Thrust modulation of solid propellant rockets by a fluidic vortex valve with secondary combustion

An analytical model for calculation of the thrust and pressure modulation of a solid propellant rocket by means of a fluidic vortex valve with secondary combustion has been developed. Thrust control by the vortex valve method was found superior to the axial injection of control flow. Addition of oxygen in the injected flow improves the energetic performance of the system as well as the thrust modulation capability. Experiments have been conducted using a mixture of nitrogen and oxygen as the injection gas. The two main parameters investigated in a series of experiments were the oxygen percentage in the injection gas and the ratio between the mass flow rates of the control gas and the solid propellant combustion products. The results show an increase of thrust by a factor of 2 for a 25% addition in mass flow rate by secondary injection at optimal conditions.     

Corotating interplanetary streams and associated ionospheric disturbances at Venus and Earth

During the summer of 1979, solar coronal structure was such that a sequence of recurrent regions produced a corresponding sequence of corotating solar wind streams, with pronounced downstream signatures. One of these stream events passed Earth on July 3, and was observed later at Venus late on July 11th, with similar characteristics. Corresponding in-situ measurements at Earth from the Atmospheric Explorer-E satellite and at Venus from the Pioneer Venus Orbiter are examined for evidence of comparable perturbations of the planetary ionospheres. The passage of the stream shock front is found to be associated with pronounced fluctuations in n(0⁺) which appear as pronounced local depletion of ion concentrations in both ionospheres. The ionosphere disturbances appear to be closely associated with large variations in the solar wind momentum flux. The implied local ionospheric depletions observed at each planet are interpreted to be the consequence of plasma redistribution, rather than actual depletions of plasma.     

Landsat data for population estimates — Approaches to inter-censal counts in the rural Sudan

The accuracy of traditional censuses and the need for other census methods are discussed, and remote sensing methods for rough population estimates are described.     

Software assisted authoring and viewing of ISS crew procedures

The European Space Agency (ESA) initiated a joint project with the National Aeronautics and Space Administration (NASA) and industry partners for improved authoring and execution of Operations Data File (ODF) procedures. The system consists of an authoring tool and a viewer. The authoring tool is currently used by NASA and ESA to write/convert ODF procedures. The viewer will be used onboard the International Space Station (ISS) starting from Flight Increment 11. The new system, thanks to its interaction capability, will help astronauts and operators in the execution of checklist and logic flow procedures that ensure precise performance of experiments and smooth operation of the various systems.     

仍旧是最前沿的降地

NASA的马歇尔航空中心(位于阿拉巴马州的Hunstville)无疑要肩负更具挑战性的重要使命,因为他们需要负责研发一系列大型地月火箭发射至月球上的指定地点.时至今日,马歇尔航空中心已成为高级"地球至轨道"推进系统和技术方面的佼佼者. 1975年7月15日,马歇尔航空中心研发的Salum 1-B装载着美国和苏联首次合作的成果飞向了太空,此即Apollo-Soyuz计划.完成阿波罗项目后,马歇尔团队随即投入更有挑战性的工作中,设计一种代表革命性飞越的运载系统:航天飞机.     

Plant mineral nutrition,gas exchange and photosynthesis in space: A review

Successful growth and development of higher plants in space rely on adequate availability and uptake of water and nutrients, and efficient energy distribution through photosynthesis and gas exchange. In the present review, literature has been reviewed to assemble the relevant knowledge within space plant research for future planetary missions. Focus has been on fractional gravity, space radiation, magnetic fields and ultimately a combined effect of these factors on gas exchange, photosynthesis and transport of water and solutes.     

Enhanced operations efficiency by using the unified synoptic system

The unified synoptic system (USS) was developed by ESA for replacing the existing Columbus display solutions and to unify the display system used on-board and on-ground. USS provides enhanced flight operations efficiency and reduced effort for product preparation, qualification and maintenance for synoptic displays. Additional to its use for Columbus it is installed at JAXA and NASA to support requirements definition and review of NASA generated ISS displays. Due to its advanced capabilities, which go beyond existing known solutions, it has been made available to be reused for future spacecraft EGSEs and control centres (e.g. exploration missions, satellites) as well. Use of synoptic display is mostly guided by operational procedures which are in electronic format. However, till now the full operational benefit has not yet been realized. Procedure viewers and synoptic display systems are completely separate entities. Direct interaction of procedure viewers with synoptic display systems or underlying system control software is not supported at all. Therefore astronauts, flight controllers and operators still have to carry out a lot of mundane activities when executing operational procedures. The USS based procedural display viewer provides the user with a coherent, task oriented user interface for using synoptic displays and executing procedures in an efficient manner.