Pub Date : 2021-03-01DOI: 10.5140/JASS.2021.38.1.1
Luis E. Salazar-Manzano, E. Quintero
The observation of stellar occultations constitutes one of the most important techniques for determining the dimensions and establishing the physical parameters of small Solar System bodies. The most substantial calculations are obtained from multiple observations of the same event, which turns the observation of stellar occultations into highly collaborative work and groups teams of observers through international networks. The above situation also requires the participation of both professional and amateur observers in these collaborative networks. With the aim of promoting the participation of professional and amateur groups in the collaborative observation of stellar occultations, we present the methodology developed by the Astronomical Observatory of the Technological University of Pereira (OAUTP) for the observations of occultations due small Solar System bodies. We expose the three fundamental phases of the process: the plan to make observations, the capture of the events, and the treatment of the data. We apply our methodology using a fixed station and a mobile station to observe stellar occultations due to MBAs (354) Eleonora (61) Danae (15112) Arlenewolfe (3915) Fukushima (61788) 2000 QP181 (425) Cornelia (257) Silesia (386) Siegena and (41) Daphne, and due to TNOs 1998BU48 and (529823) 2010 PP81. The positive detections for the objects (257) Silesia (386) Siegena and (41) Daphne allow us to derive lower limits in the diameter of the MBAs of 63.1 km, 166.2 km and 158.7 km and offsets in the astrometric position (Δαc cosδc, Δδc) of 622.30 ± 0.83, 15.23 ± 9.88 mas, 586.06 ± 1.68, 43.03 ± 13.88 mas and –413.44 ± 9.42, 234.05 ± 19.12 mas, respectively.
{"title":"Methodology for the Observations of Stellar Occultations by Small Bodies of the\u0000 Solar System","authors":"Luis E. Salazar-Manzano, E. Quintero","doi":"10.5140/JASS.2021.38.1.1","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.1.1","url":null,"abstract":"The observation of stellar occultations constitutes one of the most important\u0000 techniques for determining the dimensions and establishing the physical parameters of\u0000 small Solar System bodies. The most substantial calculations are obtained from multiple\u0000 observations of the same event, which turns the observation of stellar occultations into\u0000 highly collaborative work and groups teams of observers through international networks.\u0000 The above situation also requires the participation of both professional and amateur\u0000 observers in these collaborative networks. With the aim of promoting the participation\u0000 of professional and amateur groups in the collaborative observation of stellar\u0000 occultations, we present the methodology developed by the Astronomical Observatory of\u0000 the Technological University of Pereira (OAUTP) for the observations of occultations due\u0000 small Solar System bodies. We expose the three fundamental phases of the process: the\u0000 plan to make observations, the capture of the events, and the treatment of the data. We\u0000 apply our methodology using a fixed station and a mobile station to observe stellar\u0000 occultations due to MBAs (354) Eleonora (61) Danae (15112) Arlenewolfe (3915) Fukushima\u0000 (61788) 2000 QP181 (425) Cornelia (257) Silesia (386) Siegena and (41) Daphne, and due\u0000 to TNOs 1998BU48 and (529823) 2010 PP81. The positive detections for the objects (257)\u0000 Silesia (386) Siegena and (41) Daphne allow us to derive lower limits in the diameter of\u0000 the MBAs of 63.1 km, 166.2 km and 158.7 km and offsets in the astrometric position (Δαc\u0000 cosδc, Δδc) of 622.30 ± 0.83, 15.23 ± 9.88 mas, 586.06 ± 1.68, 43.03 ± 13.88 mas and\u0000 –413.44 ± 9.42, 234.05 ± 19.12 mas, respectively.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79278267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-01DOI: 10.5140/JASS.2021.38.1.31
Ji-Hyeon Yoo, Dae‐Young Lee, Eojin Kim, H. Seo, Kwang-Sun Ryu, Kyung‐Chan Kim, K. Min, J. Sohn, Junchan Lee, J. Seon, K. Kang, Seunguk Lee, Jaeheung Park, G. Shin, Sung-Og Park
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.
