The original stated motivation for building BLAST was:
BLAST, or the “Balloon-borne Large-Aperture Sub-millimeter Telescope,” will fly from a Long Duration Balloon (LDB) platform and incorporate a 2-meter primary mirror with large-format bolometer arrays operating at 250, 350, and 500 μm. By providing the first sensitive large-area (~0.5-40 deg²) submillimeter surveys at these wavelengths, BLAST will address some of the most important cosmological and Galactic questions regarding the formation and evolution of stars, galaxies and clusters.

BLAST's primary goals are to:

• Measure photometric redshifts, rest-frame FIR luminosities and star formation rates of high-redshift starburst galaxies, thereby constraining the evolutionary history of those galaxies that produce the FIR/submillimeter background
• Measure cold pre-stellar sources associated with the earliest stages of star and planet formation
• Make high-resolution maps of diffuse galactic emission over a wide range of galactic latitudes

Through its 2 science flights, BLAST has succeeded in all of these goals!