NASA's Science Mission Directorate Awards Funding for 15 Projects Under
the Advanced Component Technology (ACT) program of the Earth Science Technology Office
(Research Opportunities in Space and Earth Sciences
NNH10ZDA001N-ROSES-2010, A.36 ACT)

NASA's Science Mission Directorate, NASA Headquarters, Washington, DC, has selected proposals for the Advanced Component Technology Program (ACT-10) in support of the Earth Science Division (ESD). The ACT-10 will support the development of instrument component and subsystem technologies for Earth Science Missions/measurements recommended by National Research Council (NRC) decadal survey.

The ESD is awarding 15 proposals, for a total dollar value over a three-year period of approximately $16 million, through the Earth Science Technology Office located at Goddard Space Flight Center, Greenbelt, Md.

The Advanced Component Technology (ACT) program seeks proposals for technology development activities leading to new component- and subsystem-level airborne and space-based measurement techniques to be developed in support of the Science Mission Directorate’s Earth Science Division. The objectives of the ACT program are to research, develop, and demonstrate component- and subsystem-level technology development that:

The ACT program brings instrument components to a maturity level that allows their integration into other NASA technology programs such as the Instrument Incubator Program. Some of these components are directly infused into mission designs by NASA flight projects and others “graduate” to other technology development programs for further development.

Ninety-six ACT-10 proposals were evaluated of which 15 have been selected for award. The awards are as follows (click on the name to go directly to the project abstract):

Gregory Agnes, Jet Propulsion Laboratory
Precision Deployable Mast for the SWOT KaRIn Instrument

James Anderson, Harvard University
High Power Mid-IR Laser Development 2.8 to 3.5 Microns
William Blackwell, Massachusetts Institute of Technology Lincoln Laboratory
Demonstration of a Hyperspectral Microwave Receiver Subsystem
Goutam Chattopadhyay, Jet Propulsion Laboratory
Advanced Amplifier Based Receiver Front Ends for Submillimeter-Wave Sounders
Thomas Delker, Ball Aerospace & Technologies Corporation
Combined HSRL and Optical Autocovarience Wind Lidar (HOAWL) Demonstration
Jeremy Dobler, ITT Industries, Incorporated
Advancement of the O2 Subsystem to Demonstrate Retrieval of XCO2 Using Simultaneous Laser Absorption Spectrometer Integrated Column Measurements of CO2 and O2
King Fung, Jet Propulsion Laboratory
Advanced W-Band Gallium Nitride Monolithic Microwave Integrated Circuits (MMICs) for Cloud Doppler Radar Supporting ACE
James Hoffman, Jet Propulsion Laboratory
High Efficiency, Digitally Calibrated TR Modules Enabling Lightweight SweepSAR Architectures for DESDynI-Class Radar Instruments
Daniel Jaffe, University of Texas
Development of Immersion Gratings to Enable a Compact Architecture for High Spectral and Spatial Resolution Imaging
Rafael Rincon, Goddard Space Flight Center
Advanced Antenna for Digital Beamforming SAR
Haris Riris, Goddard Space Flight Center
A Compact Remote Sensing Lidar for High Resolution Measurements of Methane
Upendra Singh, NASA Langley Research Center
Design and Fabrication of a Breadboard, Fully Conductively Cooled, 2-Micron, Pulsed Laser for the 3-D Winds Decadal Survey Mission
Xiaoli Sun, Goddard Space Flight Center
HgCdTe Infrared Avalanche Photodiode Single Photon Detector Arrays for the LIST and Other Decadal Missions
Sara Tucker, Ball Aerospace & Technologies Corporation
Fabry-Perot for the Integrated Direct Detection Lidar (FIDDL)

Jirong Yu, NASA Langley Research Center
A 2-Micron Pulsed Laser Transmitter for Direct Detection Column CO2 Measurement from Space

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Gregory Agnes, Jet Propulsion Laboratory
Precision Deployable Mast for the SWOT KaRIn Instrument

