Steven Li

Steven Li
National Aeronautics and Space Administration

About

62
Publications
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789
Citations

Publications

Publications (62)
Article
Full-text available
At NASA Goddard Space Flight Center (GSFC), we have been developing spaceborne lidar instruments for space sciences. We have successfully flown several missions in the past based on mature diode pumped solid-state laser transmitters. In recent years we have been developing advanced laser technologies for applications such as laser spectroscopy, las...
Poster
Full-text available
ICE µProbe will meet the baseline and threshold requirements for a "vibrational spectrometer" payload that would compliment tthe Europa Lander model payload experimental suite and would address many investigations of the three science goals cited in the Europa Lander 2016 Report Science Traceability Matrix, i.e., (i) search for evidence life (ii) a...
Conference Paper
Full-text available
At NASA Goddard Space Flight Center, we have been developing spaceborne lidar instruments for space sciences. We have successfully flown several missions in the past based on mature diode pumped solid-state laser transmitters. In recent years, we have been developing advanced laser technologies for applications such as laser spectroscopy, laser com...
Conference Paper
The ability to discriminate between different mineral phases in lunar materials is critical in reconstructing the origin and evolution of the moon and understanding its relationship to Earth. Resource identification is also critical to develop a viable long-term lunar exploration program enabling a continued human presence. Mineral-bound metals are...
Conference Paper
The use of epoxies in space-based instruments is often unavoidable in situations where the bonding of dissimilar materials such as glass and metal is required. While there are epoxies that exhibit low total mass loss (TML) and collected volatile condensable materials (CVCM) in vacuum, in some applications they can still be a source of problematic c...
Conference Paper
NASA GSFC is developing a space-based sodium resonance fluorescence lidar for the International Space Station (ISS). We discuss the technology, prototypes, risks and trades for two laser architectures - Raman laser and sum frequency generation.
Conference Paper
We are developing a multi-wavelength laser for the two-step laser time-of-flight mass-spectrometer (L2MS). The L2MS is designed to detect hydrocarbons in organically-doped analog minerals, including cryogenic Ocean World-relevant ices and mixtures for future astrobiology missions.
Conference Paper
Future astrobiology missions will focus on planets with significant astrochemical or potential astrobiological features, such as small, primitive bodies and the icy moons of the outer planets that may host diverse organic compounds. We have made significant progress in the laser desorption/ionization mass spectrometry area with advancement in the t...
Article
Full-text available
The Mercury Laser Altimeter (MLA) is one of the payload instruments on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which was launched on August 3, 2004. MLA maps Mercury's shape and topographic landforms and other surface characteristics using a diode-pumped solid-state laser transmitter and a silicon a...
Article
The LCRD will demonstrate optical communications relay services between a geosynchronous satellite and Earth over an extended period, and thereby gain the knowledge and experience base that will enable NASA to design, procure, and operate cost-effective future optical communications systems and relay networks. LCRD is the next step in NASA eventual...
Article
Full-text available
We report airborne measurements of the column abundance of atmospheric methane made over an altitude range of 3–11 km using a direct detection integrated-path differential-absorption lidar with a pulsed laser emitting at 1651 nm. The laser transmitter was a tunable, seeded optical parametric amplifier pumped by a Nd:YAG laser, and the receiver used...
Article
We demonstrate the airborne measurement of atmospheric methane using a pulsed lidar at 1650 nm using an integrated path differential absorption scheme. Our seeded nanosecond-pulsed optical parametric amplifier (OPA)-based instrument works up to the highest altitudes flown (> 10 km). Our airborne measurements are in good agreement with the expected...
Article
Full-text available
We report on the development effort of a nanosecond-pulsed optical parametric amplifier (OPA) for remote trace gas measurements for Mars and Earth. The OPA output has ˜500 MHz linewidth and is widely tunable at both near-infrared and mid-infrared wavelengths, with an optical-optical conversion efficiency of up to ˜39%. Using this laser source, we d...
