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Research studies have recently illustrated a plausible relationship between seismic activity and ionospheric disturbances. To elucidate seismo-ionospheric disturbances, we analyzed the temporal and spatial characteristics of ionospheric disturbances associated with large earthquakes that occurred in North America. We selected two strong events with M ≥ 6.5 that took place in 2009 and 2010 during the solar minimum. We used the United States total electron content (US-TEC) measurements as a main dataset, and the changes in the TEC were compared with the variations in the topside plasma density measured by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite. Positive or negative TEC anomalies were observed before (as a precursor) and after the earthquakes. In addition, we found that positive anomalies occurred more frequently than negative ones. Although TEC anomalies occurred at all local times, strong anomalies usually appeared from late afternoon to dawn (16–6 local time). Seismic activity-related TEC anomalies were typically limited to the earthquake region, whereas geomagnetic activity-related TEC anomalies were observed over a vast region. Furthermore, local TEC anomalies occurred over a long period of 20 days preceding and succeeding the earthquakes, in contrast to those associated with geomagnetic activities which occurred concurrently with the geomagnetic disturbances. Additionally, most abnormal increments in the electron density obtained by the DEMETER satellite over the seismic zone coincided with the TEC anomalies. Thus, the variations observed in the TEC and topside electron density before and after these two earthquakes suggest that these ionospheric disturbances are related to seismic activities.

This paper presents the development, testing, and early operation of a space-borne instrument that can measure and identify charged particles and neutrals in the energy range of 20–400 keV with a 6.25 keV energy resolution. The instrument generates electric fields perpendicular to its entrance aperture, which allows it to identify electrons, ions, and neutrals by deflecting the trajectories of charged particles along the direction of the electric fields. Four identical detector pixels with thin windows, relatively positioned along the direction of the electric fields, independently measure each energy distribution of particles with a total geometric factor of approximately 0.01 cm2·sr. In addition, to measure higher particle fluxes, up to 109/(cm2∙sr∙s), a reduction in particle fluxes by a factor of ∼100 is possible with a mechanical attenuator. Two identical telescopes, each with a field-of-view of 15° × 70°, are orthogonally placed to measure particles with different pitch angles relative to local magnetic fields. The test results of the flight model instrument against laboratory radioisotopes, 241Am, 133Ba, and 14C, are provided, together with results from a numerical simulation to estimate the instrument’s performance. The instrument capabilities are successfully demonstrated with energy spectra of particle distributions acquired from in-orbit operations.

In this paper, we present observations of the Space Radiation Detectors (SRDs) onboard the Next Generation Small Satellite-1 (NEXTSat-1) satellite. The SRDs, which are a part of the Instruments for the study of Stable/Storm-time Space (ISSS), consist of the Medium-Energy Particle Detector (MEPD) and the High-Energy Particle Detector (HEPD). The MEPD can detect electrons, ions, and neutrals with energies ranging from 20 to 400 keV, and the HEPD can detect electrons over an energy range from 0.35 to 2 MeV. In this paper, we report an event where particle flux enhancements due to substorm injections are clearly identified in the MEPD A observations at energies of tens of keV. Additionally, we report a specific example observation of the electron distributions over a wide energy range in which we identify electron spatial distributions with energies of tens to hundreds of keV from the MEPD and with energy ranging up to a few MeV from the HEPD in the slot region and outer radiation belts. In addition, for an ~1.5-year period, we confirm that the HEPD successfully observed the well-known outer radiation belt electron flux distributions and their variations in time and L shell in a way consistent with the geomagnetic disturbance levels. Last, we find that the inner edge of the outer radiation belt is mostly coincident with the plasmapause locations in L, somewhat more consistent at subrelativistic energies than at relativistic energies. Based on these example events, we conclude that the SRD observations are of reliable quality, so they are useful for understanding the dynamics of the inner magnetosphere, including substorms and radiation belt variations.

