Stephen E. Dunagan

The MARTE VNIR Imaging Spectrometer Experiment: Design and Analysis

We report on the design, operation, and data analysis methods employed on the VNIR imaging spectrometer instrument that was part of the Mars Astrobiology Research and Technology Experiment (MARTE). The imaging spectrometer is a hyperspectral scanning pushbroom device sensitive to VNIR wavelengths from 400-1000 nm. During the MARTE project, the spectrometer was deployed to the Río Tinto region of Spain. We analyzed subsets of three cores from Río Tinto using a new band modeling technique. We found most of the MARTE drill cores to contain predominantly goethite, though spatially coherent areas of hematite were identified in Core 23. We also distinguished non Fe-bearing minerals that were subsequently analyzed by X-ray diffraction (XRD) and found to be primarily muscovite. We present drill core maps that include spectra of goethite, hematite, and non Fe-bearing minerals.

The 2005 MARTE Robotic Drilling Experiment in Río Tinto, Spain: Objectives, Approach, and Results of a Simulated Mission to Search for Life in the Martian Subsurface

The Mars Astrobiology Research and Technology Experiment (MARTE) simulated a robotic drilling mission to search for subsurface life on Mars. The drill site was on Peña de Hierro near the headwaters of the Río Tinto river (southwest Spain), on a deposit that includes massive sulfides and their gossanized remains that resemble some iron and sulfur minerals found on Mars. The mission used a fluidless, 10-axis, autonomous coring drill mounted on a simulated lander. Cores were faced; then instruments collected color wide-angle context images, color microscopic images, visible-near infrared point spectra, and (lower resolution) visible-near infrared hyperspectral images. Cores were then stored for further processing or ejected. A borehole inspection system collected panoramic imaging and Raman spectra of borehole walls. Life detection was performed on full cores with an adenosine triphosphate luciferin-luciferase bioluminescence assay and on crushed core sections with SOLID2, an antibody array-based instrument. Two remotely located science teams analyzed the remote sensing data and chose subsample locations. In 30 days of operation, the drill penetrated to 6 m and collected 21 cores. Biosignatures were detected in 12 of 15 samples analyzed by SOLID2. Science teams correctly interpreted the nature of the deposits drilled as compared to the ground truth. This experiment shows that drilling to search for subsurface life on Mars is technically feasible and scientifically rewarding.

Spectrometer for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR): Instrument Technology

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air-pollution/climate. Direct beam hyper-spectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. 4STAR measurements will tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and future detector evolution. Technical challenges include compact optical collector design, radiometric dynamic range and stability, and broad spectral coverage. Test results establishing the performance of the instrument against

The Two-Column Aerosol Project: Phase I - Overview and Impact of Elevated Aerosol Layers on Aerosol Optical Depth

The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to aerosol mixing state and aerosol radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energys (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had aerosol layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. In addition, while there was a great deal of spatial and day-to-day variability in the aerosol chemical composition and optical properties, no systematic differences between the two columns were observed.

MARTE: Technology development and lessons learned from a Mars drilling mission simulation

29 pages, 21 figures, 2 tables.-- ISI Article Identifier: 000250768000006.-- Special issue: Mining Robotics.

Platform options of free-flying satellites, UAVs or the International Space Station for remote sensing assessment of the littoral zone

Over the years, making or creating a choice for a specific platform from which to conduct remote sensing observations of specific targets brings in many factors related to the target characteristics and how the data are going to be used. Attempts to measure Earths diverse objects have generated a wide range of platform alternatives, from geostationary satellites to low-flying aircraft. Now several additional options possessing unique attributes are available: the International Space Station (ISS) and Un-inhabited Aerial Vehicles (UAVs). This paper explores some of the tradeoffs among these alternatives for the special problem of remotely sensing the littoral zone, but especially the shallow ecosystems. Though the surface area of the littoral zone is relatively large, it is geographically disbursed and somewhat linear. Also, the spatial, spectral and temporal variability of ecosystems in this zone is very high, and signals are masked by the overlying water column. Ideally, a frequent revisit time would be desirable to monitor their health and changing condition. These characteristics place important constraints on platform choice as one tries to design a system to monitor these critical ecosystems and provide useful information for managing them. This paper discusses these tradeoff issues as offered mainly by three platform choices: free-flying satellites, ISS, UAVs and other aircraft.