We will prototype a deployable boom for a 10-m deployable reflectarray interferometer antenna for use on the Surface Water and Ocean Topography (SWOT) mission, a recently accelerated Tier-2 Decadal mission to measure the earth’s water inventory.  The Ka-Band Radar Interferometer (KaRIn) instrument requires a 10-m class separation of two 5-m x 0.3-m reflectarrays.  During launch, the KaRIn must stow compactly and then deploy with an azimuth mispointing of less than 0.01 degrees and must maintain elevation stability to within 16 milli-arcsec for minutes at a time, far exceeding any heritage systems in both size and accuracy.  Compared to heritage technology, our precision deployable boom technology will reduce the boom's mass by ~25% while increasing its stiffness by over 300%.  This represents a significant improvement of instrument performance margins, cost and mass.

Our objective is to reduce the SWOT mission's performance margin and cost risk by designing and prototyping a lightweight, precision-deployable boom for the SWOT KaRIn antenna.  We will leverage the components currently being developed by ongoing Instrument Incubator Program (IIP) and Advanced Component Technology (ACT) tasks. This effort will enable SWOT to proceed with a reduced performance risk, boom mass, and development time.

Specifically, during the 3 year period of performance  of January 2012 to December 2014, we will:

 

By performing these tests and exercising this model within the SWOT operational scenario, the Precision Deployable Boom technology will advance from an entry Technology Readiness Level (TRL) of 2 to an exit TRL of 4, i.e. "Component model ... in a laboratory environment."


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James Anderson, Harvard University
High Power Mid-IR Laser Development 2.8 to 3.5 Microns

Central to the advancement of both satellite and in situ science are improvements in continuous wave (CW) and pulsed infrared laser systems coupled with integrated miniaturized optics and electronics, allowing for the use of powerful single mode light sources aboard both satellite and UAV platforms. This response to the Advanced Component Technology NRA proposes to further mid-infrared laser technology in order advance two key Earth Science mission concepts recommended by the NRC, The GACM and ASCENDS.

Harvard/JPL proposes to cement their existing partnership in order to develop two high power laser systems (DFB & OPG lasers) that are specifically tuned to measure atmospheric constituents related to ASCENDS and the GACM. By focusing our laser development on the key spectral region between 2.8 # 3.5 ìm, the TRL 5 products of this ACT would enable enhanced in situ and remote detection of several molecules of interest to NASA including OH, H2O, H218O, HDO, CH4, 13CH4, CO2, 13CO2, CH2O, and C2H6.

Support is requested for the three years beginning at the start of the ACT program, approximately 1 January 2012.  For both the CW and pulsed systems, the entry TRL is 3 with a planned exit of TRL 5.


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William Blackwell, Massachusetts Institute of Technology Lincoln Laboratory
Demonstration of a Hyperspectral Microwave Receiver Subsystem

We propose a technology development and demonstration program that would improve both the performance and cost/risk/schedule profiles of multiple NRC Decadal Survey missions, with a focus on the PATH mission.

The first element of the proposed work is the demonstration of a hyperspectral microwave receiver subsystem that was recently shown using a comprehensive simulation study to yield performance that substantially exceeds current state-of-the-art.  Hyperspectral microwave sounders with ~100 channels offer temperature and humidity sounding improvements similar to those obtained when infrared sensors became hyperspectral, but with the relative insensitivity to clouds that characterizes microwave sensors. Hyperspectral microwave operation is achieved using independent RF antenna/receiver arrays that sample the same area/volume of the Earth’s surface/atmosphere at slightly different frequencies and therefore synthesize a set of dense, finely spaced vertical weighting functions. 

