IN24A-01
GRSPI, Demonstrating a Prototype for an Optimal Orbiting GNSS Science Instrument
Science-based instruments which use radio signals from Global Navigation Satellite Systems (GNSS) have been successfully deployed on several NASA missions. Applications range from Precise Orbit Determination (POD), limb sounding and formation flying. Remotely sensing the Earth's surface using GNSS signals as a RADAR source is one of the most challenging applications of radiometric instrumentation. As part of NASA's Instrument Incubator Program, our group at JPL is building a prototype instrument, GRSPI (GNSS, Remote- Sensing, POD Instrument), to address a variety of GNSS science needs. Observing GNSS reflections is major focus of the design/development effort but technology for additional science needs will also be developed. Here we outline the GRSPI design approach as it applies specifically to observing science quality GNSS-R signals from low Earth orbit and provide results from the first aircraft demonstration over ocean.
IN24A-02
Ice Sheet Roughness Estimation Based on Impulse Responses Acquired in the Global Ice Sheet Mapping Orbiter Mission
The Global Ice Sheet Mapping Orbiter (GISMO) mission was developed to address scientific needs to understand the polar ice subsurface structure. This NASA Instrument Incubator Program project is a collaboration between Ohio State University, the University of Kansas, Vexcel Corporation and NASA. The GISMO design utilizes an interferometric SAR (InSAR) strategy in which ice sheet reflected signals received by a dual-antenna system are used to produce an interference pattern. The resulting interferogram can be used to filter out surface clutter so as to reveal the signals scattered from the base of the ice sheet. These signals are further processed to produce 3D-images representing basal topography of the ice sheet. In the past three years, the GISMO airborne field campaigns that have been conducted provide a set of useful data for studying geophysical properties of the Greenland ice sheet. While topography information can be obtained using interferometric SAR processing techniques, ice sheet roughness statistics can also be derived by a relatively simple procedure that involves analyzing power levels and the shape of the radar impulse response waveforms. An electromagnetic scattering model describing GISMO impulse responses has previously been proposed and validated. This model suggested that rms-heights and correlation lengths of the upper surface profile can be determined from the peak power and the decay rate of the pulse return waveform, respectively. This presentation will demonstrate a procedure for estimating the roughness of ice surfaces by fitting the GISMO impulse response model to retrieved waveforms from selected GISMO flights. Furthermore, an extension of this procedure to estimate the scattering coefficient of the glacier bed will be addressed as well. Planned future applications involving the classification of glacier bed conditions based on the derived scattering coefficients will also be described.
IN24A-03
GEO-CAPE application, demonstrated for CO by the IIP Tropospheric Infrared Mapping Spectrometers (TIMS), and scaled to an expanded application that adds the 9.6, 3.3 and 3.6 um bands for multi-layer tropospheric ozone and for HCHO
The NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP) Tropospheric Infrared Mapping Spectrometers (TIMS) have been developed to demonstrate measurement capability, when deployed in space, for multi-layer retrieval of CO from spectral measurements acquired in the solar reflective (SR) region ~ 4281 to 4301 cm-1 and in the thermal InfraRed (TIR) region ~ 2110 to 2165 cm 1. As presented at this meeting in our poster "...multi-layer CO retrieval from atmospheric data..." very encouraging retrieval for CO, H2O, CH4 and albedo were obtained in an operational mode of ground based atmospheric observations that simulated space based operations in an application that would meet Decadal Survey GEO- CAPE air quality observation requirements for coverage, footprint size and refresh time. In this presentation we'll describe the details of how the ground based operations map to the space based operations. We will discuss concept details including [a] the approach for instrument cooling, [b] the scanning mirror and telescope system that would provide input to the TIMS in a way that meets the GEO-CAPE measurement requirements, [c] telemetry requirements, and [d] the scaling of retrieval precision from the ground based actuals to the space based operations. For example, the ground based actual TIMS column precisions for retrieval from the SR data scale to space deployed TIMS column retrieval precisions for CO(=8.6%), H2O(=3.7%), CH4(=0.9%) and for albedo(=0.2%) on the GEO-CAPE minimum footprint. We'll also present the actuals, and the scaling to the GEO-CAPE case, for multi-layer CO and H2O retrieval from the combined SR and TIR data sets. The required aperture is quite small, 7.5 cm. We will also present a straight forward approach to expand the GEO-CAPE TIMS concept to additional spectral regions near 3.3, 3.6 and 9.6 um that will provide for multi-layer retrieval of tropospheric ozone, and for HCHO column. The approach adds relatively small mass, but it does significantly boost telemetry and power.
IN24A-04
Panchromatic Fourier Transform Spectrometer (PanFTS) for the Geostationary Coastal and Air Pollution Events (GEO-CAPE)Mission
The NRC decadal survey proposed the GEO-CAPE and GACM missions to study changes in atmospheric composition and the coastal oceans. To properly address air quality, the decadal survey highlighted the need for vertical profile measurements with sensitivity into the atmospheric boundary layer. The Panchromatic Fourier Transform Spectrometer (PanFTS), a new project within the NASA Instrument Incubator Program, will measure all of the trace species called out in the decadal survey for GEO-CAPE and GACM. With continuous sensitivity from 0.26 to 15 micron and high spectral resolution, PanFTS combines the functionality of separate UV, visible and IR instruments in a single package. These capabilities also permit PanFTS to meet the requirements for high spatial resolution hyperspectral imaging of the coastal zone. This presentation will discuss the design approach and technology development challenges for PanFTS including high speed, high resolution focal plane arrays, and wide spectral coverage optical design.
