Compact FUV camera concept for space weather applications

Abstract

Far ultraviolet (FUV) images of Earth from space have proven invaluable in revealing contextual phenomena associated with space weather in the high latitude auroral regions and in the mid and equatorial regions. Images of this nature can be used to investigate compelling questions associated with the interaction of the ionosphere/mesospheremagnetosphere-solar wind.Observations using images that lead to quantitative analyses are required to significantly advance the state of knowledge with regard to the affects of space weather and the interaction between and within these regions of Geospace. Current available image data sets are sufficient for qualitative analysis and morphological investigations, and while quantitative analyses are possible, they are difficult and limited to few events at best 1,2 . In order to qualitatively access the time, spatial, and causal phenomena on global scales, simultaneous images of various FUV emissions with a combination of better spatial, temporal and spectral resolution and sensitivity than currently available are required.We present an instrument concept that is being developed to improve the spatial, temporal and spectral resolution and sensitivity needed to perform the quantitative analysis that enable significant advancement in our understanding of the impact of space weather on Geospace. The approach is to use the "self-filtering" concept 3 that combines the imaging and filtering functions and thus reduces the size of the 4-mirror off-axis optical system. The optical and filter design will de described. IntroductionThis paper describes a camera design, referred to as "compact camera" that in principle improves the spatial, temporal, and spectral resolution and sensitivity needed to perform quantitative analysis of earth observations in the far ultraviolet. These observations are required in order to enable significant advancement in our understanding of the impact of space weather on Geospace.Far ultraviolet (FUV) images of Earth from space have proven invaluable in revealing contextual phenomena in the high latitude auroral regions and in the mid and equatorial regions. Images of this nature can be used to investigate compelling questions associated with the interaction of the ionosphere/mesosphere-magnetosphere-solar wind. To significantly advance the state of knowledge with regard to the interaction between and within these regions of geospace, observations that lead to quantitative analyses are required. Current available image data sets are sufficient for qualitative analysis and morphological investigations, and while quantitative analyses are possible, they are difficult and limited to few events at best 1,2 . In order to qualitatively access the time, spatial, and causal phenomena on global scales, simultaneous images of various FUV emissions with a combination of better spatial, temporal and spectral resolution and sensitivity than currently available are required.The coupling between the Magnetosphere and Ionosphere, as reflected in the fluctuating acceleration pot...

Far ultraviolet instrument technology

“…See also Yu et al [] and Yu []. For additional concepts see Spann [] and Tsuruda and Oya []. Auroral Imaging is reviewed in Paxton and Zhang [].…”

The Geospace Dynamics Observatory: a paradigm-changing geospace mission

“…3 The wavelengths, and the spectral, spatial and temporal resolution, are selected to effectively probe the critical interface regions between the Earth's magnetosphere, its ionosphere/thermosphere, and its plasmasphere. This combination provides the key observations to investigate (1) the connections between the Earth's upper atmosphere and the Sun, (2) the dynamics between the neutral dominated region of Earth's upper atmosphere and the plasma dominated region of the ionosphere/thermosphere, and (3) the mechanisms that control the evolution of planetary atmospheres. A comparison of the imaging capability the GDO and previous missions is shown in Table 1.…”

“…GDO observes Geospace, the near-Earth space environment, with unprecedented resolution, scale and sensitivity. In a near-polar circular orbit at 60 Re (~380,000 km) with a ~27-day period, GDO images the earth's full disk with (1) a three-channel far ultraviolet (FUV) imager, (2) an extreme ultraviolet (EUV) imager of the plasmasphere, and (3) a spectrometer in the near to far ultraviolet range that will probe any portion of the disk and simultaneously observe the limb. At the end of a 5-year prime mission, the GDO will be placed into a halo orbit about the Earth-Moon L2 point and continue Geospace observations.…”

Selection of FUV auroral imagers for satellite missions

“…A four-mirror off-axis 20°FOV design was proposed by Spann [2005], which represents a significant increase in image quality and compactness over previous designs, as well as adding the advantageous suppression of out-of-band light inside the FOV of the imager. This design has the combination of two negative mirrors followed by two positive mirrors with the optical axis of the system concentric with the third mirror (also used as the system stop).…”

“…If one were to increase the diameter of the 48°FOV imager photocathode to 40 mm, the corresponding gathering power would significantly increase, by a factor of 2.56 to 1.615 sr cm 2 , while increasing the instrument size to approximately the same dimensions as the 20°FOV imager. The comparison made in Spann [2005] uses a figure of merit that includes the mass of the instrument by dividing the gathering power of the imager by the mass. Since the designs presented have not been carried through to include all the mechanical and electrical components, an estimate of the mass will have to suffice.…”