The second, enabling element of the proposal is the development of a compact 52-channel Intermediate Frequency processor module.  A principal challenge in the development of a hyperspectral microwave system is the size of the IF filter bank required for channelization.  Large bandwidths are simultaneously processed, thus complicating the use of digital back-ends with associated high complexities, costs, and power requirements.  Our approach involves passive filters implemented using low-temperature co-fired ceramic (LTCC) technology to achieve an ultra-compact module that can be easily integrated with existing RF front-end technology.  This IF processor is universally applicable to other microwave sensing missions requiring compact IF spectrometry.

We propose to advance the TRL of the ultra-compact IF processor module from 3 to 5 through ground thermal and radiometric testing.  The TRL of the hyperspectral microwave receiver subsystem will advance from 3 to 5 upon successful thermal and radiometric assessment.  TRL advancement criteria include 50 operational channels with low IF module volume (<100cm3) and mass (<300g) and linearity better than 0.3% over a 330K dynamic range.


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Goutam Chattopadhyay, Jet Propulsion Laboratory
Advanced Amplifier Based Receiver Front Ends for Submillimeter-Wave Sounders

High Electron Mobility Transistor (HEMT) amplifier based broadband low noise receivers in space will enable an unprecedented combination of sensitivity, resolution, and coverage to study Earth's atmosphere. Implemented on NASA's Global Atmospheric Composition Mission (GACM), these ultra-sensitive receivers will provide the high sensitivity required to complete measurements essential for making informed policy decisions affecting ozone chemistry, climate, and air quality. Integrated with transistor based subharmonic mixers and frequency multipliers as local oscillator sources, these receivers will provide a compact, low-mass, and low-power instrument which will allow very short integration times for rapid detection of weak chemical species important to stratospheric composition studies. Broadband coverage will enable simultaneous measurements of multiple chemicals in the stratosphere.

The objectives are to develop 180-270 GHz and 620-660 GHz sideband separating low-noise amplifier-based receivers for the Scanning Microwave Limb Sounder (SMLS) on GACM.  SMLS was originally planned using superconductor insulator super conductor (SIS) mixers cooled to 4 K. However, this approach of using amplifier-based receivers cooled to 20 K will represent a major simplification in design and mass, power as well as risk reduction for SMLS. 

The first year will begin with testing existing HEMT amplifiers at 20 K temperature and perform stability analysis. We will also design the 230 GHz (180-270 GHz) and 640 GHz (620-660 GHz) amplifiers and mixers to be fabricated at Northrop Grumman. In the second year, we will demonstrate sideband separating receivers operating at room temperature.

In the final year we will focus on the cryogenic testing of the 230 GHz and 640 GHz sideband separating receivers and evaluate them for their noise temperature and stability performance. In this program we will advance the technology readiness level (TRL) from entrance level TRL 3 to an exit level TRL 5 over the three-year period of performance.


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Thomas Delker, Ball Aerospace & Technologies Corporation
Combined HSRL and Optical Autocovarience Wind Lidar (HOAWL) Demonstration

Global observations of atmospheric aerosol scattering and extinction profiles are needed to directly support several Decadal survey missions (e.g. ACE, GACM). Precision passive measurements of atmospheric trace gasses and ocean color require calibrated aerosol profile measurements to perform aerosol scattering calibration corrections. While lidar is an ideal instrument to make range resolved aerosol scattering measurements, simple single channel backscatter lidars (e.g. CALIPSO) cannot directly provide the desired calibrated aerosol scattering profiles because the backscatter signal depends on backscatter cross section from each range and the optical depth to the scattering volume. Fortunately, molecular backscatter is Doppler broadened, while aerosol backscatter remains narrow.

The High Spectral Resolution Lidar (HSRL) technique spectrally separates molecules and aerosols lidar returns. With known air density, HSRL separately measures extinction and scattering at every range. The best current HSRL method uses an iodine absorption filter to eliminate aerosol scatter from the molecular signal, but is limited to iodine absorption feature wavelengths. The most research-valuable wavelength-dependent aerosol property retrievals require three aerosol backscatter wavelength and two extinction wavelength profiles spanning the UV to NIR. Ball has developed the theory for extraction of HSRL data products from a multi-wavelength Optical Autocovariance Wind Lidar (OAWL) instrument simultaneously with Doppler wind lidar measurements. Ground-based Doppler wind lidar measurements from OAWL have successful been demonstrated under a NASA IIP award which will also perform an airborne demonstration.

