RSO Inspection
This example demonstrates the configuration of a resident space object (RSO) inspection environment, in which a servicer spacecraft circumnavigates a RSO to image the illuminated facets.
[1]:
from functools import partial
from importlib.metadata import version
from typing import ClassVar
import numpy as np
from Basilisk.architecture import bskLogging
from Basilisk.utilities.orbitalMotion import elem2rv
from Basilisk.utilities.RigidBodyKinematics import C2MRP
from bsk_rl import ConstellationTasking, act, data, obs, sats, scene
from bsk_rl.obs.relative_observations import rso_imaged_regions
from bsk_rl.sim import dyn, fsw
from bsk_rl.utils.orbital import (
fibonacci_sphere,
random_orbit,
random_unit_vector,
relative_to_chief,
)
bskLogging.setDefaultLogLevel(bskLogging.BSK_WARNING)
RLlib is actively developed and can change significantly from version to version. For this script, the following version is used:
[2]:
version("ray") # Parent package of RLlib
[2]:
'2.35.0'
Defining the Satellites
First, the RSO satellite is configured. A simple model is used that has no actuators modelled and just deterministically points nadir.
[3]:
class RSOSat(sats.Satellite):
observation_spec: ClassVar[list[obs.Observation]] = [
obs.SatProperties(dict(prop="one", fn=lambda _: 1.0)),
]
action_spec: ClassVar[list[act.Action]] = [act.NadirPoint(duration=1e9)]
dyn_type = (dyn.ConjunctionDynModel, dyn.RSODynModel)
fsw_type = fsw.FSWModel
Arguments for the satellite are configured for smooth pointing behavior.
[4]:
rso_sat_args = dict(conjunction_radius=2.0)
The inspector satellite has a more complex configuration. First, an observation function for the sun vector is defined.
[5]:
def sun_hat_chief(self, other):
r_SN_N = (
self.simulator.world.gravFactory.spiceObject.planetStateOutMsgs[
self.simulator.world.sun_index
]
.read()
.PositionVector
)
r_BN_N = self.dynamics.r_BN_N
r_SN_N = np.array(r_SN_N)
r_SB_N = r_SN_N - r_BN_N
r_SB_N_hat = r_SB_N / np.linalg.norm(r_SB_N)
HN = other.dynamics.HN
return HN @ r_SB_N_hat
The inspector satellite is configured with observations relating to the relative state and the mission objectives. The satellite is given an action for impulsively thrusting and drifting. The dynamics and flight software models introduce a maximum range check, collision checking orbital maneuvers, and RSO inspection.
[6]:
class InspectorSat(sats.Satellite):
observation_spec: ClassVar[list[obs.Observation]] = [
obs.SatProperties(
dict(prop="dv_available", norm=10),
dict(prop="inclination", norm=np.pi),
dict(prop="eccentricity", norm=0.1),
dict(prop="semi_major_axis", norm=7000),
dict(prop="ascending_node", norm=2 * np.pi),
dict(prop="argument_of_periapsis", norm=2 * np.pi),
dict(prop="true_anomaly", norm=2 * np.pi),
dict(prop="beta_angle", norm=np.pi),
),
obs.ResourceRewardWeight(),
obs.RelativeProperties(
dict(prop="r_DC_Hc", norm=500),
dict(prop="v_DC_Hc", norm=5),
dict(
prop="rso_imaged_regions",
fn=partial(
rso_imaged_regions,
region_centers=fibonacci_sphere(15),
frame="chief_hill",
),
),
dict(prop="sun_hat_Hc", fn=sun_hat_chief),
chief_name="RSO",
),
obs.Eclipse(norm=5700),
obs.Time(),
]
action_spec: ClassVar[list[act.Action]] = [
act.ImpulsiveThrustHill(
chief_name="RSO",
max_dv=1.0,
max_drift_duration=5700.0 * 2,
fsw_action="action_inspect_rso",
)
]
dyn_type = (dyn.MaxRangeDynModel, dyn.ConjunctionDynModel, dyn.RSOInspectorDynModel)
fsw_type = (
fsw.SteeringFSWModel,
fsw.MagicOrbitalManeuverFSWModel,
fsw.RSOInspectorFSWModel,
)
Generous configurations are used for the inspector, allowing for “sloppy” attitude control with a low simulation step rate.
