The Energy Sources Powering the Late-Time Bolometric Evolution of SN 1987A

New optical and infrared data show that a third radioactive nuclide, ^57^Co, is now powering the supernova nebula. The best fit to the late- time bolometric light curve is with 0.01 M_sun_^57^Co (5 times the amount expected based on the solar ratio of ^57^Fe/^56^Fe). However, if recent theoretical upper limits on the expected production of ^57^Co and ^44^Ti are correct, then either an additional energy input is needed or one of the fundamental assumptions used in the modeling of the data is in error. If a pulsar is present in the center of SN 1987A, it can be providing no more than ~8 x 10^36^ ergs s^-1^ on day 1500.