def __init__(
self,
body: Body,
periapsis: Quantity,
energy: Quantity,
rot: Optional[Quaternion] = None,
):
assert periapsis.has_units(METERS)
assert energy.has_units(METERS**2 / SECS**2)
# For a periapsis P, not all energies are allowed. The smallest allowed
# energy is a circular orbit. From E we can find the semimajor axis
# so we can tell whether the apsis we have is the peri- or apo-apsis.
# We only have to worry about this when the orbit is elliptical.
if energy.value < 0:
sma = -body.mu / 2 / energy
if periapsis > sma:
periapsis = 2 * sma - periapsis
self.body = body
self.periapsis = periapsis
self.energy = energy
self.rot = rot or Quaternion(1, 0, 0, 0)
def adjust_height(self, distance: Quantity, sea_level: bool = True) -> Quantity:
assert distance.has_units(METERS)
if sea_level:
return distance + self.radius
return distance
def escape_velocity(self, r: Quantity) -> Quantity:
assert r.has_units(METERS)
return (2 * self.mu / r).root(2)
def __init__(self, mu: Quantity, radius: Quantity):
assert mu.has_units(_MU_UNITS)
assert radius.has_units(METERS)
self.mu = mu
self.radius = radius