Dust and gas contributions to the energy output of SN 1987A on day 1153

We present 16-30 micron spectra of SN 1987A taken with the Kuiper Airborne Observatory on 1990 April 20 and 22, days 1152 and 1154 after core collapse. The spectrum is characterized by a flat continuum of 0.62 +/- 0.65 Jy, and a strong line at ~26 microns which we attribute to the [Fe II] 25.98 micron transition. The observations are used to derive the mass of radiating Fe II in the ejecta, the mass and temperature of the dust that gives rise to the continuum emission, and combined with optical and near infrared observations, the total bolometric luminosity of the supernova. The latter quantity constrains the contribution of the radioactive elements ^57^Co and ^44^Ti to the late-time energy output from the supernova. Specifically, we find that the observed luminosity requires that the ^57^Co/^56^Co mass production rate be enhanced by a factor of (4.5 +/- 1.6) compared to its solar value, if 10^-4^ M_sun_ of ^44^Ti were produced in the ejecta. Such overproduction could be inferred from observations of the 122 keV decay line of ^57^Co with the OSSE instrument on board the Gamma Ray Observatory. However, this overproduction factor for ^57^Co represents an upper limit, since other sources, including an infrared echo, may be contributing to the observed luminosity from the supernova.