The United States in space

The US program is examined in three contexts: its position internationally, its role domestically, and NASA's workings internally. Some of the principal issues explored are: what it means for NASA to be simply a lead agency instead of the sole agency charged with implementing the US space program; whether the types of technical and managerial troubles NASA has recently experienced are different in quality from the troubles it had during the Apollo era; how the various pressures to which it is being subjected are effecting its internal ways of doing business; and whether there are lessons from the experiences of other nations' space programs and their ways of overseeing projects are doing business that could be useful to the US space program, and vice versa     

There Will Be Cooking on Mars

This paper presents the NASA's upcoming Phoenix lander mission. Phoenix, scheduled to be launched this August and to touch down in May 2008, may resolve lingering questions about organic molecules and liquid water on Mars. It main objectives are to determine whether the Martian arctic could support life, to evaluate the history of water near the landing site, and to investigate how the planet's climate is affected by polar dynamics. Phoenix will carry TEGA (thermal and evolved gas analyzer) that could shed light on whether organics are present. Designed primarily to look at ice chemistry and carbonate minerals. TEGA can also detect organic molecules. Other instruments on Phoenix include Mars' first-ever atomic force microscope and electrochemistry instrument.     

Active learning through multimedia

As a child, did you learn how to walk by taking a walking class? No. Children learn by doing. Then why force them into passivity in school? Properly designed educational software on multimedia computers supports active participation and puts the student in control. Such software demands the right teaching architecture, as explained here     

Procedural knowledge

Much of commonsense knowledge about the real world is in the form of procedures or sequences of actions for achieving particular goals. In this paper, a formalism is presented for representing such knowledge using the notion of process. A declarative semantics for the representation is given, which allows a user to state facts about the effects of doing things in the problem domain of interest. An operational semantics is also provided, which shows how this knowledge can be used to achieve particular goals or to form intentions regarding their achievement. Given both semantics, our formalism additionally serves as an executable specification language suitable for constructing complex systems. A system based on this formalism is described, and examples involving control of an autonomous robot and fault diagnosis for NASA's space shuttle are provided.     

Art and technology II. A call for collaboration

As decribed in Part I, the collaboration of art and engineering in the creation of new art works has become a serious preoccupation of many modern artists, who are asking for the help of engineers. A number of organizations now exist whose aim is to facilitate the contact between artists and engineers and to help support them in their collaborative projects. You need not be a Renaissance Man, it is said, to apply for a match with an artist. It won't be all fun and games, although part of it will be, and you might even end up doing something so useless from an engineering point of view, and so right from another point of view, that you could begin wondering why engineering is practiced the way it is?i.e., you might get turned on. This article tells you a bit about what it was like for some others who have already tried, and calls on you to join the action.     

Watershed identification of polygonal patterns in noisy SAR images

The paper describes a new approach to pattern recognition in synthetic aperture radar (SAR) images. A visual analysis of the images provided by NASA's Magellan mission to Venus has revealed a number of zones showing polygonal-shaped faults on the surface of the planet. The goal of the paper is to provide a method to automate the identification of such zones. The high level of noise in SAR images and its multiplicative nature make automated image analysis difficult and conventional edge detectors, like those based on gradient images, inefficient. We present a scheme based on an improved watershed algorithm and a two-scale analysis. The method extracts potential edges in the SAR image, analyzes the patterns obtained, and decides whether or not the image contains a "polygon area". This scheme can also be applied to other SAR or visual images, for instance in observation of Mars and Jupiter's satellite Europa.     

COTS器件空间应用的可靠性保证技术研究

 为保证COTS(Commercial off-the-shelf)器件成功应用于我国高可靠的航天产品中,本文总结分析了国内外空间应用COTS器件的发展情况,提出了空间应用COTS器件的可靠性保证总体思路.该思路特点是首先进行与任务剖面相结合的可靠性评估试验,再对COTS器件进行可靠性筛选.对于热环境的可靠性保证,通过研究NASA的筛选规定,提出了不同任务要求下的老练温度-老练时间的对应关系式;实例表明温度可靠性评估试验方法能够指导工程.对于电离总剂量的可靠性保证,提出了不同任务条件下的回归筛选模型,并进行了验证,相对误差为1%.结果表明本文能够系统性地指导空间工程应用COTS器件.     

The Multi-angle Imaging SpectroRadiometer science data system, its products, tools, and performance

Ground processing of data from the Multi-angle Imaging SpectroRadiometer (MISR) instrument, part of NASA's Earth Observing System (EOS), exploits new and unique science algorithms not previously used operationally. A range of data products from Level 1 through Level 3 is being produced. Because of MISR's unprecedented design, extensive prototyping was required from a relatively early stage. The data throughput is large, necessitating an innovative software design approach that maximizes performance. The systematic science processing software was developed at the Jet Propulsion Laboratory, with data processing occurring at the NASA Langley Research Center using the EOS Core System, a collaborative arrangement that works well. With the availability of actual mission data following launch on the Terra spacecraft in December 1999, MISR's computational needs have become better known, and many improvements have been made to both the science software and the production system to achieve a successful overall data processing capability. This paper provides information about MISR data for the science user, and describes the nature and scope of implementation and operations activities.     