[7]:
inspector_sat_args = dict(
imageAttErrorRequirement=1.0,
imageRateErrorRequirement=None,
instrumentBaudRate=1,
dataStorageCapacity=1e6,
batteryStorageCapacity=1e9,
storedCharge_Init=1e9,
conjunction_radius=2.0,
dv_available_init=10.0,
max_range_radius=1000,
chief_name="RSO",
u_max=1.0,
)
Environment Generation
A satellite argument randomizer is defined to configure the initial state of the satellites. The RSO is put into a random orbit with an apogee and perigee between 500 km and 1100 km. The inspector is placed in the region 250 to 750 meters from the RSO, with up to 1 m/s of relative velocity. Finally, the RSO’s attitude and body rate are set up to be in the nadir-pointing initial configuration.
[8]:
def sat_arg_randomizer(satellites):
# Generate the RSO orbit
R_E = 6371.0 # km
a = R_E + np.random.uniform(500, 1100)
e = np.random.uniform(0.0, min(1 - (R_E + 500) / a, (R_E + 1100) / a - 1))
chief_orbit = random_orbit(a=a, e=e)
inspectors = [sat for sat in satellites if "Inspector" in sat.name]
rso = next(satellite for satellite in satellites if satellite.name == "RSO")
# Generate the inspector initial states.
args = {}
for inspector in inspectors:
relative_randomizer = relative_to_chief(
chief_name="RSO",
chief_orbit=chief_orbit,
deputy_relative_state={
inspector.name: lambda: np.concatenate(
(
random_unit_vector() * np.random.uniform(250, 750),
random_unit_vector() * np.random.uniform(0, 1.0),
)
),
},
)
args.update(relative_randomizer([rso, inspector]))
# Align RSO Hill frame for initial nadir pointing
mu = rso.sat_args_generator["mu"]
r_N, v_N = elem2rv(mu, args[rso]["oe"])
r_hat = r_N / np.linalg.norm(r_N)
v_hat = v_N / np.linalg.norm(v_N)
x = r_hat
z = np.cross(r_hat, v_hat)
z = z / np.linalg.norm(z)
y = np.cross(z, x)
HN = np.array([x, y, z])
BH = np.eye(3)
a = chief_orbit.a
T = np.sqrt(a**3 / mu) * 2 * np.pi
omega_BN_N = z * 2 * np.pi / T
args[rso]["sigma_init"] = C2MRP(BH @ HN)
args[rso]["omega_init"] = BH @ HN @ omega_BN_N
return args
The scenario is configured to set the RSO geometry as a sphere with 100 points at a radius of 1 meter. Points must be imaged within 30 degrees of their normal, with illumination coming from no more than 60 degrees from normal. The inspector must be within 250 meters to inspect the RSO.
[9]:
scenario = scene.SphericalRSO(
n_points=100,
radius=1.0,
theta_max=np.radians(30),
range_max=250,
theta_solar_max=np.radians(60),
)
This scenario uses two rewarders. For the RSO inspection component of the task, a bonus of 1.0 is yielded once at least 90% of the illuminated points have been inspected. The ResourceReward is used to penalize fuel use, with some basic logic add to only apply the reward to the Inspector.
[10]:
rewarders = (
data.RSOInspectionReward(
completion_bonus=1.0,
completion_threshold=0.90,
),
data.ResourceReward(
resource_fn=lambda sat: sat.fsw.dv_available
if isinstance(sat.fsw, fsw.MagicOrbitalManeuverFSWModel)
else 0.0,
reward_weight=np.random.uniform(0.0, 0.5),
),
)
With all the components defined, the environment can be instantiated.
[11]:
env = ConstellationTasking(
satellites=[
RSOSat("RSO", sat_args=rso_sat_args),
InspectorSat("Inspector", sat_args=inspector_sat_args, obs_type=dict),
],
sat_arg_randomizer=sat_arg_randomizer,
scenario=scenario,
rewarder=rewarders,
time_limit=60000,
sim_rate=5.0,
log_level="INFO",
)
Environment Interaction
The environment is reset and randomly stepped through.
Future Work: This example will be updated with an actual trained policy in the future.
[12]:
env.reset()
for i in range(4):
env.step(dict(RSO=0, Inspector=env.action_space("Inspector").sample()))
2026-07-28 23:40:08,715 gym INFO Resetting environment with seed=828915284
2026-07-28 23:40:08,792 utils.orbital WARNING <0.00> Could not find eclipse transitions in next 12000.0 seconds
2026-07-28 23:40:08,792 gym INFO <0.00> Environment reset
/opt/hostedtoolcache/Python/3.11.15/x64/lib/python3.11/site-packages/gymnasium/spaces/box.py:130: UserWarning: WARN: Box bound precision lowered by casting to float32
gym.logger.warn(f"Box bound precision lowered by casting to {self.dtype}")
2026-07-28 23:40:08,794 gym INFO <0.00> === STARTING STEP ===
2026-07-28 23:40:08,795 sats.satellite.RSO INFO <0.00> RSO: action_nadir_point tasked for 1000000000.0 seconds
2026-07-28 23:40:08,795 sats.satellite.RSO INFO <0.00> RSO: setting timed terminal event at 1000000000.0
2026-07-28 23:40:08,796 sats.satellite.Inspector INFO <0.00> Inspector: Thrusting with inertial dV [0.55110597 0.33915596 0.075077 ] with 6759.79248046875 second drift.
2026-07-28 23:40:08,797 sats.satellite.Inspector INFO <0.00> Inspector: setting timed terminal event at 6759.8
2026-07-28 23:40:08,798 sats.satellite.Inspector INFO <0.00> Inspector: FSW action action_inspect_rso activated.
2026-07-28 23:40:08,831 sats.satellite.Inspector INFO <1010.00> Inspector: Exceeded maximum range of 1000 m from RSO
2026-07-28 23:40:08,835 data.rso_inspection INFO <1010.00> Inspected/Illuminated/Total: 0/51/100
2026-07-28 23:40:08,835 data.composition INFO <1010.00> ResourceReward reward: {'Inspector': np.float64(-0.012910321995891332)}
2026-07-28 23:40:08,836 data.base INFO <1010.00> Total reward: {'Inspector': np.float64(-0.012910321995891332)}
2026-07-28 23:40:08,836 sats.satellite.Inspector WARNING <1010.00> Inspector: failed range_valid check
2026-07-28 23:40:08,839 utils.orbital WARNING <1010.00> Could not find eclipse transitions in next 12000.0 seconds
2026-07-28 23:40:08,840 gym INFO <1010.00> Step reward: {'Inspector': np.float64(-1.0129103219958913)}
2026-07-28 23:40:08,841 gym INFO <1010.00> Episode terminated: ['Inspector']
2026-07-28 23:40:08,841 gym INFO <1010.00> === STARTING STEP ===
2026-07-28 23:40:08,842 sats.satellite.RSO INFO <1010.00> RSO: action_nadir_point tasked for 1000000000.0 seconds
2026-07-28 23:40:08,842 sats.satellite.RSO INFO <1010.00> RSO: setting timed terminal event at 1000001010.0
2026-07-28 23:40:08,843 sats.satellite.Inspector INFO <1010.00> Inspector: Thrust clamped from 1.2469069250757125 m/s to 1.0 m/s.
2026-07-28 23:40:08,844 sats.satellite.Inspector INFO <1010.00> Inspector: Thrusting with inertial dV [-0.28996613 0.57683883 0.76366 ] with 7897.4306640625 second drift.
2026-07-28 23:40:08,844 sats.satellite.Inspector INFO <1010.00> Inspector: setting timed terminal event at 8907.4
2026-07-28 23:40:08,845 sats.satellite.Inspector INFO <1010.00> Inspector: FSW action action_inspect_rso activated.
