Planetary atmosphere observation analysis

Abstract:

© 2017 Optical Society of America. The Cassini spacecraft orbiting Saturn carries the composite infrared spectrometer (CIRS) designed to study thermal emission from Saturn and its rings and moons. CIRS, a Fourier transform spectrometer, is an indispensable part of the payload providing unique measurements and important synergies with the other instruments. It takes full advantage of Cassini's 13-year-long mission and surpasses the capabilities of previous spectrometers on Voyager 1 and 2. The instrument, consisting of two interferometers sharing a telescope and a scan mechanism, covers over a factor of 100 in wavelength in the mid and far infrared. It is used to study temperature, composition, structure, and dynamics of the atmospheres of Jupiter, Saturn, and Titan, the rings of Saturn, and surfaces of the icy moons. CIRS has returned a large volume of scientific results, the culmination of over 30 years of instrument development, operation, data calibration, and analysis. As Cassini and CIRS reach the end of their mission in 2017, we expect that archived spectra will be used by scientists for many years to come.

Abstract:

We present retrievals of the vertical temperature profile of Jupiter's high latitudes from Infrared Telescope Facility-Texas Echelon Cross Echelle Spectrograph measurements acquired on 10–11 December 2014 and 30 April to 1 May 2016. Over this time range, 1 mbar temperature in Jupiter's northern and southern auroral regions exhibited independent evolution. The northern auroral hot spot exhibited negligible net change in temperature at 1 mbar and its longitudinal position remained fixed at 180°W (System III), whereas the southern auroral hot spot exhibited a net increase in temperature of 11.1 ± 5.2 K at 0.98 mbar and its longitudinal orientation moved west by approximately 30°. This southern auroral stratospheric temperature increase might be related to (1) near-contemporaneous brightening of the southern auroral ultraviolet/near-infrared H + 3 emission measured by the Juno spacecraft and (2) an increase in the solar dynamical pressure in the preceding 3 days. We therefore suggest that 1 mbar temperature in the southern auroral region might be modified by higher-energy charged particle precipitation.

Abstract:

The scientific objectives of the ExoMars rover are designed to answer several key questions in the search for life on Mars. In particular, the unique subsurface drill will address some of these, such as the possible existence and stability of subsurface organics. PanCam will establish the surface geological and morphological context for the mission, working in collaboration with other context instruments. Here, we describe the PanCam scientific objectives in geology, atmospheric science, and 3-D vision. We discuss the design of PanCam, which includes a stereo pair of Wide Angle Cameras (WACs), each of which has an 11-position filter wheel and a High Resolution Camera (HRC) for high-resolution investigations of rock texture at a distance. The cameras and electronics are housed in an optical bench that provides the mechanical interface to the rover mast and a planetary protection barrier. The electronic interface is via the PanCam Interface Unit (PIU), and power conditioning is via a DC-DC converter. PanCam also includes a calibration target mounted on the rover deck for radiometric calibration, fiducial markers for geometric calibration, and a rover inspection mirror. Key Words: Mars-ExoMars-Instrumentation-Geology-Atmosphere-Exobiology-Context. Astrobiology 17, 511-541.

Abstract:

We have measured a precise optical transmission spectrum forWASP-52b, a highly inflated hot Jupiter with an equilibrium temperature of 1300 K. Two transits of the planet were observed spectroscopically at low resolution with the auxiliary-port camera on the William Herschel Telescope, covering a wide range of 4000-8750 Å. We use a Gaussian process approach to model the correlated noise in the multiwavelength light curves, resulting in a high precision relative transmission spectrum with errors of the order of a pressure scaleheight.We attempted to fit a variety of different representative model atmospheres to the transmission spectrum, but did not find a satisfactory match to the entire spectral range. For the majority of the covered wavelength range (4000-7750 Å), the spectrum is flat, and can be explained by an optically thick and grey cloud layer at 0.1 mbar, but this is inconsistent with a slightly deeper transit at wavelengths > 7750 Å.We were not able to find an obvious systematic source for this feature, so this opacity may be the result of an additional unknown absorber.