Yoshiaki Ohkami

Autonomous Rendezvous and Docking by Engineering Test Satellite VII : A Challenge of Japan in Guidance, Navigation and Control-Breakwell Memorial Lecture

Abstract Since 1969, National Development Agency (NASDA) has learned plenty of technologies from the United States in the field of guidance, navigation and control. As a next step beyond the GN&C technology for conventional rockets and spacecraft, rendezvous and docking experiment by using ETS-VII was a real challenge of NASDA in this field. This lecture outlines this project including the background, the trajectory design philosophy, the sensors and actuators, experiment plan as well as the summary of the on-orbit experiment results. Future projects to utilize the established technology will be also explained briefly.

Generalized Multicommodity Network Flow Model for the Earth–Moon–Mars Logistics System

Simple logistics strategies such as “carry-along” and Earth-based “resupply” were sufficient for past human space programs. Next-generation space logistics paradigms are expected to be more complex, involving multiple exploration destinations and in situ resource utilization. Optional in situ resource utilization brings additional complexity to the interplanetary supply chain network design problem. This paper presents an interdependent network flow modeling method for determining optimal logistics strategies for space exploration and its application to the human exploration of Mars. It is found that a strategy using lunar resources in the cislunar network may improve overall launch mass to low Earth orbit for recurring missions to Mars compared to NASA’s Mars Design Reference Architecture 5.0, even when including the mass of the in situ resource utilization infrastructures that need to be predeployed. Other findings suggest that chemical propulsion using liquid oxygen/liquid hydrogen, lunar in situ resou...

Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services

Location-Based Services (LBS), an emerging new business based on smartphone and mobile networks, are becoming more and more popular. Most of these LBSs, however, only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role. Our specific aim is to solve these issues. This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders.

A Generalized Multi-Commodity Network Flow Model for Space Exploration Logistics

In transition to a new era of human space exploration, the question is what the nextgeneration space logistics paradigm should be. The past studies on space logistics have been mainly focused on a vehicle perspective such as propulsive feasibility, cargo capacity constraints, and manifesting strategies, with the arbitrarily predetermined logistics network. But how do we select an optimal logistics network? Especially if we can utilize insitu resources on the Moon and Mars, it will add complexity to network selection problem. The objective of this paper is to develop a comprehensive graph-theoretic modeling framework to quantitatively evaluate and optimize space exploration logistics from a network perspective. In an attempt to create such a modeling framework, we develop a novel network flow model referred to as the generalized multi-commodity network flow (GMCNF) model. On top of the classical network flow problems, the GMCNF model proposed in this paper introduces three types of matrix multiplications (requirement, transformation, and concurrency), and also allows loop edges associated with nodes (graph loops) and multiple edges between the same end nodes (multigraph). With this modification, the model can handle multiple commodities that interact with each other in the form of requirement at nodes, transformation on edges, and concurrency within edges. A linear programming (LP) formulation of the GMCNF model is applied to human exploration of Mars. First we solve the baseline problem with a demand that is equivalent to that of the NASA’s Mars Design Reference Architecture (DRA) 5.0 scenario. It is found that the solution saves 67.5% from the Mars DRA 5.0 reference scenario in terms of the initial mass in low-Earth orbit (IMLEO) primarily because chemical (LOX/LH2) propulsion is used along with oxygen-rich ISRU. We also present one possible scenario with two gateway resource depots at GTO and DTO with orbital transfer vehicles (OTVs) running in the cislunar and Martian systems. Then we solve variant problems that have different settings to see the effect of each factor. Findings include: taking advantage of oxygen-rich ISRU, LOX/LH2 is preferred to nuclear thermal rocket (NTR), the aerobraking option as well as ISRU availability on the Moon make great contributions in reducing the total mass to be launched from Earth, and as the ISRU production rate decreases, ISRU in each location becomes worthless at a certain threshold and the network topology changes toward direct paths using NTR.

Systems engineering education for inexperienced students by providing hand-on practices

This paper presents results and lessons learned from a trial course on systems engineering for graduate students with little experience in industries. This course provides students with hand-on education for system engineering using commercially-off-the-shelf (COTS) components and a sizable amount of development works within the limitation in one semester (26 slots of lectures).

