The Remote Atmospheric and Ionospheric Detection System (RAIDS) experiment is an optical remote sensing platform consisting of eight sensors, (spectrographs, spectrometers, and photometers) covering the wavelength range 550 to 8744 Angstrom. RAIDS employs a mechanical scan platform to view the Earth's limb and measure line-of-sight column emission from tangent altitudes from 50 to 750 km. These measurements provide vertical profiles of atmospheric dayglow and nightglow from the mesosphere to the upper regions of the F-region ionosphere. RAIDS will be flown on the National Oceanographic and Atmospheric Administration (NOAA) J weather satellite through the auspices of the U.S. Air Force Space Test Program, The RAIDS wavelength and altitude coverage allows remote sensing of the major and many minor constituents in the thermosphere and ionosphere. These measurements will be used as part of a proof of concept for remote sensing of ionospheric and neutral density profiles. The RAIDS database will be used to study composition, thermal structure, and couplings between the mesosphere, thermosphere, and ionosphere. RAIDS is a joint venture of the Naval Research Laboratory (NRL) and The Aerospace Corporation. We describe the subset of RAIDS instruments developed at NRL covering the far to near UV regions (1300 to 4000 Angstrom).

The Remote Atmospheric and lonospheric Detection System experiment consists of eight instruments spanning the wavelength range from the extreme ultraviolet (55 nm) to the near infrared (800 nm) oriented to view the Earth's limb from the National Oceanic and Atmospheric Administration TIROS-J spacecraft to be launched into a circular orbit in 1993. Through measurements of the natural optical emissions and scattered sunlight originating in the upper atmosphere including the mesosphere and thermosphere, state variables such as temperature, composition, density, and ion concentration of this region will be inferred. The subset of instruments fabricated or otherwise provided by the Space and Environment Technology Center (formerly Space Sciences Laboratory) at The Aerospace Corporation are described.

The RAIDS experiment is an optical remote sensing platform consisting of eight sensors (spectrographs, spectrometers and photometers) covering the wavelength range 550 A to 8744 A. RAIDS employs a mechanical scan platform to view the Earth's limb and measure vertical profiles of atmospheric dayglow and nightglow from the mesosphere to the upper regions of the F region ionosphere (75 -750 km). RAIDS will be flown on the NOAA J weather satellite through the auspices of the Air Force Space Test Program (STP). The RAIDS wavelength and altitude coverage allows remote sensing of the major, and many minor constituents in the thermosphere and ionosphere. These measurements will be used as part of a proof-of-concept for remote sensing of ionospheric and neutral density profiles. The RAIDS database will be used to study composition, thermal structure and couplings between the mesosphere, thermosphere and ionosphere. RAIDS is a joint venture of the Naval Research Laboratory (NRL) and The Aerospace Corporation. This paper describes the subset of RAIDS instruments developed at NRL covering the far to near ultraviolet (1300 A - 4000 A). A companion paper describes the balance of the experiment complement.

The RAIDS experiment consists of eight instruments spanning the wavelength range from the extreme ultraviolet (55 nm) to the near infrared (800 nm) oriented to view the Earth's limb from the NOAA-J spacecraft to be launched into a circular orbit in 1993. Through measurements of the natural optical emissions and scattered sunlight origmating in the upper atmosphere including the mesosphere and thermosphere, state variables such as temperature, composition, density and ion concentration of this region will be inferred. This paper describes the subset of instruments fabricated or otherwise provided by the Space and Environment Technology Center (formerly Space Sciences Laboratory) at The Aerospace Corp. The companion to this paper describes the instruments from the Naval Research Laboratory. The Extreme Ultraviolet Spectrograph (EUVS), the three fixed filter photometers 0! (630), 0! (777), and Na (589), and the near infrared spectrometer (NIR) will be described. These are all mounted on a mechanical scan platform that scans the limb from approximately 75 to 750 km in the orbital plane of the satellite every 90 seconds.

