Journal of Geophysical Research: Planets

Schema of a CRISM targeted observation. Only three images out of 11 are shown. The central scan at full spatial resolution is drawn in green, while the most extreme scans of the EPF are pictured in blue. Dash-dotted and dashed lines depict the first and last scanned lines of each single image, respectively. All scans are acquired as a combination of the gimbal and the motion of MRO which results in a VZA range of θ ∈ [0°, 30°] for the quasi-nadir central scan. The two modes in relative azimuth (φin + φout ≈ 180°) are shown.

Map of Libya Montes region on MOLA elevation. Libya Montes and other nearby locations are noted.

Two possible timelines for the level of aqueous activity at the martian surface: a steady, secular decrease with time having little aqueous activity since the Late Hesperian or the MEGAOUTFLO scenario with generally low, but episodically high, water activity throughout history. Both scenarios envision a warm, wet, volcanically dominated Noachian beginning with the early influx of volatiles from planetary bombardment and are consistent with a present-day obliquity-dominated climate. Changes in aqueous activity today are controlled by shifts in axial tilt over the 105 year obliquity cycle (enlargement).

Scatter plot of brightness temperature versus normalized radar cross-section for selected regions on Titan, including the core of Xanadu, hummocky terrains, radar-gray plains, and dunes. These regions show different behaviors, Xanadu and the hummocky terrains being especially bright relative to their emissivity [Janssen et al., ]. The shaded areas indicate where to search for putative hot spots. If Tb is larger than ~95 K, there is a definite thermal anomaly (dark gray shaded area). Otherwise, the consistency between Tb and σ0 must be investigated (light gray shaded area). This figure is adapted from Janssen et al. [].

Schematic illustration of computational grid used in PHOENICS. A 1 m thick lava flow initially at 1500 K is instantaneously emplaced on a 200 K substrate measuring 1–15 m deep, depending on material and heating conditions. Lava domain contains 60–240 vertical cells, and substrate domain contains 60–360 cells, with finer cell sizes near boundaries. Heat is lost from the lava flow through radiation to space environment and conduction to the substrate. Heat is released as latent heat of crystallization in cooling lava.

Detailed scheme of the estimation of surface photometric properties. The blue blocks represent the initial FRT CRISM observations (from i = 1 to n). The green blocks represent the aerosol optical thickness retrieval and the correction for atmospheric contribution for the determination of the surface bidirectional reflectance, which is carried out by the methodology described in the companion paper [Ceamanos et al., ]. The red blocks correspond to the work presented in this article, that is, the estimation of surface photometric properties.

Cartoon of SHARAD sounding operation and a typical pulse record. Each radar pulse initiates a recording cycle whose start time is set to allow a small delay window before the surface return. Processing numerous such pulse records over a period of time defined by the synthetic aperture allows for a much narrower footprint in the along-track dimension. Echoes from the surface come from a region perpendicular to the center of each posted radargram record. The incidence angle ϕ between the transmitted signal and a plane reference surface increases with distance from the ground track. The peak echo comes from mirror-like scattering close to the sub-spacecraft point, with sidelobes due to Fourier-transform processing that is required to yield a narrow pulse from the original chirp.