{"title":"A Substorm Injection Event and the Radiation Belt Structure Observed by Space\u0000 Radiation Detectors onboard Next Generation Small Satellite-1 (NEXTSat-1)","authors":"Ji-Hyeon Yoo, Dae‐Young Lee, Eojin Kim, H. Seo, Kwang-Sun Ryu, Kyung‐Chan Kim, K. Min, J. Sohn, Junchan Lee, J. Seon, K. Kang, Seunguk Lee, Jaeheung Park, G. Shin, Sung-Og Park","doi":"10.5140/JASS.2021.38.1.31","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.1.31","url":null,"abstract":"In this paper, we present observations of the Space Radiation Detectors (SRDs)\u0000 onboard the Next Generation Small Satellite-1 (NEXTSat-1) satellite. The SRDs, which are\u0000 a part of the Instruments for the study of Stable/Storm-time Space (ISSS), consist of\u0000 the Medium-Energy Particle Detector (MEPD) and the High-Energy Particle Detector (HEPD).\u0000 The MEPD can detect electrons, ions, and neutrals with energies ranging from 20 to 400\u0000 keV, and the HEPD can detect electrons over an energy range from 0.35 to 2 MeV. In this\u0000 paper, we report an event where particle flux enhancements due to substorm injections\u0000 are clearly identified in the MEPD A observations at energies of tens of keV.\u0000 Additionally, we report a specific example observation of the electron distributions\u0000 over a wide energy range in which we identify electron spatial distributions with\u0000 energies of tens to hundreds of keV from the MEPD and with energy ranging up to a few\u0000 MeV from the HEPD in the slot region and outer radiation belts. In addition, for an\u0000 ~1.5-year period, we confirm that the HEPD successfully observed the well-known outer\u0000 radiation belt electron flux distributions and their variations in time and L shell in a\u0000 way consistent with the geomagnetic disturbance levels. Last, we find that the inner\u0000 edge of the outer radiation belt is mostly coincident with the plasmapause locations in\u0000 L, somewhat more consistent at subrelativistic energies than at relativistic energies.\u0000 Based on these example events, we conclude that the SRD observations are of reliable\u0000 quality, so they are useful for understanding the dynamics of the inner magnetosphere,\u0000 including substorms and radiation belt variations.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82718172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-01DOI: 10.5140/JASS.2021.38.1.45
Jee-Ho Lee, E. Park, Mansoo Choi, D. Kucharski, Y. Yi, J. Park
GLONASS, a satellite navigation system developed in Russia since 1976, is defunct and orbits in an unstable attitude. The satellites in these problems are not managed and there is no precise information, which can increase the risk of collisions with other space objects. In this study, detailed attitude dynamic have to be analyzed through photometry data, which requires spin period and spin axis. The light curve data is obtained by observing through the photometer at the Graz station and the power spectrum is calculated to obtain the cycle of the satellite. The geometric relationship between observer and sun is analyzed for GLONASS-50 satellite. The box-wing model is applied to obtain the phase reflection of the satellite and obtain the Irradiation of the satellite through this information. In Light Curve and Irradiation, the spin axis is calculated for each peak points with the distance square minimum technique. The spin axis of the GLONASS-50 satellite is RA = 116°, Dec = 92°.