In the next few years the Remote Atmospheric and Ionospheric Detector System (RAIDS) package will be flown on a TIROS spacecraft. The Extreme Ultraviolet Spectrometer (EUVS) experiment contains a position-sensitive detector based on wedge and strip anode technology. A detector design has been implemented in brazed alumina and Kovar to provide a rugged bakeable housing and anode. A stack of three 80:1 microchannel plates is operated at 3500-4100 V to achieve a gain of about 10{sup 7} power. The top MCP is to be coated with MgF for increased quantum efficiency in the range of 500-1150 A. Fabrication of the wedge and strip anode on brazed alumina has presented some challenging problems. In this report, a summary of fabrication techniques and detector performance characteristics is presented.

We have obtained two mechanically ruled replica gratings from Hyperfine Inc. and one holographically ion-etched grating from Ferranti Astron, Ltd. The gratings, made on spheroid cervit blank, are 86.3 x 86.3 x 12mm and have a groove density of 1710 grooves per mm with a platinum overcoating. The grating manufacturers were given identical specifications (size, groove density reflective coating, etc.). Both gratings were blazed to reflect into the first inside order for a wavelength of ≈ 700 Å. We have evaluated the two gratings at the extreme ultraviolet (EUV) calibration facility at the University of California, Berkeley, Space Sciences Laboratory to determine the suitability for adoption in an EUV spectrometer, the primary instrument of the Remote Atmospheric and Ionospheric Detection System (RAIDS) to be flown aboard a TIROS satellite in 1991. The grating efficiency was measured at five EUV wavelengths using a pencil beam at five positions on the grating. Our measurements show that the efficiencies of the mechanically ruled grating were higher than the holographically ruled grating for the operating order. However, the efficiencies of the holographic grating into the other orders were unexpectedly higher than the ruled ones. The holographically ruled grating displayed about an order of magnitude less scattered light than the mechanically ruled grating.

In the next few years the Remote Atmospheric and Ionospheric Detector System (RAIDS) package will be flown on a Tiros spacecraft. The EUV spectrometer experiment contains a position-sensitive detector based on wedge and strip anode technology. A detector design has been implemented in brazed alumina and kovar to provide a rugged bakeable housing and anode. A stack of three 80:1 microchannel plates is operated at 3500-4100 V. to achieve a gain of about 10 to the 7th. The top MCP is to be coated with MgF for increased quantum efficiency in the range of 50-115 nm. A summary of fabrication techniques and detector performance characteristics is presented.

OH nightglow emissions from the (6, 2) band were observed during February 12–14, 1986, at Sondre Stromfjord, Greenland. The data were analyzed using time series analysis techniques to determine , where ΔI and ΔT represent correlated fluctuations from the mean OH intensity (Ī) and temperature ( ) in various frequency bands. For correlated fluctuations due to measurement error, |η| < 1, while for correlated fluctuations caused by atmospheric gravity waves (AGWs) that pass through the OH emission layer the measured |η| should be generally greater than 1.5. While some of the observed OH intensity‐temperature fluctuations were correlated and had an |η| < 1, two correlated intensity‐temperature waves with periods of 4 and 2 hours were seen with an |η| > 1.5. The 4‐hour (2‐hour) period wave had an |η| equal to 3.1 ± 1.1 (1.6 ± 0.5) and a phase angle, between the intensity and temperature components, of 5° ± 23° (40° ± 20°). These results are consistent with a recent theoretical model for the passage of AGWs through an OH emission layer. Agreement is closest for the 4‐hour (2‐hour) period wave when the layer is peaked at 87 km (83 km) and the O scale height is −2.0 (−4.0km).

The Remote Atmospheric and Ionospheric Detection System (RAIDS) experiment, to fly on a TIROS spacecraft in the late 1980's, consists of a comprehensive set of one limb imaging and seven limb scanning optical sensors. These eight instruments span the spectral range from the extreme ultraviolet to the near infrared, allowing simultaneous observations of the neutral and ion composition on the day and night side as well as in the auroral region. The primary objective of RAIDS is to demonstrate a system for remote sensing of the ionosphere to produce global maps of the electron density, peak altitude and critical frequency.

A microcomputer-controlled and piezoelectrically scanned Fabry–Perot spectrometer capable of being transported to remote field sites has been constructed. The Fabry–Perot has a 70-mm aperture and has a provision for computer control of the cavity drift. The instrument has been operated at resolutions from 0.06–1.5 Å in making high-speed observations of the aurora from 7500–8500 Å. A separate filter-wheel photometer section provides information on other auroral and airglow emissions such as N+2(4278) and OI(6300). The apparatus is portable and has been operated at Poker Flat, Alaska and Churchill, Canada.

