Variable Shape Attitude Control Demonstration with Microsat Hibari

This paper presents the ongoing feasibility study and bus system for microsatellite “Hibari”. The main technical missions for Hibari is called “Variable Shape Attitude Control (VSAC)”. This VSAC is based on an idea to utilize a reaction torque when a part of the satellite structure, for example, solar array paddles is appropriately rotated by actuators. The previous research concluded that VSAC successfully achieved the rapid maneuvering while maintain the high attitude stability against disturbances [1], and thus, it can be applied to a variety of advanced attitude control missions. Hibari project also aims at its application to astronomical mission requiring high pointing stability and agile maneuvering. This paper is mainly comprised of 3 parts: detail mission statement, ongoing feasibility studies and bus system configuration. First, we mention the mission requirement and detail mission sequence for both technical and science missions. Second, we show the ongoing feasibility studies to confirm that all mission requirement is satisfied by VSAC. Third, this paper describes each subsystem configuration to meet the system requirement stated in the mission’s section. And then, we wrap up in the conclusion section and stated the future study for advanced VSAC use in the end

Development of Attitude Sensor using Deep Learning

A new method for attitude determination utilizing color earth images taken with COTS visible light camera is presented. The traditional earth camera has been used for coarse attitude determination by detecting the edge of the earth, and therefore it can only provide coarse and 2-axis information. In contrast, our method recognizes the ground pattern with an accuracy of sub-degrees and can provide 3-axis attitude information by comparing the detected ground pattern and the global map. Moreover, this method has advantages in the size, mass and cost of the detector system which consists of a cheap optical color camera and a single board computer. To demonstrate the method in space, we have developed a sensor system named “Deep Learning Attitude Sensor (DLAS)”. DLAS uses COTS camera modules and single board computers to reduce the cost. The obtained images are promptly analyzed with a newly developed real-time image recognition algorithms

Development and Initial On-orbit Performance of Multi-Functional Attitude Sensor using Image Recognition

This paper describes a multi-functional attitude sensor mounted on the “Innovative Satellite 1st” led by Japan Aerospace Exploration Agency which was launched in January 2019. In order to achieve the high accuracy determination in low cost, we developed a novel attitude sensor utilizing real-time image recognition technology, named “Deep Learning Attitude Sensor (DLAS)”. DLAS has two type of attitude sensors: Star Tracker(STT) and Earth Camera (ECAM). For the low-cost development, we adopted commercial off-the-shelf cameras. DLAS uses real-time image recognition technology and a new attitude determination algorithm. In this paper, we present the missions, methods and system configuration of DLAS and initial results of on-orbit experiment that was conducted after the middle of February 2019, and it is confirmed that attitude determinations using ECAM and STT are performed correctly

Engineering Model Development of HIBARI: MicroSatellite for Technology Demonstration of Variable-Shape Attitude Control

We are developing a 40kg class microsatellite “HIBARI”. The main technical mission is demonstration a novel attitude control method called “Variable Shape Attitude Control (VSAC)” proposed by Matunaga, Tokyo Institute of Technology. This VSAC is based on an idea to utilize a reaction torque generated by changing the shape of satellites, for example driving solar array paddles by actuators. HIBARI is planned to be launched in fiscal year 2021 under “Innovative Satellite Technology Demonstration Program” led by JAXA. We are developing EM of HIBARI and describes those in this paper. Specifically, the results of missions, systems, and various tests are shown and the validity is derived

Conceptual design of a wide-field near UV transient survey in a 6U CubeSat

A conceptual design of a wide-field near UV transient survey in a 6U CubeSat is presented. Ultraviolet is one of the frontier in the transient astronomy. To open up the discovery region, we are developing a 6U CubeSat for transient exploration. The possible targets will be supernova shock-breakouts, tidal disruption events, and the blue emission from NS-NS mergers in very early phase. If we only focused on nearby/bright sources, the required detection limit is around 20 mag (AB). To avoid the background and optical light, we chose a waveband of 230-280 nm. As an imaging detector, we employ a delta-doped back-illuminated CMOS. In addition to delta doping, the multi-layer coating directly deposited on the detector enables both a high in-band UV QE and the ultra-low optical rejection ratio. Taking into account these specifications, even an 8 cm telescope can achieve the detection limit of 20 magAB. The expected FoV is larger than 60 deg^2

Conceptual design of a wide-field near UV transient survey in a 6U CubeSat

A conceptual design of a wide-field near UV transient survey in a 6U CubeSat is presented. Ultraviolet is one of the frontier in the transient astronomy. To open up the discovery region, we are developing a 6U CubeSat for transient exploration. The possible targets will be supernova shock-breakouts, tidal disruption events, and the blue emission from NS-NS mergers in very early phase. If we only focused on nearby/bright sources, the required detection limit is around 20 mag (AB). To avoid the background and optical light, we chose a waveband of 230-280 nm. As an imaging detector, we employ a delta-doped back-illuminated CMOS. In addition to delta doping, the multi-layer coating directly deposited on the detector enables both a high in-band UV QE and the ultra-low optical rejection ratio. Taking into account these specifications, even an 8 cm telescope can achieve the detection limit of 20 magAB. The expected FoV is larger than 60 deg^2

Concept Design and Development of 30kg Microsatellite HIBARI for Demonstration of Variable Shape Attitude Control

We are developing a 30kg class microsatellite “HIBARI”. The main technical missions for HIBARI is demonstration a novel attitude control method called “Variable Shape Attitude Control (VSAC)” proposed by Matunaga, Tokyo Institute of Technology. This VSAC is based on an idea to utilize a reaction torque generated by changing the shape of satellites, for example driving solar array paddles by actuators. HIBARI is planned to be launched within a few years under “Innovative Satellite Technology Demonstration Program” led by Japan Aerospace Exploration Agency (JAXA). We designed the concept of HIBARI and describes those in this paper. Specifically, we confirmed the validity of the mission and system, and selected equipment based on radiation tolerance tests and orbital results in the past. Currently we are making Breadboard Model and checking its operation. We plan to develop Engineering Model and Proto-Fright model and conduct various ground tests this year, and proceed to Fright Model next year