  Balloon-borne telescopes present unique thermal design challenges which are a
combination of those present for both space and ground telescopes. At altitudes
of 35-40 km, convection effects are minimal and difficult to characterize.
Radiation and conduction are the predominant heat transfer mechanisms reducing
the thermal design options. For long duration flights payload mass is a
function of power consumption making it an important optimization parameter.
SuperBIT, or the Super-pressure Balloon-borne Imaging Telescope, aims to study
weak lensing using a 0.5m modified Dall-Kirkham telescope capable of achieving
0.02" stability and capturing deep exposures from visible to near UV
wavelengths. To achieve the theoretical stratospheric diffraction-limited
resolution of 0.25", mirror deformation gradients must be kept to within 20nm.
The thermal environment must thus be stable on time scales of an hour and the
thermal gradients must be minimized on the telescope. SuperBIT plans to
implement two types of parameter solvers; one to validate the thermal design
and the other to tightly control the thermal environment.
