Subpixel-Scale Topography Retrieval of Mars Using Single-Image DTM Estimation and Super-Resolution Restoration

We propose using coupled deep learning based super-resolution restoration (SRR) and single-image digital terrain model (DTM) estimation (SDE) methods to produce subpixel-scale topography from single-view ESA Trace Gas Orbiter Colour and Stereo Surface Imaging System (CaSSIS) and NASA Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (HiRISE) images. We present qualitative and quantitative assessments of the resultant 2 m/pixel CaSSIS SRR DTM mosaic over the ESA and Roscosmos Rosalind Franklin ExoMars rover’s (RFEXM22) planned landing site at Oxia Planum. Quantitative evaluation shows SRR improves the effective resolution of the resultant CaSSIS DTM by a factor of 4 or more, while achieving a fairly good height accuracy measured by root mean squared error (1.876 m) and structural similarity (0.607), compared to the ultra-high-resolution HiRISE SRR DTMs at 12.5 cm/pixel. We make available, along with this paper, the resultant CaSSIS SRR image and SRR DTM mosaics, as well as HiRISE full-strip SRR images and SRR DTMs, to support landing site characterisation and future rover engineering for the RFEXM22.

Landing site positioning and descent trajectory reconstruction of Tianwen-1 on Mars

Tianwen-1 (TW-1) is the first Chinese interplanetary mission to have accomplished orbiting, landing, and patrolling in a single exploration of Mars. After safe landing, it is essential to reconstruct the descent trajectory and determine the landing site of the lander. For this purpose, we processed descent images of the TW-1 optical obstacle-avoidance sensor (OOAS) and digital orthophoto map (DOM) of the landing area using our proposed hybrid-matching method, in which the landing process is divided into two parts. In the first, crater matching is used to obtain the geometric transformations between the OOAS images and DOM to calculate the position of the lander. In the second, feature matching is applied to compute the position of the lander. We calculated the landing site of TW-1 to be 109.9259° E, 25.0659° N with a positional accuracy of 1.56 m and reconstructed the landing trajectory with a horizontal root mean squared error of 1.79 m. These results will facilitate the analyses of the obstacle-avoidance system and optimize the control strategy in the follow-up planetary-exploration missions.

Stabilization of unmanned aerial vehicle on trajectory in high wind conditions

Stationary proportional control laws have been synthesized to ensure stable motion of an unmanned aerial vehicle along a trajectory under the action of a storm wind. We give the values of the regulator coefficients for all sections of the trajectory from the starting point to the landing. Shown are the realizations of wind disturbances and the parameters of the controlled motion of the aircraft under their action. We consider the accuracy of altitude control and the error of the coordinates of the landing site. The control laws use the values of constant coefficients obtained at five points of the trajectory. Three points are used for the climb phase and one for level flight and one for descent. We took into account the wind speed as the sum of the three-dimensional turbulent component, the average horizontal component, considering the vertical shear, and discrete vertical gusts. The parameters of the Dryden shaping filters, as well as the vertical shear, are calculated for an average wind speed at a height of 6 m equal to 23.15 m / s. The speed of discrete upward gusts is 40 m/s, and downward -25 m / s. In such conditions, the unmanned aerial vehicle successfully passes the specified trajectory from the launch to the landing. For thirty realizations of flight simulation, the standard deviation of the landing site error from the wind acting was calculated.

Raising and matching in Pharasiot Greek relative clauses: A diachronic reconstruction

This paper studies the structure and origin of prenominal and postnominal restrictive relative clauses in Pharasiot Greek. Though both patterns are finite and introduced by the invariant complementizer tu, they differ in two important respects. First, corpus data reveal that prenominal relatives are older than their postnominal counterparts. Second, in the present-day language only prenominal relatives involve a matching derivation, whereas postnominal ones behave like Head-raising structures. Turning to diachrony, we suggest that prenominal relatives came into being through morphological fusion of a determiner t- with an invariant complementizer u. This process entailed a reduction of functional structure in the left periphery of the relative clause, to the effect that the landing site for a raising Head was suppressed, leaving a matching derivation as the only option. Postnominal relatives are analyzed as borrowed from Standard Modern Greek. Our analysis corroborates the idea that both raising and matching derivations for relatives must be acknowledged, sometimes even within a single language.

Intensive Commercialization of Endangered Sharks and Rays (Elasmobranchii) Along the Coastal Amazon as Revealed by DNA Barcode

Elasmobranchs represent a well-defined group, composed of about 1,150 species inhabiting diverse aquatic environments. Currently, several of these species have been classified as threaten due to overexploitation. Therefore, we used DNA barcode to identify traded species of sharks and stingrays in the municipality of Bragança (Amazon coastal region), a major fishery landing site in northern Brazil. We collected a total of 127 samples labeled into 24 commercial nomenclatures over 1-year period. Twenty species were discriminated and 13 of them are recognized under some threatening status. In relation to sharks, Carcharhinidae showed the highest number of species, half of them classified as endangered, followed by hammerhead sharks (Sphyrnidae), with four species also regarded as threatened with extinction. The Rhinopteridae and Dasyatidae rays were the most abundant groups, with trade records of the following threatened species: Rhinoptera brasiliensis, Rhinoptera bonasus, Hypanus berthalutzae, and Fontitrygon geijskesi. It is noteworthy that threatened species of elasmobranchs have been frequently and regularly exploited because of inefficient fishery management policies. Therefore, effective inspection practices need to be incorporated in fisheries, including the use of DNA barcode to enable a reliable method of species authentication and to assure the proper commercialization.

Igneous Rock Associations 28. Construction of a Venusian Greenstone Belt: A Petrological Perspective

The crustal evolution of Venus appears to be principally driven by intraplate processes that may be related to mantle upwelling as there is no physiographic (i.e. mid-ocean ridge, volcanic arc) evidence of Earth-like plate tectonics. Rocks with basaltic composition were identified at the Venera 9, 10, 13, and 14, and Vega 1 and 2 landing sites whereas the rock encountered at the Venera 8 landing site may be silicic. The Venera 14 rock is chemically indistinguishable from terrestrial olivine tholeiite but bears a strong resemblance to basalt from terrestrial Archean greenstone belts. Forward petrological modeling (i.e. fractional crystallization and partial melting) and primary melt composition calculations using the rock compositions of Venus can yield results indistinguishable from many volcanic (ultramafic, intermediate, silicic) and plutonic (tonalite, trondhjemite, granodiorite, anorthosite) rocks that typify Archean greenstone belts. Evidence of chemically precipitated (carbonate, evaporite, chert, banded-iron formation) and clastic (sandstone, shale) sedimentary rocks is scarce to absent, but their existence is dependent upon an ancient Venusian hydrosphere. Nevertheless, it appears that the volcanic–volcaniclastic–plutonic portion of terrestrial greenstone belts can be constructed from the known surface compositions of Venusian rocks and suggests that it is possible that Venus and Early Earth had parallel evolutionary tracks in the growth of proto-continental crust.