Tracking elevated pollution layers with a newly developed hyperspectral Sun/Sky spectrometer (4STAR): Results from the TCAP 2012 and 2013 campaigns

Total columnar water vapor (CWV), nitrogen dioxide (NO2), and ozone (O3) are derived from a newly developed, hyperspectral airborne Sun-sky spectrometer (4STAR) for the first time during the two intensive phases of the Two-Column Aerosol Project (TCAP) in summer 2012 and winter 2013 aboard the DOE G-1 aircraft. We compare results with coincident measurements. We find 0.045 g/cm2 (4.2%) negative bias and 0.28 g/cm2 (26.3%) root-mean-square difference (RMSD) in water vapor layer comparison with an in situ hygrometer and an overall RMSD of 1.28 g/m3 (38%) water vapor amount in profile by profile comparisons, with differences distributed evenly around zero. RMSD for O3 columns average to 3%, with a 1% negative bias for 4STAR compared with the Ozone Measuring Instrument along aircraft flight tracks for 14 flights during both TCAP phases. Ground-based comparisons with Pandora spectrometers at the Goddard Space Flight Center, Greenbelt, Maryland, showed excellent agreement between the instruments for both O3 (1% RMSD and 0.1% bias) and NO2 (17.5% RMSD and −8% bias). We apply clustering analysis of the retrieved products as a case study during the TCAP summer campaign to identify variations in atmospheric composition of elevated pollution layers and demonstrate that combined total column measurements of trace gas and aerosols can be used to define different pollution layer sources, by comparing our results with trajectory analysis and in situ airborne miniSPLAT (single-particle mass spectrometer) measurements. Our analysis represents a first step in linking sparse but intense in situ measurements from suborbital campaigns with total column observations from space.

Interferometric imagery from a solar powered RPV

Describes the design, integration, and deployment of a compact, high-spectral-resolution imaging interferometer built specifically for use on the Pathfinder solar powered remotely piloted aircraft (RPA) that has been developed under NASAs Environmental Research Aircraft and Sensor Technology (ERAST) program. Emphasis is placed on the engineering challenges associated with RPA instruments, including low power and weight constraints, extreme thermal and pressure environment, and remote operation. Sample data are presented that illustrate the strengths and weaknesses of the composite RPA/scanned interferometer remote sensing system.

A Multi-Sensor Imaging Payload for Mission-Adaptive Remote Sensing Applications [invited]

†† Future Earth Science remote sensing missions will require aircraft operating as subsystems in support of multi -scale mission systems that integrate data from ground, aircraft, and orbital sensors to provide a comprehensive understanding of global phenomena. Unmanned aerial vehicles (UAVs) will enhance mission range and duration and enable measurements of phenomena considered too risky for manned aircraft. These aircraft also represent a very adaptable element in a sensor web system, having the ability to provide both remotely sensed and in-situ data at a broad range of spatial and temporal scales. The use of on -board autonomous agents to optimize flight profile, sensor, and measurement domain parameters will provide a revolutionary improvement in the utility of remotely sensed data, particularly for the study of temporally localized phenomena, and is extendable to NASA requirements for improved autonomy in space exploration. This paper provides a description of a multi-sensor imaging payload designed around the concept of intelligent mission management using on-board autonomous agents to optimize mission productivity. Imaging sensors include high-resolution color, low-resolution thermal infrared, and push-broom hyper-spectral imagers. Ancillary payload sub-systems provide meta-data for image interpretation and geo-registration, and communications for near-time instrument control and data delivery. The payload has been designed, integrated, and tested on a small (<55 lbs) UAV in a wildfire management mission context.

UAS Enabled Communications for Tactical Firefighting

Tactical firefighting requires effective communication systems to protect property and preserve life, and fire fighting organizations rely on dedicated radio systems for reliable, deconflicted communication. These systems operate on line-of-sight transmission and are often impeded by terrain, particularly in regions of high surface relief. Fire fighters have traditionally addressed this problem with the use of radio relay equipment, usually mounted on points of prominence to improve the line-of-sight geometry. However, the use of unmanned aerial systems (UAS) in this application offers some distinct advantages, both in reduced time required to deploy and in the flexibility to optimize communications in an evolving situation. This paper documents the development and testing of a proof-of-concept system based on the communications protocols of the National Interagency Fire Center (NIFC). A single channel half-duplex radio relay compatible in cost and logistics requirements with existing NIFC radio communications systems was integrated into a small (under 50 lbs gross weight) UAS and deployed in a tactical firefighting demonstration program over controlled burns in rugged terrain. The demonstration proved the utility of the UAS and relay payload to enable communications. Enhancements that include visualization software for evaluating the line-of-sight geometry in real time, and the synergistic use of communications and imaging payload elements are also discussed.