P53C-1458
TNS - A compact, light-weight sensor for thermal neutrons
Future solar-system exploration missions will have an increasing focus on the habitability of the moon or planet under investigation. A key aspect of habitability is the availability of water which can be detected by observing signatures of thermal and epithermal neutrons. State-of-the-art instruments which detect thermal and epithermal neutrons are normally heavy and consume substantial spacecraft resources. Therefore, there is substantial interest in developing small, light-weight instruments with a high detection efficiency. We are currently investigating an innovative detector design based on solid-state detectors and will present initial results.
P53C-1459
Light-output response of the plastic scintillator for the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD)
The Radiation Assessment Detector (RAD) onboard NASA's Mars Science Laboratory (MSL) rover mission has been designed to detect a wide range of particle types (charged and neutral) and energies on the Mars surface. The BC432m plastic scintillator coupled to PIN photodiodes has been used as a neutron detector as well as an anticoincidence shield for the RAD instrument. We present an experimental study of the non-linear light-output response of the BC432m for protons and neutrons beams. The experimental results have been compared to the parametric formula based on the theoretical work of Birks and Chou. Furthermore, a comparison between the quenching effect found in the BC432m and in other inorganic scintillators (CsI:Tl) used in the RAD instrument has been performed.
P53C-1460
Detection of neutral particle radiation with the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD)
RAD, the Radiation Assessment Detector on NASA's Mars Science Laboratory (MSL) rover mission is designed to detect a wide range of different particle species at energies up to 100 MeV/nuc. We present the beam testing results for the flight units of the RAD Sensor Head unit (RSH). Neutral particle response, anti-coincidence efficiency as well as behaviour for relativistic high-Z (up to iron) particles will be shown. Additionally, we present the response of our RSH GEANT4 model for the expected (simulated) Mars surface radiation environment.
P53C-1461
Mars Analog Tunable Laser Spectroscopy at a Site of Active Serpentinization
The Tunable Laser Spectrometer (TLS) is one of three instruments (QMS, GC, TLS) that comprise the Sample Acquisition Mission (SAM) on NASA's 2009 Mars Science Laboratory (MSL). TLS has unprecedented capability for measuring methane, water and carbon dioxide abundances in the martian atmosphere and in gas evolved from heated soil samples. In addition, TLS will measure the 12C/13C isotope ratios in both CH4 and CO2 and the 16O/17O/18O isotope ratios in CO2. Comparison among atmospheric and soil isotope ratios will yield unique insight into the role of water in Mars's interior, and potentially life- sustaining fluid-rock interactions. We present measurements of methane and water isotope compositions from spring-derived gases collected at The Cedars, a site of active serpentinization, using tunable laser spectroscopy with instrumentation similar to TLS (detection at 3.27 microns for methane). A four-port absorption cell was developed for simultaneous measurements of isotopic compositions in comparison with a reference standard. We discuss implications for the origins of water and methane at the Cedars with an eye toward understanding similar systems that may exist on Mars.
P53C-1462
Triboelectric Charging of Fine Particles: Understanding Sample Transport Under Simulated Martian Conditions for the Mars Science Laboratory
We report on the nature of fine particle (lees than 150 micron) transport under simulated Martian conditions, in order to better understand the Mars Science Laboratory's sample acquisition, processing and handling subsystem (SA/SPaH). We find that triboelectric charging due to particle movement may have to be controlled in order for successful transport of fines that are created within the drill, processed through the sample handing system (CHIMERA), and delivered to the SAM and CheMin instruments. These fines will be transferred to the portioner, a 3 mm diameter, 8 mm deep distribution center where they will drop ~ 2 cm to the instrument inlet funnels. In our experiments, charging of the simulant (Mars Mojave Simulant - MMS) resulted in 1.5 to 3 nanocoulombs of charge for a 3g aliquot. Due to electrostatics, this process may result in clumping or charge repulsion of fines, which can result in particle sorting. Both of these results can potentially result in an inaccurate sample analysis for the onboard instruments.