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High resolution observations of the OI(7774) and OI(8446) multiplet auroral emissions were made using a Fabry‐Perot spectrometer at Churchill, Canada during March, 1984. The intensity of each of these lines, relative to N2+ (4278) may depend on atmospheric composition. The OI(8446) emission linewidths are under 40 mÅ while the OI(7774) emission linewidths have two components; one narrow (∼ 40 mÅ) and one broad (∼ 275 mÅ). The broad to narrow intensity ratio increases with decreasing red to blue ratio. These results are consistent with electron impact excitation of O being the dominant source of both emissions at high altitudes. However, at lower thermospheric altitudes, dissociative excitation of O2 molecules may be an important source of OI(7774) emission.

A concave grating Wadsworth spectrometer designed to scan the UV limb of the earth was flown on a Defense Department meteorological satellite to obtain measurements of atmospheric emissions in the 85-395-nm wavelength range as a function of height above the solid earth. The instrument field of view was 0.14 x 3.8 degrees corresponding to 6 km in the vertical and 230 km in the horizontal at the limb. The scanning motion was controlled by a momentum compensated dc-torque motor mechanism that panned the line of sight across the limb corresponding to tangent altitudes of 80-480 km. A set of three photon counting detectors, each viewing a separate exit slit, provided simultaneous coverage of the wavelength bands of 85-120 nm (EUV), 110-163 nm (far UV), and 290-395 nm (UV) at a wavelength resolution of 0.4, 0.8, and 1.2 nm, respectively. A separate photometric channel isolated the atmospheric sodium doublet at 589.0-589.6 nm. The grating position and instrument view angle were controlled by digital circuitry operating on hardwired and uplinked command instructions. The operating modes included a variety of scanning and fixed wavelength and view angle operations. A description of the instrument and several examples of the data are presented. These include the dayglow emissions from thermospheric oxygen and nitrogen that form the basis of a thermospheric density determination, auroral enhancements observed in these emissions and in hydrogen Ly-alpha, and nighttime sodium emissions.

: A concave grating Wadsworth spectrometer designed to scan the ultraviolet limb of the earth was flown on a DoD satellite to obtain measurements of atmospheric emissions in the wavelength range of 85 nm to 395 nm as a function of height above the solid earth. The instrument field of view was 0.14 deg x 3.8 deg corresponding to 8 km in the vertical and 230 km in the horizontal at the limb. Scanning motion was controlled by a momentum-compensated DC-torque motor mechanism that panned the line of sight across the limb corresponding to tangent altitudes of 80 km to 480 km. A set of three photon counting detectors, each viewing a separate exit slit, provided simultaneous coverage of the wavelength bands 85-120 nm (EUV), 110-163 nm (FUV) and 290-395 nm (UV), respectively. A separate photometric channel isolated the atmospheric sodium doublet at 589.0-589.6 nm. The grating position and instrument view angle were controlled by digital circuitry operating on hardwired and uplinked command instructions. The operating modes included a variety of scanning and fixed wavelength and view angle operations. A description of the instrument and several examples of the data are presented. These include the dayglow emissions from thermospheric oxygen and nitrogen that form the basis of a thermospheric density determination; auroral enhancements observed in these emissions and in hydrogen Ly alpha; and night-time sodium emissions.

Measurement of densities of the neutral constituents in the thermosphere is of continuing interest to aeronomers. As understanding is improved of the gross response of the thermosphere to such things as changes in solar ultraviolet flux and geomagnetic activity, more and more specific questions are being asked about the detailed thermospheric behavior. The search for greater understanding requires ever more detailed measurements. In the past, measurement of the thermospheric density has been done primarily through drag studies or rocket and satellite borne instruments which directly sample the atmosphere. Only methods employing satellite borne sensors have been able to provide global scale measurements. A common limitation of almost all of the satellite borne sensor techniques used in the past is that neutral densities and compositions are measured only at the satellite location. Thus, while good latitude and longitude coverage is possible, altitude profiles above a fixed surface point have not been possible. In the lower thermosphere (below 150 km) the high drag experienced by satellites with such low perigees makes in situ measurements unattractive.