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 importlib.metadata import version
from bsk_rl import sats, obs, act, ConstellationTasking, scene, data
from bsk_rl.obs.relative_observations import rso_imaged_regions
from bsk_rl.utils.orbital import fibonacci_sphere
from bsk_rl.sim import dyn, fsw
import types
import numpy as np
from Basilisk.architecture import bskLogging
from functools import partial
from bsk_rl.utils.orbital import random_orbit, random_unit_vector, relative_to_chief
from Basilisk.utilities.orbitalMotion import elem2rv
from Basilisk.utilities.RigidBodyKinematics import C2MRP
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. It is given support for nadir pointing through the ImagingDynModel and Downlink action.
[3]:
class RSOSat(sats.Satellite):
observation_spec = [
obs.SatProperties(dict(prop="one", fn=lambda _: 1.0)),
]
action_spec = [act.Downlink(duration=1e9)]
dyn_type = types.new_class(
"Dyn", (dyn.ImagingDynModel, dyn.ConjunctionDynModel, dyn.RSODynModel)
)
fsw_type = fsw.ContinuousImagingFSWModel
Arguments for the satellite are configured for smooth pointing behavior.
[4]:
rso_sat_args = dict(
conjunction_radius=2.0,
K=7.0 / 20,
P=35.0 / 20,
Ki=1e-6,
dragCoeff=0.0,
batteryStorageCapacity=1e9,
storedCharge_Init=1e9,
wheelSpeeds=[0.0, 0.0, 0.0],
u_max=1.0,
)
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 = [
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 = [
act.ImpulsiveThrustHill(
chief_name="RSO",
max_dv=1.0,
max_drift_duration=5700.0 * 2,
fsw_action="action_inspect_rso",
)
]
dyn_type = types.new_class(
"Dyn",
(
dyn.MaxRangeDynModel,
dyn.ConjunctionDynModel,
dyn.RSOInspectorDynModel,
),
)
fsw_type = types.new_class(
"FSW",
(
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 = [satellite for satellite in satellites if satellite.name == "RSO"][0]
# 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()))
2025-07-24 00:12:42,354 gym INFO Resetting environment with seed=187026680
2025-07-24 00:12:42,509 gym INFO <0.00> Environment reset
/opt/hostedtoolcache/Python/3.11.13/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}")
2025-07-24 00:12:42,511 gym INFO <0.00> === STARTING STEP ===
2025-07-24 00:12:42,512 sats.satellite.RSO INFO <0.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-07-24 00:12:42,512 sats.satellite.RSO INFO <0.00> RSO: setting timed terminal event at 1000000000.0
2025-07-24 00:12:42,514 sats.satellite.Inspector INFO <0.00> Inspector: Thrusting with inertial dV [-0.30079654 -0.70043422 -0.37597991] with 10717.314453125 second drift.
2025-07-24 00:12:42,515 sats.satellite.Inspector INFO <0.00> Inspector: setting timed terminal event at 10717.3
2025-07-24 00:12:42,516 sats.satellite.Inspector INFO <0.00> Inspector: FSW action action_inspect_rso activated.
2025-07-24 00:12:42,543 sats.satellite.Inspector INFO <525.00> Inspector: Exceeded maximum range of 1000 m from RSO
2025-07-24 00:12:42,564 data.rso_inspection INFO <525.00> Inspected/Illuminated/Total: 0/27/100
2025-07-24 00:12:42,565 data.composition INFO <525.00> ResourceReward reward: {'Inspector': np.float64(-0.3610591490192903)}
2025-07-24 00:12:42,566 data.base INFO <525.00> Total reward: {'Inspector': np.float64(-0.3610591490192903)}
2025-07-24 00:12:42,567 sats.satellite.Inspector WARNING <525.00> Inspector: failed range_valid check
2025-07-24 00:12:42,580 gym INFO <525.00> Step reward: {'Inspector': np.float64(-1.3610591490192903)}
2025-07-24 00:12:42,580 gym INFO <525.00> Episode terminated: ['Inspector']
2025-07-24 00:12:42,581 gym INFO <525.00> === STARTING STEP ===
2025-07-24 00:12:42,583 sats.satellite.RSO INFO <525.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-07-24 00:12:42,583 sats.satellite.RSO INFO <525.00> RSO: setting timed terminal event at 1000000525.0
2025-07-24 00:12:42,584 sats.satellite.Inspector INFO <525.00> Inspector: Thrusting with inertial dV [-0.68692512 -0.40316618 0.59466472] with 10512.1982421875 second drift.