P53C-1463
Robotic Thin Section Sample Preparation Device for In Situ Planetary Exploration
Petrographic thin sections are used on Earth to identify minerals. The data from thin sections together with chemical rock data could result in a much better interpretation of planetary geology. A petrographic thin section is a well polished thin (~30 micron) sample of rock mounted on a glass slide. When viewed under a polarizing microscope one can quickly observe minerals from the interference colors. With unpolarized light some textural and structural features can be identified. Making of thin section is an art that takes many years of experience to acquire. All thin sections on Earth have been done manually. The Colorado School of Mines and Honeybee Robotics have been developing a robotic thin section device that one day may be used on planetary surface missions to autonomously slice, grind and polish a piece of rock. In particular, we have been developing methods for rough cutting, epoxy/slide application, and grinding/polishing of a rock to thin section quality. Examination of rock surface finish was done quantitatively using surface roughness measurement and qualitatively by a thin section expert. Here we report on the progress to date.
P53C-1464
Characterization of the Basalt of Broken Tank, NM for the 'in situ' Calibration Target for the Alpha-Particle X-ray Spectrometer (APXS) on the Upcoming Mars Science Laboratory (MSL) Rover
The MSL rover mission will launch in Fall 2009. It is equipped with an APXS for analyzing the bulk chemistry of rocks and soils. To monitor the APXS performance in situ on the martian surface over the extended mission, a calibration target will be included on the MSL rover. Engineering constraints led to a 4.2 cm diameter, 3 mm thick, homogeneous rock disc that would survive vibrations during launch. The basalt from Broken Tank, NM was chosen for the flight disc from ~200 volcanic rocks. The basalt is relatively homogeneous, fine- and even-grained, vesicle-free, and extremely dense and hard due to its ophitic texture. Other volcanic rocks – even well characterized samples of BCR – were ruled out due to vesicles, or high contents of glass, phenocrysts, secondary minerals, or fractures. The flight disc was prepared by hand- polishing to a 0.05 micron finish. We obtained scanning electron microscope back-scattered electron maps and X-ray maps (Al, Mg, Ca, Fe, Ti, Na, and K) on the polished, uncoated surface of the target. One pit (~0.03 mm2) and three tiny surface imperfections (<0.04 mm2) were observed on the surface. Electron microprobe analyses on two C-coated thin sections give the following compositions: olivine cores Fa23Fo77 and rims Fa40Fo60; plagioclase cores Ab42An56Or2 and discrete rims Ab62An7Or31; oxides Ilm67Hm33 and also trace chromite, apatite, chlorite, clays and devitrified glass. The NIH software Scion Image was used to determine the modal abundance of each phase in the basalt disk and in two thin sections. Bulk composition was established with multiple XRF laboratory analyses. There is no significant heterogeneity on the scale of the APXS analysis (~1.5 cm). Sulfides were not observed and XRF verified low Ni (<90 ppm) and S (70 ppm), making these elements ideal to monitor any Martian dust build-up during the surface operation. The rock slab is glued into a Ni frame, mounted vertically and accessible with a brush tool. The K- and L- X-ray lines of Ni can be used to monitor the energy efficiency of the X-ray detector. This work was supported by the Space Science Enhancement Program of the Canadian Space Agency and the New Mexico Space Grant Consortium.
P53C-1465
Hollow-Core Optical Fiber Gas Correlation Radiometer for CH4, H2CO, and H2O vapor measurements on Mars
We present the development of a reduced mass and volume gas correlation radiometer that implements a hollow-core fiber gas correlation cell. The reduction in size makes this technology appropriate for a Mars orbital or aircraft probe mission – capable of pin-pointing sources of atmospheric trace gases potentially indicative of life (methane, formaldehyde and water). The relative simplicity of this technique allows it to be easily expanded to include other species measurements such as 12C/13C ratios of methane. This instrument will consist of three sub-instruments for detecting CH4, H2CO, and H2O at 3.44 μm, 3.63 μm, and 3.12 μm respectively. Within each sub-instrument, a hollow-core optical fiber filled with a sample of the gas of interest acts as a spectral filter. Performance of a Mars orbiting version of the hollow-core fiber instrument has been simulated assuming a 2 meter long, 500 micron inner diameter hollow- core fiber gas correlation cell, a 92.8 degree sun-synchronous orbit from 400 km with a horizontal sampling scale of 10 km x 10 km. Initial results indicate that for one second of averaging, a detection limit of 1 ppbv is possible for formaldehyde, with slightly better than 1 ppbv. Preliminary results are presented for the formaldehyde sub-instrument development.
