• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.57.2-57.2
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• 2019

BITSE is a balloon mission, which is a solar coronagraph to measure speed and temperature of the solar wind using 4 different wavelength filters and an pixelated polarization camera. KASI and NASA jointly designed, developed, and tested the solar coronagraph. Mainly KASI developed an imaging system and a control system, and NASA developed an optical system and mechanical structures. We mount the BITSE on Wallops Arc-Second Pointer (WASP) of Wallops Flight Facility, and launch it with a 39 mcf balloon of Columbia Scientific Ballon Facility. We will introduce the overall system of the BITSE.

• Journal of Astronomy and Space Sciences
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• v.41 no.1
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• pp.1-15
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• 2024

The Korean heliospheric community, led by the Korea Astronomy and Space Science Institute (KASI), is currently assessing the viability of deploying a spacecraft at the Sun-Earth Lagrange Point L4 in collaboration with National Aeronautics and Space Administration (NASA). The aim of this mission is to utilize a combination of remote sensing and in situ instruments for comprehensive observations, complementing the capabilities of the L1 and L5 observatories. The paper outlines longterm scientific objectives, underscoring the significance of multi-point in-situ observations to better understand critical heliospheric phenomena. These include coronal mass ejections, magnetic flux ropes, heliospheric current sheets, kinetic waves and instabilities, suprathermal electrons and solar energetic particle events, as well as remote detection of solar radiation phenomena. Furthermore, the mission's significance in advancing space weather prediction and space radiation exposure assessment models through the integration of L4 observations is discussed. This article is concluded with an emphasis on the potential of L4 observations to propel advancements in heliospheric science.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.468-477
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• 2014

In this research, how a solar powered HALE (high altitude long endurance) UAV (Unmanned Aerial Vehicle) can climb and reach mission altitude, 18km, starting from the ground using only solar energy. A glider type aircraft was assumed as a baseline configuration which has wing area of $35.98m^2$ and aspect ratio of 25. Configuration parameters, lift and drag coefficients were calculated using OpenVSP and XFLR5 that are NASA open source programs, and climb flights were predicted through energy balance between available energy from solar power and energy necessary for a climb flight. Minimum time climb flight was obtained by minimizing flight velocities at each altitude and total time and total energy consumption to reach the mission altitude were predicted for different take off time. Also, aircraft moving distances due to westerly wind and flight speed were calculated.

• Journal of Astronomy and Space Sciences
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• v.28 no.2
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• pp.133-141
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• 2011

A satellite power system should generate and supply sufficient electric power to perform the satellite mission successfully during the satellite mission period, and it should be developed to be strong to the failure caused by the severe space environment. A satellite power system must have a high reliability with respect to failure. Since it cannot be repaired after launching, different from a ground system, the failures that may happen in space as well as the effect of the failures on the system should be considered in advance. However, it is difficult to use all the hardware to test the performance of the satellite power system to be developed in order to consider the failure mechanism of the electrical power system. Therefore, it is necessary to develop an accurate model for the main components of a power system and, based on that, to develop an accurate model for the entire power system. Through the power system modeling, the overall effect of failure on the main components of the power system can be considered and the protective design can be devised against the failure. In this study, to analyze the failure mode of the power system and the effects of the failure on the power system, we carried out modeling of the main power system components including the solar array regulator, and constituted the entire power system based on the modeling. Additionally, we investigated the effects of representative failures in the solar array regulator on the power system using the power system model.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.329-342
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• 2004

In this paper, we present preliminary feasibility studies on three types of solar observation payloads for future Korean Science and Technology Satellite (STSAT) programs. The three candidates are (1) an UV imaging telescope, (2) an UV spectrograph, and (3) an X-ray spectrometer. In the case of UV imaging telescope, the most important constraint seems to be the control stability of a satellite in order to obtain a reasonably good spatial resolution. Considering that the current pointing stability estimated from the data of the Far ultraviolet Imaging Spectrograph (FIMS) onboard the Korean STSAT-1, is around 1 arc minutes/sec, we think that it is hard to obtain a spatial resolution sufficient for scientific research by such an UV Imaging Telescope. For solar imaging missions, we realize that an image stabilization system, which is composed of a small guide telescope with limb sensor and a servo controller of secondary mirror, is quite essential for a very good pointing stability of about 0.1 arcsec. An UV spectrograph covering the solar full disk seems to be a good choice in that there is no risk due to poor pointing stability as well as that it can provide us with valuable UV spectral irradiance data valuable for studying their effects on the Earth's atmosphere and satellites. The heritage of the FIMS can be a great advantage of developing the UV spectrograph. Its main disadvantage is that two major missions are in operation or scheduled. Our preliminary investigations show that an X-ray spectrometer for the full disk Sun seems to be the best choice among the three candidates. The reasons are : (1) high temporal and spectral X-ray data are very essential for studying the acceleration process of energetic particles associated with solar flares, (2) we have a good heritage of X-ray detectors including a rocket-borne X-ray detector, (3) in the case of developing countries such as India and Czech, solar X-ray spectrometers were selected as their early stage satellite missions due to their poor pointing stabilities, and (4) there is no planned major mission after currently operating Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) mission. Finally, we present a preliminary design of a solar X-ray spectrometer covering soft X-ray (2 keV) to gamma ray (10 MeV).