This paper describes the initial operations and preliminary results of the Instrument for the study of Stable/Storm-time Space (ISSS) onboard the microsatellite Next Generation Small Satellite-1 (NEXTSat-1), which was launched on December 4, 2018 into a sun-synchronous orbit at an altitude of 575 km with an orbital inclination angle of 97.7°. The spacecraft and the instruments have been working normally, and the results from the observations are in agreement with those from other satellites. Nevertheless, improvement in both the spacecraft/instrument operation and the analysis is suggested to produce more fruitful scientific results from the satellite operations. It is expected that the ISSS observations will become the main mission of the NEXTSat-1 at the end of 2020, when the technological experiments and astronomical observations terminate after two years of operation.

Ionosphere disturbance which was seen prior to an earthquake which occurred on 11 March 2011 off the coast of Tohoku was studied. Ionosphere data which were used are: O+ density acquired with US satellite DMSP, and NmF2, h’F, and fmin obtained by ionosondes. Global Ionosphere Model (GIM) is used as side evidence to compliment findings from DMSP data and ground- based data. Although magnetic disturbance is strong during the earthquake preparation period, global survey of ground based NmF2 shows that special disturbance is limited to earthquake area. Satellite data (DMSP and GIM) analysis shows four important findings before the occurrence of the earthquake; (1) Over geomagnetic equator enhancement of O+ is found, (2) midlatitude trough (MLT) is formed before the earthquake and it moves toward lower latitude as EQ day approaches, (3) O+ enhancement at the equator side edge of the MLT, and (4) no clear difference of O+ behavior between east and west of the epicenter is identified. These four features are connected each other. Night time NmF2 at high latitude ionosonde stations such as Khabarovsk shows 2 days oscillation from 5 March and disappears on 12 March. As the latitude of the station is lower, 2 days oscillation becomes unclear, and the duration of the appearance is shorter. In order to explain both ground – based and satellite data consistently, enhanced east (west) ward dynamo electric field during daytime (nighttime) are proposed. Our speculation is that internal gravity waves of extremely small amplitude due to the ground motion interact with planetary scales waves below 10 km and is amplified. The amplified IGW propagates to the dynamo region, modifies the wind system, or conductivity, which modifies the electric field. Several observational facts which are favor to the generation of IGW are described. Finally, we stress the need of satellite constellation in order to obtain the global morphology of ionosphere disturbance and to identify the mechanism, which at least provides us the material to judge applicability to future earthquake prediction.

This paper describes the Space Plasma Detectors (SPD) on board the Next Generation Small Satellite-1 (NEXTsat-1), which will observe the thermal plasmas of the ionosphere, especially the plasma irregularities in the low and the middle latitude regions. A SPD consists of a disk-type Langmuir Probe (LP), a Retarding Potential Analyzer (RPA), and an Ion Drift Meter (IDM), which will measure the electron densities and temperatures, the ion densities and temperatures as well as the ion components, and the ion drift velocities, respectively. Whereas SPD employ conventional designs, a high cadence of nominal 100 msec will enable us to study small-scale structures of irregularities, such as plasma bubbles and blobs, with a spatial resolution of less than a kilometer at an altitude of ~ 575 km. Furthermore, the high-resolution mode of the LP operating at a 20 msec cadence will provide data on the electron density and temperature variations with an even better spatial resolution. The NEXTSat-1 is scheduled for launch in early 2018.

The earthquake (EQ) time coupling processes between equator-low-mid latitude ionosphere are complex due to inherent dynamical status of each latitudinal zone and qualified geomagnetic roles working in the system. In an attempt to identify such process, the paper presents temporal and latitudinal variations of ionization density (foF2) covering 45°N to 35°S, during a number of earthquake events (M > 5.5). The approaches adopted for extraction of features by the earthquake induced preparatory processes are discussed in the paper through identification of parameters like the ‘EQ time modification in density gradient’ defined by δ = (foF2 max − foF2 min)∕τmm, where τmm – time span (in days) between EQ modified density maximum and minimum, and the Earthquake time Equatorial Anomaly, i.e. EEA, one of the most significant phenomenon which develops even during night time irrespective of epicenter position. Based on the observations, the paper presents the seismic time coupling dynamics through anomaly like manifestations between equator, low and mid latitude ionosphere bringing in the global Total Electron Content (TEC) features as supporting indices.

