SEIRIOS: A Demonstration of Space Infrared Interferometer by Formation Flying of Micro-Satellites

In several decades, space infrared interferometer missions with formation flying have been proposed, but most of the missions were relinquished because their requirements for position and attitude control of satellites are extremely accurate. In order to overcome this issue, we propose to apply the densified pupil spectroscopy to relax control requirements of the baseline distance and attitude to overlap the rays. SEIRIOS is a micro-satellite project to demonstrate the concept of space infrared interferometer with the densified pupil spectrograph. The interferometer is constructed by one 50kg class micro-satellite and two 9U CubeSats in line. The micro-satellite is placed at the center of the two CubeSats that keep a constant distance between 5 to 50-m from the micro-satellite. The CubeSats reflect rays from target celestial bodies to the micro-satellite, and the micro-satellite collects the rays by the pupil spectrometer. The baseline control requirement is 1 mm, and it could be achieved by using COTS laser distance meters, low force thrusters, and the mirror control by piezo stages. This paper introduces the mission concept, a preliminary design result, and the future plan of our interferometer mission

Experimental Study for Synthetic Aperture Telescope Using Formation Flying Micro-Satellites for High-Frequency and High-Resolution GEO Remote Sensing

Earth remote sensing from geostationary orbit (GEO) realizes high time resolution that is essential for disaster monitoring; however, the spatial resolution is commonly worse than observation from low Earth orbit. In order to achieve high-resolution and high-frequency GEO remote sensing, we have proposed a “Formation Flying Synthetic Aperture Telescope (FFSAT)” with multiple micro-satellites. The FFSAT can improve the spatial resolution by using the technique of a synthetic aperture, and therefore the relative positions and attitudes between the optical units of each satellite must be controlled with an accuracy better than 1/10 of the observation wavelength. In order to verify feasibility of such highly accurate control, the characteristics of sensors and actuators which are essential for an ultra-high-accuracy formation flying were numerically modeled. We consider control laws for keeping the relative position and attitude of the μm-class formation flying using the high-precision simulator built on the numerical models. In addition, the cooperative control of the piezo stages and the thrusters is studied to reduce the fuel consumption of the FFSAT system. The simulation results made the FFSAT mission more feasible

Initial Operation Results of a 50kg-class Deep Space Exploration Micro-Spacecraft PROCYON

This paper presents the development and initial operation results of 50kg-class deep space exploration microspacecraft PROCYON (Proximate Object Close flYby with Optical Navigation), which was jointly developed by the University of Tokyo and Japan Aerospace Exploration Agency (JAXA). The primary mission of PROCYON is the world’s first demonstration of 50kg-class deep space exploration bus system which includes the demonstration of high-efficiency GaN-based SSPA (Solid State Power Amplifier) for communication and high-precision navigation by a novel method of DDOR (Delta Differential One-way Range) observation. PROCYON also has some secondary advanced missions, which are deep space flight to a Near-earth asteroid and high resolution observation of the asteroid during close and fast flyby, and the wide view scientific observation of geocorona by a Lyman alpha imager from a vantage point outside of the Earth’s geocoronal distribution. PROCYON was developed at very low cost (a few million dollars) and within very short period (about 1 year), taking advantage of the heritage from Japanese Earth-orbiting micro satellite missions. PROCYON was launched into an Earth departure trajectory together with Japanese second asteroid sample return spacecraft Hayabusa-2 on December 3, 2014, and it has achieved its primary mission and some of the secondary missions

幾何学情報の事前計算テンソル化に基づく精密太陽輻射圧外乱モデル構築に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 中須賀 真一, 東京大学教授 岩崎 晃, 東京大学准教授 矢入 健久, 東京大学准教授 船瀬 龍, 宇宙航空研究開発機構准教授 津田 雄一University of Tokyo(東京大学

On-Orbit Operation Results of the World\u27s First CubeSat XI-IV – Lessons Learned from Its Successful 15-years Space Flight

In recent years, the size and cost of satellites have been reduced, and the frequent launch of satellites have been realized even by small private companies and universities. The first step of this big wave was the first successful launch of CubeSats, 1kg nano-satellites, in June 2003. One of the CubeSats was XI-IV, which was developed by Intelligent Space Systems Laboratory (ISSL) of the University of Tokyo. Its mission was the world’s first on-orbit demonstration of the CubeSat bus system. Due to the spatial, power and cost constraints, most of the bus system was composed of low-cost COTS parts, and a “cross-check” type fault redundancy system against the radiation effects was implemented to achieve as better reliability as possible within the resource constraints. Since the successful launch by the ROCKOT launch vehicle from Russia, the satellite has been in normal operation for over fifteen years since the launch (as of June 2019). The operation has been jointly conducted by the University of Tokyo and amateur radio operators in Japan. This paper reports its more-than-15-years world\u27s longest CubeSat operation results and the lessons learned from it

Effects of dietary inulin, statin, and their co-treatment on hyperlipidemia, hepatic steatosis and changes in drug-metabolizing enzymes in rats fed a high-fat and high-sucrose diet