{"title":"Spin Axis Determination of Defunct GLONASS Satellites Using Photometry\u0000 Observation","authors":"Jee-Ho Lee, E. Park, Mansoo Choi, D. Kucharski, Y. Yi, J. Park","doi":"10.5140/JASS.2021.38.1.45","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.1.45","url":null,"abstract":"GLONASS, a satellite navigation system developed in Russia since 1976, is defunct\u0000 and orbits in an unstable attitude. The satellites in these problems are not managed and\u0000 there is no precise information, which can increase the risk of collisions with other\u0000 space objects. In this study, detailed attitude dynamic have to be analyzed through\u0000 photometry data, which requires spin period and spin axis. The light curve data is\u0000 obtained by observing through the photometer at the Graz station and the power spectrum\u0000 is calculated to obtain the cycle of the satellite. The geometric relationship between\u0000 observer and sun is analyzed for GLONASS-50 satellite. The box-wing model is applied to\u0000 obtain the phase reflection of the satellite and obtain the Irradiation of the satellite\u0000 through this information. In Light Curve and Irradiation, the spin axis is calculated\u0000 for each peak points with the distance square minimum technique. The spin axis of the\u0000 GLONASS-50 satellite is RA = 116°, Dec = 92°.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84431677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-01DOI: 10.5140/JASS.2021.38.1.65
Hyung-Je Woo, Björn Buckwalter
For the vast majority of geostationary satellites currently in orbit, station keeping activities including orbit determination and maneuver planning and execution are ground-directed and dependent on the availability of ground-based satellite control personnel and facilities. However, a requirement linked to satellite autonomy and survivability in cases of interrupted ground support is often one of the stipulated provisions on the satellite platform design. It is especially important for a geostationary military-purposed satellite to remain within its designated orbital window, in order to provide reliable uninterrupted telecommunications services, in the absence of ground-based resources due to warfare or other disasters. In this paper we investigate factors affecting the robustness of a geostationary satellite’s orbit in terms of the maximum duration the satellite’s station keeping window can be maintained without ground intervention. By comparing simulations of orbit evolution, given different initial conditions and operations strategies, a variation of parameters study has been performed and we have analyzed which factors the duration is most sensitive to. This also provides valuable insights into which factors may be worth controlling by a military or civilian geostationary satellite operator. Our simulations show that the most beneficial factor for maximizing the time a satellite will remain in the station keeping window is the operational practice of pre-emptively loading East-West station keeping maneuvers for automatic execution on board the satellite should ground control capability be lost. The second most beneficial factor is using short station keeping maneuver cycle durations.
{"title":"Geostationary Satellite Station Keeping Robustness to Loss of Ground\u0000 Control","authors":"Hyung-Je Woo, Björn Buckwalter","doi":"10.5140/JASS.2021.38.1.65","DOIUrl":"https://doi.org/10.5140/JASS.2021.38.1.65","url":null,"abstract":"For the vast majority of geostationary satellites currently in orbit, station\u0000 keeping activities including orbit determination and maneuver planning and execution are\u0000 ground-directed and dependent on the availability of ground-based satellite control\u0000 personnel and facilities. However, a requirement linked to satellite autonomy and\u0000 survivability in cases of interrupted ground support is often one of the stipulated\u0000 provisions on the satellite platform design. It is especially important for a\u0000 geostationary military-purposed satellite to remain within its designated orbital\u0000 window, in order to provide reliable uninterrupted telecommunications services, in the\u0000 absence of ground-based resources due to warfare or other disasters. In this paper we\u0000 investigate factors affecting the robustness of a geostationary satellite’s orbit in\u0000 terms of the maximum duration the satellite’s station keeping window can be maintained\u0000 without ground intervention. By comparing simulations of orbit evolution, given\u0000 different initial conditions and operations strategies, a variation of parameters study\u0000 has been performed and we have analyzed which factors the duration is most sensitive to.\u0000 This also provides valuable insights into which factors may be worth controlling by a\u0000 military or civilian geostationary satellite operator. Our simulations show that the\u0000 most beneficial factor for maximizing the time a satellite will remain in the station\u0000 keeping window is the operational practice of pre-emptively loading East-West station\u0000 keeping maneuvers for automatic execution on board the satellite should ground control\u0000 capability be lost. The second most beneficial factor is using short station keeping\u0000 maneuver cycle durations.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88812368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.5140/JASS.2020.37.4.219
H. Lim, Sung-Yeol Yu, Ki-Pyoung Sung, J. Park, C. Choi, Mansoo Choi
A CubeSat platform has become a popular choice due to inexpensive commercial off-the-shelf (COTS) components and low launch cost. However, it requires more power-efficient and higher-data rate downlink capability for space applications related to remote sensing. In addition, the platform is limited by the size, weight and power (SWaP) constraints as well as the regulatory issue of licensing the radio frequency (RF) spectrum. The requirements and limitations have put optical communications on promising alternatives to RF communications for a CubeSat platform, owing to the power efficiency and high data rate as well as the license free spectrum. In this study, we analyzed the performance of optical downlink communications compatible with CubeSat platforms in terms of data rate, bit error rate (BER) and outage probability. Mathematical models of BER and outage probability were derived based on not only the log-normal model of atmospheric turbulence but also a transmitter with a finite extinction ratio. Given the fixed slot width, the optimal guard time and modulation orders were chosen to achieve the target data rate. And the two performance metrics, BER and outage data rate, were analyzed and discussed with respect to beam divergence angle, scintillation index and zenith angle.