Using the ionospheric measurements of CHAMP, DEMETER and DMSP F15, the seasonal and spatial variations of the topside ionosphere during the last solar minimum period were investigated and compared with ionospheric models. In all the satellite measurements, equatorial ionization anomaly (EIA) shows clearly longitudinal asymmetry with wave number -3 or -4 patterns. Anomalous increases of Ne in the nighttime surpassing daytime Ne, known as the Weddell Sea anomaly (WSA) or mid-latitude summer nighttime anomaly (MSNA), were also observed in the global Ne distribution with differences in detailed geometry of the geomagnetic field according to the altitude. In the nighttime ionosphere, the reduced Te in the equatorial region at the DMSP altitude, identified as the equatorial plasma temperature anomaly (EPTA), was ascribed to the leftover of the prereversal enhancement of the upward plasma drift. Though the EIA, WSA, MSNA, and EPTA are all associated with the upward plasma movement, the difference in the thermal evolution is ascribable to the geometry of drift in which the plasma moves across the geomagnetic field line for the EIA and the EPTA, while along the field line for the WSA and the MSNA.

We develop Langmuir probes with different gains to measure the electron density in the lower ionosphere and thermosphere at altitudes of 200 − 380 km on board a CubeSat. These probes sweep over a wide range of voltage, but the data are acquired mostly in the electron saturation region, from which the electron density is calculated. The frequency of the voltage sweep is set at a high level (10 Hz) to reduce the effect of probe contamination. The probes are tested and calibrated in a laboratory chamber that simulates plasma densities similar to those of the lower ionosphere. We report here the measurement principles, system architecture, and test results.

To investigate whether the link between seismic activity and EIA (equatorial ionization anomaly) enhancement is valid for mid-latitude seismic activity, DEMETER observations around seven large earthquakes in the north-east Asian region were fully analyzed ( M ⩾ 6.8 ). In addition, statistical analysis was performed for 35 large earthquakes ( M ⩾ 6.0 ) that occurred during the DEMETER observation period. The results suggest that mid-latitude earthquakes do contribute to EIA enhancement, represented as normalized equatorial N e , and that ionospheric change precedes seismic events, as has been reported in previous studies. According to statistical studies, the normalized equatorial density enhancement is sensitive and proportional to both the magnitude and the hypocenter depth of an earthquake. The mechanisms that can explain the contribution of mid-latitude seismic activity to EIA variation are briefly discussed based on current explanations of the geochemical and ionospheric processes involved in lithosphere–ionosphere interaction.

We have developed a 2.5-dimensional electromagnetic particle simulation code using the particle-in-cell (PIC) method to investigate electromagnetic phenomena that occur in space plasmas. Our code is based on the leap-frog method and the centered difference method for integration and differentiation of the governing equations. We adopted the relativistic Buneman-Boris method to solve the Lorentz force equation and the Esirkepov method to calculate the current density while maintaining charge conservation. Using the developed code, we performed test simulations for electron two-stream instability and electron temperature anisotropy induced instability with the same initial parameters as used in previously reported studies. The test simulation results are almost identical with those of the previous papers.

In this study, we investigated the effect of space plasmas on the floating potential variation of a low-altitude, polar-orbiting satellite using the Langmuir Probe (LP) measurement onboard the STSAT-1 spacecraft. We focused on small potential drops, for which the estimation of plasma density and temperature from LP is available. The floating potential varied according to the variations of plasma density and temperature, similar to the previously reported observations. Most of the potential drops occurred around the nightside auroral region. However, unlike the previous studies where large potential drops were observed with the precipitation of auroral electrons, the potential drops occurred before or after the precipitation of auroral electrons. Statistical analysis shows that the potential drops have good correlation with the temperature increase of cold electrons, which suggests the small potential drops be mainly controlled by the cold ionospheric plasmas.

The FPGA (field programmable gate array) manufactured by using the CCGA484 (ceramic column grid array 484) package has been increasingly growing in demand day by day. However, the CCGA484 package has not been evaluated in space programs yet. In addition, the CCGA484 package is soldered on a PCB (printed circuit board) by the combination of Pb and Sn in ratios from 37% to 67%. If the thermal characteristics of the device for use in space program is to be improved and the numbers of input ports, output ports and internal gates are to increased, the pin quantity and other characteristics of the CCGA484 package must be ensured. During the qualification test for the application of the CCGA484 package in space programs, the changes in properties of the materials in the soldered parts and the changes in the electrical and the physical characteristic were investigated and yielded results that the dose increased from 0 krad to 100 krad. The difference between the electric potential before the radiation and after the accumulation of radiation was less than 0.01%.

We developed a mass-memory chip by staking 1 Gbit double data rate 2 (DDR2) synchronous dynamic random access memory (SDRAM) memory core up to 4 Gbit storage for future satellite missions which require large storage for data collected during the mission execution. To investigate the resistance of the chip to the space radiation environment, we have performed heavy-ion-driven single event experiments using Heavy Ion Medical Accelerator in Chiba medium energy beam line. The radiation characteristics are presented for the DDR2 SDRAM (K4T1G164QE) fabricated in 56 nm technology. The statistical analyses and comparisons of the characteristics of chips fabricated with previous technologies are presented. The cross-section values for various single event categories were derived up to ~80 MeVcm2/mg. Our comparison of the DDR2 SDRAM, which was fabricated in 56 nm technology node, with previous technologies, implies that the increased degree of integration causes the memory chip to become vulnerable to single-event functional interrupt, but resistant to single-event latch-up.

In this paper, we introduce radioisotope facilities and medical particle accelerators that can be applied to space radiation experiments and the experimental conditions required by the space radiation experiments. Space radiation experiments on the ground are critical in determining the lifetimes of satellites and in choosing or preparing the appropriate electrical parts to assure the designated mission lifetime. Before the completion of building the 100-MeV proton linear accelerator in Gyeongju, or even after the completion, the currently existing proton accelerators for medical purposes could suggest an alternative plan. We have performed experiments to calibrate medical proton beam accelerators to investigate whether the beam conditions are suitable for applications to space radiation experiments. Based on the calibration results, we propose reference beam operation conditions for space radiation experiments.

The artificial increase in the solar intensity incident on solar cells using lenses or mirrors can allow solar cells to generate equivalent power with a lower cost. There are two types of concentration optics for solar energy conversion. One is to use mirrors, and the other is to use Fresnel lenses. The gains that can be achieved with a Fresnel lens or a parabolic mirror are compared. The result showed the gains are comparable and the two configurations were developed competitively. In application areas of Fresnel lenses as solar concentrators, several variations of design were devised and tested. Some PV systems still use commercially available flat Fresnel lenses as concentrators. A convex linear Fresnel lens to improve the concentration ratio and the efficiency is devised and flat linear Fresnel lens in thermal energy collection is utilized. In this study, we designed and optimized flat Fresnel lens and the `light pipe` to develop 500X concentrated solar PV system. In the process, we compare the transmission efficiencies according to groove types. We performed rigorous ray tracing simulation of the flat Fresnel lenses. The computer aided simulation showed the `grooves in case` has the better efficiency than that of `grooves out case`. Based on the ray-trace results we designed and manufactured sample Fresnel lenses. The optical performance were measured and compared with ray-trace results. Finally, the optical efficiency was measured to be above 75%. All the design and manufacturing were performed based on that InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. Field test will be made and analyzed in the near future.

We present the first far-ultraviolet (FUV; 1350-1750 A) diffuse emission map of the Eridanus superbubble, obtained using the FIMS/SPEAR instrument. The features seen in the FUV image closely resemble those seen in the Hα map, including two prominent arcs identified earlier in Hα. While it has been argued that the FUV emission in this region is mostly due to the scattering of star light by dust, a close spectral examination reveals that one of the arcs is abundant in molecules and dust while the other is mainly composed of atomic species. Upon comparison to emission maps in other bands (X-ray, IR, optical Hα), we propose the most plausible geometrical structure of this region.

Single Event Upset Measurements of Memory Chips for the Langmuir Probe on STSAT-2 Kwangsun Ryu, Goo-Hwan Shin, Hyung-Myung Kim and Heejoon Kim Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejeon 305-701 Kyungwook Min Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Received 21 September 2007) We have measured the single event e ect (SEE) of candidate memory chips for a Langmuir probe, one of the secondary payloads of STSAT-2 (Science and Technology Satellite-2). The measurements were performed using the cyclotron proton accelerator at Korea Institute of Radiological and Medical Sciences. An ion chamber detector was used for the calibration of the ux of the proton beam. SEU (single event upset) cross-sections for 3 di erent kinds of memory chips were derived according to the incident proton energy. The SEU rate at the STSAT-2 orbit environment was estimated from the SEU cross-section and the modeled particle ux. The program memory chip for the ight model was selected from the candidates. PACS numbers: 61.80.Az, 61.82.Fk, 95.40.+s

An enhanced low dose rate effect (ELDRE) was observed in the radiation-sensitive field effect transistors (RADFETs) developed by the National Microelectronics Research Centre (NMRC) for a low total accumulated dose of less than ∼45 Gy in silicon, or 45 Gy(Si). The effect was seen to persist even after∼8 days of annealing at room temperature, implying that it was not a transient effect but rather a permanent one. On the other hand, the ELDRE was seen to disappear at high total doses of above ∼90 Gy(Si).

We present far-ultraviolet observations of the Antlia supernova remnant obtained with Far-ultraviolet IMaging Spectrograph (FIMS, also called SPEAR). The strongest lines observed are C IV 1548,1551 and C III 977. The C IV emission of this mixed-morphology supernova remnant shows a clumpy distribution, and the line intensity is nearly constant with radius. The C III 977 line, though too weak to be mapped over the whole remnant, is shown to vary radially. The line intensity peaks at about half the radius, and drops at the edge of the remnant. Both the clumpy distribution of C IV and the rise in the C IV to C III ratio towards the edge suggest that central emission is from evaporating cloudlets rather than thermal conduction in a more uniform, dense medium., Comment: 9 pages, 4 figures, will be published in ApJ December 1, 2007, v670n2 issue. see http://astro.snu.ac.kr/~jhshinn/ms.pdf

We have designed a high resolution proton and electron telescope for the detection of high energy particles, which constitute a major part of the space environment. The flux of the particles, in the satellite orbits, can vary abruptly according to the position and solar activities. In this study, a conceptual design of the detector, for adapting these variations with a high energy resolution, was made and the performance was estimated. In addition, a parallel processing algorithm was devised and embodied using FPGA for the high speed data processing, capable of detecting high flux without losing energy resolution, on board a satellite.

A compact far ultraviolet (FUV) spectrograph has been developed and applied to space observation on a micro-satellite. The dual channel imaging spectrograph utilized two micro-channel plate (MCP) detectors with a single crossed delay line (XDL) anode to record photon arrival events. The unconventional anode design allows for the use of a single set of position encoding electronics for both detector fields, thereby reducing the size, weight, and power of the associated electronics. The ground and on-orbit performance tests verified the successful application of the system for astrophysical observations. In this note, we report the design, the development, and the test results of the system, focusing on the XDL anode system.

In this paper, we propose a new configuration of solar concentration optics utilizing modularly faceted Fresnel lenses to achieve a uniform intensity on the absorber plane with a moderate concentration ratio. The uniform illumination is obtained by the superposition of flux distributions resulted from modularly faceted Fresnel lenses. Based on the concept of modularly faceted Fresnel lenses, the cost effective 3-D concentration solar PV system is designed for future applications. Mathematical treatments for deriving the flux distribution and the concentration efficiency at the absorber plane are introduced. As an example, the distribution of the solar flux, at the cell position, is simulated using ray-trace technique for 9, 25, 49, 81, and 121 suns concentration systems. The irradiance distributions at the cell plane are estimated to be uniform within ∼20%, with a transmission efficiency larger than 70% for low and medium concentration ratios (less than 50 suns).

