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()))
2025-11-05 22:49:46,622 gym INFO Resetting environment with seed=601141186
2025-11-05 22:49:46,767 gym INFO <0.00> Environment reset
/opt/hostedtoolcache/Python/3.11.14/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}")
2025-11-05 22:49:46,769 gym INFO <0.00> === STARTING STEP ===
2025-11-05 22:49:46,770 sats.satellite.RSO INFO <0.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-11-05 22:49:46,770 sats.satellite.RSO INFO <0.00> RSO: setting timed terminal event at 1000000000.0
2025-11-05 22:49:46,772 sats.satellite.Inspector INFO <0.00> Inspector: Thrusting with inertial dV [-0.13731725 -0.28502491 -0.14717804] with 141.06459045410156 second drift.
2025-11-05 22:49:46,773 sats.satellite.Inspector INFO <0.00> Inspector: setting timed terminal event at 141.1
2025-11-05 22:49:46,774 sats.satellite.Inspector INFO <0.00> Inspector: FSW action action_inspect_rso activated.
2025-11-05 22:49:46,782 sats.satellite.Inspector INFO <145.00> Inspector: timed termination at 141.1
2025-11-05 22:49:46,784 data.rso_inspection INFO <145.00> Inspected/Illuminated/Total: 0/27/100
2025-11-05 22:49:46,784 data.composition INFO <145.00> ResourceReward reward: {'Inspector': np.float64(-0.13396551287992484)}
2025-11-05 22:49:46,785 data.base INFO <145.00> Total reward: {'Inspector': np.float64(-0.13396551287992484)}
2025-11-05 22:49:46,786 sats.satellite.Inspector INFO <145.00> Inspector: Satellite Inspector requires retasking
2025-11-05 22:49:46,791 gym INFO <145.00> Step reward: {'Inspector': np.float64(-0.13396551287992484)}
2025-11-05 22:49:46,791 gym INFO <145.00> === STARTING STEP ===
2025-11-05 22:49:46,792 sats.satellite.RSO INFO <145.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-11-05 22:49:46,793 sats.satellite.RSO INFO <145.00> RSO: setting timed terminal event at 1000000145.0
2025-11-05 22:49:46,794 sats.satellite.Inspector INFO <145.00> Inspector: Thrust clamped from 1.0620913571401422 m/s to 1.0 m/s.
2025-11-05 22:49:46,795 sats.satellite.Inspector INFO <145.00> Inspector: Thrusting with inertial dV [ 0.31088206 0.69576574 -0.64750473] with 1230.985107421875 second drift.
2025-11-05 22:49:46,796 sats.satellite.Inspector INFO <145.00> Inspector: setting timed terminal event at 1376.0
2025-11-05 22:49:46,796 sats.satellite.Inspector INFO <145.00> Inspector: FSW action action_inspect_rso activated.
2025-11-05 22:49:46,821 sats.satellite.Inspector INFO <650.00> Inspector: Exceeded maximum range of 1000 m from RSO
2025-11-05 22:49:46,824 data.rso_inspection INFO <650.00> Inspected/Illuminated/Total: 0/29/100
2025-11-05 22:49:46,824 data.composition INFO <650.00> ResourceReward reward: {'Inspector': np.float64(-0.3839253137326725)}
2025-11-05 22:49:46,825 data.base INFO <650.00> Total reward: {'Inspector': np.float64(-0.3839253137326725)}
2025-11-05 22:49:46,826 sats.satellite.Inspector WARNING <650.00> Inspector: failed range_valid check
2025-11-05 22:49:46,830 gym INFO <650.00> Step reward: {'Inspector': np.float64(-1.3839253137326726)}
2025-11-05 22:49:46,831 gym INFO <650.00> Episode terminated: ['Inspector']
2025-11-05 22:49:46,831 gym INFO <650.00> === STARTING STEP ===
2025-11-05 22:49:46,832 sats.satellite.RSO INFO <650.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-11-05 22:49:46,833 sats.satellite.RSO INFO <650.00> RSO: setting timed terminal event at 1000000650.0
2025-11-05 22:49:46,834 sats.satellite.Inspector INFO <650.00> Inspector: Thrust clamped from 1.02058311288579 m/s to 1.0 m/s.
2025-11-05 22:49:46,835 sats.satellite.Inspector INFO <650.00> Inspector: Thrusting with inertial dV [-0.14700785 -0.98855703 -0.03381851] with 8947.404296875 second drift.
2025-11-05 22:49:46,835 sats.satellite.Inspector INFO <650.00> Inspector: setting timed terminal event at 9597.4
2025-11-05 22:49:46,836 sats.satellite.Inspector INFO <650.00> Inspector: FSW action action_inspect_rso activated.
2025-11-05 22:49:47,241 sats.satellite.Inspector INFO <9600.00> Inspector: timed termination at 9597.4
2025-11-05 22:49:47,255 data.rso_inspection INFO <9600.00> Inspected/Illuminated/Total: 0/51/100
2025-11-05 22:49:47,255 data.composition INFO <9600.00> ResourceReward reward: {'Inspector': np.float64(-0.3839253137326725)}
2025-11-05 22:49:47,256 data.base INFO <9600.00> Total reward: {'Inspector': np.float64(-0.3839253137326725)}
2025-11-05 22:49:47,257 sats.satellite.Inspector INFO <9600.00> Inspector: Satellite Inspector requires retasking
2025-11-05 22:49:47,259 gym INFO <9600.00> Step reward: {}
2025-11-05 22:49:47,259 gym INFO <9600.00> === STARTING STEP ===
2025-11-05 22:49:47,260 sats.satellite.RSO INFO <9600.00> RSO: action_downlink tasked for 1000000000.0 seconds
2025-11-05 22:49:47,261 sats.satellite.RSO INFO <9600.00> RSO: setting timed terminal event at 1000009600.0
2025-11-05 22:49:47,262 sats.satellite.Inspector INFO <9600.00> Inspector: Thrust clamped from 1.0963794712887964 m/s to 1.0 m/s.
2025-11-05 22:49:47,262 sats.satellite.Inspector INFO <9600.00> Inspector: Thrusting with inertial dV [0.30389618 0.57381357 0.76051634] with 2841.50341796875 second drift.
2025-11-05 22:49:47,263 sats.satellite.Inspector INFO <9600.00> Inspector: setting timed terminal event at 12441.5
2025-11-05 22:49:47,264 sats.satellite.Inspector INFO <9600.00> Inspector: FSW action action_inspect_rso activated.
2025-11-05 22:49:47,391 sats.satellite.Inspector INFO <12445.00> Inspector: timed termination at 12441.5
2025-11-05 22:49:47,399 data.rso_inspection INFO <12445.00> Inspected/Illuminated/Total: 0/51/100
2025-11-05 22:49:47,400 data.composition INFO <12445.00> ResourceReward reward: {'Inspector': np.float64(-0.3839253137326725)}
2025-11-05 22:49:47,400 data.base INFO <12445.00> Total reward: {'Inspector': np.float64(-0.3839253137326725)}
2025-11-05 22:49:47,401 sats.satellite.Inspector INFO <12445.00> Inspector: Satellite Inspector requires retasking
2025-11-05 22:49:47,403 gym INFO <12445.00> Step reward: {}