新技术设备进入战场的捷径"先进概念技术验证"(ACTD)计划

美国国防部的"先进概念技术验证"(ACTD)计划,主要用来验证新型采购方式与信息技术的快速发展相适应的兼容性,并通过开发利用已经或正在成熟的技术来解决一些迫切的重要军用装备问题."联合蓝军态势报告"技术的成功应用是其中一个典型例子.     

An investigation into the roles of ECH and whistler mode waves in the formation of “pancake” electron distributions using data from the CRRES satellite

Electron pitch angle distributions sharply peaked at 90° pitch angle were first recorded in the energy range 50 eV < E < 500 eV by the GEOS-1 and GEOS-2 spacecraft in 1977/8, from the plasmapause out to geostationary orbit. At the time they were explained as the remnants of pitch angle diffusion driven solely by Electron Cyclotron Harmonic (ECH) waves. Here we use observations by instruments on board the CRRES spacecraft to study these distributions in more detail. The pancake distributions are now seen to develop from injected distributions that are nearly isotropic in velocity space, on a time scale that is greater than 2 hours. The freshly injected distributions are associated with strong ECH and whistler mode waves suggesting that the pancake distributions are likely to be caused by a combination of both wave types. Our results suggest that whistler mode waves play a dominant role in the formation of pancake distributions outside L = 6.0, whereas inside L = 6.0 and, in particular, in the vicinity of the plasmapause, the ECH waves also play a significant role. Consequently both types of waves should be considered in any attempt to explain the diffuse aurora and the variation with L taken into account.     

航空货运如何在变化的市场中求胜

前所未有充满挑战的环境2008年,我们面对的挑战源源不断。一开年,诸多市场发展放缓和生产过剩,燃油价格创历史新高,美元疲软后又反弹以及信用     

QSO number counts to B < 24.5 from hubble space telescope WFPC2 images

We have conducted a survey for faint quasars to B < 24.5, z < 2.1 based on archival high-latitude Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images covering 0.04 deg² of the sky in three filters spanning 2300–9600 Å. Taking advantage of the superb 0.1″ resolution of WFPC2, we have developed an approach to select quasar candidates based on their morphology and position in multicolor space. We derive cumulative surface densities and compare them with our previous survey in the Groth–Westphal Strip and other faint quasar surveys that utilize very different selection approaches. In most cases the agreement with these surveys is good, however, we find approximately twice as many quasar candidates to B = 24.5 as the COMBO-17 survey. Although we are confident that our approach eliminates most contaminating stars and galaxies, spectroscopic follow-up will be required to determine the level of residual contamination and confirm or refute this excess.     

Key ecological challenges for closed systems facilities

Closed ecological systems are desirable for a number of purposes. In space life support systems, material closure allows precious life-supporting resources to be kept inside and recycled. Closure in small biospheric systems facilitates detailed measurement of global ecological processes and biogeochemical cycles. Closed testbeds facilitate research topics which require isolation from the outside (e.g. genetically modified organisms; radioisotopes) so their ecological interactions and fluxes can be studied separate from interactions with the outside environment. But to achieve and maintain closure entails solving complex ecological challenges. These challenges include being able to handle faster cycling rates and accentuated daily and seasonal fluxes of critical life elements such as carbon dioxide, oxygen, water, macro- and mico-nutrients. The problems of achieving sustainability in closed systems for life support include how to handle atmospheric dynamics including trace gases, producing a complete human diet, recycling nutrients and maintaining soil fertility, the maintenance of healthy air and water and preventing the loss of critical elements from active circulation. In biospheric facilities, the challenge is also to produce analogues to natural biomes and ecosystems, studying processes of self-organization and adaptation in systems that allow specification or determination of state variables and cycles which may be followed through all interactions from atmosphere to soils. Other challenges include the dynamics and genetics of small populations, the psychological challenges for small isolated human groups and backup technologies and strategic options which may be necessary to ensure long-term operation of closed ecological systems.     

