Scarabaeus Quickstart#

The example below propagates a spacecraft in a low-Earth orbit for 90 minutes using a two-body gravity model. It covers the core Scarabaeus workflow: units, frames, SPICE kernels, spacecraft definition, force model, and propagation.

import scarabaeus as scb
import numpy as np

# define units and frame
kg, km, sec = scb.Units.get_units(["kg", "km", "sec"])
J2000 = scb.Frame('J2000')

# Load SPICE kernels
scb.SpiceManager.load_kernel_from_mkfile("path/to/metakernel.tm")

# Define a spacecraft
sc = scb.Spacecraft(
    name     = "Orbiter",
    spice_id = -1000,
    tot_mass = scb.ArrayWUnits(2000.0, kg),
    area     = scb.ArrayWUnits(1e-6, km**2),
    ref_coeff= 1.5,
)

# Define the central body
earth = scb.CelestialBody.from_constants("EARTH")

# Initial state (position [km], velocity [km/s])
r0 = scb.ArrayWUnits(np.array([6778.0, 0.0, 0.0]), km)
v0 = scb.ArrayWUnits(np.array([0.0, 7.784, 0.0]), km / sec)
state = scb.StateArray(earth, J2000, sc, r0, v0)

# Define epochs
t0 = scb.EpochArray("2024-JAN-01 00:00:00.000 TDB", "TDB")
tf = scb.EpochArray("2024-JAN-01 01:30:00.000 TDB", "TDB")

# Build force model and propagate
gravity = scb.PointMassGravity(earth)
fm = scb.ForceModelTranslation([gravity])

prop = scb.Propagator(spacecraft=sc, force_model=fm, epoch_start=t0, epoch_end=tf)
traj = prop.propagate(state)

Note

The SPICE metakernel path above is illustrative. Replace it with the path to your own metakernel file. See Installation for details.

Next Steps#

The tutorial suite in Examples walks through progressively more complex workflows:

  • Basics — units, epochs, frames, spacecraft definition, Keplerian propagation

  • Intermediate — perturbation models, mission sequences, measurement simulation

  • Advanced — orbit determination with simulated and real DSN measurements, multi-arc OD, finite burn modelling, parameter estimation

See the API Reference for full documentation of every class and method.

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