  We report an up-turn in the soft X-ray light curve of supernova remnant (SNR)
1987A in late 2003 (~6200 days after the explosion), as observed with the
Chandra X-ray Observatory. Since early 2004, the rapid increase of the 0.5-2
keV band X-ray light curve can no longer be described by the exponential
density distribution model with which we successfully fitted the data between
1990 and 2003. Around day ~6200, we also find that the fractional contribution
to the observed soft X-ray flux from the decelerated shock begins to exceed
that of the fast shock and that the X-ray brightening becomes "global" rather
than "spotty". We interpret these results as evidence that the blast wave has
reached the main body of the dense circumstellar material all around the inner
ring. This interpretation is supported by other recent observations, including
a deceleration of the radial expansion of the X-ray remnant, a significant
up-turn in the mid-IR intensities, and the prevalence of the optical hot spots
around the entire inner ring, all of which occur at around day 6000. In
contrast to the soft X-ray light curve, the hard band (3-10 keV) X-ray light
curve increases at a much lower rate which is rather similar to the radio light
curve. The hard X-ray emission may thus originate from the reverse shock where
the radio emission is likely produced. Alternatively, the low increase rate of
the hard X-rays may simply be a result of the continuous softening of the
overall X-ray spectrum.
