@misc{oai:jaxa.repo.nii.ac.jp:00003311,
 author = {Wiedemann, Carsten},
 month = {Mar},
 note = {第7回スペースデブリワークショップ (2016年10月18-20日. 宇宙航空研究開発機構調布航空宇宙センター(JAXA)(CAC)), 調布市, 東京, The 7th Space Debris Workshop (October 18-20, 2016. Chofu Aerospace Center, Japan Aerospace Exploration Agency (JAXA)(CAC)), Chofu, Tokyo, Japan, A significant amount of the larger orbital objects is continuously tracked by sensors. The existence of smaller objects is known from sporadic measurement campaigns. But their orbits cannot be tracked. The number and the orbital distribution of small objects must be described by statistical models. These models must have the capability to reproduce the sporadically obtained measured data. Especially in the millimeter and centimeter range there are large uncertainties due to missing data. Currently there are about 700,000 man-made objects larger than one centimeter on all Earth orbits. The number of objects larger than one millimeter is estimated to be 200 million. The number of objects in the sub-millimeter range is several trillions. The most dangerous objects exist between one and ten centimeters in diameter. They are too small to be tracked and too big for protective measures. It is important to identify the main risk factors for the most important orbits. For these orbits it is useful to implement regulations on the mitigation of space debris. The highest spatial object density exists at altitudes near 900 km. (Only in the micrometer size range, the highest density is found near 1000 km.) This can be shown by simulations. Below 900 km, the orbital lifetime of objects decreases due to the atmospheric drag, leading to a reduction in spatial object density towards lower altitudes. Above 900 km altitude, space activities decrease because less debris is produced there. Important tasks in the field of updating the existing model are the consideration of new fragmentation events, the review of historic events, and the validation of the new population with measurement data., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1630052003, レポート番号: JAXA-SP-16-011},
 title = {Ongoing Activities in the Field of Space Debris Modeling},
 year = {2017}
}