{"title":"Performance Analysis of M-ary Optical Communication over Log-Normal Fading Channels\u0000 for CubeSat Platforms","authors":"H. Lim, Sung-Yeol Yu, Ki-Pyoung Sung, J. Park, C. Choi, Mansoo Choi","doi":"10.5140/JASS.2020.37.4.219","DOIUrl":"https://doi.org/10.5140/JASS.2020.37.4.219","url":null,"abstract":"A CubeSat platform has become a popular choice due to inexpensive commercial\u0000 off-the-shelf (COTS) components and low launch cost. However, it requires more\u0000 power-efficient and higher-data rate downlink capability for space applications related\u0000 to remote sensing. In addition, the platform is limited by the size, weight and power\u0000 (SWaP) constraints as well as the regulatory issue of licensing the radio frequency (RF)\u0000 spectrum. The requirements and limitations have put optical communications on promising\u0000 alternatives to RF communications for a CubeSat platform, owing to the power efficiency\u0000 and high data rate as well as the license free spectrum. In this study, we analyzed the\u0000 performance of optical downlink communications compatible with CubeSat platforms in\u0000 terms of data rate, bit error rate (BER) and outage probability. Mathematical models of\u0000 BER and outage probability were derived based on not only the log-normal model of\u0000 atmospheric turbulence but also a transmitter with a finite extinction ratio. Given the\u0000 fixed slot width, the optimal guard time and modulation orders were chosen to achieve\u0000 the target data rate. And the two performance metrics, BER and outage data rate, were\u0000 analyzed and discussed with respect to beam divergence angle, scintillation index and\u0000 zenith angle.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88520557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.5140/JASS.2020.37.4.249
U. Nam, W. Park, Jung-Lae Hwang, J. Sohn, B. Moon, Sunghwan Kim
We develop the tissue-equivalent proportional counter (TEPC) type’s space radiation dosimeter to measure in-situ aviation radiation. That was originally developed as a payload of small satellite in the low-earth orbit. This dosimeter is based on a TEPC. It is made of an A-150 tissue-equivalent plastic shell of an internal diameter of 6 cm and a thickness of 0.3 cm. TEPC is filled with pure propane at 13.9 torrs to simulate a cell diameter of 2 μm. And the associated portable and low power electronics are also implemented. The verification experiments have been performed by the calibration experiments at ground level and compared with Liulin observation at aircraft altitude during the flight between Incheon airport (ICN) and John F. Kennedy airport (JFK). We found that the TEPC dosimeter can be used as a monitor for space radiation dosimeter at aviation altitude based on the verification with Liulin observation.