Article
Full-text available
NASA is currently developing several Earth science laser missions that were recommended by the US National Research Council (NRC) Earth Science Decadal Report. The Ice Cloud and Land Elevation Satellite-2 (ICESat-2) will carry the Advanced Topographic Laser Altimeter System (ATLAS) is scheduled for launch in 2016. The Active Sensing of CO2 Emission...
Article
Full-text available
A high efficiency, narrow linewidth tunable laser source is developed for greenhouse trace gas remote sensing. It features broad, continuous tuning range at 1570–1655 nm and 3291 nm with narrow linewidth (500 MHz) and high spectral purity. This laser is based on seeded optical parametric generator (OPG) technology. Several trace gas species were co...
Article
Full-text available
We present current and near-term uses of high-power fiber lasers and amplifiers for NASA science and spacecraft applications. Fiber lasers and amplifiers offer numerous advantages for the deployment of instruments on exploration and science remote sensing satellites. Ground-based and airborne systems provide an evolutionary path to space and a mean...
Article
Full-text available
At NASA's Goddard Space Flight Center we are developing next generation laser transmitters for future spaceflight, remote instruments including a micropulse altimeter for ice-sheet and sea ice monitoring, laser spectroscopic measurements of atmospheric CO2 and an imaging lidar for high resolution mapping of the Earth's surface. These laser transmit...
Article
In this paper we present the final configuration of the space flight laser transmitter as delivered to the Lunar Orbiter Laser Altimeter (LOLA) instrument along with some in-space operation performance data. The LOLA instrument is designed to map the lunar surface and provide unprecedented data products in anticipation of future manned flight missi...
Article
At NASA's Goddard Space Flight Center, we are developing the next generation laser transmitters for future remote sensing applications including a micropulse altimeter for ice-sheet monitoring, laser spectroscopic measurements and high resolution mapping of the Earth's surface as well as potential missions to other planets for trace gas measurement...
Article
Full-text available
Trace gases in planetary atmospheres offer important clues as to the origins of the planet's hydrology, geology, atmosphere, and potential for biology. We report on the development effort of a nanosecond-pulsed optical parametric amplifier (OPA) for remote trace gas measurements for Mars and Earth. The OPA output light is single frequency with high...
Conference Paper
Full-text available
We present the final configuration of the space flight laser transmitter as delivered to the Lunar Orbiter Laser Altimeter (LOLA) instrument. The instrument was launched in 2009 and has been in operation for close to two years and accumulated over 1.3 billion laser shots in space.
Article
Full-text available
Many fundamental questions about planetary evolution require monitoring of the planet's atmosphere with unprecedented accuracy at both high and low latitudes, over both day and night and all seasons. Each planetary atmosphere presents its own unique challenges. For the planets/moons that have relatively low surface pressure and low trace gas concen...
Conference Paper
We demonstrated up to 2 W average power, CW-pumped, passively- Q-switched, 1.5 ns monolithic microchip laser with single-longitudinal mode-operation. We discuss various design approaches to bring the average power to 10W and beyond.
Article
We demonstrated up to 2 W average power, CW-pumped, passively-Q-switched, 1.5 ns monolithic MCL with single-longitudinal mode-operation. We discuss laser design issues to bring the average power to 5-10W and beyond.
Article
Full-text available
NASA Goddard Space Flight Center (GSFC) has been engaging in Earth and planetary science remote sensing instruments development for many years. The latest instrument was launched in 2008 to the moon providing the most detailed topographic map of the lunar surface to-date. NASA GSFC is preparing for several future missions, which for the first time...
Article
Atmospheric methane levels have remained relatively constant over the last decade around 1.78 parts per million (ppm) but observations since 2007 show that levels may be increasing. This trend may be caused by increased fossil fuel production, rice farming, livestock and landfills, but the underlying causes are quite uncertain. One hypothesis is th...
Article
The objective of this effort is to develop more reliable, higher efficiency diode pumped Nd:YAG laser systems for space applications by leveraging technology investments from the DoD and other commercial industries. Our goal is to design, build, test and demonstrate the effectiveness of combining 885 nm laser pump diodes and the use of ceramic Nd:Y...
