Use new serialization method for Propagator in adam-core

* Uses new serialization in adam-core

---------

Co-authored-by: Joachim Moeyens <moeyensj@gmail.com>

pyproject.toml

@@ -17,7 +17,7 @@ classifiers = [
     "Programming Language :: Python :: 3",
     "Topic :: Scientific/Engineering :: Astronomy"
 ]
-requires-python = ">=3.10,<4.0"
+requires-python = ">=3.11,<3.13"
 dependencies = [
     "adam-core>=0.2.5",
     "naif-de440",
@@ -57,7 +57,7 @@ dev = [
     "pytest-benchmark",
     "black",
     "isort",
-    "ipython"
+    "ipython",
 ]
 
 [tool.pdm.scripts]

src/adam_assist/propagator.py

@@ -81,6 +81,14 @@ def __init__(
         self.adaptive_mode = adaptive_mode
         self.epsilon = epsilon
 
+    def __getstate__(self):
+        state = self.__dict__.copy()
+        state.pop("_last_simulation", None)
+        return state
+
+    def __setstate__(self, state):
+        self.__dict__.update(state)
+
     def _propagate_orbits(self, orbits: OrbitType, times: TimestampType) -> OrbitType:
         """
         Propagate the orbits to the specified times.

tests/test_propagate.py

@@ -5,6 +5,7 @@
 from adam_core.coordinates import CartesianCoordinates, Origin
 from adam_core.coordinates.residuals import Residuals
 from adam_core.orbits import Orbits
+from adam_core.orbits.query import query_sbdb
 from adam_core.orbits.query.horizons import query_horizons
 from adam_core.time import Timestamp
 from astropy import units as u
@@ -208,4 +209,23 @@ def test_propagate_different_input_times(mocker):
     assert watched_propagate_orbits_inner.call_count == 2, "Inner function should be called once for each unique input epoch"
 
     assert len(propagated_orbits.coordinates.time.unique()) == 2
-    assert len(propagated_orbits) == 8, "Should have input orbits x epochs number of results"
+    assert len(propagated_orbits) == 8, "Should have input orbits x epochs number of results"
+
+
+def test_back_to_back_propagations():
+    """
+    Ensure that back-to-back multiprocessed propagations work. This test should 
+    fail at the moment since the ray remote cannot initialize a propagator object with an already
+    defined simulation.
+
+    """
+    prop = ASSISTPropagator()
+    orbits = query_sbdb(["2013 RR165"])
+
+    time = Timestamp.from_mjd([60000], scale="tdb")
+    first_prop = prop.propagate_orbits(orbits, time, max_processes=1)
+
+    # Propagator has to be pickleable, which uses __getstate__ and __setstate__
+    # This doesn't work if _last_simulation is in the state
+    first_dict = prop.__getstate__()
+    second_prop = ASSISTPropagator(**first_dict)