NOAA's Geostationary Operational Environmental Satellites (GOES) include instruments focused on both terrestrial
weather patterns as well as solar activity. These solar X-ray measurements enable the NWS Space Environment Center
to perform operational specification and to forecast Space Weather phenomenon. The disk-integrated solar X-ray flux
has been recorded for more than three decades by the GOES X-ray Sensor (XRS). GOES-12 Solar X-ray Imager (SXI)
has provided real-time images of the Sun and lower corona since 2003. In October 2004, a sounding rocket underflight
was undertaken with the Avalanche X-ray Spectrometer (AXS) to provide reference or "solar truth" spectra and these
data are being used to provide absolute calibration for the XRS and SXI instruments. We present a report on the progress
of this effort, including results of the data reduction and analysis for the XRS, SXI and AXS. This calibration effort will
increase our understanding of SXI and XRS instrument response functions and will improve the accuracy of space
Solar EUV irradiance plays a critical role in the variability of the upper atmosphere and ionosphere of Earth. Many
systems are impacted by these terrestrial changes including radio communication, GPS navigation, and satellite orbits.
Monitoring the solar EUV irradiance in the past has been left to research satellites and there have been long periods
where gaps in the observational record make it difficult to study and understand the long-term trends and impacts on
Earth. The National Oceanic and Atmospheric Administration (NOAA) has, for the first time, included an EUV Sensor
(EUVS) on the Geostationary Environmental Operational Satellite (GOES). This EUV Sensor (EUVS), launched in
May 2006, is design to provide the solar EUV irradiance information most critical to understanding and modeling
Earth's upper atmosphere. The EUVS has five broad EUV channels between 5 and 125 nm. It uses transmission
gratings and thin-film filters for wavelength discrimination and silicon diodes for detectors. The EUVS was extensively
calibrated at the Brookhaven National Labs Synchrotron Light Source with calibration standards traceable to NIST. It
samples the solar irradiance every ten seconds on a continuous basis from geosynchronous orbit. This paper will provide
an overview of the EUVS design, calibration, and performance results.
NOAA's Geostationary Operational Environmental Satellites (GOES) monitor the solar X-ray activity that enable the NWS Space Environment Center to perform operational specification and forecast of the space environment. The disk-integrated solar X-ray flux has been recorded for more than two decades by the GOES X-ray Sensor (XRS). Since 2003, GOES Solar X-ray Imager (SXI) has provided real-time images of the Sun and lower corona. On 2004 October 15, a sounding rocket launched from White Sands Missile Range marked an important milestone in the first-ever attempt at on-orbit response calibration of GOES X-ray instrumentation. This paper provides an overview of this effort, which includes participation of NOAA, NASA, University of Alaska, and University of Colorado. In addition, results of initial data reduction and analysis for the XRS, SXI, and the sounding rocket are presented.
A series of three-second firings of Space Shuttle Orbiter's 870-lbf Primary Reaction Control System thruster motors were photographed from the crew cabin with an intensified video camera. The spectral imager sequentially recorded 4 ms exposures at 30 Hz in six 20 to 30 nm FWHM channels centered from 400 to 800 nm, chosen specifically to study bi- propellant (monomethyl hydrazine fuel/nitrogen dioxide oxidizer) thruster exhaust chemistry. The species producing the visible radiance were earlier identified as CN, CH, C2, NO2, and HNO; the electronic bands originating from the same excited states of CN (B-X) and CH (A-X) extend into the near UV. Images of the vacuum core viewing within a few degrees of perpendicular to the first several meters from the exit plane were analyzed to relate the spatial distribution of exhaust product species and afterburning chemistry to a flowfield-kinetics model. Profiles of radiance transverse to the exhaust symmetry-axis show substantial limb brightening in all six channels, indicating that the distribution of the radiating species corresponds to a `zone'-type model of liquid-fuel film-cooled engine performance. Profiles of band radiance along the axis indicate the production and quenching of excited species as the exhaust gas adiabatically expands and cools.