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.50-56
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• 2010

Most mission trajectory design technologies for space exploration have been utilized the Patched Conic Approximation which is based on Hohmann transfer in two-body problem. The Hohmann transfer trajectory is basically an elliptic trajectory, and Patched Conic Approximation consists of Hohmann transfer trajectories in which each trajectory are patched to the next one. This technology is the most efficient method when considering only one major planet at each patch trajectory design. The disadvantages of the conventional Patched Conic Approach are more fuel (or mass) needed and only conic trajectories are designed. Recent space exploration missions need to satisfy more various scientific or engineering goals, and mission utilizing smaller satellites are needed for cost reduction. The geometrical characteristics of three-body dynamics could change the paradigm of the conventional solar system. In this theoretical concept, one can design a trajectory connecting around the solar system with comparably very small energy. In this paper, the basic three-body dynamics are introduced and a spacecraft mission trajectory is designed utilizing the three-body dynamics.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.58.4-59
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• 2021

This presentation introduces Korea's SNIPE (Small scale magNespheric and Ionospheric Plasma Experiment) mission, formation flying CubeSat constellation. Observing particles and waves on a single satellite suffers from inherent space-time ambiguity. To observe spatial and temporal variations of the micro-scale plasma structures on the topside ionosphere, four 6U CubeSats (~ 10 kg) will be launched into a polar orbit of the altitude of ~500 km in 2021. The distances of each satellite will be controlled from 10 km to more than 100 km by formation flying algorithm. The SNIPE mission is equipped with identical scientific instruments, solid-state telescope, magnetometer, and Langmuir probe. All the payloads have a high temporal resolution (sampling rates of about 10 Hz). Iridium modules provide an opportunity to upload changes in operational modes when geomagnetic storms occur. SNIPE's observations of the dimensions, occurrence rates, amplitudes, and spatiotemporal evolution of polar cap patches, field-aligned currents (FAC), radiation belt microbursts, and equatorial and mid-latitude plasma blobs and bubbles will determine their significance to the solar wind-magnetosphere-ionosphere interaction and quantify their impact on space weather.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.48.2-48.2
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• 2018

SPHEREx is expected to provide us with the opportunity of unbiased sampling of small Solar System objects along with near-infrared ($0.75-5.0{\mu}m$) spectroscopic (R ~ 41) information. The estimated numbers of detections are tens of thousands for asteroids, thousands for Trojans, hundreds for comets, and several for Kuiper Belt Objects, Centaurs and Scattered Disk Objects. Wide spectral range covering many bands from carbon-bearing molecules and ices will enable us to systematically survey the volatile materials throughout the Solar System. SPHEREx will, for the first time, produce the near-infrared spectral map of the zodiacal light to pin-down the relative contributions of various populations of Solar System objects and interstellar dust to the dust grains in the interplanetary space. The study of the zodiacal light is also important to remove the foreground for the EBL (extragalactic background light) study, one of the main topics of the mission.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.43.4-44
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• 2021

99942 Apophis is an Sq-type Aten group Near-Earth Asteroid (NEA) with an estimated size of 370 m. It will approach the Earth to come within the geostationary orbit during the upcoming encounter on April 13, 2029 to offer a unique chance to study its 1) global properties, 2) surface arrangements, and 3) their detectable changes expected to happen, in sub-meter scale. What measurable scientific goals for the asteroid in this "once a millennium" event could transform our knowledge of planetary science and defense? The Apophis rendezvous mission aims to understand the characteristics of the small solar system body's nature. It also prepares for potential threats from natural objects by measuring in-situ surface, shape, rotation, and orbit changes expected to occur when the target asteroid passes close to the Earth in 2029. We will present an overview of the mission scheduled to be launched from late 2026 to early 2027 and introduce scientific objectives.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.66.3-66.3
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• 2017

Korea Astronomy and Space Science Institute (KASI) is developing a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) which will be installed on the International Space Station (ISS). The coronagraph can measure speed and temperature by using four filters approximately 400 nm and polarization filter in three different angles, differently with older coronagraphs. For the successful mission, it has development and experiment progress in three phases; total solar eclipse experiment in 2017, balloon experiment in 2019, and the ISS installation in 2021. As a first experiment, we developed a coronagraph without an occulter named with Diagnostic Coronagraph Experiment (DICE) for experiment for filter system and imaging sensor. We designed optics with a field of view from 2.5 to 15 solar radii. It has four filters approximately 400 nm and polarizer to measure speed and velocity of the solar corona. For the selection of filter or polarization angle, it has two mechanism parts; filter wheel assembly and a polarizer wheel assembly. Especially we used Core Flight System (CFS) platform which was developed by NASA, when we develop the coronagraph operation software. It provides us stability, reusability, and compatibility.