IN24A-05
Geostationary Fabry-Perot Imagery for the Measurement of Trace Gases and Clouds
Long-term measurements of the global distributions of trace gases (e.g., CO, O3, CH4, H2O, N2O) and clouds are needed for the study and monitoring of global change and air quality. The Geostationary Imaging Fabry-Perot Spectrometer (GIFS) instrument is an example of a next-generation satellite concept, to be deployed on a geostationary satellite for continuous hemispheric imaging of trace gas concentrations (including the boundary layer) and clouds. GIFS uses an innovative tunable imaging triple-etalon Fabry- Perot interferometer to obtain images of very high-resolution spectral line shapes of individual lines in backscattered solar radiation, which contain trace gas and cloud information. An airborne GIFS prototype and the measurement technique have been successfully demonstrated in a recent field campaign onboard the NASA P3B over Wallops Island, Virginia. In this paper, we present the preliminary GIFS instrument design and use GIFS prototype measurements to demonstrate the instrument functionality and measurement capabilities.
IN24A-06
Development Status of Multiangle SpectroPolarimetric Imager (MSPI) Prototype Cameras
We have been developing the Multiangle SpectroPolarimetric Imager (MSPI) as a candidate for the multi- directional, multi-wavelength, polarimetric imager identified by Earth Sciences Decadal Survey as one component of the Aerosol-Cloud-Ecosystem (ACE) mission. MSPI is conceptually similar to the Terra Multi- angle Imaging SpectroRadiometer (MISR), but contains a new camera design that widens the spectral range, increases the swath width, and adds high-accuracy polarimetry in selected spectral bands to supplement intensity measurements with additional constraints on aerosol microphysical properties. To provide low degree of polarization uncertainty (0.5%) and high polarimetric sensitivity, MSPI includes a novel dual- photoelastic modulator system that generates a temporally modulated signal from which the linear Stokes vector components can be synchronously recovered. The first prototype MSPI camera is a field-deployable system ("GroundMSPI") operating at 660 nm. A second prototype will contain 8 spectral bands from 355 to 935 nm and is aimed at future deployment aboard the NASA ER-2 aircraft ("AirMSPI"). Along with the instrument hardware, a ground data processing system for generating calibrated, georectified imagery is being built. Initial experimental results from the assembled GroundMSPI camera will be presented.
IN24A-07
Ka-band SAR interferometry studies for the SWOT mission
The primary objective of the NRC Decadal Survey recommended SWOT (Surface Water and Ocean Topography) Mission is to measure the water elevation of the global oceans, as well as terrestrial water bodies (such as rivers, lakes, reservoirs, and wetlands), to answer key scientific questions on the kinetic energy of ocean circulation, the spatial and temporal variability of the world's surface freshwater storage and discharge, and to provide societal benefits on predicting climate change, coastal zone management, flood prediction, and water resources management. The SWOT mission plans to carry the following suite of microwave instruments: a Ka-band interferometer, a dual-frequency nadir altimeter, and a multi-frequency water-vapor radiometer dedicated to measuring wet tropospheric path delay to correct the radar measurements. We are currently funded by the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP) to reduce the risk of the main technological drivers of SWOT, by addressing the following technologies: the Ka-band radar interferometric antenna design, the on-board interferometric SAR processor, and the internally calibrated high-frequency radiometer. The goal is to significantly enhance the readiness level of the new technologies required for SWOT, while laying the foundations for the next-generation missions to map water elevation for studying Earth. The first two technologies address the challenges of the Ka-band SAR interferometry, while the high- frequency radiometer addresses the requirement for small-scale wet tropospheric corrections for coastal zone applications. In this paper, we present the scientific rational, need and objectives behind these technology items currently under development.
IN24A-08
Development of Miniaturized Intra-Cavity DFG, Fiber-Optic, and Quantum Cascade Laser Systems in Conjunction with Integrated Electronics for Global Studies of Climate Forcing and Response using UASs as a Partner with Satellite and Adaptive Models
The 2007 National Research Council (NRC) report, Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, delineates an array of challenges facing society as the global climate system passes through a period of unprecedented changes. The Decadal Survey goes further, recommending specific science missions that will concentrate NASA's tremendous technical resources on meeting these challenges. Central to completing these science missions will be the effective union of advancing laser, electro-optical, and computing technologies with emerging Uninhabited Aerial Systems (UAS), allowing for satellite validation and independent science missions of unprecedented duration and scientific capability, in effect linking NASA's orbital and sub-orbital programs to each other and to the objectives of society as a whole. In order to harness the power of UASs for in situ atmospheric monitoring of tracers such as CO2, N2O, and CH4 as a precursor for extending detection limits to encompass sub-ppb level species, we have developed small, lightweight, single mode laser systems with co-developed integrated electronics. The laser sources are of various types, including newly developed cavity-enhanced difference frequency generation (CE DFG), distributed feedback quantum cascade lasers (DFB QCLs), and new types of commercially available DFB diode lasers. All are continuous wave (cw) and thermo-electrically cooled, ensuring a high instrument duty cycle in a compact, low maintenance package. The light sources are collimated with miniature aspherical lenses and coupled into a custom-built astigmatic Herriott cell for detection of the various targets using direct absorption. In parallel with the optical components, we have developed integrated electronic systems for laser control, data processing, and acquisition. A prototype instrument suite is described that illustrates the importance of parallel development of optical and electronic components in achieving an apparatus that is compact, fully automated, and highly capable scientifically. Although the emphasis here is on atmospheric tracers, we are applying these technologies to spectroscopic measurements of other atmospheric species such as isotopes, free radicals, and reactive intermediates in order address several urgent science priorities defined by the NRC.