python-sgp4	Speedup
1 day (minute res)	0.24 ms	0.65 ms	2.7x
1 week (minute res)	1.99 ms	3.41 ms	1.7x
2 weeks (minute res)	3.22 ms	7.00 ms	2.2x
2 weeks (second res)	144 ms	438 ms	3.0x
1 month (minute res)	5.29 ms	14.84 ms	2.8x

Multi-Satellite Constellation

Satellites	Time Points	Total Props	Throughput
100	10,080	1M	7.9M props/sec
13,000+	120	1.5M	6M+ props/sec

The Cesium visualization example propagates the entire active satellite catalog (~13,000 satellites) at interactive rates. Try the live demo →

Python

pip install astroz

from astroz import Tle, Sgp4, Sgp4Constellation
import numpy as np

tle = Tle("1 25544U 98067A   24127.82853009 ...\n2 25544  51.6393 ...")
sgp4 = Sgp4(tle)

# Single propagation
pos, vel = sgp4.propagate(30.0)  # 30 min after epoch

# Batch propagation (zero-copy into pre-allocated arrays)
times = np.arange(1209600, dtype=np.float64) / 60.0  # 2 weeks in minutes
positions = np.empty((len(times), 3), dtype=np.float64)
velocities = np.empty((len(times), 3), dtype=np.float64)
sgp4.propagate_into(times, positions, velocities)

# Multi-satellite constellation (SIMD-accelerated)
tles = [Tle(tle_str) for tle_str in tle_strings]
constellation = Sgp4Constellation(tles)
times = np.arange(1440, dtype=np.float64)  # 1 day in minutes
out = np.empty((len(times) * constellation.num_batches * 4 * 6,), dtype=np.float64)
constellation.propagate_into(times, out)  # ~6M propagations/sec

Usage

• Add astroz as a dependency in your build.zig.zon.

zig fetch --save https://github.com/ATTron/astroz/archive/<git_tag_or_commit_hash>.tar.gz
#or
zig fetch --save git+https://github.com/ATTron/astroz/#HEAD

• Use astroz as a module in your build.zig.

const astroz_dep = b.dependency("astroz", .{
    .target = target,
    .optimize = optimize,
});
const astroz_mod = astroz_dep.module("astroz");
exe.root_module.addImport("astroz", astroz_mod);

Examples

Orbital Mechanics

• Planet Transfer & Mission Planning

  Demonstrates interplanetary transfers with mission planning (Hohmann vs Bi-Elliptic comparison) and trajectory propagation.

• Orbit Maneuvers

  Comprehensive example showing TLE-based orbit propagation with various maneuver types: impulse, plane change, and phase change.

• Monte Carlo Simulation

  Statistical analysis for mission planning with uncertainty.

• SGP4 Propagation

  Analytical orbit propagation using SGP4 with TLE input. Demonstrates both direct SGP4 usage and the modular propagator interface.

• Cesium Satellite Visualization — Live Demo

  Interactive 3D visualization of the entire near-earth satellite catalog (~13,000 satellites) using Cesium. Features real-time SGP4 propagation at ~6M props/sec, constellation filtering, search, and satellite tracking.

Spacecraft Operations

• Orbit Orientation Determination

  Calculate spacecraft attitude and orientation.

Telemetry & Data Handling

• Parse Vita49 / with Callback

  VITA Radio Transport (VRT) packet stream parsing.

• Parse CCSDS / with File Sync

  Parse CCSDS space packet protocol from files.

• Create CCSDS Packet / with Config

  Generate CCSDS packets for telemetry.

Astronomy & Astrometry

• Generate Image from FITS File

  Parse and render FITS astronomical image data.

• Precess Star Coordinates

  Calculate stellar precession to a target epoch.

• Calculate WCS from TLE

  Compute World Coordinate System values from orbital elements.