Chronology of the Basalt Units Surrounding Chang’e-4 Landing Area

The Chang’e-4 (CE-4) lunar probe, the first soft landing spacecraft on the far side of the Moon, successfully landed in the Von Kármán crater on 3 January 2019. Geological studies of the landing area have been conducted and more intensive studies will be carried out with the in situ measured data. The chronological study of the maria basalt surrounding the CE-4 landing area is significant to the related studies. Currently, the crater size-frequency distribution (CSFD) technique is the most popular method to derive absolute model ages (AMAs) of geological units where no returned sample is available, and it has been widely used in dating maria basalt on the lunar surface. In this research, we first make a mosaic with multi-orbital Chang’e-2 (CE-2) images as a base map. Coupled with the elevation data and FeO content, nine representative areas of basalt units surrounding the CE-4 landing area are outlined and their AMAs are derived. The dating results of the nine basalt units indicate that the basalts erupted from 3.42 to 2.28 Ga ago in this area, a period much longer than derived by previous studies. The derived chronology of the above basalt units establishes a foundation for geological analysis of the returned CE-4 data

Characterization of traverse slippage experienced by Spirit rover on Husband Hill at Gusev crater

Spirit rover experienced significant slips traversing Husband Hill. This paper analyzes the slippage Spirit experienced from Sol 154 to Sol 737. Slippage with respect to terrain type and slope is computed using data downlinked from the rover, rover position, and orientation estimations from visual odometry (VO) and photogrammetry based bundle adjustment (BA) method. Accumulated slippage reached a maximum of 83.86 m on Sol 648. However, as Spirit descended into the Inner Basin, the direction of slippage reversed, and accumulated slippage approached zero by the end of the entire traverse. Eight local regions with significant slips and nineteen traverse segments have been analyzed. Slippage was found to be highly correlated to slope direction and magnitude; the reverse of slope directions in the ascending and descending portions of the traverse proves to be the main contributor to the observed cancellation of slippage. While the horizontal component of the slippage almost canceled out, the difference in elevation continually accumulated, mainly during the ascent. In general, long traverse segments created more slips than short ones. This is reflected in both the accumulated and individual slippages. In considering the four major Mars terrain types, Spirit performed best on bedrock, managing to drive on slopes close to 30°. Fine-grain surfaces were the most challenging; though progress was made on slopes up to 15°, slippages of over 100% (more slippage than distance traveled) occurred for short segments. The results of this work can be incorporate into a traverse planning framework in which rover slippage is minimized. Results can be employed in landed planetary missions for precision navigation to avoid potentially dangerous regions by considering expected slippage

Opportunity rover localization and topographic mapping at the landing site of Meridiani Planum, Mars

This paper presents the results of Mars topographic mapping and lander and rover localization for the Opportunity rover at Meridiani Planum during the Mars Exploration Rover (MER) 2003 mission. By Sol 458, the Opportunity rover traversed a distance of 5.20 km. We localized the lander using two-way Doppler radio positioning and cartographic triangulation of craters visible in both orbital and ground images. Additional high-resolution orbital images were taken to verify the determined lander position. Visual odometry and bundle adjustment techniques were applied to overcome wheel slippages, azimuthal angle drift, and other navigation errors (as large as 21% within Eagle crater). In addition, orbit-to-ground image-based adjustment was applied to correct rover location errors where bundle adjustment was not applicable. We generated timely topographic products, including orthoimages, digital terrain models (DTMs), three-dimensional (3-D) crater models, and rover traverse maps. In particular, detailed 3-D terrain models of major features, such as Endurance crater, have been generated using multisite panoramic stereo images based on bundle adjustment and wide baseline stereo technique