We propose to leverage the OAWL IIP hardware by augmenting the hardware, and developing the control, acquisition, and processing software to simultaneously demonstrate a multi-wavelength HOAWL implementing an integrated 2alpha+2beta+2delta system, exiting at TRL 4 with a ground-validated HOAWL demonstration. An instrument capable of both wind and HSRL measurements would provide an opportunity to combine the lidar portion of the ACE mission with the 3D-Winds mission, resulting in major cost savings to NASA.


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Jeremy Dobler, ITT Industries, Incorporated
Advancement of the O2 Subsystem to Demonstrate Retrieval of XCO2 Using Simultaneous Laser Absorption Spectrometer Integrated Column Measurements of CO2 and O2

This proposal provides significant risk reduction for the Active Sensing of CO2 Emissions over Nights Days and Seasons (ASCENDS) mission through advancement of the O2 transmitter and the associated algorithms to couple the CO2 and O2 integrated column measurements for retrieval of dry air mole fraction of CO2 (XCO2).  This risk reduction directly aligns with NASA's plan for a Climate-Centric Architecture, which calls for the ASCENDS mission to follow OCO-2 in the 2019 LRD timeframe. The proposed methodology is to leverage the significant progress made by the proposing team during a current 2008 ACT to accomplish the following tasks:

 

Presently, FRAs at the 1.26 micron wavelength are TRL-4 while algorithms for the full retrieval of CO2 mixing ratio are TRL-3. The proposed effort will advance the O2 LAS component for the retrieval of XCO2 to TRL-5+, and the retrieval algorithm/software package developed to support the assessment of the O2 LAS component to TRL-4 through integrated testing with the CO2 LAS instrument.

The benefits of this work include enabling the retrieval of CO2 sources and sinks over all latitudes to improve global models for climate change prediction and enhancing the knowledge base of pressure retrievals in sparsely represented regions for improved numerical weather prediction.  The period of performance will be from 2/2012 - 9/2013.


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King Fung, Jet Propulsion Laboratory
Advanced W-Band Gallium Nitride Monolithic Microwave Integrated Circuits (MMICs) for Cloud Doppler Radar Supporting ACE

We propose to develop advanced electronic Monolithic Microwave Integrated Circuit (MMIC) components that will target the radar instrument for the Aerosol-Cloud-Ecosystem (ACE) Decadal Survey mission.  The MMIC components we will develop will enable radars with improved resolution, reduced ground clutter interference, increased speed of observations, reduce instrument mass and volume, and provide for an inherently redundant system that will reduce risk.  Our team has developed a cloud cross-track scanning dual-frequency Doppler radar (C2D2) concept which makes use of a linear MMIC RF front-end array that satisfies 80 % of the ACE radar goals - more than the ACERAD baseline system.  Critical to C2D2's linear MMIC array are gallium nitride (GaN) semiconductor components that will allow for W-band scanning capability, and improved W-band vertical resolution and swath width size for observations. 

Our objective is to provide better electronic capabilities through utilization of recently emerging GaN MMIC technology for amplifiers, switches and phase shifters in the RF front end.  GaN is capable of higher power density operation (more than 8x) and higher efficiency circuits (more than 2x) than the prior art - gallium arsenide technology, such as that used for W-band power amplifiers in the Herschel Heterodyne Instrument for the Far Infrared.  GaN allows for smaller and more efficient components, and will be critical for allowing implementation of compact efficient radars as well as receiver/transmitter arrays for spectrometers and communication systems.