The GLO experiment is an on-going shuttle-based spectrograph/imager project that has returned ultraviolet (100 - 400 nm) limb views. High spectral (0.35 nm FWHM) and temporal (4 s) resolution spectra include simultaneous altitude profiles (in the range of 80 - 400 km tangent height with 10 km resolution) of dayglow and nightglow features. Measured emissions include the NO gamma, N2 Vegard-Kaplan and second positive, N2+ first negative, and O2 Herzberg I band systems and both atomic and cation lines of N, O, and Mg. This data represents a low solar activity benchmark for future observations. We report on the status of the GLO project, which included three space flights in 1995, and present spectral data on important ultraviolet band systems.
The GLO experiment includes a ground-controlled shuttle- based UV-vis-IR spectrograph and imager set, and has flown on four space shuttle flights, including three in 1995. Each flight returned limb-view on metal atom and ion emissions in the 80-350 km tangent height region. Improved optics provided 0.3 nm FWHM resolution in the ultraviolet, and simultaneous altitude profiles were routinely measured that spanned 150 km in tangent height with 10-15 km resolution. CLouds of metal ions, particularly Mg+, were observed in daytime above 120 km tangent height near the geomagnetic equator. The GLO project returned approximately 30 gigabytes of spectral data in 1995. The current high altitude metal ion emission measurements are reported here.
Limb observations of UV dayglow emissions from 80 to 300 km tangent heights were made in December 1992 using the GLO instrument, which flew on STS-53 as a Hitchhiker-G experiment. STS-53 was at 330 km altitude and had an orbit inclination of 57 degree(s). The orbit placed the shuttle near the terminator for the entire mission, resulting in a unique set of observations. The GLO instrument consisted of 12 imagers and 9 spectrographs on an Az/El gimbal system. The data was obtained over 6 days of the mission. Emissions from Mg+ and Ca+ were observed, as were emissions from the neutral metallic species Mg and Na. The ultimate source of the metals is ablation of meteors; however, the spatial distribution of the emissions is controlled by upper mesospheric and thermospheric winds and, in the case of the ions, by the electromagnetic fields of the ionosphere. The observed Mg+ emission was the brightest of the metal emissions, and was observed near the poles and around the geomagnetic equator near sunset. The polar emissions were short-lived and intense, indicative of auroral activity. The equatorial emissions were more continuous, with several luminous patches propagating poleward over the period of several orbits. The instrumentation is described, as are spatial and temporal variations of the metal emissions with emphasis on the metal ions. These observations are compared to previous observations of thermospheric metallic species.
The Arizona Imager/Spectrograph is a set of imaging spectrographs and two-dimensional imagers for space flight. Nine nearly identical spectrographs record wavelengths from 114 to 1090 nm with resolution of 0.5 - 1.3 nm. The spatial resolution along the slit is electronically selectable and can reach 192 elements. Twelve passband imagers cover wavelengths in the 160 - 900 nm range and have fields of view from 2 degree(s) to 21 degree(s). The spectrographs and imagers rely on intensified CCD detectors to achieve substantial capability in an instrument of minimum mass and size. By use of innovative coupling techniques only two CCDs are required to record images from 12 imagers, and single CCDs record spectra from pairs of spectrographs. The fields of view of the spectrographs and imagers are coaligned, and all spectra and images can be exposed simultaneously. A scan platform can rotate the sensor head about two orthogonal axes. The Arizona Imager/Spectrograph is designed for investigations of the interaction between the Space Shuttle and its environment. It was flown on a sub-satellite deployed from and retrieved by STS-39.
Results of an analysis of intensified video photographs of a twilight venting of excess water from Space Shuttle are presented. The particle sizes, densities, and temperatures derived from the visible data are applied in estimating UV and IR radiances of the ice/vapor-containing volumes near Shuttle Orbiter, using a recently developed gas-transport/excitation model. The mean radius of the fragmentation-product droplets is 0.13 +/- 0.02 cm. This radius decreases by less than 5 percent over a 2.5-km initial flight path, and these particles survive for several hr. In the UV, intensities of radiation from the fragmentation particles fall off with decreasing wavelength due to the decrease in spectral irradiance of sunlight. In the IR, the mm particles are optically thick, while ice particles not greater than 0.3 micron are inefficient scatterer-radiators, except near 2.7 microns. The large-droplet component thus dominates the radiances even in projections to distant sensors, suppressing the severe spectral structure characteristic of the small droplets.