P53C-1466
A contribution to the next steps in Mars landing site selection
Following preliminary work that led to possible Martian landing sites to be considered for future Mars exploration missions, and in the context of the current search for candidate sites for MSL and Exomars lander missions, further development is being carried out in the area of engineering and scientific constraints that shall be combined in order to identify prime and backup sites suitable for landing. The distribution of rocks on Mars is critical for the analysis of the engineering constraints for both the Entry, Descent and Landing (EDL) risk and the in-situ operational requirements. Any mission attempting a landing on Mars must deal with what size and frequency of rocks can accommodate safely the landing system and the operation of the probe and what altitude acquisition system during descent is required given the rockiness of the landing site. The knowledge of the rock distribution plays also an important role in the scientifically-driven selection process that studies the geologic history and evolution of the surface. The present surface has been shaped by different physical and morphological processes that eroded, transported, and deposited the surface materials. The study of these materials at small-scale is essential to understand all these processes. Such data, combined with other morphological and remote sensing information, provides a basis for discussing the science interest of a landing site. Based on engineering constraints and a model taking into account the EDL sequence, the landing risk can be evaluated and defined as the percentage of times that the EDL system exceeds its capability performances (e.g. entry thermal constraints, touchdown velocity and attitude, etc). By repeating the process for all possible landing sites, an EDL Risk Map is obtained as main output of the procedure. However, an EDL accuracy map can be also obtained as a secondary output by performing a dispersion analysis of the successful landing simulations to evaluate the landing ellipses associated to each site. By combining precise landing requirements, a science interest assessment and a landing viability assessment, such a procedure will be applied to the sites already identified as potential candidates (e.g., Syrtis Major area, Mawrth Vallis) or applied via an iteration process to refine the search by means of the use of high-resolution mapping products. Additionally, the same procedure can be used together with optimisation techniques to enhance the design of the different EDL system elements to extend its capabilities to high-priority candidate sites.
P53C-1467
Cooperative Observation Network: Mars in the 2005-2006 and 2007-2008 apparitions
In our previous works, we reported Mars phenomena extracted from more than 7000 images obtained in the 2003 apparition by the professional-amateur cooperation networks (Nakakushi et al., 2004 and 2005, on Publ. Astron. Soc. Jpn.; Nakakushi et al., 2006 in the AGU Fall Meeting 2004). Here we report the results in the 2005--2006 and 2007--2008 apparitions. In both of the apparitions, many events were detected: recession of the south polar cap, the north and south polar hoods, orographic clouds, other water-ice clouds, and changes in albedo features probably due to dust storms. Flashing phenomenon was not detected. In addition to reports of those events, we focus in this paper on dust events and the north polar hood. We observed three large dust storms in 2005--2006, and two in 2007--2008. The north polar hood showed dual components of its longitudinally asymmetric form: the sun- synchronous asymmetry and the longitude-dependent asymmetry. This project has one more important purpose other than scientific research --- social science education. Amateur observers are waiting professional researchers to use their data in the up-to-date scientific studies. We intend to expand this project to other planets. In the near future, we plan to build a new planetary data archive center on the internet, which serves daily planetary images and links up professional and amateur observers.