A Proposal for Graph-Theoretic Modeling Approach to Resource-Economy in Spaceflight Campaign Logistics

NASA’s new direction for human spaceflight reaffirms that Mars is the ultimate goal of human exploration of the inner solar system. In response to this background, we can expect to see an increasing number of robotic explorations of Mars over the next several decades, followed by human missions. In a period of transition to a new era of space exploration, the question is what the next space logistics paradigm should be. Adding to the technical challenges, logistical concerns should be considered far in advance. A well-planned logistics strategy is essential to balance risks, ensure robustness, and achieve maximum exploration capability. Space logistics is an emerging topic in recent years as we start to see space exploration not as a set of isolated missions but as an intricately-linked exploration campaign. A vast body of research exists for terrestrial transportation networks and supply chain logistics in business and military applications. However, space exploration introduces several fundamental differences such as infrequent launch windows, long transport durations, and minimal cargo capacity. The past studies on space logistics have been mainly focused on a “vehicle” perspective such as propulsive feasibility, cargo capacity constraints, manifesting strategies, and demand satisfaction, assuming a pre-defined logistics network. However, there is more than one way to define a logistics network (transfer points) between origin and destination such as ISRU on the surface nodes and resource depots in orbital nodes or Lagrangian nodes. Therefore, this paper proposes a graph-theoretic modeling approach to analyze spaceflight campaign logistics seeking for “resource-economy” from a “network” perspective. We define resource-economy in the context of space exploration, identify the building blocks of logistics network (nodes, arcs, and costs), and present a quick example to show the potential benefits of ISRU and resource depots. Once the generic framework has been modeled and implemented, it will be able to be used a proof of concept, providing a useful index of resource-economy to quantitatively compare different concepts of exploration. Moreover, this framework will not only evaluate and compare specific scenarios but also find the key drivers of resource-economy in space logistics.

Dual-Use system architecture for a space situational awareness system in Japan

The use of outer space plays a vital role in both defense and civil fields. Since the separation of space activities between civil and defense applications is extremely inefficient, the Dual-Use concept has been considered fundamental for promoting the effective use of space. To the best of the authors knowledge, most previous studies on Dual-Use focused on the technological aspects, and very few on a system engineering approach to Dual-Use. This left some important issues untouched such as the operational aspects of a system of systems, which need to be understood in a more generic context. This paper presents the results of a conceptual study, system design and management analysis of Dual-Use system architecture. First, an outline of the Dual-Use concept will be described and a definition of Dual-Use given. The effectiveness of applying the Dual-Use system concept to Space Situational Awareness (SSA) for both defense and civil users as a system of systems will then be discussed and investigated with a stakeholders analysis, context diagram and design structure matrix method. It has demonstrated that there is a need for a Dual-Use SSA Data Center which works as a binder between defense and civil systems as well as a data policy for constructing a Dual-Use SSA system.

Decomposition Analysis Resolution Process (DAR) of Systems Engineering Applied to Development of Countermeasure on Leakage of Engine Head-Gasket

This paper reviews a countermeasure development of leakage from coolant seals of head-gaskets in a diesel engine applying the Decomposition Analysis and Resolution Process (DAR). We can find complexity arising from some causes of leakage even in a simple square-ring rubber seal. The major causes are (1) large displacement around a head-gasket generated by the combustion, (2) seal distortion at a high compression, (3) seal rubber degradation induced by coolant microorganism deterioration, (4) uncontrolled seal production and (5) unsuitable rubber composition. Through our DAR, we can resolve the complexity of the leakage and can clarify all the cause positions and their relationships. We can confirm that an improved silicone rubber seal, which has a higher fatigue strength, an excellent acid-resistance and a uniform contact property, is the correct resolution. This paper also shows development of a hydrogenated nitrile rubber seal as a permanent measure, which can extend the Middle of Life (MOL) of Product Lifecycle Management (PLM) of the industrial diesel engine production.

Proposal of space debris indemnification fund

Throughout our space development and utilization activities since 1957, we have left many man-made objects in space, what is called, space debris. Situation of space debris is getting worse as the number of space debris increases, leading to the collisions between an operational spacecraft and space debris. More seriously, a massive object may fall down and hit the ground causing large-scale damage and/or fatalities. This implies that space debris may bring a serious and growing problem and the recognition of necessity and emergency of space debris treatment is increasing in space community. Technically, several countermeasures have been proposed such as the Active Debris Removal (ADR) which is one of the feasible solutions to remedy space environment immediately. In order to realize the countermeasure in action, this paper makes an attempt to solve issues from the system engineering point of view including business and legal aspects by referring the IOPCF for an oil spill risk by a huge-tanker.

Uplink Radio Frequency Signal Fluctuations

KAGUYA was a Japanese large lunar explorer that orbited and observed the moon from 2007 to 2009. During in-orbit operation, unexpected fluctuations and lock-offs of KAGUYA’s uplink radio frequency telecommand signal were sometimes observed. To investigate the cause of the fluctuations, archived telemetry data were surveyed, and the telemetry data that showed the fluctuation were extracted. According to fault tree analysis of the telemetry data, multipath interference from the lunar surface and the spacecraft structure was deemed the most probable cause. This finding was verified by geometrical analysis of multipath interference. On the basis of the analysis results, the fluctuation map for a lunar polar orbiter was presented for the first time. This map was used to avoid the telecommand operation failure of KAGUYA. This lesson can be generally applied to operations of planet and lunar orbiters.