<p>Abstract</p> <p>Background</p> <p>Rats fed a high-fat and high-sucrose (HF) diet develop hepatic steatosis and hyperlipidemia. There are several reports that a change in nutritional status affects hepatic levels of drug-metabolizing enzymes. Synthetic inulin is a dietary component that completely evades glucide digestion. Supplementing a HF diet with inulin ameliorates hypertriglycemia and hepatic steatosis, but not hypercholesterolemia. This study aimed at distinguishing the effects of synthetic inulin and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin), which inhibit cholesterol biosynthesis.</p> <p>Methods</p> <p>We examined effects of co-treatment with synthetic inulin (5%) and fluvastatin (0, 4, and 8 mg/kg, <it>per os</it>) on body weight, epidydimal white adipose tissue weight, serum and hepatic lipid profiles, and hepatic cytochrome P450 (CYP) mRNA and protein profiles in rats fed a standard diet or a HF diet for 3 weeks.</p> <p>Results</p> <p>Treatment with the synthetic inulin (5%) or fluvastatin at 4 mg/kg (lethal dose in rats fed the HF diet, 8 mg/kg) ameliorated the elevation in hepatic triacylglycerol and total cholesterol levels in rats fed the HF diet. Whereas co-treatment with the inulin (5%) and fluvastatin (4 mg/kg) had a tendency to more strongly suppress the elevation in serum levels of very low density lipoprotein triacylglycerol than either treatment alone, no additive or synergistic effect was found in decrease in hepatic lipid levels. Hepatic levels of CYP1A1/2 and CYP2E1 mRNA and protein and methoxyresorufin <it>O</it>-demethylase and ethoxyresorufin <it>O</it>-deethylase activities were reduced in rats fed the HF diet. The synthetic inulin alleviated the reduction in hepatic levels of CYP1A1/2 and CYP2E1 mRNA and protein more strongly than fluvastatin, and no synergistic effects were observed on co-treatment. Furthermore, hepatic levels of aryl hydrocarbon receptor mRNA were decreased in rats fed the HF diet and recovered to near normal values with the intake of dietary inulin, which correlated with change in CYP1A1/2.</p> <p>Conclusions</p> <p>Dietary inulin alone was effective to prevent the development of hepatic steatosis, ameliorate nutritional effects, and alleviate the hepatic change in the expression of CYP1A1/2 and CYP2E1, while co-treatment with statin did not have additive or synergistic effects and statin may cause adverse effects in rats fed the HF diet.</p

Flight Model Design and Development Status of the Earth - Moon Lagrange Point Exploration CubeSat EQUULEUS Onboard SLS EM-1

EQUULEUS (EQUilibriUm Lunar-Earth point 6U Spacecraft) will be the world’s smallest spacecraft to explore the Earth―Moon Lagrange point. The spacecraft is being jointly developed by JAXA and the University of Tokyo and will be launched by NASA’s SLS (Space Launch System) EM-1 (Exploration Mission-1). The spacecraft will fly to a libration orbit around the Earth―Moon Lagrange point L2 (EML2) and demonstrate trajectory control techniques within the Sun-Earth-Moon region for the first time by a nano spacecraft. This spacecraft also carries several scientific observation missions which will be conducted during and after the flight to EML2; imaging of the entire Earth’s plasmasphere by extreme UV wavelength, observation of the space dust flux in the cis-lunar region, and observation of the lunar meteor impact flashes at the far side of the moon from EML2. The development of the spacecraft started in the summer of 2016 and the engineering model integration and testing was completed by the end of 2017. The design of the flight model was completed based on the engineering model test results. The integration and testing of the flight model will be completed by the end of 2018, to be ready for the launch by SLS’ first flight in 2019

On-Orbit Verification of Luminance Based Target Tracking and Faint Body Extractions by a Small Telescope on the World\u27s First Micro-Interplanetary Space Probe

In recent years, low cost and quick development of very small satellites ranging from CubeSats of 1 kg to micro-satellites of approximately 50 kg have allowed advances in space development and application. Although most of these satellites are in Earth orbits, a small spacecraft for deep-space missions has been developed and launched for the first time in the world. The Proximate Object Close Flyby with Optical Navigation (PROCYON) micro-interplanetary spacecraft, developed by the University of Tokyo and the Japan Aerospace Exploration Agency, was launched in December 2014 as one of the secondary payloads of the asteroid sample return spacecraft Hayabusa-2. The main mission of PROCYON is to demonstrate critical technologies of 50-kg-class interplanetary spacecraft exploration such as communication, attitude control, thermal control, and power generation. Furthermore, advanced missions of PROCYON enable a close flyby of an asteroid at an altitude of approximately several dozen kilometers and the capture of high-resolution images of approximately several meters per pixel by a telescope. In the flyby missions, the change of the target direction vector from the spacecraft to the asteroid is steeper than that of past flyby interplanetary probes. Thus, the spacecraft could not keep the asteroid in a telescope\u27s field of view only by performing an attitude maneuver of the entire body. To overcome this attitude maneuverability problem, a small and line-of-sight controllable telescope using a rotating mirror was developed and implemented on PROCYON. Due to the system constraint of the micro-spacecraft, this telescope should also be used for optical navigation by the faint asteroid images performed before several days of closest approach. The telescope is very lightweight, approximately 680 g. Moreover, its exposure time range is very high; thus, it can capture images of very dark astronomical bodies of approximately 12 magnitudes to supply information for trajectory correction maneuvers as well as bright bodies observed at a short distance during the close flyby. The results of experiments in the interplanetary orbit are shown in the presentation. Several 12 magnitude stars were identified from the images captured in orbit by utilizing the noise reduction techniques. This result complies with mission requirement of the optical navigation of PROCYON to extract the target images at least three days before closest approach. During the Earth approaching period, a visual feedback tracking experiment was performed utilizing the reflected light from the Earth. Time history of the rotation angle of the telescope shows the direction determination accuracy of the target body by the luminance center extraction using on-board image processing system. The know-how of the optical system of PROCYON enables a variety of missions in the interplanetary field performed by micro-spacecraft