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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Possibilities of observing air pollution from orbital altitudes

Research carried out over a number of years has indicated the feasibility of monitoring global air pollution from orbiting satellites. Optical methods show considerable promise of measuring the burdens of pollution, both gaseous and particulates. Important pollution gases, such as sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone, as well as some hydrocarbon vapors, appear amenable to optical remote sensing. Satellite platforms for carrying out this work would not compete with ground monitoring stations but rather supplement them with a different type of data which could be integrated with ground level measurements to provide an all-embracing picture of pollution buildup, mass migration, and dissipation.

Barringer, A.↗
NASA NTRS1973

Detection of S02 and N02 in Stack Plume by Raman Scattering and Fluorescence

We have been studying laser-Raman radar which can be used as the remote detector of sulfur dioxide concentration in the stack plume of boiler exhaust gas, and some results have been published. In this paper, we report the interference of nitrogen dioxide fluorescence against sulfur dioxide Raman scattering and the measuring method of sulfur dioxide and nitrogen dioxide concentration. In a stack plume, high density dust and high concentration carbon dioxide are included, therefore very strong Mie back-scattering and carbon dioxide Raman scattering are observed. The separation of these scattering signals from sulfur dioxide Raman signal was the first problem for the laser-Raman radar. But, this problem was solved by using the filter which have high resolving power. It is well known that nitrogen dioxide can be excited to emit fluorescence of broad spectrum by blue-green light. The light source of the laser-Raman radar is SH of Nd:YAG laser, and boiler exhaust gas includes several tens ppm of nitrogen dioxide, then the interference of nitrogen dioxide fluorescence brings the error to sulfur dioxide measurement. 'rhe rejection of the interference can be achieved by the subtraction of the nitrogen dioxide fluorescence contribution from detected signal at sulfur dioxide Raman scattering wavelength. The nitrogen dioxide fluorescence contribution can be measured by two methods. The first is to convert the nitrogen dioxide fluorescence intensity which is measured at a different wavelength from sulfur dioxide Raman line into the one at sulfur dioxide Raman line. The second is to convert the detected signal intensity, which is obtained when the range gate is set just behind the plume, into the one obtained at the range of the plume using the difference of the time dependence between sulfur dioxide Raman scattering and nitrogen dioxide fluorescence. Nitrogen dioxide fluorescence has lifetime of about 300nS, while Raman scattering has none. By either of the two methods, the contribution of nitrogen dioxide fluorescence is determined. Then, we can measure the nitrogen dioxide and sulfur dioxide concentration.The minimum detectable concentration and the experimental results of the remote sensing of sulfur dioxide and nitrogen dioxide in stack plume will be discussed in detail.

Nakahara, S.↗
NASA NTRS1979

Monitoring harmful gases

Instruments are developed for monitoring presence of hydrazine and nitrogen dioxide in air. Nitrogen dioxide and hydrazine are highly toxic and explosive substances used in propellants for rocket engines. Instruments discussed are inexpensive and most useful for detecting above substances in concentrations as low as few parts per million.

Helms, W. R.↗
NASA NTRS1971

Application of a Chemiluminescence Detector for the Measurement of Total Oxides of Nitrogen and Ammonia in the Atmosphere

By means of the thermal conversion of nitrogen dioxide to the nitric oxide, the chemiluminescent nitric oxide monitor, based on the nitric oxide plus ozone reaction, may be used for monitoring nitrogen dioxide plus nitric oxide (NO(x)). Under conditions previously described, ammonia is also converted to nitric oxide and therefore interferes. A metal surface, gold wool or stainless steel, operated at two different temperatures has been used to convert only nitrogen dioxide or nitrogen dioxide plus ammonia. Quantitative conversion of nitrogen dioxide to nitric oxide has been obtained at temperatures as low as 200 C. Conversion of ammonia is effected at temperatures of 300 C or higher. By the addition of a converter the basic nitric oxide monitor may be used for measuring NO(x) or NO(x) plus ammonia. As an alternate mode, for a fixed high temperature, a specific scrubber is described for removing NH3 without affecting NO2 concentrations.

