Far-ultraviolet and extreme-ultraviolet rocket instrumentation for measuring the solar spectral irradiance and terrestrial airglow

A NASA sounding rocket experiment is being developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) are to be remotely measured from a sounding rocket in September 1992. The rocket experiment also includes EUV instruments from University of California at Berkeley (Supriya Chakrabarti and Kent Tobiska), but only the University of Colorado LASP instruments are discussed here. There are three solar EUV instruments from LASP. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has previously flown on rockets in 1988 and 1989 to measure the solar spectral irradiance from 30 to 110 nm with 0.1 nm resolution. The other solar irradiance instrument is an array of silicon XUV photodiodes with each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 5 to 100 nm with about 15 nm resolution. The third solar LASP instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph will measure the terrestrial FUV airglow emissions along the horizon from 125 to 180 nm with 0.1 nm spectral resolution. The photon-counting detectors used for these instruments, except for the photodiode system, are the CODACON detectors which are coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors are developed at LASP by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations are performed at the LASP calibration laboratory and at the Synchrotron Ultraviolet Radiation Facility (SURF) at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland.