• 천문학회보
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• 제35권1호
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• pp.40.1-40.1
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• 2010

The Main payload of the STSAT-3 (Korea Science & Technology Satellite-3), MIRIS (Multipurpose Infra-Red Imaging System) has been developed for last 3 years by KASI, and its Flight Model (FM) is now being developed as the final stage. All optical lenses and the opto-mechanical components of the FM have been completely fabricated with slight modifications that have been made to some components based on the Engineering Qualification Model (EQM) performances. The components of the telescope have been assembled and the test results show its optical performances are acceptable for required specifications in visual wavelength (@633 nm) at room temperature. The ensuing focal plane integration and focus test will be made soon using the vacuum chamber. The MIRIS mechanical structure of the EQM has been modified to develop FM according to the performance and environment test results. The filter-wheel module in the cryostat was newly designed with Finite Element Analysis (FEM) in order to compensate for the vibration stress in the launching conditions. Surface finishing of all components were also modified to implement the thermal model for the passive cooling technique. The FM electronics design has been completed for final fabrication process. Some minor modifications of the electronics boards were made based on EQM test performances. The ground calibration tests of MIRIS FM will be made with the science grade Teledyne PICNIC IR-array.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2007년도 한국우주과학회보 제16권2호
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• pp.139-143
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• 2007

전기 추진시스템은 저렴한 개발비와 높은 신뢰성을 제공하는 추진 장치로 많은 분야에서 응용 되어 왔다. 특히 최근에 발사된 SMART-1과 MUSES-C는 우리에게 시사하는 바가 크다. 각각 European Space Agency(ESA)와 Japan Aerospace Exploration Agency(JAXA)에서 개발한 행성 탐사선으로, SMART-1은 달 탐사를 목적으로 하고 MUSES-C는 소행성 Itokawa의 토양을 채취해오는 것을 목적으로 한다. 이 두 탐사선에는 각각 Hall effect thruster와 Micro wave ion engine이 탑재되었는데, 작고 저렴한 비용의 탐사선을 이용해서 충분히 행성 탐사가 가능하다는 좋은 선례를 남겼다. 현재 개발되고 있는 과학기술위성 3호(STSAT-3)에도 전기추진 장치가 탑재되는데, SMART-1에 탑재 되었던 것과 유사한 Hall effect thruster가 인공위성 연구센터와 KAIST 물리학과의 GDPL과 공동으로 개발되고 있다. 성능이 좋은 전기 추력 장치를 개발하기 위해 추력기 내부에서 발생하는 플라즈마의 물리적 특성을 파악하는 것은 매우 중요한 일이다. 이 논문에서는 이러한 플라즈마의 특성을 모사하는 방법으로 Particle In Cell 모사와 더불어 독립적인 개개 입자의 운동을 기술하는 입자모사(particle simulation)를 이용하는 방법을 제시 하고자 한다. 이러한 접근 방법은 실제 전기추력장치를 설계하고 실험하는 담당자에게 플라즈마 운동에 대한 명료한 지식을 제공해 줄 수 있을 것으로 생각된다.

• 천문학회보
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• 제37권2호
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• pp.97.2-97.2
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• 2012

The main payload of Science and Technology Satellite 3 (STSAT-3), Multipurpose InfraRed Imaging System (MIRIS) is the first Korean infrared space mission to explore the near-infrared sky with a small astronomical instrument developed by KASI. The 8-cm passively cooled telescope with a wide field of view (3.67 deg. ${\times}$ 3.67 deg.) will be operated in the wavelength range from 0.9 to $2{\mu}m$. It will carry out wide-band imaging and the Paschen-${\alpha}$ emission line survey. After the calibration of MIRIS in our laboratory, MIRIS has been delivered to SaTReC and successfully assembled into the STSAT-3. The main purposes of MIRIS are to perform the observation of Cosmic Infrared Background (CIB) at two wide spectral bands (I and H band) and to survey the Galactic plane at $1.88{\mu}m$ wavelength, the Paschen-${\alpha}$ emission line. CIB observation enables us to reveal the nature of degree-scale CIB fluctuation detected by the IRTS (Infrared Telescope in Space) mission and to measure the absolute CIB level. The MIRIS will continuously monitor the seasonal variation of the zodiacal light towards the both north and south ecliptic poles for the purpose of calibration as well as the effective removal of zodiacal light. The Pashen-${\alpha}$ emission line survey of Galactic plane helps us to understand the origin of Warm Ionized Medium (WIM) and to find the physical properties of interstellar turbulence related to star formation. Here, we also discuss the observation plan with MIRIS.

• 한국광학회지
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• 제22권6호
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• pp.262-268
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• 2011

한국천문연구원이 개발한 다목적적외선영상시스템(Multi-purpose IR Imaging System, MIRIS)은 과학기술위성 3호(STSAT-3)의 주탑재체이다. 지구관측카메라(Earth Observation Camera, EOC)는 MIRIS를 구성하는 두 개의 적외선 카메라 중에 하나로, 지구의 $3{\sim}5{\mu}m$ 파장대의 적외선을 관측하기 위한 카메라이다. EOC의 광학계는 카세그레인 방식으로써 구경이 100 mm이고, 주경과 부경은 모두 비구면 반사경이다. EOC 주경의 플렉서는 링 타입으로써 발사환경에서 주경이 겪을 수 있는 충격과 진동을 견디도록 예압을 가하며 주경을 지지한다. 이는 마치 리테이너로 렌즈를 지지하는 것과 같은 메커니즘으로 주경을 지지하기 위한 시도이다. 광기계 해석을 통해 EOC 주경이 효과적으로 지지되고 있음을 확인했다.

• 천문학회보
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• 제40권1호
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• pp.81.1-81.1
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• 2015

FIMS/SPEAR is a dual-channel far-ultraviolet imaging spectrograph on board the Korean microsatellite STSAT-1, which was launched on 2003 September 27. While the instrument is optimized for the observation of diffuse emissions, it was able to observe a number of bright stars without much contamination from the diffuse background or other faint stars. In this paper, we present a catalog of the far-ultraviolet spectra for 543 stars observed by FIMS/SPEAR during its mission lifetime of a year and a half, covering over the 80% of the sky. Of these, 296 stars were also observed by the International Ultraviolet Explorer (IUE), which covered a wide spectral band including the FIMS wavelength band (1370--1710 A). The stellar spectral types involved in the catalog span from B0 to A3. We compare the new spectra with those of IUE when they are available, and discuss some examples. We also revised the effective area of FIMS that the FIMS stellar spectra are consistent with the IUE spectra.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.317-325
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• 2015

Energy spectra of electron microbursts from 170 keV to 340 keV have been measured by the solid-state detectors aboard the low-altitude (680 km) polar-orbiting Korean STSAT-1 (Science and Technology SATellite). These measurements have revealed two important characteristics unique to the microbursts: (1) They are produced by a fast-loss cone-filling process in which the interaction time for pitch-angle scattering is less than 50 ms and (2) The e-folding energy of the perpendicular component is larger than that of the parallel component, and the loss cone is not completely filled by electrons. To understand how wave-particle interactions could generate microbursts, we performed a test particle simulation and investigated how the waves scattered electron pitch angles within the timescale required for microburst precipitation. The application of rising-frequency whistler-mode waves to electrons of different energies moving in a dipole magnetic field showed that chorus magnetic wave fields, rather than electric fields, were the main cause of microburst events, which implied that microbursts could be produced by a quasi-adiabatic process. In addition, the simulation results showed that high-energy electrons could resonate with chorus waves at high magnetic latitudes where the loss cone was larger, which might explain the decreased e-folding energy of precipitated microbursts compared to that of trapped electrons.

• 천문학회지
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• 제38권2호
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• pp.69-72
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• 2005

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 $H_2$ 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.

• 천문학회보
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• 제40권2호
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• pp.52.1-52.1
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• 2015

FIMS/SPEAR is a dual-channel far-ultraviolet imaging spectrograph on board the Korean microsatellite STSAT-1, which was launched on 2003 September 27. The primary mission goal of FIMS was to conduct a survey of diffuse far UV emissions in our Galaxy. For this purpose, FIMS completed a survey of about 84% of the sky during its operation of a year and a half. The present study aims to analyze this survey data made in the far UV wavelengths to understand the global evolution of our Galaxy. The far UV wavelength band is known to contain important cooling lines of hot gas: hence, the study will show how the hot gas in our Galaxy, produced by stellar winds and supernova explosion, evolves globally to cool down and become mixed with ambient cooler medium. One of the main findings from previous analyses of the FIMS data is that molecular hydrogen exists ubiquitously in our Galaxy. This discovery leads to another important scientific question: how is molecular hydrogen distributed in our Galaxy and how does it affect globally the evolution of our Galaxy as a cold component? Hence, the present study will cover both the hot and cold components of the ISM, which will also provide the opportunity to investigate the interactions between the two.

• 한국항공우주학회지
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• 제44권8호
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• pp.710-717
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• 2016

인공위성 탑재체는 요구되는 임무 목적에 따라 전자광학탑재체, 영상레이더, 마이크로파 라디오미터, 통신탑재체, 항법탑재체 및 다양한 우주과학탑재체 등으로 분류된다. 우리나라의 경우 아리랑위성, 천리안위성, 과학위성 등의 개발을 통해 각종 탑재체 개발을 위한 기술들을 확보하려고 노력하였다. 본 논문에서는 탑재체 개발에 필요한 기술들과 세계 동향을 확인하고, 1994년 아리랑위성 1호의 개발로부터 본격적으로 시작된 우리나라의 탑재체 개발기술의 현황과 앞으로의 전망에 대해 정리하고자 하였다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.31.1-31.1
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• 2008

While some observations in the geomagnetic tail region supported electrons could be accelerated by reconnection processes, we still need more observation data to confirm electron acceleration in this region. Because most acceleration processes accompany strong pitch angle diffusion, if the electrons were accelerated in this region, strong energetic electron precipitation should be observed near earth on aurora oval. Even though there are several low altitude satellites observing electron precipitation, intense and small scale precipitation events have not been identified successfully. In this presentation, we will show an observation of strong energetic electron precipitation that might be analyzed by relativistic electron acceleration in the confined region. This event was observed by low altitude Korean STSAT-1, where intense several hundred keV electron precipitation was seen simultaneously with 10 keV electrons during storm time. In addition, we observed large magnetic field fluctuations and an ionospheric plasma depletion with FUV aurora emissions. Our observation implies relativistic electrons can be generated in the small area where Fermi acceleration might work.