Diffuse far-ultraviolet (FUV: 1370-1670 A) flux from the Taurus molecular cloud region has been observed with the SPEAR/FIMS imaging spectrograph. An FUV continuum map of the Taurus region, similar to the visual extinction maps, shows a distinct cloud core and halo region. The dense cloud core, where the visual extinction is A_v > 1.5, obscures the background diffuse FUV radiation, while a scattered FUV radiation is seen in and beyond the halo region where A_v < 1.5. The total intensity of H2 fluorescence in the cloud halo is I_{H2} = 6.5 x 10^4 photons cm^{-2} s^{-1} sr^{-1} in the 1370-1670 A wavelength band. A synthetic model of the H2 fluorescent emission fits the present observation best with a hydrogen density n_H = 50 cm^{-3}, H2 column density N(H2) = 0.8 x 10^{20} cm^{-2}, and an incident FUV intensity I_{UV} = 0.2. H2 fluorescence is not seen in the core presumably because the required radiation flux to induce fluorescence is unable to penetrate the core region., Accepted for ApJL, 4 pages, 3 figures

We present far-ultraviolet (FUV) spectral images, measured at C IV 1550, He II 1640, Si IV+O IV] 1400, and O III] 1664, of the entire Cygnus Loop, observed with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR) instrument, also known as FIMS. The spatial distribution of FUV emission generally corresponds with a limb-brightened shell, and is similar to optical, radio and X-ray images. The features found in the present work include a ``carrot'', diffuse interior, and breakout features, which have not been seen in previous FUV studies. Shock velocities of 140-160 km/s is found from a line ratio of O IV] to O III], which is insensitive not only to resonance scattering but also to elemental abundance. The estimated velocity indicates that the fast shocks are widespread across the remnant. By comparing various line ratios with steady-state shock models, it is also shown that the resonance scattering is widespread.

The SPEAR (or 'FIMS') instrumentation has been used to conduct the first large-scale spectral mapping of diffuse cosmic far ultraviolet (FUV, 900-1750 AA) emission, including important diagnostics of interstellar hot (10^4 K - 10^6 K) and photoionized plasmas, H_2, and dust scattered starlight. The instrumentation's performance has allowed for the unprecedented detection of astrophysical diffuse far UV emission lines. A spectral resolution of 550 and an imaging resolution of 5' is achieved on-orbit in the Short (900 - 1175 AA) and Long (1335 - 1750 AA) bandpass channels within their respective 7.4 deg x 4.3' and 4.0 deg x 4.6' fields of view. We describe the SPEAR imaging spectrographs, their performance, and the nature and handling of their data.

Diffuse far-UV emission arising from the edge of the Orion-Eridanus superbubble was observed with the SPEAR imaging spectrometer, revealing numerous emission lines arising from both atomic species and H2. Spatial variations in line intensities of CIV, SiII, and OVI, in comparison with soft X-ray, H-alpha and dust data, indicate that these ions are associated with processes at the interface between hot gas inside the bubble and the cooler ambient medium. Thus our observations probe physical conditions of an evolved thermal interface in the ISM.

The FIMS(Far-ultraviolet IMaging Spectrograph), the main payload onboard the first Korean Science Technology SATellite, STSAT-1, has performed various astronomical observations, including the Cygnus Loop, Vela supernova remnants, LMC(Large Magellanic Cloud), since its launch on September 2003. It has been found that the attitude information provided by spacecraft bus system has the errors of more than about 10-15 arcmins due to the time offset problem and errors in attitude knowledge. We develop an algorithm for correction of position errors in FIMS data. The aspect for the FIMS data is determined by comparing the positions of observed bright stars with the Tycho-II and TD-1 catalogs. The position errors of the bright stars along the scanning () and spatial () directions were considered as functions of , ignoring errors in position angle. The corrected positions of the bright stars coincided very well to their Tycho-II and TD-I positions. The correction algorithm is essential for the FIMS data analysis, and is being used for the FIMS data analysis.