Hodgeson, J. A.↗
NASA NTRS2015

Earth Science With the Stratospheric Aerosol and Gas Experiment III (SAGE III) on the International Space Station

The Stratospheric Aerosol and Gas Experiment (SAGE) III is the fourth generation of solar occultation instruments operated by NASA, the first coming under a different acronym, to investigate the Earth's upper atmosphere. Three flight-ready SAGE III instruments were built by Ball Aerospace in the late 1990s, with one launched aboard the former Russian Aviation and Space Agency (now known as Roskosmos) Meteor-3M platform on 10 December 2001 (continuing until the platform lost power in 2006). Another of the original instruments was manifested for the ISS in the 2004 time frame, but was delayed because of budgetary considerations. Fortunately, that SAGE III/ISS mission was restarted in 2009 with a major focus upon filling an anticipated gap in ozone and aerosol observation in the second half of this decade. Here we discuss the mission architecture, its implementation, and data that will be produced by SAGE III/ISS, including their expected accuracy and coverage. The 52-degree inclined orbit of the ISS is well-suited for solar occultation and provides near-global observations on a monthly basis with excellent coverage of low and mid-latitudes. This is similar to that of the SAGE II mission (1985-2005), whose data set has served the international atmospheric science community as a standard for stratospheric ozone and aerosol measurements. The nominal science products include vertical profiles of trace gases, such as ozone, nitrogen dioxide and water vapor, along with multi-wavelength aerosol extinction. Though in the visible portion of the spectrum the brightness of the Sun is one million times that of the full Moon, the SAGE III instrument is designed to cover this large dynamic range and also perform lunar occultations on a routine basis to augment the solar products. The standard lunar products were demonstrated during the SAGE III/M3M mission and include ozone, nitrogen dioxide & nitrogen trioxide. The operational flexibility of the SAGE III spectrometer accomplishes the main goal of producing ozone and aerosol extinction profiles, while allowing exploration of new possibilities for the occultation technique, such as night-time aerosol extinction profiles or other trace gases not measured by SAGE in the past.

Zawodny, Joe↗
NASA NTRS1976

Meteorological adjustment of yearly mean values for air pollutant concentration comparison

Using multiple linear regression analysis, models which estimate mean concentrations of Total Suspended Particulate (TSP), sulfur dioxide, and nitrogen dioxide as a function of several meteorologic variables, two rough economic indicators, and a simple trend in time are studied. Meteorologic data were obtained and do not include inversion heights. The goodness of fit of the estimated models is partially reflected by the squared coefficient of multiple correlation which indicates that, at the various sampling stations, the models accounted for about 23 to 47 percent of the total variance of the observed TSP concentrations. If the resulting model equations are used in place of simple overall means of the observed concentrations, there is about a 20 percent improvement in either: (1) predicting mean concentrations for specified meteorological conditions; or (2) adjusting successive yearly averages to allow for comparisons devoid of meteorological effects. An application to source identification is presented using regression coefficients of wind velocity predictor variables.

Sidik, S. M.↗
NASA NTRS1976

Imaging air pollutants in the near ultraviolet

This paper discusses a program for remote sensing of air pollutants called Multispectral Observation of Pollutants System (MOPS). The broad objective of the program is to photograph 'invisible' gaseous pollutants by combining ultraviolet imaging in several spectral bands with portable data processing equipment. Electronic cameras using solid state imaging arrays of large dynamic range will permit very low contrast images to be electronically ratioed and contrast enhanced, thus bringing out pollutant images which are below the contrast threshold of film. Such photographs will allow synoptic coverage of geographic areas providing source, sink, and flow data on pollutants, and will provide reconnaissance and pointing information for other remote sensors. The principle gases to be mapped by MOPS will be ozone, sulfur dioxide, and nitrogen dioxide.

Norris, D.↗