英国防部发起新型航空母舰的竞争

日前，英国国防部向全球航空航天制造商发起了价值244亿美元、为英国海军制造两艘航空母舰的竞标活动。有6家公司参与了竞标，它们是波音、英国宇航防御系统、洛克希德、马丁、马可尼电子系统、雷神和汤姆逊一CSF公司。这6家公司都具有较强的海军系统综合能力。但英国政府坚持，新型航空母舰必须在英国制造。计划的第一阶段是在今年秋季选出3家承包商进行初步研究，台问价值830万美元。然后再从中选出两家公司进行减少风险的研究，台同价值3300万美元。最终承包商的确定预计将在2001年，第一艘航空母舰计划于2012年投入使用。该项目由国防…     

MArs Neutron Energy Spectrometer (MANES): an instrument for the Mars 2003 Lander

We describe the instrument design and detector development for MANES which has been selected to fly on the Mars 2003 Lander. Section 1 explains the need for the spectrometer in determining the increased risk of carcinogenesis for astronauts. Section 2 presents the instrument design including an outline drawing, a cross-sectional view and a detailed block diagram. Sections 3 and 4 describe the low and high energy detector components of the spectrometer and present responses to monoenergetic neutron beams. Sections 5 and 6 explain the design approaches to charged particle discrimination and instrument transfer function modeling.     

The New Horizons Spacecraft

The New Horizons spacecraft was launched on 19 January 2006. The spacecraft was designed to provide a platform for seven instruments designated by the science team to collect and return data from Pluto in 2015. The design meets the requirements established by the National Aeronautics and Space Administration (NASA) Announcement of Opportunity AO-OSS-01. The design drew on heritage from previous missions developed at The Johns Hopkins University Applied Physics Laboratory (APL) and other missions such as Ulysses. The trajectory design imposed constraints on mass and structural strength to meet the high launch acceleration consistent with meeting the AO requirement of returning data prior to the year 2020. The spacecraft subsystems were designed to meet tight resource allocations (mass and power) yet provide the necessary control and data handling finesse to support data collection and return when the one-way light time during the Pluto fly-by is 4.5 hours. Missions to the outer regions of the solar system (where the solar irradiance is 1/1000 of the level near the Earth) require a radioisotope thermoelectric generator (RTG) to supply electrical power. One RTG was available for use by New Horizons. To accommodate this constraint, the spacecraft electronics were designed to operate on approximately 200 W. The travel time to Pluto put additional demands on system reliability. Only after a flight time of approximately 10 years would the desired data be collected and returned to Earth. This represents the longest flight duration prior to the return of primary science data for any mission by NASA. The spacecraft system architecture provides sufficient redundancy to meet this requirement with a probability of mission success of greater than 0.85. The spacecraft is now on its way to Pluto, with an arrival date of 14 July 2015. Initial in-flight tests have verified that the spacecraft will meet the design requirements.