P53C-1468
Geologist's Field Assistant for Remote Science Exploration: Using High-Resolution Images
An autonomous Geologist's field assistant (GFA) is being developed to aid in the classification of remote geological data. This abstract focuses on experimental results from the unsupervised classification of unaltered igneous rocks. GFA uses a high-resolution digital camera to acquire close-up images of rock samples. All samples are classified by geologists and a database is created with ground truth data. Autonomous classification of an unknown rock is performed using an image retrieval method that uses the database (of more than 400 samples to date) to determine properties such as main texture (aphanitic, porphyritic, phaneritic) and general composition (felsic, intermediate, mafic). GFA's performance is evaluated using a "leave-one-out" procedure that provides a large data set to train the system against itself. While earlier experiments with low-resolution images required less computing power at the expense of losing important textural data, the latest experiments use high- to full-resolution images with comparable results. Training experiments show that, using black-and-white Gabor texture-based image retrieval, the highest classification rates occur for phaneritic samples (averaging at 80% correct with some instances achieving up to 91%), with considerably lower rates for aphanitic and porphyritic samples. At the same time, data indicate that many aphanitic samples are mistakenly identified as porphyritic. In response, several approaches that offer complementary information to fill the performance gap have been considered. For example, mean-shift color clustering seems to improve porphyritic classification rates by an average of 14%, which may prove crucial to improving overall classification; the aforementioned imaging procedures are being combined with Raman spectral data, which is expected to greatly improve results since accurate classification often hinges on detecting the presence of certain minerals; various other methods have been proposed including color Gabor texture image retrieval methods, and segmentation and thresholding to increase the sensitivity to grains and porphyries.
P53C-1469
Automatic Landmark Identification in Mars Orbital Imagery
We have developed new methods for automatically identifying landmarks such as craters, gullies, dark slope streaks, and dust devil tracks in remote sensing imagery. These methods are based on statistical measures of local terrain salience. The salience of a region is defined as the degree to which it differs from its surrounding context. We use pixel intensity histograms to represent each candidate region, and we compute salience in one of two ways. The first method calculates the Kullback-Leibler divergence between the region's histogram and a larger enclosing region. The second method calculates the entropy of the region's histogram independently. The KL-divergence approach is useful for detecting unusual landmarks, while the entropy approach detects high-contrast features such as ridges and crater edges. We have automatically identified landmarks in several Mars surface images collected from orbit (MOC and THEMIS data) and evaluated them against manual annotations of dark slope streaks and dust devil tracks. We have also trained a landmark machine classifier that can assign new landmarks to one of several categories. In an evaluation on dark slope streaks, dust devil tracks, and craters, the classifier achieved an accuracy of 93%. Further, because detections are made based on a generic notion of salience, they are not restricted to known landmark types. It is possible to identify landmarks that do not fit into any existing category as novel features, enabling scientific advances that otherwise rely on serendipity to bring them to light. Automated landmark identification can be useful both onboard a remote spacecraft and in ground-based processing on the Earth. In an onboard setting, salient landmarks can be detected and catalogued as they are observed, providing a highly compressed summary of the region under study (e.g., "five craters, two gullies, and 37 sand dunes" along with their locations). On the ground, gigabyte archives of past images can be analyzed and annotated with meta-data indicating the existence and location of different landmark types. These annotations can enable a content-based search facility that will permit the easy retrieval of images that contain a specific feature of interest.
P53C-1470
Visualizing NASA's Planetary Data with Google Earth
There is a vast store of planetary geospatial data that has been collected by NASA but is difficult to access and visualize. As a 3D geospatial browser, the Google Earth client is one way to visualize planetary data. KML imagery super-overlays enable us to create a non-Earth planetary globe within Google Earth, and conversion of planetary meta-data allows display of the footprint locations of various higher-resolution data sets. Once our group, or any group, performs these data conversions the KML can be made available on the Web, where anyone can download it and begin using it in Google Earth (or any other geospatial browser), just like a Web page. Lucian Plesea at JPL offers several KML basemaps (MDIM, colorized MDIM, MOC composite, THEMIS day time infrared, and both grayscale and colorized MOLA). We have created TES Thermal Inertia maps, and a THEMIS night time infrared overlay, as well. Many data sets for Mars have already been converted to KML. We provide coverage polygons overlaid on the globe, whose icons can be clicked on and lead to the full PDS data URL. We have built coverage maps for the following data sets: MOC narrow angle, HRSC imagery and DTMs, SHARAD tracks, CTX, and HiRISE. The CRISM team is working on providing their coverage data via publicly-accessible KML. The MSL landing site process is also providing data for potential landing sites via KML. The Google Earth client and KML allow anyone to contribute data for everyone to see via the Web. The Earth sciences community is already utilizing KML and Google Earth in a variety of ways as a geospatial browser, and we hope that the planetary sciences community will do the same. Using this paradigm for sharing geospatial data will not only enable planetary scientists to more easily build and share data within the scientific community, but will also provide an easy platform for public outreach and education efforts, and will easily allow anyone to layer geospatial information on top of planetary data. Our presentation will demonstrate how to leverage the latest Google Earth and KML features to visualize planetary data. In the future we hope to make additional planetary KML data available for Mars, the Moon, and other planets in the solar system. This will vastly increase the public's ability to easily access NASA's store of planetary geospatial information.
