Active Optical Remote Sensing Sensors and Instrumentation for NASAs Future Earth and Space Science Measurements/Missions

AbstractActive optical (Laser/Lidar) measurement techniques are critical for the future National Aeronautics and Space Administration (NASA) Earth, Planetary Science, Exploration, and Aeronautics measurements. The latest science decadal surveys recommend a number of missions requiring active optical systems to meet the science measurement objectives and the aeronautics community continues to use Laser/Lidar technologies to meet the aeronautics measurement objectives. This presentation will provide an overview of NASA efforts in developing and maturing state-of-the-art advanced solid-state flight laser/lidar systems for airborne and space-borne remote sensing measurements. The presentation will also provide details of a strategic approach for active optical technologies and techniques to meet the NASAs future Earth and Space Science measurement ments for space-based applications

A Crop Growth Model For Predicting Corn (Zea mays L.) Preformance in the Tropics

The Crop Environment Resource Synthesis (CERES) maize model was verified, calibrated, and validated on data from a wide range of agroenvironments in the tropics. These agroenvironments ranged from 5 S to 20 N latitude and from sea level to 800 meters above sea level. The model assumed: (i) complete irrigation; (ii) all nutrients at optimum level except nitrogen; (iii) no weeds, pests, and pathogens; and (iv) no wind damage. Adjustments were made only on physiological basis. These adjustments were made to: (i) incorporate soil temperature as a means of computing thermal time up to the tassel initiation stage; (ii) modify maize genotype coefficients based on field data; (iii) raise optimum temperature for photosynthesis; (iv) reflect the effect of minimum temperature instead of mean temperature on grain filling ; (v) reflect the effect of nitrogen deficiency and water stress on grain numbers; and (vi) lower the nitrogen mineralization constant based on mineralogical and chemical properties of the soil. The model was designed to minimize the need for future model calibration when the factors currently not simulated are later incorporated into the model. CEELES maize model predictions for phonological development, kernel weight, kernels per ear, and grain yield were nonsite-specific. The model was sensitive to latitudinal differences, seasonal variation, altitudinal differences, response to nitrogen fertilizer applications and planting density. However, unmeasured environmental and management variables caused considerable differences between simulated and observed values. These variables affected yield predictions and phenological development. The CERES maize model was able to mimic the high sensitivity of maize to temperature and solar radiation. Evaluation of statistical validation techniques indicated that both the R and the Freese statistics required improvements. The R test accepted model predictions which were subjectively "poor" because the field experiment had a large coefficient of variation. The Freese statistics, on the other hand, showed that the CERES maize model was capable of simulating grain yields from 2,500 to 11,200 kg ha”^ with a critical error of approximately 1,200 kg ha“^, in a wide range of agroenvironments, when a model bias to overestimate in yield was taken into account. Phosphorus regression models were developed to determine labile phosphorus, organic phosphorus, buffering capacity, and phosphorus availability index from readily available soil test F methods and soil physical and chemical properties. These models were used to generate input data for the phosphorus simulation model. With the above changes the P model simulated maize grain yields with high accuracy

Development of eye-safe lidar for aerosol measurements

Research is summarized on the development of an eye safe Raman conversion system to carry out lidar measurements of aerosol and clouds from an airborne platform. Radiation is produced at the first Stokes wavelength of 1.54 micron in the eye safe infrared, when methane is used as the Raman-active medium, the pump source being a Nd:YAG laser at 1.064 micron. Results are presented for an experimental study of the dependence of the 1.54 micron first Stokes radiation on the focusing geometry, methane gas pressure, and pump energy. The specific new technique developed for optimizing the first Stokes generation involves retroreflecting the backward-generated first Stokes light back into the Raman cell as a seed Stokes beam which is then amplified in the temporal tail of the pump beam. Almost 20 percent conversion to 1.54 micron is obtained. Complete, assembled hardware for the Raman conversion system was delivered to the Goddard Space Flight Center for a successful GLOBE flight (1989) to measure aerosol backscatter around the Pacific basin

Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. 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. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements

Two Micron Laser Technology Advancements at NASA Langley Research Center

An Independent Laser Review Panel set up to examine NASA s space-based lidar missions and the technology readiness of lasers appropriate for space-based lidars indicated a critical need for an integrated research and development strategy to move laser transmitter technology from low technical readiness levels to the higher levels required for space missions. Based on the review, a multiyear Laser Risk Reduction Program (LRRP) was initiated by NASA in 2002 to develop technologies that ensure the successful development of the broad range of lidar missions envisioned by NASA. This presentation will provide an overview of the development of pulsed 2-micron solid-state laser technologies at NASA Langley Research Center for enabling space-based measurement of wind and carbon dioxide

Solid-State, High Energy 2-Micron Laser Development for Space-Based Remote Sensing

Lidar (light detection and ranging) remote sensing enjoys the advantages of excellent vertical and horizontal resolution; pointing capability; a signal source independent from natural light; and control and knowledge of transmitted wavelength, pulse shape, and polarization and received polarization. Lidar in space is an emerging technology now being developing to fit applications where passive sensors cannot meet current measurement requirements. Technical requirements for space lidar are more demanding than for ground-based or airborne systems. Perhaps the most distinguishing characteristics of space lidars are the environmental requirements. Space lidar systems must be specially designed to survive the mechanical vibration loads of launch and operate in the vacuum of space where exposure to ionizing radiation limits the electronic components available. Finally, space lidars must be designed to be highly reliable because they must operate without the need for repair or adjustment. Lifetime requirements tend to be important drivers of the overall system design. The maturity of the required technologies is a key to the development of any space lidar system. NASA entered a new era in the 1990 s with the approval of several space-based remote sensing missions employing laser radar (lidar) techniques. Following the steps of passive remote sensing and then active radar remote sensing, lidar sensors were a logical next step, providing independence from natural light sources, and better spatial resolution and smaller sensor size than radar sensors. The shorter electromagnetic wavelengths of laser light also allowed signal reflectance from air molecules and aerosol particles. The smaller receiver apertures allowed the concept of scanning the sensor field of view. However, technical problems with several space-based lidar missions during that decade led to concern at NASA about the risk of lidar missions. An external panel was convened to make recommendations to NASA. Their report in 2000 strongly advocated that NASA maintain in-house laser and lidar capability, and that NASA should work to lower the technology risk for all future lidar missions. A multi-Center NASA team formulated an integrated NASA strategy to provide the technology and maturity of systems necessary to make Lidar/Laser systems viable for space-based study and monitoring of the Earth's atmosphere. In 2002 the NASA Earth Science Enterprise (ESE) and Office of Aerospace Technology (OAT) created the Laser Risk Reduction Program (LRRP) and directed NASA Langley Research Center (LaRC) and Goddard Space Flight Center to carry out synergistic and complementary research towards solid-state lasers/lidars developments for space-based remote sensing applications

ESTIMATION OF LEAF AREA OF TARO [COLOCASIA ESCULENTA (L.) SCHOTT] FROM LINEAR MEASUREMENTS

ESTIMATION OF LEAF AREA OF TARO [COLOCASIA ESCULENTA (L.) SCHOTT] FROM LINEAR MEASUREMENT

FLUCONAZOLE NANOGEL: FABRICATION AND IN VITRO EVALUATION FOR TOPICAL APPLICATION

Objective: The aim of this study is to develop and in vitro evaluation of prepared fluconazole nanogel for seborrheic dermatitis Methods: Fluconazole nanogel was formulated to act against seborrheic dermatitis. The fluconazole nanoparticles were prepared by a simplified evaporation method and evaluated for particle size, entrapment efficiency, and percent in vitro drug release. The nanogel was also characterized based on parameters like particle size, percent entrapment efficiency, shape surface morphology, rheological properties, in vitro release R² = 0.9046, and release kinetics. Results: The nanoparticle with a combination of Eudragit RS and Tween 80 showed the best result with particle size in the range of 119.0 nm to 149.5 nm, with a cumulative percent drug release of 95 % up to 18 h. The formulated nanogel with optimum concentration of HPMC authenticate with particle size 149.50±0.5 with maximum drug release (92.13±0.32) %. Conclusion: Different percentages of polymers (ethyl-cellulose, eudragit, and tween 80) are used as variable components in the formulation of nanogel. The optimized batch showed good physical properties (flow index, spreadability, and viscosity) along with rapid drug release. Therefore, it can be concluded that nanogel containing fluconazole has potential application in topical delivery