On-Orbit Demonstrations of Robust Autonomous Operations on Cubesat

As we accumulate experiences of satellite developments, we clearly recognize the importance of successful operations and difficulty to achieve them. There are many anomalous events in orbit especially for small satellites. It is costly or impossible to consider all anomalies in advance. The autonomous operation functions, we have developed, can operate the satellite without operators and achieve operation intents. The functions have the satellite behavior (state) models and the given operation intents. They generate the on-board operation procedures from the behavior models and execute them. Even if the status may not transit as expected due to anomalies, they can re-recognize the new status, generate the operation procedures again, and achieve the operation intents robustly. We have demonstrated the autonomous operation functions on a 3U CubeSat called TRICOM-1R that was launched by the newly developed and dedicated small satellite launcher SS-520 on 3rd Feb. 2018. The autonomous functions worked correctly and tried turning on the cameras without any predetermined operation procedures during the very first cycle of the orbit. The demonstration of them has successfully completed. We have several CubeSats and small satellites now in development and we will implement the upgraded version of the autonomous functions on them

AQT-D: Demonstration of the Water Resistojet Propulsion System by the ISS-Deployed CubeSat

AQT-D (AQua Thruster-Demonstrator) is a 3U CubeSat for a demonstration of a water resistojet propulsion system developed by The University of Tokyo. AQT-D installed the 1U propulsion system using water as a propellant, named AQUARIUS-1U (AQUA ResIstojet propUlsion System 1U). We completed the design and assembly of the AQT-D flight model. AQUARIUS-1U was fired on a pendulum-type thrust balance, and its performance was directly characterized in both a stand-alone test and an integrated test using an entire spacecraft system. AQT-D is currently scheduled to be delivered to JAXA in July 2019 and launched to the International Space Station (ISS) in the middle of 2019 by the H-IIB rocket. AQT-D will be deployed from the Japanese Experiment Module (JEM), known as Kibo, and demonstrate water propulsion technology

PETREL: Platform for Extra and Terrestrial Remote Examination with LCTF

A small satellite ”PETREL” for UV astronomy and remote sensing with ”tunable” multi-spectral cameras conducted by an academia-industrial collaboration is presented. This project was originally proposed by an astronomer who desired a satellite for exploration of explosive objects in ultraviolet. To avoid the earthshine the astronomical observations are scheduled only in the nighttime. To utilize the daytime more electively we conceived a plan of ”satellite sharing” with the industrial collaborators, that can also reduce the developing cost drastically. The daytime mission is spectroscopy that is one of the potential fields in terms of data business, because that can provide chemical and biological information on the surface of the earth. We employ multi-spectral cameras making use of liquid crystal tunable filters (LCTFs) that enable adaptive observations at the optimized wave-bands for each targets. In 2020, this remote-sensing project and ultraviolet astronomy mission were accepted as a small satellite project of JAXA’s Innovative Satellite Technology Demonstration program and as an ISAS/JAXA’s small-scale program, respectively. This satellit

The Japanese space gravitational wave antenna; DECIGO

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry– Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre- DECIGO first and finally DECIGO in 2024

DECIGO pathfinder

DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article

The status of DECIGO

DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consists of three drag-free spacecraft arranged in an equilateral triangle with 1000 km arm lengths whose relative displacements are measured by a differential Fabry-Perot interferometer, and four units of triangular Fabry-Perot interferometers are arranged on heliocentric orbit around the sun. DECIGO is vary ambitious mission, we plan to launch DECIGO in era of 2030s after precursor satellite mission, B-DECIGO. B-DECIGO is essentially smaller version of DECIGO: B-DECIGO consists of three spacecraft arranged in an triangle with 100 km arm lengths orbiting 2000 km above the surface of the earth. It is hoped that the launch date will be late 2020s for the present

On-orbit Demonstration of Satellite Software Architecture With a Flexible Reconfiguration Capability

In recent years, as practical applications of microsatellites spread, missions of them have become advanced and it has been required that the development of them is short-term and low-cost. In order to achieve these requirements, two points of improvement, such as reliability of software due to high re-usability and flexible reconfiguration capability on orbit, are important in terms of onboard software. The conventional development of on-board software for microsatellites has been performed individually each satellite, and software which can achieve the two points mentioned above has not been developed. Therefore, as a framework to develop on-board software for microsatellites that satisfies high re-usability and flexible reconfiguration capability, the software architecture named Command Centric Architecture (C2A) was proposed as a doctoral dissertation at The University of Tokyo. This software architecture has three characteristics: describing common functions among every spacecraft as commands and functions associated with them, modularizing unique functions for each satellite, and coupling common functions with unique functions via definition tables. With these features, the onboard software realizes the flexible reconfiguration capability of itself, which is the middle of the parameter change and the memory rewrite from a viewpoint of the load for implementation, the risk of reconfiguration and the ability to deal with anomalies. Furthermore, this software framework separates functions common to spacecraft and spacecraft-specific functions and narrows hardware-dependent parts by modularizing spacecraft-specific functions. Thanks to them, it is possible to reuse many parts of the software in different spacecraft. C2A was applied to some Earth-orbiting microsatellites, UNIFORM, Hodoyoshi-3 and 4, and it was refined. After that, it was applied to PROCYON which is the first interplanetary micro-spacecraft. Porting C2A to PROCYON was quite easy because these four spacecraft use the same model of onboard computer. By using C2A on its onboard software, development of the software was completed in only about 5.5 months. Also, we were able to deal with various events by utilizing C2A\u27s flexible reconfiguration capability during operation of PROCYON. In addition, we have completed implementation of C2A to the onboard software of EQUULEUS, which is 6U CubeSat currently under development. C2A porting from PROCYON to EQUULEUS was realized in a very short time in spite of EQUULEUS using a different model of onboard computer. In this way, C2A has various advantages such as shortening development period of small spacecraft, improving the reliability of onboard software, the flexibility of operation, therefore it gives a great advantage to the mission using the small spacecraft

Advanced System of Micro Satellite for Hyperspectral Remote Sensing Mission

The Space-Science Industries Program has been performing investigations for the Micro-satellite and Hyperspectral remote sensing missions.The Earth Observation Micro-satellite “TAIKI” is a 50kg satellite which has low-cost and small bus-subsystems for advanced remote sensing missions.This bus-subsystem will be developed and manufactured products.The TAIKI is characterized by a small Hyperspectral sensor “HSC-III” which is targeted at the performances of 30m of ground sampling distance and 61 spectral bands in VINR (Visible and Near Infrared).The advanced remote sensing data such as Hyperspectral data are large volume so the downlink uses the laser communication of 100Mbps.The terrestrial laser communication has already been successfully experimented.In addition, HSC-III optics instrument which mainly consists of spectrometer, detector and on-board calibration systems has been developed in 2008.This paper reports the small bus-subsystem including the laser communication systems for the TAIKI and Hyperspectral sensor instrument