P53C-1471
A New Capability for Automated Target Selection and Sampling for use with Remote Sensing Instruments on the MER Rovers
The Onboard Autonomous Science Investigation System (OASIS) evaluates geologic data gathered by a planetary rover. The system is designed to operate onboard a rover identifying and reacting to serendipitous science opportunities, such as rocks with novel properties. OASIS operates by analyzing data the rover gathers, and then using machine learning techniques, prioritizing the data based on criteria set by the science team. This prioritization can be used to organize data for transmission back to Earth and it can be used to search for specific targets it has been told to find by the science team. If one of these targets is found, it is identified as a new science opportunity and a "science alert" is sent to a planning and scheduling system. After reviewing the rover's current operational status to ensure that it has enough resources to complete its traverse and act on the new science opportunity, OASIS can change the command sequence of the rover in order to obtain additional science measurements. Currently, OASIS is being applied on a new front. OASIS is providing a new rover mission technology that enables targeted remote-sensing science in an automated fashion during or after rover traverses. Currently, targets for remote sensing instruments, especially narrow field-of-view instruments (such as the MER Mini- TES spectrometer or the 2009 MSL ChemCam spectrometer) must be selected manually based on imagery already on the ground with the operations team. OASIS will enable the rover flight software to analyze imagery onboard in order to autonomously select and sequence targeted remote-sensing observations in an opportunistic fashion. We are in the process of scheduling an onboard MER experiment to demonstrate the OASIS capability in early 2009.
P53C-1472
Probabilistic Digital Elevation Model Generation For Spatial Accuracy Assessment
We propose a new method for the measurement of high resolution topography from a stereo pair. The main application area is the study of planetary surfaces. Digital elevation models (DEM) computed from image pairs using state of the art algorithms usually lack quantitative error estimates. This can be a major issue when the result is used to measure actual physical parameters, such as slope or terrain roughness. Thus, we propose a new method to infer a dense bidimensional disparity map from two images, that also estimates the spatial distribution of errors. We adopt a probabilistic approach, which provides a rigorous framework for parameter estimation and uncertainty evaluation. All the parameters are described in terms of random variables within a Bayesian framework. We start by defining a forward model, which mainly consists of warping the observed scene using B-Splines and using a spatially adaptive radiometric change map for robustness purposes. An a priori smoothness model is introduced in order to stabilize the solution. Solving the inverse problem to recover the disparity map requires to optimize a global non-convex energy function, which is difficult in practice due to multiple local optima. A deterministic optimization technique based on a multi-grid strategy, followed by a local energy analysis at the optimum, allows to recover the a posteriori probability density function (pdf) of the disparity, which encodes both the optimal solution and the related error map. Finally, the disparity field is converted into a DEM through a geometric camera model. This camera model is either known initially, or calibrated automatically using the estimated disparity map and available measurements of the topography (existing low-resolution DEM or ground control points). Automatic calibration from uncertain disparity and topography measurements allows for efficient error propagation from the initial data to the generated elevation model. Results from Mars Express HRSC data are presented. A pair of images (including the nadir view) at 30m resolution was used to obtain a DEM with a vertical accuracy better than 10m in well-textured areas. The lack of information in smooth regions naturally led to large uncertainty estimates.