  We present new proper motion measurements of optically emitting oxygen-rich
knots of supernova remnant 1E 0102.2-7219 (E0102), which are used to estimate
the remnant's center of expansion and age. Four epochs of high resolution
Hubble Space Telescope images spanning 19 yr were retrieved and analyzed. We
found a robust center of expansion of alpha=1:04:02.48 and delta=-72:01:53.92
(J2000) with 1-sigma uncertainty of 1.77 arcseconds using 45 knots from images
obtained with the Advanced Camera for Surveys using the F475W filter in 2003
and 2013 having the highest signal-to-noise ratio. We also estimate an upper
limit explosion age of 1738 +/- 175 yr by selecting knots with the highest
proper motions, that are assumed to be the least decelerated. We find evidence
of an asymmetry in the proper motions of the knots as a function of position
angle. We conclude that these asymmetries were most likely caused by
interaction between E0102's original supernova blast wave and an inhomogeneous
surrounding environment, as opposed to intrinsic explosion asymmetry. The
observed non-homologous expansion suggests that the use of a free expansion
model inaccurately offsets the center of expansion and leads to an
overestimated explosion age. We discuss our findings as they compare to
previous age and center of expansion estimates of E0102 and their relevance to
a recently identified candidate central compact object.
