Development and Alignment of the Thermal InfraRed Composite Imaging Spectrometer (TIRCIS) Instrument
Abstract
Io, Jupiter's third largest moon, is the most volcanically active body in the Solar System. Its dynamic surface, the result of its planet's potent gravity and the pull of nearby moons Europa and Ganymede, makes Io subject to tremendous tidal forces. The Thermal Infra-Red Composite Imaging Spectrometer instrument, or TIRCIS, is developed to map Io's surface temperature. The instrument is designed to make spectral measurements in the mid-infrared from 7-14 µm, with 40 nm spectral resolution as this best identifies the surface composition of silicate bodies such as Io. We will thus be able to determine its thermal properties and map its volcanic deposits to understand the nature of the moon's active volcanism. The surface temperature and emissivity the instrument measures can then be used to constrain various thermophysical properties of the surface, including albedo and thermal inertia which can both be derived through models by taking into account the diurnal variation in surface temperatures. TIRCIS is a modified Offner system, which consists of three spherical and concentric surfaces: two concave mirrors and a convex mirror. Creating an appropriate coordinate system for the breadboard layout, we replaced the convex mirror with a convex grating, which is preferred, as grating spectrometers offer higher dispersion with a compact dispersing element. To replace the mirror, we characterized the grating, including taking images of the surface with the use of an interferometer, as well as established its diffraction orders. A spectrum of the wavefront transmitted through the breadboard was made using an IR-blackbody source.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23531107G