Massachusetts Institute of Technology
Planetary Observations in the Near IR
SOFIA currently has an instrumentation gap in the NIR with no active instruments being sensitive in the wavelength regime just beyond a micron. Here, we present a number of science cases that would argue in favor of improving the NIR capabilities of the observatory for aid in these planetary observations both in our solar system and beyond. Historically, airborne astronomy has been at the forefront of planetary observation, combining the infrared wavelengths available to a high-altitude observer with the flexible mobility of the platform. These strengths are clearly capitalized upon in stellar occultation observations, a regime where the visible and NIR capabilities of the instrumentation have proven more important than the far infrared, and mobility is key to being well placed in the shadow path. Inside the solar system, stellar occultations are employed for a variety of scientific goals, including characterizing the atmospheres of distant bodies, measuring the sizes of Trans-Neptunian objects (which can constrain albedos, shapes, and densities), and even discovering new atmospheres, rings, and satellites around minor planets. Combining visible-wavelength with NIR observations is a particularly powerful tool to study tenuous atmospheres and dusty surroundings of TNOs, Centaurs, comets, and active asteroids. These observations are sensitive to particles on the order of the observational wavelengths: micron-sized and smaller ring particles, atmospheric haze, and dusty comae can be detected through comparisons in flux versus wavelength at the NIR scale. Rings around Centaurs, regularly-outgassing Centaurs, and active asteroids are relatively new topics of study, and multiple observations would greatly contribute towards our understanding of the time-varying evolution of these objects and the dust environments they create. Beyond our sun, extrasolar planetary observations would be aided by the capability to do simultaneous observations of transits or eclipses in multiple wavelengths, which would allow a measurement of the planetary albedo. Two observations of an ultra-hot-Jupiter, spaced tens of days apart, could demonstrate variability in the planet phase curve, which would give insight into the planet's magnetic field.