def __init__(self, state, status = SAT_ST["On"], spec = None, instruments=None, epoch=J2000 ): """Constructor. Parameters ---------- state : ~poliastro.twobody.states.ClassicalState State for satellite orbit status : string, optional SAT_STATUS string spec : ~Ctlldes.core.spec specifications epoch : ~astropy.time.Time, optional Epoch, default to J2000. instruments : list, optional List of Instrument objects """ self.state = state self.status = status self.spec = spec if spec else Specifications() self._epoch = epoch if not instruments: self.instruments = [] elif not isinstance(instruments,list): self.instruments = [instruments] else: self.instruments = instruments self._id = uuid.uuid4() self._orbit = Orbit(state,epoch) self._Propagator = Propagator(self.orbit)