Lemuel E. Mauldin

Stratospheric aerosol and gas experiment III

SAGE III is part of the Mission to Planet Earths Earth Observatory System with a first launch in the summer of 1998. SAGE III will provide long term monitoring of atmospheric species such as ozone and aerosols which play an important role in global environmental and climatic changes. This paper will briefly describe the goal of the SAGE III experiment, the instrument design, and the development of the processing algorithm for routine data processing to produce scientifically important data products for the science community.

Meteor-3M(1)/Stratospheric Aerosol and Gas Experiment III (SAGE III) jointly sponsored by the National Aeronautics and Space Administration and the Russian Space Agency

The SAGE III is a joint Earth Observing System (EOS) mission between the US NASA and the Russian Space Agency (RSA) to fly aboard the Russian Meteor-3M(1) spacecraft to be launched from the Baikonur Cosmodrome in mid-1999. SAGE III is a spectrometer that measures attenuated radiation in the 282 nm to 1550 nm wavelength range which can be inverted to yield vertical profiles of ozone, aerosols and other species that are critical in studying trends and global change. In addition to SAGE III, the Meteor-3M(1) spacecraft carries nine Russian instruments for analyzing and forecasting environmental change and climate, for hydro-meteorological monitoring and for helio-geophysical research. Both the RSA and NASA are coordinating the activities associated with the joint mission development and implementation, including instrument development, spacecraft development, and mission operations.

The Stratospheric Aerosol and Gas Experiment II (SAGE II) Design and In-Orbit Performance

The design and in-orbit performance data are presented for the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument which was launched by Shuttle on the Earth Radiation Budget Satellite. SAGE II is a Sun photometer that measures the extinction of Solar radiation caused by the Earths atmosphere in seven spectral channels ranging in center wavelength from 0.385 to 1.02 micrometers. These measurements, which occur twice each orbit during satellite sunrise and sunset, are inverted to yield vertical distributions of stratospheric aerosols, ozone, water vapor, and nitrogen dioxide. The SAGE II instrument consists of a Cassegrain telescope with a two axis gimbal mounting, a grating spectrometer, and a 12 bit data system. The instrument tracks the Solar centroid in the aximuth plane and vertically scans the instruments instantaneous field of view across the Sun for tangent altitudes ranging from the Earths horizon to 150 km. SAGE II is a third generation instrument following the highly successful Stratospheric Aerosol Measurement II (SAM II) and SAGE I programs.

Stratospheric aerosol and gas experiment III: aerosol and trace gas measurements for the Earth Observing System

The SAGE III instrument, the latest in a series of satellite-based instruments employing the self-calibrating solar occultation technique to monitor aerosols and trace gases in the atmosphere, and potential contributions to monitoring global change and other EOS objectives are described. Uses of these data are illustrated with SAGE I and II long-term ozone, aerosol, and water vapor data. The SAGE III instrument will improve the SAM II and SAGE data products with greater overall accuracy, and will provide the ability to extend these measurements over a greater height range. SAGE III will provide long-term self-calibrating global data sets from the midtroposphere to mesosphere, which will contribute greatly to the quantification and understanding of global change.

Overview of the SAGE III experiment

The Stratospheric Aerosol and gas Experiment III (SAGE III) is part of the NASA EOS program designed for long term monitoring of atmospheric ozone and aerosol, together with other atmospheric species important to the study of global change. SAGE III is an advanced version of the previous occultation instruments such as SAM II, SAGE I, and SAGE II which have provided long term data on aerosol and ozone for the last twenty years. SAGE III will continue these long term measurements well into the first decade of the 21st century. SAGE III will measure profiles of aerosols, ozone, water vapor, nitrogen dioxide, temperature, pressure, chlorine dioxide, and nitrogen trioxide using the solar and lunar occultation techniques. Currently two SAGE III instruments will be launched between 1999 and 2003. The First SAGE III will be on a Russian Meteor 3M spacecraft to be launched in the Fall of 1999. The second SAGE III will be on the Space Station in 2003.

Application Of The Langley Plot For Calibration Of Sun Sensors For The Halogen Occultation Experiment (Haloe)

The calibration of the Halogen Occultation Experiment (HALOE) sun sensor is described. This system consists of two energy-balancing silicon detectors to provide coarse azimuth and elevation control signals and a silicon photodiode array to provide top and bottom solar edge data for fine elevation control. All three detectors were calibrated on a mountaintop near Tucson, Ariz., using the Langley plot technique. The conventional Langley plot technique was modified to allow calibration of the two coarse detectors, which operate wideband. A brief description of the test setup is given. The HALOE instrument is a gas correlation radiometer that is now being developed for the Upper Atmospheric Research Satellite. A significant part of the paper includes other key features of the instrument for completeness of the subject.

