Supernovae are powered by the radioactive decay of Ni56. The
 mass of Ni56, which is short lived (tau 8.8d) is almost impossible
 to measure directly. However by studying the daughter products of
 the decay we can pin down the energetics of the explosion. The
 experiments proposed here aim to use the density and temperature
 insensitive mid IR lines of the iron group elements to determine
 the mass of Ni56. We wish to study the stages of explosive
 burning occuring further out in the progenitor star by measuring the
 abundances of Argon. Only ISO can perform these
 experiments since the lines are inaccessible  from the ground. The
 abundances of these elements directly test the explosion models for
 supernovae. The evolution of these lines tests spectral synthesis
 models which are currently being used to interpret the spectra of
 supernovae. A further experiment is planned to look for
 emission from dust in the ejecta. The epoch of dust formation and
 the temperature of the dust probe the chemistry and physical
 conditions of the supernova. We plan to observe 2 nearby
 supernovae of types Ib and IIb  which have been well studied
 from the ground and HST. The ISO observations are critical to
 our understanding of these objects and will probe a regime of
 astrophysics which to date has only been explored for SN1987A. In
 addition we plan to observe a type Ia supernova to determine the
 mass of iron and test for the ir catastrophe scenario.

 As the studies of SN1987A have shown supernovae a few hundred days
 after explosion change from objects best studied in the optical
 to infrared objects. The ISO observations proposed here
 will directly test theoretical models and probe supernovae at
 the wavelengths at which they are most interesting.