The ablative material is supposed to be one of good candidates for LRE （liquid rocket engine） combustion chamber to achieve both high reliability and low cost and a numerical analysis for the ablator is considered t...The ablative material is supposed to be one of good candidates for LRE （liquid rocket engine） combustion chamber to achieve both high reliability and low cost and a numerical analysis for the ablator is considered to be a potentially efficient tool to reduce cost as well. So far, ablators have been successfully applied for many SRM （solid rocket motors）, but the application to LRE is still quite limited in Japan. The authors believe that this is primarily because of the unpredictable nature of the heat load from combustion gases to the combustor wall. Indeed, reliable thermal design of ablative combustion chamber, namely reliable prediction of thermal performance, needs both reliable heat load model and reliable ablator response model. This paper elaborates our research activities and our recent research findings.展开更多
Subsurface exploration is one of the most ambitious scientific objectives of the Hayabusa2 mission.A small device called small carry-on impactor(SCI)was developed to create an artificial crater on the surface of aster...Subsurface exploration is one of the most ambitious scientific objectives of the Hayabusa2 mission.A small device called small carry-on impactor(SCI)was developed to create an artificial crater on the surface of asteroid Ryugu.This enables us to sample subsurface materials,which will provide a window to the past.The physical properties of the resulting crater are also useful for understanding the internal structure of Ryugu.Accurate understanding of the crater and ejecta properties,including the depth of excavation of subsurface materials,requires accurate information on impact conditions.In particular,the impact angle is a critical factor because it greatly influences the size and shape of the crater.On April 5,2019,the Hayabusa2 spacecraft deployed the SCI at 500 m of altitude above the asteroid surface.The SCI gradually reduced its altitude,and it shot a 2 kg copper projectile into the asteroid 40 min after separation.Estimating the position of the released SCI is essential for determining the impact angle.This study describes the motion reconstruction of the SCI based on the actual operation data.The results indicate that the SCI was released with high accuracy.展开更多
文摘The ablative material is supposed to be one of good candidates for LRE （liquid rocket engine） combustion chamber to achieve both high reliability and low cost and a numerical analysis for the ablator is considered to be a potentially efficient tool to reduce cost as well. So far, ablators have been successfully applied for many SRM （solid rocket motors）, but the application to LRE is still quite limited in Japan. The authors believe that this is primarily because of the unpredictable nature of the heat load from combustion gases to the combustor wall. Indeed, reliable thermal design of ablative combustion chamber, namely reliable prediction of thermal performance, needs both reliable heat load model and reliable ablator response model. This paper elaborates our research activities and our recent research findings.
文摘Subsurface exploration is one of the most ambitious scientific objectives of the Hayabusa2 mission.A small device called small carry-on impactor(SCI)was developed to create an artificial crater on the surface of asteroid Ryugu.This enables us to sample subsurface materials,which will provide a window to the past.The physical properties of the resulting crater are also useful for understanding the internal structure of Ryugu.Accurate understanding of the crater and ejecta properties,including the depth of excavation of subsurface materials,requires accurate information on impact conditions.In particular,the impact angle is a critical factor because it greatly influences the size and shape of the crater.On April 5,2019,the Hayabusa2 spacecraft deployed the SCI at 500 m of altitude above the asteroid surface.The SCI gradually reduced its altitude,and it shot a 2 kg copper projectile into the asteroid 40 min after separation.Estimating the position of the released SCI is essential for determining the impact angle.This study describes the motion reconstruction of the SCI based on the actual operation data.The results indicate that the SCI was released with high accuracy.