Uplink Arrays for the Deep Space Network

Deep-space communication and navigation is faced with two challenges in the future: (1) the potential retirement of the largest antennas of NASA's Deep Space Network and (2) an anticipated need for increasing ground system capacity so as to support higher data rates to and from missions operating at remote locations in the solar system, as well as in anticipation of a larger number of simultaneously flying missions. In the transmitting, or uplink, direction, one approach to increasing the effective transmitted power is to array multiple antennas. This is attractive mainly because it promises a lower construction cost than equivalent (large) single antenna systems. In addition, it has the potential for increasing the reliability of the uplink and reducing maintenance costs. This paper introduces the concept of uplink arraying by examining technological challenges and possible solutions to them. Arraying principles are presented and error sources described. The main challenge is to maintain carrier phase alignment among the antennas, and this must be done by periodic calibration. Presently, two calibration methods are being developed at the Jet Propulsion Laboratory as part of an uplink arraying demonstration effort. These methods are briefly discussed.     

Throughput behavior of link adaptive 802.11 DCF with MUD capable access node

Conventional IEEE 802.11 medium access control (MAC) protocol discourages simultaneous transmission to avoid collisions. With fast advances in physical layer technologies, multi-user detection (MUD) capable receivers which can detect multiple frames from different users simultaneously become available. If we are to utilize them in today's wireless LAN, however, it is not entirely clear how we should change the MAC and how much benefit is available and can be obtained by doing so. The primary objective of this paper is to investigate such questions. We approach this objective by developing a new throughput expression for 802.11 distributed coordination function (DCF). The derived expression has been verified in simulation. We show that significant throughput gain can be garnered with slight modification in 802.11 DCF.     

雷达组网探测系统任务规划软件设计

对雷达组网探测系统任务规划技术进行了深入的研究,分析了系统业务流程,提出了任务管理的概念,设计了探测系统任务规划软件,其中包括任务管理、场景管理、探测方案生成、场景推演和匹配等子模块的分析设计。同时,还研究了在数据量大、业务逻辑复杂、系统要素繁多的情况下,如何有效地设计数据库管理系统来进行高效的任务数据存储和查询。该文所设计的任务规划软件能够在既定的任务场景下,对探测过程实现可视化操作,有效地提高了雷达组网探测系统任务规划过程信息化水平。     

Use of fiducials and unsurveyed landmarks as geolocation tools in vehicular-based landmine search

When searching for land mines using vehicular-mounted sensors, it is important that the ground locations of the detected mines be accurately determined. This is useful for data association when one has multiple looks at a mine by a single sensor or if one uses multiple sensors. It is of ultimate importance for the primary mission, which is to neutralize the detected mines or mark them for avoidance. This paper addresses the use of surveyed landmarks, i.e., fiducials, as well as unsurveyed but visible landmarks within the sensor field of view for improving the geolocation accuracy. Preliminary results show that in fact geolocation accuracy can be improved significantly by using these tools. The method is primarily applicable to combat situations where a road is to be cleared for advancing troops and equipment. This is in contrast to humanitarian demining where one has more time and can approach suspected landmines from different viewpoints.     

The big turn-off

The EU member states bring into force laws that comply with the energy-using products (EuP) directive. Laws based on the directive mean designers will soon have to account for how much power their products will draw. It is a wide-ranging directive that covers not just how much energy is used while pieces of electronics are in use, but how much energy is needed to make them. However, one of the biggest effects the directive is likely to have is to focus attention on the energy wasted by products sitting in standby mode, when they are doing little more than waiting for a ping from a remote control or for something to be charged     

Node Synchronization for the Viterbi Decoder

Motivated by the needs of NASA's Voyager 2 mission, in this paper we describe an algorithm which detects and corrects losses of node synchronization in convolutionally encoded data. This algorithm, which would be implemented as a hardware device external to a Viterbi decoder, makes statistical decisions about node synch based on the hard-quantized undecoded data stream. We will show that in a worst-case Voyager environment, our method will detect and correct a true loss of synch (thought to be a very rare event) within several hundred bits; many of the resulting outages will be corrected by the outer Reed-Solomon code. At the same time, the mean time between false alarms is on the order of several years, independent of the signal-to-noise ratio.     