Article
A compact, passively q-switched, single mode laser has been developed for space based lidar applications. The Nd:YAG laser produces 50mJ pulse-energy at 100 Hz repetition rate in a near diffraction limited beam with more than 99.99% of the pulses in a single longitudinal mode. This laser was initially developed as a candidate for the ICESat-2 missi...
Article
Full-text available
We report on the development effort of a nanosecond-pulsed seeded optical parametric generator (OPG) for remote trace gas measurements. The seeded OPG output light is single frequency with high spectral purity and is widely tunable both at 1600nm and 3300nm with an optical-optical conversion efficiency of ~40%. We demonstrated simultaneous tuning o...
Article
Photon-counting detectors are required for numerous NASA future space-based laser receivers including science instruments and free-space optical communication terminals. Silicon avalanche photodiode (APD) single photon counting modules (SPCMs) are used in the Geoscience Laser Altimeter System (GLAS) on Ice, Cloud, and land Elevation Satellite (ICES...
Article
Photon-counting detectors are required for numerous NASA future space-based laser receivers including science instruments and free-space optical communication terminals. Silicon avalanche photodiode (APD) single photon counting modules (SPCMs) are used in the Geoscience Laser Altimeter System (GLAS) on Ice, Cloud, and land Elevation Satellite (ICES...
Article
Measurements of CO2 mixing ratios within the planetary boundary layer will be required to validate the performance of the future ASCENDS instrument. We have adapted the well-known DIAL technique to measure CO2 mixing ratios with the PBL using the 1570 nm band of CO2 and an Optical Parametric Amplifier (OPA). The short-term focus of this effort is t...
Article
We present the final configuration of the space flight laser transmitter as delivered to the LOLA instrument. The laser consists of two oscillators on a single bench, each capable of providing one billion plus shots.
Conference Paper
Full-text available
We present the final configuration of the space flight laser transmitter as delivered to the LOLA instrument. The laser consists of two oscillators on a single bench, each capable of providing one billion plus shots.
Conference Paper
The development and vacuum life-testing of a diode pumped Cr:Nd:YAG laser for space applications is presented. Furthermore results from long life-testing of 808-nm laser diode arrays in air and vacuum are discussed.
Article
Full-text available
A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter, an instrument on the Mercury Surface, Space Environment, Geochemistry, and Ranging mission to the planet Mercury. The laser achieves 5.4% efficiency with a near-diffraction-limited beam. It passed all space-flight environmental tests at subsystem, instr...
Article
We have designed and built two versions of a space-qualifiable, single-frequency Nd:YAG laser. Our approach to frequency stabilization of the seeded oscillator is a variation of the "ramp and fire" technique. In this design, the length of the pulsed laser cavity is periodically varied until a resonance with the seed laser is optically detected. At...
Article
Full-text available
The Goddard Lidar Observatory for Winds (GLOW) is a mobile direct detection Doppler lidar system which uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. In the spring of 2002 GLOW was deployed to the western Oklahoma profiling site (36° 33.500´N500´N, 100° 36.371´W371´...
Article
A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter (MLA) instrument which is an instrument on the MESSENGER mission to the planet Mercury. The laser achieves 5.4 percent efficiency with a near diffraction limited beam. It has passed all space flight environmental tests at system, instrument, and satellit...
Article
The Goddard Lidar Observatory for Winds (GLOW) is a mobile direct detection Doppler lidar system hich uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. In the spring of 2002 GLOW was deployed to the western Oklahoma profiling site (36 deg 33.500 min N, 100 deg 36.371 m...
Article
Full-text available
A Doppler lidar system based on the molecular double-edge technique is described. The system is mounted in a modified van to permit deployment in field operations. The lidar operates with a tripled Nd:YAG laser at 355 nm, a 45-cm-aperture telescope, and a matching azimuth-over-elevation scanner to permit full sky access. Validated atmospheric wind...
