Yuko Miyamoto

Hazard Analysis of Complex Spacecraft Using Systems-Theoretic Process Analysis

A new hazard analysis technique, called systems-theoretic process analysis, is capable of identifying potential hazardous design flaws, including software and system design errors and unsafe interactions among multiple system components. Detailed procedures for performing the hazard analysis were developed, and the feasibility and utility of using it on complex systems was demonstrated by applying it to the Japanese Aerospace Exploration Agency H-II Transfer Vehicle. In a comparison of the results of this new hazard analysis technique to those of the standard fault tree analysis used in the design and certification of the H-II Transfer Vehicle, systems-theoretic hazard analysis found all the hazardous scenarios identified in the fault tree analysis as well as additional causal factors that had not been identified by fault tree analysis.

Scoping software process models: initial concepts and experience from defining space standards

Defining process standards by integrating, harmonizing, and standardizingheterogeneous and often implicit processes is an important task, especiallyfor large development organizations. However, many challenges exist,such as limiting the scope of process standards, coping with different levels ofprocess model abstraction, and identifying relevant process variabilities to beincluded in the standard. On the one hand, eliminating process variability bybuilding more abstract models with higher degrees of interpretation has manydisadvantages, such as less control over the process. Integrating all kinds ofvariability, on the other hand, leads to high process deployment costs. This articledescribes requirements and concepts for determining the scope of processstandards based on a characterization of the potential productzs to be producedin the future, the projects expected for the future, and the respective process capabilitiesneeded. In addition, the article sketches experience from determiningthe scope of space process standards for satellite software development. Finally,related work with respect to process model scoping, conclusions, and an outlookon future work are presented.

Application of GQM+Strategies® in the Japanese Space Industry

Aligning organizational goals and activities is of great importance for large organizations in order to improve their performance and achieve top-level business goals. Through alignment, organizational sub-units can optimize and explicitly highlight their contributions towards the achievement of top-level business goals. GQM+Strategies provides a systematic, measurement-based approach for explicitly linking goals and contributions on different organizational levels. This paper presents results and experiences from applying the GQM+Strategies approach at the Japan Aerospace Exploration Agency.

Comparing Model Generated with Expert Generated IV&V Activity Plans

Modularity is one of the key features of the Object- Oriented (00) paradigm. Low coupling and high cohesion help to achieve good modularity. Inheritance is one of the core concepts of the 00 paradigm which facilitates modularity. Previous research has shown that the use of the friend construct as a coupling mechanism in C+ + software is extensive. However, measures of the friend construct are scarse in comparison with measures of inheritance. In addition, these existing measures are coarse-grained, in spite of the widespread use of the friend mechanism. In this paper, a set of software metrics are proposed that measure the actual use of the friend construct, inheritance and other forms of coupling. These metrics are based on the interactions for which each coupling mechanism is necessary and sufficient. Previous work only considered the declaration of a relationship between classes. The software metrics introduced are empirically assessed using the LEDA software system. Our results indicate that the friend mechanism is used to a very limited extent to access hidden methods in classes. However, access to hidden attributes is more common.

Software Independent Verification and Validation for Spacecraft at JAXA

In order to achieve mission success with more demanding mission requirements and more complex onboard software, our software independent verification and validation (IV&V) has been applied to various spacecraft software programs, such as software on satellites, ground stations, and the Japanese Experimental Module (JEM) of the International Space Station (ISS). The malfunction procedure in the operations data file for JEM is also the target for applying software IV&V. Suitable software IV&V can be performed for each spacecraft throughout the entire development life cycle. The objectives for software IV&V activity are the following: applying suitable software IV&V to each spacecraft, creating new software IV&V technologies for spacecraft, and spreading new software engineering technologies based on our software IV&V to development teams and contractors. This paper introduces our software IV&V activities and several examples to confirm that our activities are effective and efficient for spacecraft.

JAXA's optical data relay satellite programme

After 13 years successful operation of Japanese first data relay satellite “KODAMA,” JAXA has initiated a new data relay satellite programme which adapts optical communication in the inter-orbit link. The programme includes development of a data relay satellite and optical terminals both for GEO (i.e. the data relay satellite) and LEO, Ka feeder link system to communicate between the data relay satellite and ground stations and has data-relay service capability up to 1.8 Gbps. Targets launch year is 2019 in Japanese fiscal year. In the paper, the authors outline the plan of the programme and its technology.

Overview of optical data relay system in JAXA

To meet increasing demands of high-speed data transmission, JAXA has started to develop a new optical data relay system. This system provides 1.8Gbit/s data relay service through optical inter-satellite link and Ka-band feeder link using JDRS, a data relay satellite. The first user satellite is the Advanced Optical Satellite, a Japanese optical observation satellite in low earth orbit. As a total data relay system, the data relay satellite, Ka-band ground stations and two optical terminals for JDRS and the Advanced Optical Satellite are developed together. Target launch year of JDRS is 2019 in Japanese fiscal year. This paper describes the development plan and technologies of the optical data relay system.