Subsumption-based architecture for autonomous movement planning for planetary rovers

The paper proposes a new architecture for autonomously generating and managing movement plans of planetary rovers. The system utilizes the uniform representation of the instantaneous subgoals in the form of virtual sensor states and the autonomous generation of the subsumption type plan network, which are expected to lead to the capability to pursue the overall goal while efficiently managing various unpredicted anomalies in a partially unknown, ill-structured environment such as a planetary surface

Applications of dynamic scheduling technique to space related problems: Some case studies

The paper discusses the applications of 'Dynamic Scheduling' technique, which has been invented for the scheduling of Flexible Manufacturing System, to two space related scheduling problems: operation scheduling of a future space transportation system, and resource allocation in a space system with limited resources such as space station or space shuttle

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

Satellite Contributions to Disaster Monitoring - Japanese Earthquake and Tsunami Case in 2011 -

In March 11, 2011, Japan was hit by a large earthquake followed by huge Tsunami. They gave tremendous damages to especially Tohoku-area with more than 18,000 lost and missing persons and more than 360,000 all or half destroyed houses. Furthermore, Fukushima Daiichi Nuclear Power Plant has been suffering from severe reactor problems caused by the electric power failure by tsunami, and still quite a large number of people cannot stay within their homes near the plants. Japan is now making every effort to restore the previous status of the people\u27s living, economics and industry power. In this presentation, we first give the overview of the disaster. Then we focus on how satellite images, not only captured by small satellites but also by mid and large satellites, were utilized to monitor the disaster, reconstruction planning and operations. Many satellites took part in the data acquisition related to the disaster, which provided useful information on tsunami inundations and landslides, etc. To enhance satellite utilization, we finally discuss what kind on disaster monitoring system would be valuable in future, including lowcost small/micro satellite constellation and orbit maneuver

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

Retrodirective Antenna Array Approach to Achieve Maximum Theoretical Beam Efficiency in Microwave Wireless Power Transfer

Efficient long range wireless power transfer (WPT) is realized if the distance between the source and receiver is less than the Fraunhoffer distance. This distance increases proportionally to the square root of the antenna size so to achieve efficient long range WPT, larger antennas are mandatory, but that comes with difficulty in implementing both the feeding network and beamforming control of the antenna. Several proposed implementations require power-hungry processors rendering implementation impractical. An alternative to reduce usage of digital processing is in the form of retrodirective antenna arrays. Its core operation is to track an incoming signal's direction of arrival and resend it to the same direction. This can be implemented by analog circuits. Retrodirective capability on both the generator and rectenna arrays creates a feedback loop that produces a high efficiency WPT channel. In this paper, we characterize the dynamics of this phenomenon using a discrete-time state-space model based on S-parameters and show that the system can naturally achieve maximum theoretical WPT efficiency. We further confirmed the theoretical analysis through a hardware experiment using a 12-port circuit board with measurable S-parameters mimicking a deterministic wireless channel. The results of the hardware experiment show agreement with the proposed theoretical framework.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible. 9 pages, 11 figures, 1 table, submitted to the IEEE Transactions on Theory and Techniques on September 22, 202

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

The Development Status of the First Demonstration Satellite of Our Commercial Small Synthetic Aperture Radar Satellite Constellation

Expectations for SAR (Synthetic Aperture Radar) satellites that can observe a target area through clouds and during nighttime are emerging, especially in Asia where high cloud cover rate prevent from the satellite monitoring with optical sensors. We are now developing a small SAR satellite based on technologies of ImPACT (Impulsing PAradigm Change through disruptive Technologies) program. This program aims to develop a responsive earth observation system with the small SAR satellite, originally target for disaster monitoring. We will build a constellation of the small SAR satellites to realize short term revisits, shorter than one day to take advantage of SAR sensor that can acquire data regardless of weather and time in a day. We expect the constellation expands needs of the SAR data to business and private decision making, and develop a market for commercial use. We have almost completed the development of mission FM components of the first demo satellite. The bus system is under EM testing and FM procurements. We will launch the first demo satellite in Q1 of 2020. We are already preparing to build the second satellite and will make six satellite constellation until 2021. Our final goal is to build a constellation of 25 satellites

CubeSat: A New Generation of Picosatellite for Education and Industry Low-Cost Space Experimentation

The launch and deployment of picosatellites from the Stanford University OPAL microsatellite in February 2000 demonstrate the feasibility and practicability of a new age of space experimentation. Two of the six picosatellites deployed from OPAL were built by The Aerospace Corporation in El Segundo, CA and demonstrated new space testing of MEMS RF switches and intersatellite and ground communication with low power wireless radios. These picosatellites weighting less than one kilogram with dimensions of 4x3x1 inch were built as test platforms for DARPA and were constructed and delivered for flight in less than nine months. From this experience, a new generation of picosats called CubeSat is being developed by a number of organizations and universities to accelerate opportunities with small, low construction cost, low launch cost space experiment platforms. California Polytechnic State University at San Luis Obispo, CA is developing launcher tubes that can be part of a satellite or attached to any orbiting platform to launch from 1-3 CubeSats per tube. These tubes will contain CubeSats of 1-2 kilograms weight and approximately 4-inch cube shape. This size as compared to the picosatellites launched on OPAL provide better surfaces for practical solar power generation, physical size for components and a shape that provides better space thermal stability. A consortium of potential CubeSat developers is now wide ranging with universities from Japan, New Zealand, the US, amateur radio clubs and industry participants. Potential launch opportunities exist with the Russian Dnepr (SS-18) about twice/year, with the OSP (Minotaur) every 18 months and possible 100 km altitude orbits from the second stage of Delta launches. This paper will review the OPAL picosatellite launch and performance, the launcher being built for the CubeSat, the development and payloads of CubeSat developers and cost and timing of launch opportunities