JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EG3105

Subject Category: Research and Development

PDF (to be added)

• Responsible Representative: Masanobu Yajima, Research and Development Directorate, Research Unit I
• Contact Information: HARADA Ryusuke(harada.ryuusuke@jaxa.jp)
• Members: Mitsuko Futami, Ryusuke Harada, Yasuhiro Kitagawa, Satomi Kawamoto, Ryuji Nakawatase, Hiroshi Oda

Abstract

Increase of space debris is a problem for reliability of sustainable space activity. JAXA has been researching space debris related technologies for the space debris mitigation and environmental remediation. The effectiveness of space debris countermeasures are evaluated based on the prediction of the future orbital environment using the orbital debris evolutionary model (NEODEEM) jointly developed by JAXA and Kyushu University.

Reference URL

Please refer to https://www.kenkai.jaxa.jp/research/spacedebris/spacedebris.html .

Reasons and benefits of using JAXA Supercomputer System

NEODEEM predicts the situation of over 200 years orbital propagations of more than 20000 elements and orbital events by using Monte-Carlo method (evaluate the average of 100 runs). Therefore, JSS3 is used to reduce the computational run time and to process a large amount of data. TOKI-RURI is used for compatibility with PC version (Linux, WINDOWS).

Achievements of the Year

As part of future on‑orbit environmental assessments, we developed a new statistical method to evaluate how non‑operational GEO satellites and upper‑stage rocket bodies impose the risk to operational GEO satellites. The results were presented at an international conference as a contribution to discussions on the long‑term sustainability of the GEO environment (Fig. 1).

We also evaluated the orbital environment using a debris index taking into account large constellations and orbital capacity. Our analysis showed that even without imposing uniformly strict rules—such as requiring all spacecraft to complete PMD within one year—targeted mitigation for objects with higher environmental impact can still lead to meaningful environmental improvement (Fig. 2). These results are being used as technical input for discussions on the effectiveness of debris-mitigation measures and future international guidelines.

Fig.1: Longitude distribution of the total number of conjunctions caused by past and future GEO-interfering objects over a seven-year period.Objects librating around the eastern stable point account for most of the events, while a smaller number of interfering objects are also present around the western stable point.

Fig.2: Projection of the number of low-Earth-orbit objects over the next 200 years. Compared with the nominal scenario, the results indicate that increasing the PMD success rate to 99% for objects with high debris-index values leads to a decreasing trend in the long-term orbital population.

Publications

- Non peer-reviewed papers

1. HARADA Ryusuke, KAWAMOTO Satomi, YOSHIMURA Yasuhiro, HANADA Toshiya, Towards a Better Understanding of Space Debris Environment, Volume 44 Issue 1 Page 49-55, Mar. 15, 2025.

2. Ryusuke Harada, Satomi Kawamoto, and Toshiya Hanada, The study of a debris cloud risk assessment in geosynchronous orbit, 9th European Conference on Space Debris, Bonn, Germany 1 - 4 Apr 2025

3. Ryusuke Harada, Satomi Kawamoto, and Toshiya Hanada, A study of risk assessment metrics of non-operational objects in Geosynchronous orbit, 76th International Astronautical Congress (IAC 2025), Sydney, Australia, 29 Sep-3 Oct 2025.

4. Satomi Kawamoto, Ryusuke Harada, Yasuhiro Kitagawa, and Toshiya Hanada, Debris index for varying debris mitigation requirements to account for large constellations and orbital capacity, 76th International Astronautical Congress (IAC 2025), Sydney, Australia, 29 Sep-3 Oct 2025.

5. Ryuji Nakawatase, Dr. Yasuhiro Yoshimura, Ryusuke Harada, Satomi Kawamoto, and Toshiya Hanada, Effectiveness evaluation of the drag augmentation in post-mission disposal, 76th International Astronautical Congress (IAC 2025), Sydney, Australia, 29 Sep-3 Oct 2025.

- Oral Presentations

1. Ryusuke Harada, Satomi Kawamoto, and Toshiya Hanada, The study of a debris cloud risk assessment in geosynchronous orbit, 9th European Conference on Space Debris, Bonn, Germany 1 - 4 Apr 2025

2. Ryusuke Harada, Satomi Kawamoto, and Toshiya Hanada, A study of risk assessment metrics of non-operational objects in Geosynchronous orbit, 76th International Astronautical Congress (IAC 2025), Sydney, Australia, 29 Sep-3 Oct 2025.

3. Satomi Kawamoto, Ryusuke Harada, Yasuhiro Kitagawa, and Toshiya Hanada, Debris index for varying debris mitigation requirements to account for large constellations and orbital capacity, 76th International Astronautical Congress (IAC 2025), Sydney, Australia, 29 Sep-3 Oct 2025.

4. Ryuji Nakawatase, Dr. Yasuhiro Yoshimura, Ryusuke Harada, Satomi Kawamoto, and Toshiya Hanada, Effectiveness evaluation of the drag augmentation in post-mission disposal, 76th International Astronautical Congress (IAC 2025), Sydney, Australia, 29 Sep-3 Oct 2025.

Usage of JSS

Computational Information

• Process Parallelization Methods: Assigning Monte-Carlo runs with same initial conditions to multiple cores
• Thread Parallelization Methods: N/A
• Number of Processes: 20 - 30
• Elapsed Time per Case: 144 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 0.03

Details

Please refer to System Configuration of JSS3 for the system configuration and major specifications of JSS3.

*1: Fraction of Usage in Total Resources: Weighted average of three resource types (Computing, File System, and Archiver).

*2: Fraction of Usage：Percentage of usage relative to each resource used in one year.

ISV Software Licenses Used

*2: Fraction of Usage：Percentage of usage relative to each resource used in one year.

JAXA Supercomputer System Annual Report February 2025-January 2026