INTEGRATION OF ORBITAL AND GROUND IMAGE NETWORKS FOR THE AUTOMATION OF ROVER LOCALIZATION

Rover localization is essential to the exploration of space. The availability of sub-meter resolution satellite imagery, especially HiRISE imagery, has opened the possibility of computing rover locations at higher accuracy by making use of detailed features seen in the satellite orbital images. This paper describes a new development towards automation of the rover localization process using orbital and ground images. Using a rigorous sensor model and bundle adjustment (BA) of HiRISE stereo imagery, high-resolution orthophotos and DEMs can be generated as soon as the orbital stereo images are acquired. A ground image network is also constructed using intra- and inter-stereo matching. From both types of imagery, a few landmarks are identified to be used as ground control points for the integration of the orbital and ground image networks. Rocks detected from both orbital and ground imagery serve as tie points for rover localization. From orbital images, rocks are extracted based on brightness values and the shape of dark spots. Rocks in ground images are extracted through dense stereo matching, rock peak and surface point extraction, and rock modeling. To narrow down a precise rover position, terrain match is performed using DEMs generated from orbital and ground imagery. Finally, distribution pattern matching is implemented for rocks detected from orbital and ground imagery. The rover position is adjusted based on 2D affine transformation obtained from rock pattern matching. The proposed method has been tested for the Spirit rover traverse. Experimental results show that the orbital/ground rock matching approach has performed successfully for MER rover localization

Abstract A Comparative Study of Shoreline Mapping Techniques

Shorelines have a dynamic nature. Hence, their definition, mapping, and subsequent utilization are a more complicated issue than people usually think. Different approaches to shoreline mapping are described and analyzed in this paper. In particular, a new method is presented in which tide-coordinated shorelines are derived from periodic satellite observations. A pilot shoreline-mapping project was carried out in the Lake Erie area using NOAA/NGS aerial images and simulated and actual IKONOS images. Several shorelines are generated using different techniques, for instance, by digitizing from aerial orthophotos, intersecting a digital water surface with a coastal terrain model (CTM), and extraction from stereo IKONOS images. In addition, existing shorelines digitized from USGS maps and NOAA T-Sheets are included. All these shorelines are compared, their differences evaluated, and the causes of possible shoreline changes are discussed. Key words: shoreline, CTM, tide-coordinated shoreline, water level, rational function 1

Geometric Modeling and Processing of QuickBird Stereo Imagery

This paper discusses geometric modelling and photogrammetric processing methods for high-precision mapping using stereo QuickBird images, and reports research results of data processing in an area in Tampa Bay, Florida,. First, a set of panchromatic “Basic ” QuickBird stereo images are evaluated using GPS control points. Systematic errors in the vendor-provided RPCs (Rational Polynomial Coefficients) are found to be 8.8m, 8.7m and 12.6m in the X, Y and Z directions, respectively. Next, a study of the improvement of 3-D geopositioning accuracy is conducted in which a comparison is made between different adjustment models that represent different numbers and configurations of ground control points. The comparison results indicate that a simple adjustment model with only a couple of ground control points is effective for the elimination of systematic errors and for the improvement of 3-D geopositioning accuracy to a 0.7-1m (1-1.5 pixel) level. In addition, a sub-pixel accuracy of 3-D measurement can be achieved for feature points in images that can be sharply identified and, thus, accurately measured. Based on this improved geometric model, a 3-D shoreline was produced semi-automatically in the area

Object modeling and matching from multiview ground images for automated Mars rover localization

Abstract—This paper presents an innovative method for object modeling and matching from multi-view ground images for automated Mars rover localization. In this method, rocks are first extracted from a selection of 3D ground points that are generated from dense matching. The extracted rocks are then modeled using analytical surfaces such as ellipsoids, hemispheres, cones, and tetrahedrons. The extracted rocks of two rover stations are matched through a robust algorithm that matches the geometric configuration patterns of the rocks from the two stations using an improved Hough transform technique, followed by a heuristic refinement. Finally, peaks of the matched rocks serve as cross-site tie points in bundle adjustment of the rover image network. Experiments conducted using Navcam images acquired from the 2003 Mars Exploratio