BRRISON Observations of Comet ISON

The BRRISON mission will fly a stratospheric balloon-borne platform from Fort Sumner, NM to measure CO2 and H20 emissions at 4.3 micron and 2.7 micron, respectively from Comet ISON. If the flight duration reaches at least 18 hours, which will depend on upper level wind conditions, BRRISON will observe both ISON and the Jupiter Family comet 2P/Encke. BRRISON will carry a near-IR camera imaging in 8 near-IR filter passbands between 2.5 and 5 microns, with an additional filter for imaging in R band. ISON is an Oort Cloud comet, which preserves icy materials which have never been heated by passage through the inner solar system. As an Oort Cloud comet, it may have formed from different materials and under different conditions than Kuiper Belt comets, and particularly the Jupiter Family comets whose orbits have evolved to make repeated passes through the inner solar system. Comet Encke is a highly evolved member of the latter population with a perihelion of only 0.33 AU, inside the orbit of Mercury. Comparing the compositions of the Oort Cloud comet ISON, versus the evolved Kuiper Belt comet Encke, will help us to understand diverse cometary origins and dynamical histories. BRRISON observations may also help us understand whether and how comets formed in different regions of the early solar system may differ, and how key volatiles, including water and CO2, were distributed in the solar nebula. I will present initial results of BRRISON comet observations.