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James Hoffman, Jet Propulsion Laboratory
High Efficiency, Digitally Calibrated TR Modules Enabling Lightweight SweepSAR Architectures for DESDynI-Class Radar Instruments

The calibration of current state-of-the-art Electronically Steered Arrays (ESAs) typically involves pre-flight TR (Transmit/Receive) module characterization over temperature, and in-flight correction based on temperature, which ignores the effects of element aging and drifts unrelated to temperature.

The objective of this technology is to reduce the development time, risk and cost of precision calibrated TR modules for Digital Beamforming (DBF) by accurately tracking modules' characteristics through closed-loop Digital Calibration, which tracks systematic changes regardless of temperature. The benefit of this effort is that it enables a new class of lightweight radar architecture, SweepSAR, providing significantly larger swath coverage than conventional SAR architectures for reduced mass and cost. The SweepSAR architecture is being developed for DESDynI's (Deformation, Ecosystem Structure, and Dynamics of Ice) radar, a mission recommended by the National Research Council as a Tier 1 Earth Science mission.

Our technology will allow tracking of phase and amplitude of the DESDynI TR modules' receiver and transmitter chains, with an accuracy of 0.06 degrees for phase and 0.01 dB for amplitude. Corrections will be made to this level on receive, by adjusting beamforming coefficients, and to 3 degrees phase on transmit using a phase-shifter. No known TR module has this performance.

We will modify existing prototypes of L-band RF TR modules and of the digital board designs to implement and demonstrate the calibration algorithm. By injecting signals of known amplitude, phase and frequency, at different points of the RF circuit, digitizing and processing the signals in real-time, we will be able to track changes in the system characteristics and modify the beamforming coefficients enabling us to correct for changes in the system's response.

The outcome of this work will be a precision, digitally calibrated TR module/beamforming system, which will enable a DBF radar that takes advantage of  lightweight SweepSAR architectures, reducing mass, risk and cost. The technology development, design, and testing will take place over a three year period. The entry TRL of our technology is 3 while the planned exit TRL is 5.


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Daniel Jaffe, University of Texas
Development of Immersion Gratings to Enable a Compact Architecture for High Spectral and Spatial Resolution Imaging

We will build and thoroughly test a set of silicon immersion gratings customized for the needs of Earth observation systems. A number of Earth Science review documents recognize the need for space-based observations of the total column amount of greenhouse gases.  Improvement in scientific understanding, in particular of the association of local variations in abundances with possible sources and sinks, however, requires simultaneous high spectral and spatial resolution as well as areal coverage that is beyond what current technology can provide at an affordable volume and mass.  

Immersion gratings can offer a breakthrough to provide this capability in the short-wave infrared.  These gratings, where light diffracts from a grating illuminated from inside a dielectric material, make it possible to reduce the mass and volume of spectrally multiplexed spectrometers with a given etendue by an order of magnitude.  Our team has extensive experience in grating production for space instruments.  UT and JPL are currently collaborating to develop immersion gratings for astrophysics applications. Several of the requirements imposed by Earth Science missions, however, force us to investigate new techniques in grating production. We propose to leverage our current effort with a program to develop and test immersion gratings suitable for the critical Earth Science missions of the future.


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Rafael Rincon, Goddard Space Flight Center
Advanced Antenna for Digital Beamforming SAR

We proposed to develop a wideband L-band phased-array antenna for airborne Synthetic Aperture Radar (SAR) applications based on a novel approach that will make possible meter-resolution and fully polarimetric measurements of permafrost and biomass. These measurements provide information on the interaction between permafrost and biomass with the atmosphere, helping us improve our understanding of the carbon cycle. Our innovative design approach provides over 500 MHz of bandwidth and cross-polarization isolation better than -50 dB, enabling high resolution imaging of the full radar backscattering matrix, and permitting an accurate characterization of permafrost and biomass. 