2025-07-24 00:12:42,585 sats.satellite.Inspector INFO <525.00> Inspector: setting timed terminal event at 11037.2
2025-07-24 00:12:42,586 sats.satellite.Inspector INFO <525.00> Inspector: FSW action action_inspect_rso activated.
2025-07-24 00:12:43,034 sats.satellite.Inspector INFO <11040.00> Inspector: timed termination at 11037.2
2025-07-24 00:12:43,511 data.rso_inspection INFO <11040.00> Inspected/Illuminated/Total: 0/81/100
2025-07-24 00:12:43,511 data.composition INFO <11040.00> ResourceReward reward: {'Inspector': np.float64(-0.42224197702639493)}
2025-07-24 00:12:43,512 data.base INFO <11040.00> Total reward: {'Inspector': np.float64(-0.42224197702639493)}
2025-07-24 00:12:43,513 sats.satellite.Inspector INFO <11040.00> Inspector: Satellite Inspector requires retasking
2025-07-24 00:12:43,515 gym INFO <11040.00> Step reward: {}
2025-07-24 00:12:43,516 gym INFO <11040.00> === STARTING STEP ===
2025-07-24 00:12:43,517 sats.satellite.RSO INFO <11040.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-07-24 00:12:43,518 sats.satellite.RSO INFO <11040.00> RSO: setting timed terminal event at 1000011040.0
2025-07-24 00:12:43,519 sats.satellite.Inspector INFO <11040.00> Inspector: Thrusting with inertial dV [ 0.69110496 -0.09386644 0.00221498] with 3998.128173828125 second drift.
2025-07-24 00:12:43,520 sats.satellite.Inspector INFO <11040.00> Inspector: setting timed terminal event at 15038.1
2025-07-24 00:12:43,520 sats.satellite.Inspector INFO <11040.00> Inspector: FSW action action_inspect_rso activated.
2025-07-24 00:12:43,683 sats.satellite.Inspector INFO <15040.00> Inspector: timed termination at 15038.1
2025-07-24 00:12:43,834 data.rso_inspection INFO <15040.00> Inspected/Illuminated/Total: 0/81/100
2025-07-24 00:12:43,835 data.composition INFO <15040.00> ResourceReward reward: {'Inspector': np.float64(-0.2962720419046197)}
2025-07-24 00:12:43,836 data.base INFO <15040.00> Total reward: {'Inspector': np.float64(-0.2962720419046197)}
2025-07-24 00:12:43,836 sats.satellite.Inspector INFO <15040.00> Inspector: Satellite Inspector requires retasking
2025-07-24 00:12:43,838 gym INFO <15040.00> Step reward: {}
2025-07-24 00:12:43,839 gym INFO <15040.00> === STARTING STEP ===
2025-07-24 00:12:43,840 sats.satellite.RSO INFO <15040.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-07-24 00:12:43,840 sats.satellite.RSO INFO <15040.00> RSO: setting timed terminal event at 1000015040.0
2025-07-24 00:12:43,841 sats.satellite.Inspector INFO <15040.00> Inspector: Thrusting with inertial dV [ 0.73060892 0.51445723 -0.1558575 ] with 8292.328125 second drift.
2025-07-24 00:12:43,842 sats.satellite.Inspector INFO <15040.00> Inspector: setting timed terminal event at 23332.3
2025-07-24 00:12:43,844 sats.satellite.Inspector INFO <15040.00> Inspector: FSW action action_inspect_rso activated.
2025-07-24 00:12:44,179 sats.satellite.Inspector INFO <23335.00> Inspector: timed termination at 23332.3
2025-07-24 00:12:44,575 data.rso_inspection INFO <23335.00> Inspected/Illuminated/Total: 0/81/100
2025-07-24 00:12:44,576 data.composition INFO <23335.00> ResourceReward reward: {'Inspector': np.float64(-0.38530832881469984)}
2025-07-24 00:12:44,577 data.base INFO <23335.00> Total reward: {'Inspector': np.float64(-0.38530832881469984)}
2025-07-24 00:12:44,578 sats.satellite.Inspector INFO <23335.00> Inspector: Satellite Inspector requires retasking
2025-07-24 00:12:44,580 gym INFO <23335.00> Step reward: {}