Interplanetary meteoroids and space debris can impact satellites orbiting the Earth or spacecraft traveling to the Moon.Targeting China Space Station(CSS),7 satellites selected from the constellation of Beidou Navigat...Interplanetary meteoroids and space debris can impact satellites orbiting the Earth or spacecraft traveling to the Moon.Targeting China Space Station(CSS),7 satellites selected from the constellation of Beidou Navigation Satellite System Phase III(BDS-3),and 3 spacecraft orbiting the Moon,we have adopted in the paper the Meteoroid Engineering Model 3,Divine-Staubach meteoroid environment model,and Jenniskens-McBride meteoroid steam model to analyze the meteoroid environment with the mass range of 10–6~10 g.Orbital Debris Engineering Model 3.1 space debris model is used to analyze the orbital debris environment faced by these satellites.The flux of space debris with a size larger than 100μm is compared with that of the meteoroids.The results show that the space debris flux encountered by China Space Station is much higher than that of the meteoroids with sizes in the above range.And quite the opposite,the meteoroids flux impacting the 7 satellites from the BDS-3 is higher.Upon adopting the double-layer Whipple protection measure,the catastrophic collision flux of these satellites encountering meteoroids is about 10–6 times of that without protection,or even less,implying that the Whipple protection effectively guarantees the safety of the satellites in orbit.Besides,it is also found that the flux of the high-density meteoroid population encountered by each satellite is greater than that of the low-density population,whereas the impact velocity is lower for each satellite.These results can aid the orbit selection and the protection design for satellites and spacecraft.展开更多
Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heat transfer coefficient.Given enough time,t...Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heat transfer coefficient.Given enough time,the tensile stress in the interior of the meteoroid can be as high as 10 kb.This stress value is greater than estimated tensile strengths of meteoroids and the aerodynamic compression they encounter.Significant thermal stress(1 kb) can develop quickly(within a few tens of seconds) in a small(radius<10 cm) stony meteoroid and a somewhat large(radius<1 m)metallic meteoroid,and thus may cause tensile fracture to initiate in the meteotoid’s interior.Fracture by thermal stress may have contributed to such observations as the existence of dust particles in upper atmosphere,the breakup of meteoroids at relatively low altitudes,the angular shape of meteorites and their wide scattering in a strewn field,and the explosive features of impact craters.In large meteoroids that require longer heating for thermal stress to fully develop,its effect is probably insignificant.The calculated stress values may be upper limits for real meteoroids which suffer melting and ablation at the surface.展开更多
Excesses of 80Kr and 82Kr, produced by secondary neutron capture effects of 79Br and 81Br, were observed in meteorites. Epithermal neutron flux, Jn (30—300 eV), and fast neutron flux, Jn( > 5 MeV), were determined...Excesses of 80Kr and 82Kr, produced by secondary neutron capture effects of 79Br and 81Br, were observed in meteorites. Epithermal neutron flux, Jn (30—300 eV), and fast neutron flux, Jn( > 5 MeV), were determined according to reactions of 79Br(n, gb)80Kr, 81Br(n, gb)82Kr, and 24Mg(n, a)21Ne, respectively. Cosmogenic noble gases of several ordinary chondrites fell in China indicate a positive relationship between Jn (30—300 eV)/Jn ( > 5 MeV) ratio and Jn (30—300 eV). This suggests large pre-atmospheric sizes of the meteorites, and a considerable fraction of the secondary neutrons were slowed down to epithermal energy. According to its relationship with Jn (30—300 eV)/Jn ( > 5 MeV) ratio, the pre-atmospheric minimum radii and masses of several Chinese chondrites were estimated as below: Zhaodong: 60 cm, 3200 kg; Laochengzhen: 23 cm, 490 kg; Suizhou: 31 cm, 450 kg; Xi Ujimgin: 22 cm, 160 kg; Dongtai: 21 cm, 140 kg.展开更多
Magnetite-ilmenite pairs in meteorites serve as reliable thermometers and oxygen fugacity (fO_(2)) indicators for constraining both nebular conditions and thermal metamorphic histories.While CK and CV chondrites exhib...Magnetite-ilmenite pairs in meteorites serve as reliable thermometers and oxygen fugacity (fO_(2)) indicators for constraining both nebular conditions and thermal metamorphic histories.While CK and CV chondrites exhibit nearly identical petrological characteristics and oxygen isotope compositions,our analysis of NWA 16813 reveals it records the highest fO_(2)(log fO_(2)=-20.51 (589.34°C)-log fO_(2)=-14.21 (608.63°C))yet measured among these meteorites.This finding provides critical evidence that CK and CV chondrites experienced fundamentally different redox conditions during their formation.The fO_(2)data from NWA16813,combined with its distinct petrological and mineralogical features,strongly suggest that CK and CV chondrites originated from chemically separate reservoirs in the protoplanetary disk despite their apparen similarities.展开更多
A corrugation stuffed shield system protecting spacecrafts against meteoroid and orbital debris （M/ OD） is presented. The semi-empirical ballistic limit equations （BLEs）defining the protection capability of the sh...A corrugation stuffed shield system protecting spacecrafts against meteoroid and orbital debris （M/ OD） is presented. The semi-empirical ballistic limit equations （BLEs）defining the protection capability of the shield system are given, and the shielding performance is also discussed. The corrugation stuffed shield （CKS） is more effective than stuffed Whipple shield for M/OD protection, and its shielding performance will be improved significantly as increasing the impact angle. Orbital debris up to 1 cm in diameter can be shielded effectively as increasing the impact angle to 25° at the corrugated angle of 30°. The results are significant to spacecraft design.展开更多