The long term goal of the proposed work is to enable the second generation airborne Digital Beamforming Synthetic Aperture Radar (DBSAR-2) which significantly enhances the scientific measuring capability of existing SAR systems. Our design will yield a compact and light weight instrument permitting its installation on a range of aircrafts, thereby enabling more opportunities to obtain the needed science measurements for carbon cycle research. Our design will also set a path for the next generation of Earth observing digital beamforming SAR in support of  NASA’s Plan for a Climate-Centric Architecture.

The large bandwidth of the antenna can also expand the scientific measuring capability of DBSAR-2 by enabling the co-incident reception and processing of reflected signals from the Global Navigation Satellite System (GNSS-R). The combined SAR and GNSS-R measurements can also provide information on important parameters such as ocean roughness, sea height, soil moisture, and ice classification, relevant to climate change.

The proposed development will be accomplished in two years. The first year will be dedicated to simulations, development, testing, characterization, and optimization of an antenna subarray. Efforts in year 2 will be devoted to the simulation, fabrication, testing and verification of the full array. The entry and exit TRL for the development is 2 and 4, respectively.

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Haris Riris, Goddard Space Flight Center
A Compact Remote Sensing Lidar for High Resolution Measurements of Methane

We propose to develop the technology for a compact, space-qualifiable laser transmitter for a lidar (LIght Detection And Ranging), operating in the near-infrared region, that can measure methane and other greenhouse gases with very high spatial resolution and sensitivity. This work is directly relevant to NRC's Decadal Survey: Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond [National Academic Press 2007] which called explicitly for cost-effective methane technology.

Methane is the second most important anthropogenically produced greenhouse gas [IPCC 2007]. Though its atmospheric abundance is much lower than CO2 (1.78 ppm vs. 380 ppm) it has much larger (×23) radiative forcing per molecule.  Methane also contributes to pollution in the lower atmosphere through chemical reactions leading to ozone production.  Atmospheric methane concentrations have been increasing as a result of increased fossil fuel production, rice farming, livestock and landfills, and the thawing of the Arctic permafrost.  Vast amounts of methane are contained in the continental shelf in the form of methane hydrates and mass extinction events in the past have been attributed to climate altering releases from these stores. Important sinks for methane include oxidation by hydroxyl radicals in the atmosphere and non-saturated.  Better knowledge of the methane global distribution, sources and sinks is imperative for a more accurate assessment of its impact on global climate change.  The Decadal Survey for Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) recognized the importance of methane and explicitly stated that: "Ideally, to close the carbon budget, methane should also be addressed, but the required technology is not now obvious. If appropriate and cost-effective methane technology becomes available, methane capability should be added."

At GSFC we have demonstrated CO2, and O2 lidar measurements from airborne platforms as part of our ASCENDS program.  We have also demonstrated and validated methane measurements in absorption cells and in open paths at 3.3 µm and 1.65 µm using a laboratory prototype lidar instrument with a low power transmitter. 
           
For this work we propose to:

The proposed work will commence in January 2012 and conclude three years later.


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Upendra Singh, NASA Langley Research Center
Design and Fabrication of a Breadboard, Fully Conductively Cooled, 2-Micron, Pulsed Laser for the 3-D Winds Decadal Survey Mission

We propose to design and fabricate a fully conductively cooled pulsed, 2-micron laser transmitter to enable a space-based, coherent-detection, Doppler wind profiling lidar system for the NRC “3-D Winds” Decadal Survey Mission. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. Development of a long-life, high energy, high efficiency, high beam quality, single frequency, compact, reliable and fully conductively cooled solid state 2-micron laser transmitter is critically needed for space-based “3-D Winds” mission envisioned in the NRC Decadal Survey.

