Onboard sensor electronics of satellites are hard real-time systems and exploit high performance of heterogeneous computing. This paper describes sensor electronics design framework with heterogeneous computing edge nodes based on onboard demonstration records of satellites. Dedicated functional processing elements (PEs) for specific purposes implemented on Field Programmable Gate Arrays (FPGAs) and Application Specific Integration Circuit (ASIC) are used in addition to conventional Micro-Processing Units (MPUs). Many core processors like General Purpose Graphics Processing Units (GPGPUs) are also used for signal processing of sensor electronics in these days. Semiconductor process shrink is accelerating this technological trend. Because it reduces power consumption, size and mass while maintaining high processing performance. The applications of artificial intelligence, such as image recognition, became common for onboard sensor electronics. Dedicated PEs for image recognition implemented on FPGAs enables wire rate processing. Sensor signals are processed without interrupting data flow, and in-situ measurement results can be used for other purposes such as optical guidance and navigation. Heterogeneous computing edge nodes are often realized with distributed memory system. In addition to that the semantic gap between hardware and application software is widening. Despite these complexities, changes to the operation scripts of onboard sensor electronics are often needed on orbit. We have found that the layered architecture of heterogeneous PEs and the middle-out approach of system integration design are practical enough for onboard operation to aim at realizing user-centric command operation scripts. The design scheme is explained in this paper.
KEYWORDS: Space operations, Satellites, Model-based design, Data processing, Asteroids, Field programmable gate arrays, Process modeling, Data modeling, Aerospace engineering, Signal processing
DESTINY⁺ is a science and technology demonstration mission to asteroid Phaethon, the parent body of the Geminids meteor shower. It will explore the asteroid during a flyby for observations of cosmic dust, which is a source of the organic matter on Earth. In-situ analysis of interplanetary and interstellar dust will be carried out. It is planned to be launched in fiscal year 2024. Model-based development process using a bread board model of an onboard mission data processor is employed prior to system level integration test to follow the tight development schedule. Hybrid and reconfigurable computers are exploited as ground-based models to pursue digital development process. Dynamically reconfigurable devices are used as the central processing unit, and extensive simulation is performed by a hardware-in-the-loop simulator.
Fast timing capability in x-ray observation of astrophysical objects is one of the key properties for the ASTRO-H (Hitomi) mission. Absolute timing accuracies of 350 or 35 μs are required to achieve nominal scientific goals or to study fast variabilities of specific sources. The satellite carries a GPS receiver to obtain accurate time information, which is distributed from the central onboard computer through the large and complex SpaceWire network. The details of the time system on the hardware and software design are described. In the distribution of the time information, the propagation delays and jitters affect the timing accuracy. Six other items identified within the timing system will also contribute to absolute time error. These error items have been measured and checked on ground to ensure the time error budgets meet the mission requirements. The overall timing performance in combination with hardware performance, software algorithm, and the orbital determination accuracies, etc. under nominal conditions satisfies the mission requirements of 35 μs. This work demonstrates key points for space-use instruments in hardware and software designs and calibration measurements for fine timing accuracy on the order of microseconds for midsized satellites using the SpaceWire (IEEE1355) network.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.