Effect of the induced contamination environment on the long-term degradation of optical payloads

Degradation of sensitive satellite surface scan adversely effect the accuracy, lifetime and mission effectiveness of a spacecraft or payload. More sophisticated and complex space systems have increased the concern about contamination. Thus, it has become necessary to develop better prediction tools and testing techniques for use in contamination prevention and control. This paper discusses the effect of the induced contamination environment on the long-term degradation of two remote sensing instruments. Both instruments were the subject of contamination control programs. The Stratospheric Aerosol Gas Experiment (SAGE II) was launched by the shuttle on the Earth Resources Budget Satellite in 1984. The result of a throughput degradation contamination assessment performed prior to launched compares actual results acquired through March, 1998. The SAGE II instrument still continues to produce data within the limits predicted. A Total Ozone Mapping Spectrometer was launched in 1991 on a Russian Meteor-3 spacecraft. Degradation of the solar calibration diffuser plates have been observed and reported earlier. A new instrument, SAGE II, will be launched in 1999 on another METEOR-3 spacecraft from the Baikonur Cosmodrome in Kazakhstan. The METEOR- 3M/SAGE III is currently undergoing an intense contamination control program in order that data of the same quality as the SAGE II instrument will be realized.

The Stratospheric Aerosol And Gas Experiment III Instrument Proposed For Eos: A Conceptual Design

A conceptual design is presented for the Stratospheric Aerosol and Gas Experiment III (SAGE III) instrument which is currently being proposed for the Earth Observing System (Eos). SAGE III is designed to monitor globally the vertical distribution of stratospheric aerosols, ozone, water vapor, nitrogen dioxide and temperature by measuring the extinction and scattering of solar radiation in the 0.3 to 1.6 μm range through the earths atmosphere. Solar radiation is reflected from a flat scanning mirror into a Cassegrain telescope, which forms an image on the entrance aperture of a grating spectrometer. The aspheric grating forms a stigmatic, flat field image on a silicon CCD array which serves as the detector for eight of the SAGE III channels. An interference filter in front of the array sorts the dispersed energy so that the desired order (either first, second, or third) reaches the focal plane. Pixels are grouped electronically to form the desired spectral bandpass of each channel. The ninth channel is taken from the grating zero order and uses a InGaAs PIN photodiode detector. A two axis gimbal system is capable of tracking (in azimuth) and scanning (in elevation) the sun through the earths atmosphere when in the solar occultation mode, and then performing earth limb scans between occultation events. Data is sampled at 64 times per second and digitized to 14 bit resolution. Wavelength and radiance calibrations can be performed on-orbit. SAGE III has evolved from the highly successful Stratospheric Aerosol Measurement II (SAM II), SAGE, and SAGE II programs.

A Conceptual Design Study For The Eos Lidar Atmospheric Sounder And Altimeter Facility

As part of the Space Station program, NASA is collaborating with the European and Japanese space agencies to develop an unmanned, polar orbiting Earth observing system (Eos) to begin operation in the mid 1990 s Eos will provide, global. measurements with active and passive remote sensors having greater resolution and accuracy than those currently in use. One of the proposed Eos facility instruments, the Lidar Atmospheric Sounder and Altimeter (LASA), is an active remote sensor that offers the possibility of measurements such as the global vertical distributions of aerosols, cloud top heights, atmospheric trace gasses such as water vapor and ozone, and atmospheric temperature and pressure; and the height of the planetary boundary layer (PBL). LASA employs the principles of optical radar (lidar), differential absorption 1 i da r (DIAL), and laser altimetry to provide these measurements with unprecedented resolution. This paper describes the conceptual design of LASA and also describes the conceptual design of one of the experiments proposed for the LASA facility the Eos Atmospheric Global Lidar Experiment (EAGLE).

Application Of A Silicon Photodiode Array For Solar Edge Tracking In The Halogen Occultation Experiment

The optical and electronic design of the Halogen Occultation Experiment (HALOE) elevation sunsensor is described. This system uses a Galilean telescope to form a Solar image on a linear silicon photodiode array. The array is a self-scanned, monolithic charge coupled device. The addresses of both Solar edges imaged on the array are used by the control/pointing system to scan the HALOE science instantaneous-field-of-view (IFOV) across the vertical Solar diameter during instrument calibration, and then maintain the science IFOV four arcmin below the top edge during the science data occultation event. Vertical resolution of 16 arcsec and a radiometric dynamic range of 100 are achieved at the 0.7 micrometer operating wavelength. The design provides for loss of individual photodiode elements without loss of angular tracking capability. The HALOE instrument is a gas correlation radiometer that is now being developed by NASA Langley Research Center for the Upper Atmospheric Research Satellite.