NASA conducted a collision destruction experiment in 1992 using satellites made with 1960s technology that extensively used metal. Approximately 10% of the debris generated by the collision was collected and analyzed, and NASA released the NASA Standard Debris Model in 2001 to describe the debris generated by collisions. However, it has been reported that the characteristics of debris generated by recent collisions (such as the satellite destruction weapon experiment conducted by China using an aging meteorological satellite in January 2007 and the collision accident between the US communication satellite Iridium 33 and the Russian communication satellite Cosmos 2251 in February 2009) cannot be described by the NASA Standard Debris Model. It was believed that debris split from multi-layer insulation materials covering the satellite's surface, solar panels that are deployed to supply sufficient power, and thermal insulation materials covering the satellite's surface, which are increasingly used for weight reduction, were involved in this. In this study, collision destruction experiments were conducted seven times using a small satellite model with a primary structure of carbon fiber-reinforced plastic plate, a small satellite model with solar panels and multi-layer insulation materials, and approximately 10,000 debris were collected and analyzed. It was revealed that the debris including metal and the debris including composite materials formed two independent peaks in the area-to-mass ratio distribution of debris, and that the debris split from multi-layer insulation materials formed two additional peaks that were separate from the two peaks formed by the debris including metal and the debris including composite materials.
To discuss the preservation of the orbital environment, a calculation model that describes the transition of the orbital environment over a long period of 50 to 100 years or more is necessary. In this study, we conducted research on the space debris environment in the geostationary orbit region (average motion between 0.9 revolutions/day and 1.1 revolutions/day, eccentricity less than 0.1, and inclination angle less than 20 degrees) from both particle collision experiments and numerical simulations. We developed our own geostationary orbit space debris environment transition model (GEODEEM) and a low Earth orbit (altitude below 2,000 km) space debris environment transition model (LEODEEM) jointly with the Japan Aerospace Exploration Agency (JAXA) and integrated them to develop a space debris environment transition model for Earth orbit (NEODEEM). We participated in international discussions, such as the research proposed by the Inter-Agency Space Debris Coordination Committee, "An Assessment of the Current LEO Debris Environment," "Stability of the Future LEO Environment," and "Benefits of Active Debris Removal in LEO," and NEODEEM is being used as a Japanese unique space debris environment transition model when Japan participates in international discussions.
In the geostationary orbit region (average motion between 0.9 revolutions/day and 1.1 revolutions/day, eccentricity less than 0.2, and inclination angle less than 70 degrees), fragmentation caused by the release of internal energy is considered to be the main cause of space debris proliferation. Among the generated debris, it is necessary to detect debris that periodically approaches satellites during operation. In this study, we developed a method to efficiently search for unknown space debris in the geostationary orbit region by combining a fragmentation model that describes the size, area-to-mass ratio, mass, and ejection velocity of debris generated by fragmentation and an orbit propagation model that calculates the orbit of artificial celestial bodies. We predict the existence probability and movement of debris groups that pass through any observation area at any time by analyzing the size, area-to-mass ratio, mass, and ejection velocity of debris generated by fragmentation and calculating the orbit of artificial celestial bodies. We demonstrated that it is possible to plan observation schedules qualitatively even when the scale and timing of fragmentation events are not identified. We also demonstrated that we can identify the origin of unknown space debris by performing tracking observation and orbit determination for unknown space debris brighter than the observation limit of the optical telescope used in the research, and by predicting the movement of the unknown space debris on consecutive images. Furthermore, we succeeded in detecting unknown space debris darker than the observation limit of the optical telescope by superimposing consecutive images based on the predicted movement of unknown space debris on consecutive images.
The IDEA (In-situ Debris Environmental Awareness) project, which stands for "on-site" recognition of debris environment, places small auxiliary satellites equipped with a space debris monitor (SDM) (developed jointly by JAXA, QPS Research Institute Co., Ltd., and IHI Corporation based on a shared patent) that measures the size of holes formed on thin films due to collisions with micro-debris (sizes ranging from about 100 µm to 2 mm) at regular time intervals in orbit. In this study, we investigated and analyzed the orbit of artificial celestial bodies that collide with the SDM using known artificial celestial bodies as references and found a simple constraint equation that applies to the orbit of artificial celestial bodies that collide with the SDM. We analyzed error factors in the constraint equation and clarified the mission requirements for applying the constraint equation to actual measurements. We also theoretically demonstrated that the origin of fragmentation can be estimated by applying this constraint equation. AstroScale Co., Ltd., which sympathized with the significance and philosophy of the IDEA project, developed and manufactured the small auxiliary satellite IDEA OSG 1 based on the results of this study with the support of OSG Co., Ltd. IDEA OSG 1 is scheduled to be launched in the second half of fiscal year 2016.
(Authored by Toshiya Hanada)
International Center for Space Weather Science and Education, Kyushu University (formerly the Center for Space Environment Research)
No.20 "Threats posed by space debris" - The universe is overflowing with garbage Toshiya Hanada (published on July 14, 2010)