Peter S. Armstrong

Analysis of hydroxyl earthlimb airglow emissions: Kinetic model for state‐to‐state dynamics of OH (υ,N)

Detailed spectroscopic analysis of hydroxyl fundamental vibration-rotation and pure rotation emission lines has yielded OH(υ,N) absolute column densities for nighttime earthlimb spectra in the 20 to 110-km tangent height region. High-resolution spectra were obtained in the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) experiment. Rotationally thermalized populations in υ = 1–9 have been derived from the fundamental bands between 2000 and 4000 cm−1. Highly rotationally excited populations with N ≤ 33 ( ≤ 2.3 eV rotational energy) have been inferred from the pure rotation spectra between 400 and 1000 cm−1. These emissions originate in the airglow region near 85–90 km altitude. Spectral fits of the pure rotation lines imply equal populations in the spinrotation states F1 and F2 but a ratio Π(A′):Π(A″) = 1.8±0.3 for the Λ-doublet populations. A forward predicting, first-principles kinetic model has been developed for the resultant OH(υ,N) limb column densities. The kinetic model incorporates a necessary and sufficient number of processes known to generate and quench OH(υ,N) in the mesopause region and includes recently calculated vibration-rotation Einstein coefficients for the high-N levels. The model reproduces both the thermal and the highly rotationally excited OH(υ,N) column densities. The tangent height dependence of the rotationally excited OH(υ,N) column densities is consistent with two possible formation mechanisms: (1) transfer of vibrational to rotational energy induced by collisions with O atoms or (2) direct chemical production via H + O3 → OH(υ,N) + O2.

MightySat II.1 hyperspectral imager: summary of on-orbit performance

The primary payload on a small-satellite, the Air Force Research Laboratorys MightySat II.1, is a spatially modulated Fourier Transform Hyperspectral Imager (FTHSI) designed for terrain classification. The heart of this instrument is a solid block Sagnac interferometer with 85cm-1 spectral resolution over the 475nm to 1050nm bands and 30m spatial resolution. Coupled with this hyperspectral imager is a Quad-C40 card, used for on-orbit processing. The satellite was launched on 19 July 2000 into a 575km, 97.8 degree inclination, sun-synchronous orbit. The hyperspectral imager collected its first data set on 1 August 2000, and has been in continuous operation since that time. To the best of our knowledge, the MightySat II.1 sensor is the first true hyperspectral imager to be successfully operated in space. The paper will describe the satellite and instrument, pre-launch calibration results, on-orbit performance, and the calibration process used to characterize the sensor. We will also present data on the projected lifetime of the sensor along with samples of the types of data being collected.

Advanced Responsive Tactically-Effective Military Imaging Spectrometer (ARTEMIS) Design

The advanced responsive tactically-effective military imaging spectrometer (ARTEMIS) is under development for tactical military applications and is the primary payload for the TacSat-3 satellite. The optical design for the telescope, imaging spectrometer, and high resolution imager is described.

Advanced responsive tactically effective military imaging spectrometer (ARTEMIS): system overview and objectives

The Advanced Responsive Tactically-Effective Military Imaging Spectrometer (ARTEMIS) is under development for tactical military applications and is the primary payload for the TacSat-3 satellite. The optical design for the telescope, imaging spectrometer, and high resolution imager is described.

Advanced Responsive Tactically-Effective Military Imaging Spectrometer (ARTEMIS) Development and On-Orbit Focus

The Advanced Responsive Tactically-Effective Military Imaging Spectrometer (ARTEMIS) has been developed by the Raytheon Corporation for tactical military applications and is the primary payload for the Air Force Research Laboratory Tactical Satellite 3 (TacSat-3) initiative to explore the capability and technological maturity of small, low-cost satellites. ARTEMIS is designed to support rapid on-orbit checkout including focusing of the telescope and a robust vicarious calibration campaign. The optical design for the telescope, imaging spectrometer, and high resolution imager is described.

ADVANCED RESPONSIVE TACTICALLY-EFFECTIVE MILITARY IMAGING SPECTROMETER (ARTEMIS) DESIGN

The Advanced Responsive Tactically-Effective Military Imaging Spectrometer (ARTEMIS) is under development for tactical military applications and is the primary payload for the TacSat-3 satellite. The optical design for the telescope, imaging spectrometer, and high resolution imager is described.

Considerations in atmospheric compensation of spectral image data

Atmospheric emission, scattering, and photon absorption degrade spectral imagery data and reduce its utility. We report on the use of an atmospheric compensation code for the visible and near-infrared, based on MODTRAN 4, that includes spectral analysis, accounts for interference to a given pixel by adjacent pixels, and provides a polishing routine to clear residual atmospheric spectral features common to a group of pixels. A NASA/JPL AVIRIS data sample is analyzed.