  We present interferometric observations of $^{12}$CO and $^{13}$CO $J$=2$-$1
emission from the butterfly-shaped, young planetary nebula NGC 6302. The high
angular resolution and high sensitivity achieved in our observations allow us
to resolve the nebula into two distinct kinematic components: (1) a massive
expanding torus seen almost edge-on and oriented in the North-South direction,
roughly perpendicular to the optical nebula axis. The torus exhibits very
complex and fragmentated structure; (2) high velocity molecular knots moving at
high velocity, higher than 20 \kms, and located in the optical bipolar lobes.
These knots show a linear position-velocity gradient (Hubble-like flow), which
is characteristic of fast molecular outflow in young planetary nebulae. From
the low but variable $^{12}$CO/$^{13}$CO $J$=2$-$1 line intensity ratio we
conclude that the $^{12}$CO $J$=2$-$1 emission is optically thick over much of
the nebula. Using the optically thinner line $^{13}$CO $J$=2$-$1 we estimate a
total molecular gas mass of $\sim$ 0.1 M$_\odot$, comparable to the ionized gas
mass; the total gas mass of the NGC 6302 nebula, including the massive ionized
gas from photon dominated region, is found to be $\sim$ 0.5 M$_\odot$. From
radiative transfer modelling we infer that the torus is seen at inclination
angle of 75$^\circ$ with respect to the plane of the sky and expanding at
velocity of 15 \kms. Comparison with recent observations of molecular gas in
NGC 6302 is also discussed.

Astrophysics