Fowl typhoid (FT), caused by Salmonella gallinarum (SG), is responsible for heavy economic losses through morbidity, mortality, and reduced egg production to the poultry industry worldwide. The use of alternative medications to control FT is important in light of emergence of multiple drug-resistant strains of SG and the public's desire to have organically grown poultry. We report the efficient utilization of tissue culture medium waste after harvest of Korean wild ginseng (TCM-KWG) (Panax ginseng) as an alternative medicine in the control of FT. In a series of experiments performed in this study, we found that oral administration of TCM-KWG through drinking water significantly reduced the mortality, organ invasiveness, and fecal shedding of SG in 1-d-old chickens experimentally infected with virulent SG. The results were positively correlated with higher dose and longer duration of pretreatment with TCM-KWG in relation to reduction in mortality caused by FT. The results of this work indicate that the TCM-KWG may be used as a cost-effective and environmentally friendly alternative medicine to control and minimize the losses due to FT in chickens.

The FIMS (Far-ultraviolet IMaging Spectrograph; also known as SPEAR, Spectroscopy of Plasma Evolution from Astrophysical Radiation) is the primary payload of the STSAT-1, the first Korean science satellite, which was launched in September, 2003. The FIMS performs spectral imaging of diffuse far-ultraviolet emission with the unprecedented wide field of view and the relatively good spectral resolution. We present far-ultraviolet spectral observations of highly ionized interstellar medium including supernova remnants, superbubbles, soft X-ray shadows, and the molecular hydrogen fluorescent emission lines. The FIMS has detected He II, C III, 0 III, O IV, Si IV, O VI, and fluorescent emission lines. The emission lines arise in shocked or thermally heated and in photo-ionized gases. We present an overview of the FIMS instrument and its initial observational results.

Far-ultraviolet Imaging Spectrograph (FIMS) is the main payload of the Korea's first scientific micro satellite STSAT-1, which was launched at Sep. 27 2003 successfully. Major objective of FIMS is observing hot gas in the Galaxy in FUV bands to diagnose the energy flow models of the interstellar medium. Supernova remnants, molecular clouds, and Aurora emission in the geomagnetic pole regions are specific targets for pointing observation. Although the whole system was calibrated before launch, it is essential to perform on-orbit calibration for data analysis. For spectral calibration, we observed airglow lines in the atmosphere since they provide good spectral references. We identify and compare the observed airglow lines with model calculations, and correct the spectral distortion appeared in the detector system to improve the spectral resolution of the system.

The FIMS (Far-ultraviolet IMaging Spectrograph), the main payload onboard the first Korean science satellite STSAT-1, has performed various observations since its launch on September 2003. It has been found that the attitude informations provided by spacecraft bus system have a time offset problem, and the problem has been extensively studied. After the time offset correction, boresight offsets between FIMS fields of view, of long and short wavelength bands, respectivley, and spacecraft attitude systems, which are mainly due to alignment error between the FIMS and spacecraft mechanical systems, were calculated through the observations of well known calibration targets. Monthly status and precision of the attitude information are also described. Correction methods for spatially variable exposure, intrinsic to FIMS data, are discussed. These results are essential to the FIMS data analysis, and will be used as references for subsequent studies on more accurate attitude corrections.

FIMS (Far-ultraviolet IMaging Spectrograph) is the main payload of STSAT-1 satellite which was successfully launched on September 27, 2003. The optical system of FIMS consists of two sets of parabolic cylinder mirror, slit, ellipsoidal reflection grating, and baffle system. We designed two types of baffle system for the FIMS: FOV baffle and order baffle. FOV baffle in the mirror house controls the field of view, and the order baffle in the vacuum box blocks the rays reflected rays by different orders.