Sustained 2-micron solid-state laser research at NASA Langley Research Center during the last fifteen years, primarily funded by NASA’s Earth Science Technology Office, has demonstrated record pulse energy of 1200 mJ,  obtained the required beam quality and pulse spectrum, and demonstrated a compactly packaged 250 mJ, 10 Hz laser with the receiver. In Aug/Sept 2010, LaRC successfully flew the packaged liquid-cooled laser/lidar system on NASA’s DC-8 aircraft. For space application, NASA LaRC researchers developed and demonstrated a fully conductive-cooled 2-micron oscillator/amplifier modules delivering 400 mJ.  LaRC also teamed with Fibertek, Inc. and was awarded an Innovative Partnership Program-2007 project. Under this, LaRC transferred the 2-micron laser design to Fibertek Inc.  Fibertek is currently nearing completion of fabrication of a first generation of 2-micron pulsed conductively-cooled laser.

We propose, in partnership with Fibertek, to engineer a robustly packaged “space qualifiable” fully conductively-cooled 2-micron laser with highly efficient 808 nm diodes, and thoroughly test it for its capability to make accurate wind measurements from space. The proposed prototype will be completed in 3 years.  We will advance the TRL from entrance level 3 to exit level 5.

We will utilize approximately $265K of laser/optics parts that remain from prior projects, as a contribution to this effort.


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Xiaoli Sun, Goddard Space Flight Center
HgCdTe Infrared Avalanche Photodiode Single Photon Detector Arrays for the LIST and Other Decadal Missions

In its 2007 Earth Science Decadal Survey report, the NRC recommended that NASA conduct the LIDAR Surface Topography (LIST) mission.  The LIST mission objectives are to globally map the elevation of the Earth’s solid surface and its overlying covers of vegetation, water, snow, and ice. The mapping is to be done with a 5 km swath width, 5 m spatial resolution and with ~10 cm vertical accuracy. The LIST mission poses significant technical challenges requiring a highly efficient measurement approach and a robust lidar design that accommodates the variable atmospheric and surface conditions. 

Through prior work sponsored by the ESTO IIP program, Goddard investigators have  developed and analyzed a promising swath mapping lidar (or pushbroom lidar) approach for LIST.  This non-scanning pulsed direct detection approach is very electrically efficient and uses 1000 parallel laser beams to simultaneously profile the surface height. This permits simultaneous measurements of 5-m spatial resolution topography and vegetation structure with 10 cm vertical precision in a swath 5 km wide from a 400 km altitude orbit.  Work at Goddard has shown that this is approach is promising for meeting the demanding goals of the LIST mission.  An initial airborne demonstration lidar,  the Airborne LIST Simulator (A-LISTS), uses16 beams and is being developed now.

A key and challenging component for the LIST mission is a highly sensitive array detector for the lidar receiver, which has the needed speed, dynamic range and 5-year lifetime.   All previous candidates have had sensitivity, dynamic range or lifetime issues. Here we propose to adapt and demonstrate the new and highly sensitive HgCdTe e-APD detector array technology, developed at DRS, for the LIST lidar receiver. The detector will be the DRS solid-state, noiseless gain, linear mode, HgCdTe e APD fabricated on a custom design fanout and wire bonded to a custom designed ROIC.  The HgCdTe e-APD technology developed at DRS has demonstrated very low dark currents and noiseless gains >1000 in single pixels. DRS has demonstrated e-APD technology in large area focal plane arrays (FPAs) on several U.S. government sponsored programs.  For example, the 128x128 gated-imaging SCAs have demonstrated median gains as high as 940 with 0.4 photon noise equivalent sensitivity.  Recently DRS delivered a high sensitivity 2x8 detector array with photon counting sensitivity, a probability of detection > 20%, 6-nsec response time, and a dynamic range of 50 photoelectrons per pulse. These parameters are close to those needed for LIST.  DRS is in an excellent position to apply their expertise to LIST due to strength of their fundamental e-APD understanding and technology base.  

We propose a three year work program with the first two years concentrating on assessing, adapting and optimizing the DRS detector technology development for LIST lidar receiver. In Year 3 we will assess the performance of a delivered detector array at Goddard and demonstrate its performance with the A-LIST instrument. Our entry TRL is estimated to be at 3 and we expect to exit at TRL 6.


