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Global‐Scale Observations of the Limb and Disk Mission Implementation: 1. Instrument Design and Early Flight Performance
Author(s) -
McClintock William E.,
Eastes Richard W.,
Hoskins Alan C.,
Siegmund Oswald H. W.,
McPhate Jason B.,
Krywonos Andrey,
Solomon Stanley C.,
Burns Alan G.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja027797
Subject(s) - thermosphere , geostationary orbit , ionosphere , physics , remote sensing , environmental science , satellite , space weather , astronomy , geology
Abstract The Global‐scale Observations of the Limb and Disk (GOLD) is a National Aeronautics and Space Administration mission of opportunity designed to study how the Earth's ionosphere‐thermosphere system responds to geomagnetic storms, solar radiation, and upward propagating atmospheric tides and waves. GOLD employs an instrument with two identical ultraviolet spectrographs that make observations of the Earth's thermosphere and ionosphere from a commercial communications satellite owned and operated by Société Européenne des Satellites (SES) and located in geostationary orbit at 47.5° west longitude (near the mouth of the Amazon River). They make images of atomic oxygen 135.6 nm and N 2 Lyman‐Birge‐Hopfield (LBH) 137–162 nm radiances of the entire disk that is observable from geostationary orbit and on the near‐equatorial limb. They also observe occultations of stars to measure molecular oxygen column densities on the limb. Here, we provide an overview of the instrument and compare its prelaunch and early flight measurement performance. Direct comparison of LBH spectra of an electron lamp taken before launch with spectra on orbit provides evidence that both cascade and direct excitation are important sources of thermospheric LBH emission.