{"title":"Preliminary Results of Tissue-Equivalent Proportional Counter (TEPC) Dosimeter for\u0000 Measuring In-Situ Aviation Radiation","authors":"U. Nam, W. Park, Jung-Lae Hwang, J. Sohn, B. Moon, Sunghwan Kim","doi":"10.5140/JASS.2020.37.4.249","DOIUrl":"https://doi.org/10.5140/JASS.2020.37.4.249","url":null,"abstract":"We develop the tissue-equivalent proportional counter (TEPC) type’s space\u0000 radiation dosimeter to measure in-situ aviation radiation. That was originally developed\u0000 as a payload of small satellite in the low-earth orbit. This dosimeter is based on a\u0000 TEPC. It is made of an A-150 tissue-equivalent plastic shell of an internal diameter of\u0000 6 cm and a thickness of 0.3 cm. TEPC is filled with pure propane at 13.9 torrs to\u0000 simulate a cell diameter of 2 μm. And the associated portable and low power electronics\u0000 are also implemented. The verification experiments have been performed by the\u0000 calibration experiments at ground level and compared with Liulin observation at aircraft\u0000 altitude during the flight between Incheon airport (ICN) and John F. Kennedy airport\u0000 (JFK). We found that the TEPC dosimeter can be used as a monitor for space radiation\u0000 dosimeter at aviation altitude based on the verification with Liulin observation.\u0000","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83720606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.5140/JASS.2020.37.4.237
Young-Rok Kim, Young-Joo Song, Jae-ik Park, Donghun Lee, Jonghee Bae, Seung-Su Hong, Dae-Kwan Kim, Sang-Ryool Lee
The ground tracking support is a critical factor for the navigation performance of spacecraft orbiting around the Moon. Because of the tracking limit of antennas, only a small number of facilities can support lunar missions. Therefore, case studies for various ground tracking support conditions are needed for lunar missions on the stage of preliminary mission analysis. This study analyzes the ground supporting condition effect on orbit determination (OD) of Korea Pathfinder Lunar Orbiter (KPLO) in the lunar orbit. For the assumption of ground support conditions, daily tracking frequency, cut-off angle for low elevation, tracking measurement accuracy, and tracking failure situations were considered. Two antennas of deep space network (DSN) and Korea Deep Space Antenna (KDSA) are utilized for various tracking conditions configuration. For the investigation of the daily tracking frequency effect, three cases (full support, DSN 4 pass/day and KDSA 4 pass/day, and DSN 2 pass/day and KDSA 2 pass/day) are prepared. For the elevation cut-off angle effect, two situations, which are 5 deg and 10 deg, are assumed. Three cases (0%, 30%, and 50% of degradation) were considered for the tracking measurement accuracy effect. Three cases such as no missing, 1-day KDSA missing, and 2-day KDSA missing are assumed for tracking failure effect. For OD, a sequential estimation algorithm was used, and for the OD performance evaluation, position uncertainty, position differences between true and estimated orbits, and orbit overlap precision according to various ground supporting conditions were investigated. Orbit prediction accuracy variations due to ground tracking conditions were also demonstrated. This study provides a guideline for selecting ground tracking support levels and preparing a backup plan for the KPLO lunar mission phase.
{"title":"Ground Tracking Support Condition Effect on Orbit Determination for Korea\u0000 Pathfinder Lunar Orbiter (KPLO) in Lunar Orbit","authors":"Young-Rok Kim, Young-Joo Song, Jae-ik Park, Donghun Lee, Jonghee Bae, Seung-Su Hong, Dae-Kwan Kim, Sang-Ryool Lee","doi":"10.5140/JASS.2020.37.4.237","DOIUrl":"https://doi.org/10.5140/JASS.2020.37.4.237","url":null,"abstract":"The ground tracking support is a critical factor for the navigation performance\u0000 of spacecraft orbiting around the Moon. Because of the tracking limit of antennas, only\u0000 a small number of facilities can support lunar missions. Therefore, case studies for\u0000 various ground tracking support conditions are needed for lunar missions on the stage of\u0000 preliminary mission analysis. This study analyzes the ground supporting condition effect\u0000 on orbit determination (OD) of Korea Pathfinder Lunar Orbiter (KPLO) in the lunar orbit.