  NGC 6302 (The ''Butterfly Nebula'') is an extremely energetic bipolar nebula
whose central star is among the most massive, hottest, and presumably rapidly
evolving of all central stars of planetary nebulae. Our proper-motion study of
NGC 6302, based on excellent HST WFC3 images spanning 11 yr, has uncovered at
least four different pairs of expanding internal lobes that were ejected at
various times over the past two millennia at speeds ranging from 10 to 600 km
s^-1. In addition, we find a pair of off-axis flows in constant motion at 760
+/- 100 km s^-1 within which bright [Fe II] feathers are conspicuous. Combining
our results with those previously published, we find that the ensemble of flows
has an ionized mass > 0.1 M_sun. The kinetic energy of the ensemble, 10^46 -
10^48 ergs, lies at the upper end of gravity-powered processes such as stellar
mergers or mass accretion and is too large to be explained by stellar radiation
pressure or convective ejections. The structure and dynamics of the Butterfly
Nebula suggests that its central engine has had a remarkable history, and the
highly unusual patterns of growth within its wings challenge our current
understanding of late stellar mass ejection.