基金the National Natural Science Foundation of China(42074224)Key Research Program of the Chinese Academy of Sciences(ZDRE-KT-2021-3)Pandeng Program of National Space Science Center,Chinese Academy of Sciences。
文摘Interplanetary meteoroids and space debris can impact satellites orbiting the Earth or spacecraft traveling to the Moon.Targeting China Space Station(CSS),7 satellites selected from the constellation of Beidou Navigation Satellite System Phase III(BDS-3),and 3 spacecraft orbiting the Moon,we have adopted in the paper the Meteoroid Engineering Model 3,Divine-Staubach meteoroid environment model,and Jenniskens-McBride meteoroid steam model to analyze the meteoroid environment with the mass range of 10–6~10 g.Orbital Debris Engineering Model 3.1 space debris model is used to analyze the orbital debris environment faced by these satellites.The flux of space debris with a size larger than 100μm is compared with that of the meteoroids.The results show that the space debris flux encountered by China Space Station is much higher than that of the meteoroids with sizes in the above range.And quite the opposite,the meteoroids flux impacting the 7 satellites from the BDS-3 is higher.Upon adopting the double-layer Whipple protection measure,the catastrophic collision flux of these satellites encountering meteoroids is about 10–6 times of that without protection,or even less,implying that the Whipple protection effectively guarantees the safety of the satellites in orbit.Besides,it is also found that the flux of the high-density meteoroid population encountered by each satellite is greater than that of the low-density population,whereas the impact velocity is lower for each satellite.These results can aid the orbit selection and the protection design for satellites and spacecraft.
文摘Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heat transfer coefficient.Given enough time,the tensile stress in the interior of the meteoroid can be as high as 10 kb.This stress value is greater than estimated tensile strengths of meteoroids and the aerodynamic compression they encounter.Significant thermal stress(1 kb) can develop quickly(within a few tens of seconds) in a small(radius<10 cm) stony meteoroid and a somewhat large(radius<1 m)metallic meteoroid,and thus may cause tensile fracture to initiate in the meteotoid’s interior.Fracture by thermal stress may have contributed to such observations as the existence of dust particles in upper atmosphere,the breakup of meteoroids at relatively low altitudes,the angular shape of meteorites and their wide scattering in a strewn field,and the explosive features of impact craters.In large meteoroids that require longer heating for thermal stress to fully develop,its effect is probably insignificant.The calculated stress values may be upper limits for real meteoroids which suffer melting and ablation at the surface.
基金supported by the National Natural Science Foundation of China(Grant No.40232026).
文摘Excesses of 80Kr and 82Kr, produced by secondary neutron capture effects of 79Br and 81Br, were observed in meteorites. Epithermal neutron flux, Jn (30—300 eV), and fast neutron flux, Jn( > 5 MeV), were determined according to reactions of 79Br(n, gb)80Kr, 81Br(n, gb)82Kr, and 24Mg(n, a)21Ne, respectively. Cosmogenic noble gases of several ordinary chondrites fell in China indicate a positive relationship between Jn (30—300 eV)/Jn ( > 5 MeV) ratio and Jn (30—300 eV). This suggests large pre-atmospheric sizes of the meteorites, and a considerable fraction of the secondary neutrons were slowed down to epithermal energy. According to its relationship with Jn (30—300 eV)/Jn ( > 5 MeV) ratio, the pre-atmospheric minimum radii and masses of several Chinese chondrites were estimated as below: Zhaodong: 60 cm, 3200 kg; Laochengzhen: 23 cm, 490 kg; Suizhou: 31 cm, 450 kg; Xi Ujimgin: 22 cm, 160 kg; Dongtai: 21 cm, 140 kg.
基金supported by the Science and Technology Development Fund of Macao (FDCT)(grant 002/2024/SKL)。
文摘Magnetite-ilmenite pairs in meteorites serve as reliable thermometers and oxygen fugacity (fO_(2)) indicators for constraining both nebular conditions and thermal metamorphic histories.While CK and CV chondrites exhibit nearly identical petrological characteristics and oxygen isotope compositions,our analysis of NWA 16813 reveals it records the highest fO_(2)(log fO_(2)=-20.51 (589.34°C)-log fO_(2)=-14.21 (608.63°C))yet measured among these meteorites.This finding provides critical evidence that CK and CV chondrites experienced fundamentally different redox conditions during their formation.The fO_(2)data from NWA16813,combined with its distinct petrological and mineralogical features,strongly suggest that CK and CV chondrites originated from chemically separate reservoirs in the protoplanetary disk despite their apparen similarities.
文摘A corrugation stuffed shield system protecting spacecrafts against meteoroid and orbital debris （M/ OD） is presented. The semi-empirical ballistic limit equations （BLEs）defining the protection capability of the shield system are given, and the shielding performance is also discussed. The corrugation stuffed shield （CKS） is more effective than stuffed Whipple shield for M/OD protection, and its shielding performance will be improved significantly as increasing the impact angle. Orbital debris up to 1 cm in diameter can be shielded effectively as increasing the impact angle to 25° at the corrugated angle of 30°. The results are significant to spacecraft design.