2026-07-28 23:40:09,102 sats.satellite.Inspector INFO <8910.00> Inspector: timed termination at 8907.4
2026-07-28 23:40:09,121 data.rso_inspection INFO <8910.00> Inspected/Illuminated/Total: 0/62/100
2026-07-28 23:40:09,121 data.composition INFO <8910.00> ResourceReward reward: {'Inspector': np.float64(-0.01981796474212577)}
2026-07-28 23:40:09,122 data.base INFO <8910.00> Total reward: {'Inspector': np.float64(-0.01981796474212577)}
2026-07-28 23:40:09,122 sats.satellite.Inspector INFO <8910.00> Inspector: Satellite Inspector requires retasking
2026-07-28 23:40:09,123 gym INFO <8910.00> Step reward: {}
2026-07-28 23:40:09,124 gym INFO <8910.00> === STARTING STEP ===
2026-07-28 23:40:09,125 sats.satellite.RSO INFO <8910.00> RSO: action_nadir_point tasked for 1000000000.0 seconds
2026-07-28 23:40:09,125 sats.satellite.RSO INFO <8910.00> RSO: setting timed terminal event at 1000008910.0
2026-07-28 23:40:09,126 sats.satellite.Inspector INFO <8910.00> Inspector: Thrusting with inertial dV [0.17603763 0.24890257 0.33606817] with 5359.3623046875 second drift.
2026-07-28 23:40:09,127 sats.satellite.Inspector INFO <8910.00> Inspector: setting timed terminal event at 14269.4
2026-07-28 23:40:09,128 sats.satellite.Inspector INFO <8910.00> Inspector: FSW action action_inspect_rso activated.
2026-07-28 23:40:09,288 sats.satellite.Inspector INFO <14270.00> Inspector: timed termination at 14269.4
2026-07-28 23:40:09,300 data.rso_inspection INFO <14270.00> Inspected/Illuminated/Total: 0/63/100
2026-07-28 23:40:09,300 data.composition INFO <14270.00> ResourceReward reward: {'Inspector': np.float64(-0.008992281193802926)}
2026-07-28 23:40:09,301 data.base INFO <14270.00> Total reward: {'Inspector': np.float64(-0.008992281193802926)}
2026-07-28 23:40:09,302 sats.satellite.Inspector INFO <14270.00> Inspector: Satellite Inspector requires retasking
2026-07-28 23:40:09,302 gym INFO <14270.00> Step reward: {}
2026-07-28 23:40:09,303 gym INFO <14270.00> === STARTING STEP ===
2026-07-28 23:40:09,304 sats.satellite.RSO INFO <14270.00> RSO: action_nadir_point tasked for 1000000000.0 seconds
2026-07-28 23:40:09,305 sats.satellite.RSO INFO <14270.00> RSO: setting timed terminal event at 1000014270.0
2026-07-28 23:40:09,305 sats.satellite.Inspector INFO <14270.00> Inspector: Thrusting with inertial dV [ 0.37613924 -0.68935279 0.44739626] with 9166.5322265625 second drift.
2026-07-28 23:40:09,306 sats.satellite.Inspector INFO <14270.00> Inspector: setting timed terminal event at 23436.5
2026-07-28 23:40:09,307 sats.satellite.Inspector INFO <14270.00> Inspector: FSW action action_inspect_rso activated.
2026-07-28 23:40:09,620 sats.satellite.Inspector INFO <23440.00> Inspector: timed termination at 23436.5
2026-07-28 23:40:09,636 data.rso_inspection INFO <23440.00> Inspected/Illuminated/Total: 0/63/100
2026-07-28 23:40:09,637 data.composition INFO <23440.00> ResourceReward reward: {'Inspector': np.float64(-0.017911443376466583)}
2026-07-28 23:40:09,637 data.base INFO <23440.00> Total reward: {'Inspector': np.float64(-0.017911443376466583)}
2026-07-28 23:40:09,638 sats.satellite.Inspector INFO <23440.00> Inspector: Satellite Inspector requires retasking
2026-07-28 23:40:09,639 gym INFO <23440.00> Step reward: {}