\u0000 For the assumption of ground support conditions, daily tracking frequency, cut-off angle\u0000 for low elevation, tracking measurement accuracy, and tracking failure situations were\u0000 considered. Two antennas of deep space network (DSN) and Korea Deep Space Antenna (KDSA)\u0000 are utilized for various tracking conditions configuration. For the investigation of the\u0000 daily tracking frequency effect, three cases (full support, DSN 4 pass/day and KDSA 4\u0000 pass/day, and DSN 2 pass/day and KDSA 2 pass/day) are prepared. For the elevation\u0000 cut-off angle effect, two situations, which are 5 deg and 10 deg, are assumed. Three\u0000 cases (0%, 30%, and 50% of degradation) were considered for the tracking measurement\u0000 accuracy effect. Three cases such as no missing, 1-day KDSA missing, and 2-day KDSA\u0000 missing are assumed for tracking failure effect. For OD, a sequential estimation\u0000 algorithm was used, and for the OD performance evaluation, position uncertainty,\u0000 position differences between true and estimated orbits, and orbit overlap precision\u0000 according to various ground supporting conditions were investigated. Orbit prediction\u0000 accuracy variations due to ground tracking conditions were also demonstrated. This study\u0000 provides a guideline for selecting ground tracking support levels and preparing a backup\u0000 plan for the KPLO lunar mission phase.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77630701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.5140/JASS.2020.37.4.229
Jung-Lae Hwang, Jaeyoung Kwak, Gyeongbok Jo, U. Nam
There has been increasing necessity of more precise prediction and measurements of aviation radiation in Korea. For our air crew and passengers’ radiation safety, we develop our own radiation prediction model of KREAM. In this paper, we validate the KREAM model based on comparison with Liulin observations. During early three months of this year, we perform total 25 experiments to measure aviation radiation exposure using Liulin-6K in commercial flights. We found that KREAM’s result is very well consistent with Liulin observation in general. NAIRAS shows mostly higher results than Liulin observation, while CARI-6M shows generally lower results than the observations. The percent error of KREAM compared with Liulin observation is 10.95%. In contrast, the error for NAIRAS is 43.38% and 22.03% for CARI-6M. We found that the increase of the altitude might cause sudden increase in radiation exposure, especially for the polar route. As more comprehensive and complete analysis is required to validate KREAM’s reliability to use for the public service, we plan to expand these radiation measurements with Liulin and Tissue Equivalent Proportional Counter (TEPC) in the near future.
{"title":"Validation of KREAM Based on In-Situ Measurements of Aviation Radiation in\u0000 Commercial Flights","authors":"Jung-Lae Hwang, Jaeyoung Kwak, Gyeongbok Jo, U. Nam","doi":"10.5140/JASS.2020.37.4.229","DOIUrl":"https://doi.org/10.5140/JASS.2020.37.4.229","url":null,"abstract":"There has been increasing necessity of more precise prediction and measurements\u0000 of aviation radiation in Korea. For our air crew and passengers’ radiation safety, we\u0000 develop our own radiation prediction model of KREAM. In this paper, we validate the\u0000 KREAM model based on comparison with Liulin observations. During early three months of\u0000 this year, we perform total 25 experiments to measure aviation radiation exposure using\u0000 Liulin-6K in commercial flights. We found that KREAM’s result is very well consistent\u0000 with Liulin observation in general. NAIRAS shows mostly higher results than Liulin\u0000 observation, while CARI-6M shows generally lower results than the observations. The\u0000 percent error of KREAM compared with Liulin observation is 10.95%. In contrast, the\u0000 error for NAIRAS is 43.38% and 22.03% for CARI-6M. We found that the increase of the\u0000 altitude might cause sudden increase in radiation exposure, especially for the polar\u0000 route. As more comprehensive and complete analysis is required to validate KREAM’s\u0000 reliability to use for the public service, we plan to expand these radiation\u0000 measurements with Liulin and Tissue Equivalent Proportional Counter (TEPC) in the near\u0000 future.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77286142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.5140/JASS.2020.37.3.165
Jaesik Jeong, Suyeon Oh
Muons and neutrons are representative secondary particles that are generated by interactions between primary cosmic ray particles (mostly protons) and the nuclei of atmospheric gas compounds. Previous studies reported that muons experience seasonal variations because of the meteorological effects of temperature. The intensity of neutrons has a typical modulation with various periods and reasons, such as diurnal and solar variation or transient events. This paper reports that cosmic ray particles, which were observed by neutron monitors, have seasonal variations using the daily data at the Oulu neutron monitor. To eliminate the effects of solar activity across time, the daily data were normalized by two different transformations: transformations with respect to the grand mean and yearly mean. The data after transformation with respect to the yearly mean showed more statistical stability and clear seasonal variations. On the other hand, it is difficult to determine if the seasonal variation results from terrestrial effects, such as meteorological factors, or extraterrestrial effects, such as the position of the Earth in its orbit of revolution.