Article
We report on the development of GLOW (Goddard Lidar Observatory for Winds), a mobile Doppler lidar system which uses direct detection Doppler lidar techniques to measure wind profiles from the surface into the lower stratosphere. The system employs a Nd:YAG laser transmitter to measure winds using either aerosol backscatter at a wavelength of 1064...
Article
GLOW (Goddard Lidar Observatory for Winds) is a mobile Doppler lidar system which uses direct detection Doppler lidar techniques to measure wind profiles from the surface into the lower stratosphere. The system is contained in a modified van to allow deployment in field operations. The lidar system uses a Nd:YAG laser transmitter to measure winds u...
Article
Global monitoring by satellites is important for many types of environmental studies. Among these, the wind field is the single most important atmospheric state variable required for understanding atmospheric motion and predicting weather. Studies indicate that a global determination of the tropospheric wind field to an accuracy of 1-5 m/sec is cri...
Article
Research has established the importance of global tropospheric wind measurements for large scale improvements in numerical weather prediction. In addition, global wind measurements provide data that are fundamental to the understanding and prediction of global climate change. These tasks are closely linked with the goals of the NASA Earth Science E...
Article
Full-text available
The theory of the double-edge technique is described by a generalized formulation that substantially extends the capabilities of the edge technique. It uses two edges with opposite slopes located about the laser frequency. This doubles the signal change for a given Doppler shift and yields a factor of 1.6 improvement in the measurement accuracy com...
Article
Research has established the importance of global tropospheric wind measurements for large scale improvements in numerical weather prediction. In addition, global wind measurements provide data that are fundamental to the understanding and prediction of global climate change. These tasks are closely linked with the goals of the NASA Earth Science E...
Article
Full-text available
We have developed a Doppler lidar system using the edge technique and have made atmospheric lidar wind measurements. Line-of-sight wind profiles with a vertical resolution of 22 m have a standard deviation of 0.40 m/s for a ten-shot average. Day and night lidar measurements of the vector wind have been made for altitudes from 200 to 2000 m. We vali...
Chapter
We have developed a ground based lidar system using the edge technique and demonstrated wind measurements. Wind profiles with a vertical resolution of 22 m have a standard deviation of 0.4 m/s for a 10 shot average.
Conference Paper
In this paper we present high spatial resolution lidar wind measurements with the edge technique using a ground based lidar system we have recently developed. The edge technique [1],[2] allows measurement of small frequency shifts such as the Doppler shift of an atmospheric backscattered signal from a pulsed laser. This yields a direct measurement...
Article
The edge technique is a new and powerful method for measuring small frequency shifts such as the Doppler shift of an atmospheric backscattered signal from a pulsed laser. The edge technique can be used for high spatial resolution, high accuracy ground and airborne wind measurements as well as high accuracy spaceborne wind measurements. We have rece...
Conference Paper
The edge technique 1,2 is a new and powerful method for measuring small frequency shifts such as the Doppler shift of an atmospheric backscattered signal from a pulsed laser. The edge technique can be used for high spatial resolution, high accuracy ground and airborne wind measurements as well as high accuracy spaceborne wind measurements. We have...
Article
The edge technique can provide high accuracy spaceborne wind measurements as well as high spatial resolution, high accuracy ground and airborne measurements. Global wind measurements can be made with the edge technique from space with an accuracy of 1 m/s and a vertical resolution as high as 150 m in the boundary layer and 1 km through the troposph...
Article
The edge technique can provide high accuracy spaceborne wind measurements as well as high spatial resolution, high accuracy ground and airborne measurements. Global wind measurements can be made with the edge technique from space with an accuracy of 1 m/s and a vertical resolution as high as 150 m in the boundary layer and 1 km through the troposph...
Article
Full-text available
We discuss present and near-term uses for high- power fiber lasers and amplifiers for NASA-specific applications including planetary topography and atmospheric spectroscopy. Fiber lasers and amplifiers offer numerous advantages for both near-term and future deployment of instruments on exploration and science remote sensing orbiting satellites. Gro...

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