索贝创意21非线性编辑系统升级方案

对Sobey创意21非线性编辑系统常遇问题进行了剖析，提出对系统硬件的改造升级方案，并就如何实施及对比测试结果作介绍。     

The KidSat project

Imagine viewing our world from space; a world astronauts have described as “bright and vivid” with “no borders or boundaries”. Then consider how much can be learned by studying Earth from this unique vantage point. The National Aeronautics and Space Administration (NASA) began a three-year pilot program in 1995 designed by a team of scientists, educators, engineers, and high school and college students to share astronauts' unique view of Earth with middle school students. This pilot program was called KidSat. KidSat's primary objective was to merge real-time professional space flight with middle school education by providing students with equal access and direct contribution to the United States space program for the exploration of the Earth. KidSat's long-term intent was to produce higher student achievement and increased competence in science, math, technology, and geography, and to promote an interactive understanding of Earth as an integrated system. Similar to the regular duties of astronauts, scientists, and engineers, students around the nation planned observations and captured images to study Earth's dynamic, fragile environment, using a remotely operated high-resolution color digital camera onboard the Space Shuttle, custom flight software, the Internet, NASA's infrastructure, and a mission operations infrastructure that linked middle schools to the Shuttle through a student-built mission Control Gateway. Using accompanying curriculum, students determined which areas of Earth they wanted to explore and photograph along the Shuttle's flight path. Orbiting communications satellites and the Internet transmitted commands, telemetry and images to and from the classrooms. Via the Shuttle cargo bay video camera. NASA TV carried video of the mission and the Earth for simultaneous viewing in classrooms. The KidSat pilot program was conceived in November 1993 and ended in December 1997. This paper summarizes the results of this program     

Overview of Advanced Spaceborne Thermal Emission and ReflectionRadiometer (ASTER)

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a research facility instrument provided by the Ministry of International Trade and Industry (MITI), Tokyo, Japan to be launched on NASA's Earth Observing System morning (EOS-AM1) platform in 1998. ASTER has three spectral hands in the visible near-infrared (VNIR), six bands in the shortwave infrared (SWIR), and five bands in the thermal infrared (TIR) regions, with 15-, 30-, and 90-m ground resolution, respectively. The VNIR subsystem has one backward-viewing band for stereoscopic observation in the along-track direction. Because the data will have wide spectral coverage and relatively high spatial resolution, it will be possible to discriminate a variety of surface materials and reduce problems in some lower resolution data resulting from mixed pixels. ASTER will, for the first time, provide high-spatial resolution multispectral thermal infrared data from orbit and the highest spatial resolution surface spectral reflectance temperature and emissivity data of all of the EOS-AM1 instruments. The primary science objective of the ASTER mission is to improve understanding of the local- and regional-scale processes occurring on or near the Earth's surface and lower atmosphere, including surface-atmosphere interactions. Specific areas of the science investigation include the following: (1) land surface climatology; (2) vegetation and ecosystem dynamics; (3) volcano monitoring; (4) hazard monitoring; (5) aerosols and clouds; (6) carbon cycling in the marine ecosystem; (7) hydrology; (8) geology and soil; and (9) land surface and land cover change. There are three categories of ASTER data: a global map, regional monitoring data sets, and local data sets to be obtained for requests from individual investigators     

SMOS Validation and the COSMOS Campaigns

The Soil Moisture and Ocean Salinity (SMOS) mission is a joint ESA-CNES (F)-CDTI (E) mission within the ESA Living Planet Program, and it was the second ESA Earth Explorer Opportunity Mission to be selected. The mission objectives of SMOS are to provide soil moisture and ocean salinity observations for weather forecasting, climate monitoring, and the global freshwater cycle. This paper will describe the scientific campaigns performed to date, as well as the plans for the on-orbit calibration and validation activities.     

Pioneer Venus Occultation Radio Science Data Generation

Previous to the Pioneer Venus Orbiter mission, occultation radio science data were generated at the Deep Space Stations of NASA's Deep Space Network via the analog recording of the baseband frequency output signal of a relatively wide bandwidth open-loop receiver. Signal digitization was a separate and subsequent operation at the Jet Propulsion Laboratory. During Pioneer Venus Orbiter radio science operations, the open-loop receiver baseband frequency output signal bandwidth was substantially reduced. This was made possible by programming the open-loop receiver first local oscillator with the predicted Doppler frequency profile. In addition, the receiver output signal was digitized and recorded directly on computer compatible magnetic tape in real time. Initial results obtained with this new process, referred to as ?real-time bandwidth reduction,? during the prime Pioneer Venus Orbiter mission, compare very favorably to results obtained with the previous occultation system.     

Mobile Java Objects

This paper gives an overview of the design of a mobile Java object infrastructure. It describes why it is helpful to group objects for mobility and how, when clusters represent untrusted pieces of code (for example mobile agents), they must be encapsulated both to control their access to other objects and to control access to them. The difficulties of managing large numbers of mobile objects in an open environment are discussed, together with a solution based on the management of large distributed name spaces. The mobile object system described has been implemented, and is currently being used to support development of mobile agent-based applications within another project. The paper also explains how the infrastructure described meets the requirements of mobile agents better than other approaches.