Locating the LCROSS Impact Craters

The Lunar CRater Observations and Sensing Satellite (LCROSS) mission impacted a spent Centaur rocket stage into a permanently shadowed region near the lunar south pole. The Sheperding Spacecraft (SSC) separated ～9 hours before impact and performed a small braking maneuver in order to observe the Centaur impact plume, looking for evidence of water and other volatiles, before impacting itself. This paper describes the registration of imagery of the LCROSS impact region from the mid- and near-infrared cameras onboard the SSC, as well as from the Goldstone radar. We compare the Centaur impact features, positively identified in the first two, and with a consistent feature in the third, which are interpreted as a 20 m diameter crater surrounded by a 160 m diameter ejecta region. The images are registered to Lunar Reconnaisance Orbiter (LRO) topographical data which allows determination of the impact location. This location is compared with the impact location derived from ground-based tracking and propagation of the spacecraft’s trajectory and with locations derived from two hybrid imagery/trajectory methods. The four methods give a weighted average Centaur impact location of ?84.6796°, ?48.7093°, with a 1σ uncertainty of 115 m along latitude, and 44 m along longitude, just 146 m from the target impact site. Meanwhile, the trajectory-derived SSC impact location is ?84.719°, ?49.61°, with a 1σ uncertainty of 3 m along the Earth vector and 75 m orthogonal to that, 766 m from the target location and 2.803 km south-west of the Centaur impact. We also detail the Centaur impact angle and SSC instrument pointing errors. Six high-level LCROSS mission requirements are shown to be met by wide margins. We hope that these results facilitate further analyses of the LCROSS experiment data and follow-up observations of the impact region.     

Adjustment of systematic errors in ALS data through surface matching

Surface matching is a well researched topic in both Computer Vision (CV) and terrestrial laser scanning (TLS) or ground based light detection and ranging (LiDAR), but the extent of the range images derived from these technologies is typically orders of magnitude smaller than those derived from airborne laser scanning (ALS), also known as airborne LiDAR. Iterative closest point (ICP) and its variants have been successfully used to align and register multiple overlapping views of the range images for CV and TLS applications. However, many challenges are encountered in applying the ICP approach to ALS data sets. In this paper, we address these issues, explore the possibility of automating the algorithm, and present a technique to adjust systematic discrepancies in overlapping strips, using geometrical attributes in a given terrain. In this method, the ALS point samples used in the algorithm are selected depending on their ability to constrain the relative movement between the overlapping laser strips. The points from overlapping strips are matched through modified point to plane based on the ICP method.     

The National Space Biomedical Research Institute's education and public outreach program: Working toward a global 21st century space exploration society

Space Exploration educators worldwide are confronting challenges and embracing opportunities to prepare students for the global 21st century workforce. The National Space Biomedical Research Institute (NSBRI), established in 1997 through a NASA competition, is a 12-university consortium dedicated to space life science research and education. NSBRI's Education and Public Outreach Program (EPOP) is advancing the Institute's mission by responding to global educational challenges through activities that: provide teacher professional development; develop curricula that teach students to communicate with their peers across the globe; provide women and minority US populations with greater access to, and awareness of science careers; and promote international science education partnerships.A recent National Research Council (NRC) Space Studies Board Report, America's Future in Space: Aligning the Civil Program with National Needs, acknowledges that “a capable workforce for the 21st century is a key strategic objective for the US space program… (and that) US problems requiring best efforts to understand and resolve…are global in nature and must be addressed through mutual worldwide action”. [1] This sentiment has gained new momentum through a recent National Aeronautics and Space Administration (NASA) report, which recommends that the life of the International Space Station be extended beyond the planned 2016 termination. [2] The two principles of globalization and ISS utility have elevated NSBRI EPOP efforts to design and disseminate science, technology, engineering and mathematics (STEM) educational materials that prepare students for full participation in a globalized, high technology society; promote and provide teacher professional development; create research opportunities for women and underserved populations; and build international educational partnerships.This paper describes select EPOP projects and makes the case for using innovative, emerging information technologies to transfer space exploration knowledge to students, engage educators from across the globe in discourse about science curricula, and foster multimedia collaborations that inform citizens about the benefits of space exploration for life on Earth. Special references are made to educational activities conducted at professional meetings in Austria, Canada, France, China, Greece, Italy, Russia, Scotland and Spain.