{"title":"Seasonal Variation of Cosmic Ray Intensity Observed by the Oulu Neutron\u0000 Monitor","authors":"Jaesik Jeong, Suyeon Oh","doi":"10.5140/JASS.2020.37.3.165","DOIUrl":"https://doi.org/10.5140/JASS.2020.37.3.165","url":null,"abstract":"Muons and neutrons are representative secondary particles that are generated by\u0000 interactions between primary cosmic ray particles (mostly protons) and the nuclei of\u0000 atmospheric gas compounds. Previous studies reported that muons experience seasonal\u0000 variations because of the meteorological effects of temperature. The intensity of\u0000 neutrons has a typical modulation with various periods and reasons, such as diurnal and\u0000 solar variation or transient events. This paper reports that cosmic ray particles, which\u0000 were observed by neutron monitors, have seasonal variations using the daily data at the\u0000 Oulu neutron monitor. To eliminate the effects of solar activity across time, the daily\u0000 data were normalized by two different transformations: transformations with respect to\u0000 the grand mean and yearly mean. The data after transformation with respect to the yearly\u0000 mean showed more statistical stability and clear seasonal variations. On the other hand,\u0000 it is difficult to determine if the seasonal variation results from terrestrial effects,\u0000 such as meteorological factors, or extraterrestrial effects, such as the position of the\u0000 Earth in its orbit of revolution.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86054778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.5140/JASS.2020.37.3.209
Eojin Kim, Ji-Hyeon Yoo, Hee-Eun Kim, H. Seo, K. Ryu, J. Sohn, Junchan Lee, J. Seon, Ensang Lee, Dae‐Young Lee, K. Min, K. Kang, Sang-Yun Lee, Juneseok Kang
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.
{"title":"Initial Operation and Preliminary Results of the Instrument for the Study of\u0000 Stable/Storm-Time Space (ISSS) on Board the Next Generation Small Satellite-1\u0000 (NEXTSat-1)","authors":"Eojin Kim, Ji-Hyeon Yoo, Hee-Eun Kim, H. Seo, K. Ryu, J. Sohn, Junchan Lee, J. Seon, Ensang Lee, Dae‐Young Lee, K. Min, K. Kang, Sang-Yun Lee, Juneseok Kang","doi":"10.5140/JASS.2020.37.3.209","DOIUrl":"https://doi.org/10.5140/JASS.2020.37.3.209","url":null,"abstract":"This paper describes the initial operations and preliminary results of the\u0000 Instrument for the study of Stable/Storm-time Space (ISSS) onboard the microsatellite\u0000 Next Generation Small Satellite-1 (NEXTSat-1), which was launched on December 4, 2018\u0000 into a sun-synchronous orbit at an altitude of 575 km with an orbital inclination angle\u0000 of 97.7°. The spacecraft and the instruments have been working normally, and the results\u0000 from the observations are in agreement with those from other satellites. Nevertheless,\u0000 improvement in both the spacecraft/instrument operation and the analysis is suggested to\u0000 produce more fruitful scientific results from the satellite operations. It is expected\u0000 that the ISSS observations will become the main mission of the NEXTSat-1 at the end of\u0000 2020, when the technological experiments and astronomical observations terminate after\u0000 two years of operation.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90839741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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