2001 Mars Odyssey Mission Summary

The 2001 Mars Odyssey spacecraft, now in orbit at Mars, will observe the Martian surface at infrared and visible wavelengths to determine surface mineralogy and morphology, acquire global gamma ray and neutron observations for a full Martian year, and study the Mars radiation environment from orbit. The science objectives of this mission are to: (1) globally map the elemental composition of the surface, (2) determine the abundance of hydrogen in the shallow subsurface, (3) acquire high spatial and spectral resolution images of the surface mineralogy, (4) provide information on the morphology of the surface, and (5) characterize the Martian near-space radiation environment as related to radiation-induced risk to human explorers. To accomplish these objectives, the 2001 Mars Odyssey science payload includes a Gamma Ray Spectrometer (GRS), a multi-spectral Thermal Emission Imaging System (THEMIS), and a radiation detector, the Martian Radiation Environment Experiment (MARIE). THEMIS and MARIE are mounted on the spacecraft with THEMIS pointed at nadir. GRS is a suite of three instruments: a Gamma Subsystem (GSS), a Neutron Spectrometer (NS) and a High-Energy Neutron Detector (HEND). The HEND and NS instruments are mounted on the spacecraft body while the GSS is on a 6-m boom. Some science data were collected during the cruise and aerobraking phases of the mission before the prime mission started. THEMIS acquired infrared and visible images of the Earth-Moon system and of the southern hemisphere of Mars. MARIE monitored the radiation environment during cruise. The GRS collected calibration data during cruise and aerobraking. Early GRS observations in Mars orbit indicated a hydrogen-rich layer in the upper meter of the subsurface in the Southern Hemisphere. Also, atmospheric densities, scale heights, temperatures, and pressures were observed by spacecraft accelerometers during aerobraking as the spacecraft skimmed the upper portions of the Martian atmosphere. This provided the first in-situ evidence of winter polar warming in the Mars upper atmosphere. The prime mission for 2001 Mars Odyssey began in February 2002 and will continue until August 2004. During this prime mission, the 2001 Mars Odyssey spacecraft will also provide radio relays for the National Aeronautics and Space Administration (NASA) and European landers in early 2004. Science data from 2001 Mars Odyssey instruments will be provided to the science community via NASA’s Planetary Data System (PDS). The first PDS release of Odyssey data was in October 2002; subsequent releases occur every 3 months.     

Charge Separation Mechanisms in Clouds

Mechanisms of thunderstorm electrification are presented and discussed.     

月球仍然活跃的构造、火成和内部特征等证据

月球尽管被作为类地行星演化的最终形态的代表,被认为在25亿年前已经完全冷却,根据阿波罗时 代以来、特别是近十余年的月球轨道器和着陆器获得的关于月球构造、火成活动、月震和内部结构等多种证据,表明月球从深层内部到表面仍然活跃,尚未彻底冷却“死亡”。这将完全改变人们关于月球演化历史和状态的观念。     

The geologic development of Mars: A review

The planet Mars has been the subject of a continuing program of exploration with the flyby missions of 1964 and 1969, the orbiter of 1971, and the present Viking Project with both orbiters and landers. The overall view of Mars has changed from Earthlike in the prespacecraft era to Moonlike following the flyby missions and finally to a planet with intermediate characteristics. There are many impact craters as on the Moon, but tectonic and volcanic features resembling structures on Earth are also present. However, there is a lack of evidence for the compressional deformation associated with terrestrial plate tectonics and continental drift.The current analyses indicate that Mars has a differentiated interior with a crust and mantle and perhaps a core. Whatever the nature of interior processes, whether overall mantle expansion, plumes, or full scale convection, the effects at the surface have been predominantly vertical with formation of broad regions of uplift and depression. One of the results is hemispheric asymmetry with cratered terrain in the south and younger uncratered plains in the north.     

Deriving a sea surface temperature record suitable for climate change research from the along-track scanning radiometers

We describe the approach to be adopted for a major new initiative to derive a homogeneous record of sea surface temperature for 1991–2007 from the observations of the series of three along-track scanning radiometers (ATSRs). This initiative is called (A)RC: (Advanced) ATSR Re-analysis for Climate. The main objectives are to reduce regional biases in retrieved sea surface temperature (SST) to less than 0.1 K for all global oceans, while creating a very homogenous record that is stable in time to within 0.05 K decade⁻¹, with maximum independence of the record from existing analyses of SST used in climate change research. If these stringent targets are achieved, this record will enable significantly improved estimates of surface temperature trends and variability of sufficient quality to advance questions of climate change attribution, climate sensitivity and historical reconstruction of surface temperature changes. The approach includes development of new, consistent estimators for SST for each of the ATSRs, and detailed analysis of overlap periods. Novel aspects of the approach include generation of multiple versions of the record using alternative channel sets and cloud detection techniques, to assess for the first time the effect of such choices. There will be extensive effort in quality control, validation and analysis of the impact on climate SST data sets. Evidence for the plausibility of the 0.1 K target for systematic error is reviewed, as is the need for alternative cloud screening methods in this context.     

The fast debris evolution model

The ‘particles-in-a-box’ (PIB) model introduced by Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508–513, 1992.] removed the need for computer-intensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation’s coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FADE), employs a first-order differential equation to describe the rate at which new objects ?10 cm are added and removed from the environment. Whilst Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508–513, 1992.] based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FADE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model.     

Mass-loading and the formation of the Venus tail

Despite its lack of an intrinsic magnetic field Venus has a well defined magnetotail, containing about 3 megawebers of magnetic flux in a tail about 4 R_V across with perhaps a slightly elliptical cross section. This tail arises through the mass-loading of magnetic flux tubes passing by the planet. Mass-loading can occur due to charge exchange and photo-ionization as well as from the diffusion of magnetic field into the ionosphere. Various evidence exists for the mass-loading process, including the direct observation of the picked up ions with both the Venera and Pioneer Venus plasma analyzers.     

Modular Stores Management System

Advanced Military aircraft operational requirements demand an ever increasing variety and quantity of Stores, coupled with continuous improvement in mission success, safety of operation, aircrew and groundcrew workload, interoperability and ground support facilities. Until now these ever more demanding requirements have been met by costly customized stores management system designs. GEC Avionics has surveyed the potential SMS requirements of a comprehensive range of aircraft and weapon types, in order to define a universal SMS design concept based on system availability, integrity and reliability, operational functions, peripheral interfaces and maintenance/human factors. This advanced concept not only includes provision for all existing weapon types but also has growth potential for the evolving MIL-STD-1760 weapon interfaces. System interface requirements have been rationalized in order to achieve a Modular Stores Management System (MSMS) design based on major factors such as cost, mission requirements and customer specifications. The key work for a successful MSMS design is flexibility and GEC Avionics has evolved a set of standard modules which can be packaged to satisfy specific customer needs. Typically, the standard modules provide over 80% of the hardware in every Stores Management application. The MSM concept features much reduced development costs and timescales, commonality between aircraft types minimizing parts inventory, VLSI technology providing high reliability and a common product support and maintenance philosophy. The MSM design offers a highly cost effective low risk concept for meeting the needs of modernization and new aircraft programs.