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Sara Tucker, Ball Aerospace & Technologies Corporation
Fabry-Perot for the Integrated Direct Detection Lidar (FIDDL)

The Decadal Survey identifies the 3D-Winds mission as critical to improving both global climate change observations and weather and air quality forecasting. A successful 3D-Winds mission requires measurement of wind profiles under all aerosol loading conditions including clean air.  To achieve this with meteorologically relevant precision and necessary spatial availability requires measuring the Doppler shift from both aerosol and molecular backscatter. The Integrated Direct Detection (IDD) hybrid Doppler Wind Lidar approach proposed for the Decadal Survey 3D-Winds mission employs a single common laser, aperture/telescope, and signal processor to achieve both aerosol and molecular backscatter wind profiles. The IDD system offers beneficial reductions in cost, mass, and technical risk over the currently baselined two-wavelength/two-lidar approach which requires two complex disparate lasers and two receivers that share few system requirements or resources. The alternative IDD hybrid approach consists of the Optical Autocovariance interferometer receiver, developed at Ball Aerospace, a single receiver telescope, laser, and data system (developed under the ESTO funded Optical Autocovariance Wind Lidar (OAWL) IIP), and a proposed, novel, compact, double-edge, Fabry-Perot etalon and control system designed at Ball to easily integrate with the OAWL interferometer. The Ball etalon approach uses polarization multiplexing to generate two tunable paths within the same etalon volume providing additional cost, mass, and volume savings over stepped-mirror approaches.

Under this ACT we propose to optimize the design of and fabricate a double-edge, polarization multiplexed, etalon receiver sub-system and integrate it into the IIP OAWL. The resulting Fabry-perot for the Integrated Direct Detection Lidar (FIDDL) receiver component will complete the IDD wind lidar system, enabling it to demonstrate simultaneous wind measurements from aerosol and molecular atmospheric returns with a single common laser, telescope, and data system. Development and integration (with OAWL) of the FIDDL component over a 3-year period provides critical technology advancement and demonstrates hybrid wind profiles from a system scalable to the IDD 3D-Winds mission.  The compact FIDDL component technology (and thus the IDD hybrid) is currently at TRL2 and will be raised to TRL4 by this effort.


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Jirong Yu, NASA Langley Research Center
A 2-Micron Pulsed Laser Transmitter for Direct Detection Column CO2 Measurement from Space

We propose to develop an efficient 2µm pulsed laser for direct detection column CO2 measurement to support the Active Sensing of CO2 Emissions over Night, Days, and Seasons (ASCENDS) mission called for in the Decadal Survey [1]. Recent comprehensive CO2 mission studies considered both 1.57 and 2.05 μm wavelength bands as viable options for CO2 column measurements via the Integrated Path Differential Absorption (IPDA) method. [2-4]  The latter, being the stronger band, is more amenable to probing the atmosphere with a weighting function that emphasizes the lowest few kms above the surface, where the CO2 sources and sinks of scientific interest exist, with optimum differential absorption optical depth [5, 6]. A high energy pulsed approach also provides high-precision measurement capbility by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

The proposed pulsed 2µm laser is based on Thulium fiber laser pumped Holmium (Ho) solid-state laser technology in a Master-Oscillator-Power-Amplifier (MOPA) configuration. It leverages the technologies successfully developed under Laser Risk Reduction Program (LRRP) funded by NASA’s Earth Science Technology Office (ESTO) in the last 4 years.  The laser advantages include high energy storage, high electrical efficiency, compact size and low mass. The 2μm laser technology is at a point where there is a clear technology development path to a robust prototype with 50-100 mJ pulse energy at 50 Hz as needed for space based mission.

The proposed 2µm laser prototype will be completed in 3 years.  We will advance the TRL from entrance level 3 to exit level 5. The 2µm laser that we will demonstrate as the outcome of this investigation can be used in the development of an innovative pulsed lidar instrument to make precise, accurate, high-resolution atmospheric CO2 measurements in support of the ASCENDS mission.

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