NASA's Anderson Loop

The Anderson loop is a simply implemented measurement circuit topology that uses active subtraction instead of the passive subtraction accomplished by the classic Wheatstone bridge. Larger, inherently linear signals from sensing-element impedance change are available with less excitation power and without the use of transmitters to achieve immunity to wire-resistance variations. Transducers can be designed with any convenient quantity of sensor elements. Transducer intelligence can be implemented within the signal conditioner. The change in a single sensing element can be used in several simultaneous measurements. Sensor elements can appear to have any desired impedance level and influence on any of several outputs     

NASA's broadband satellite networking research

ATM is currently considered the primary WAN technology with Internet protocols providing the routing and transport requirements. Another WAN technology being considered is packet over SONET. Using the Advanced Communication Technology Satellite, NASA has demonstrated and is experimenting with these technologies. This article summarizes some of the major completed and ongoing experiments and demonstrations performed using commercial standard protocols such as ATM and TCP/IP over broadband satellite networks     

Ground antennas in NASA's deep space telecommunications

Ground antennas are the major visible components of NASA's Deep Space Network (DSN). The role, key characteristics, and performance of these antennas in deep-space telecommunications are described. The system analyses and tradeoffs to optimize the overall ground-to-spacecraft link and to define future missions are elaborated from an antenna perspective. Overall performance of receiving systems is compared using the widely accepted G/T figure-of-merit, i.e., net antenna gain divided by the operating system noise temperature. Performance of past, present, and future antennas and receiving systems is discussed, including the planned development of a world-wide network of 34-m diameter beam-waveguide antennas. The need for multifrequency operation, presently in the S- and X-bands, and in the future in the Ka-band, is discussed. The resulting requirements placed on antenna technology are highlighted. Beam-waveguide antenna performance to further improve performance and operational advantages is discussed     

NASA's big push for the space station

While concerned about the risks, most space experts who talked privately agreed that further waiting would be unlikely to reduce risks; it was time to do a shakedown under real night conditions. Because of the orbital stability of the space station and the presence of the fully functioning Russian modules, the actual threat of vehicle or crew loss due to hardware and software problems is lower than for any previous U.S. manned space mission. Frequent problems, including major failures, are expected during the next few months of assembling the station, but experts believe it is an ordeal that must be overcome     

Shuttle diplomacy [NASA's manned space flight programme]

The loss of Space Shuttle Columbia means NASA's manned space flight programme is in trouble. The author examines three options. One is to build a new shuttle to replace Columbia. This was the policy followed after the Challenger explosion in 1986 and, undoubtedly, would be the cheaper, faster option. The second is to accelerate the development of the Orbital Space Plane (OSP), a vehicle proposed when space agency heads met to discuss the issue of manned space access. Finally, NASA can do nothing. However, this seems unlikely.     

NASA's plans to observe the Earth's atmosphere with lidar

The requirements for lidar observations of the Earth's atmosphere and the characteristics of the systems to provide these observations are discussed. The planned Earth Observing System (Eos) will offer platforms with adequate mass and power capabilities from which to make these lidar observations. Planned Eos lidar applications include the laser atmospheric wind sounder (LAWS), and the global backscatter experiment planned for it; the lidar atmospheric sounder and altimeter (LASA); and the ESA research facility instrument ATLID (atmospheric lidar). The laser requirements of all of the Eos laser instruments are presented     

A Smart Sensor Integrated Circuit for NASA's New Millennium Spacecraft

The modern space era can greatly benefit from the rapidly growingmicroelectronics technologies in order to enable the ambitious exploratoryand commercial space endeavors of the new millennium. A smart sensor, analog/digital, integrated circuit, suitable for spacecraft avionics dataacquisition and control is presented. The Remote Input/Output (RIO) device isdeveloped by The Johns Hopkins University/Applied Physics Laboratory, for NASA's Jet Propulsion Laboratory, to support many oncoming new millenniumspace missions. TRIO—the first version of RIO—is designed to interface totemperature, pressure, total radiation dose sensors, and generally to voltage/current transducers. The microchip includes front-end conditioningcircuitry, an ADC, memory, serial and CPU interface, and a digital port.Furthermore the device is developed to meet extreme space qualification specifications such as radiation effects. This versatile system-on-a-chipdevice is becoming a key enabling technology for new-generation NASA andCommercial spacecraft systems. Missions that are intended to use the TRIOdevice are the: Europa Orbiter, Deep Space 4, Solar Probe, Pluto Express,Mars Sample Return, Stereo, Contour, etc.     

Open Architecture Standard for NASA's Software-Defined Space Telecommunications Radio Systems

NASA is developing an architecture standard for software-defined radios used in space- and ground-based platforms to enable commonality among radio developments to enhance capability and services while reducing mission and programmatic risk. Transceivers (or transponders) with functionality primarily defined in software (e.g., firmware) have the ability to change their functional behavior through software alone. This radio architecture standard offers value by employing common waveform software interfaces, method of instantiation, operation, and testing among different compliant hardware and software products. These common interfaces within the architecture abstract application software from the underlying hardware to enable technology insertion independently at either the software or hardware layer. This paper presents the initial Space Telecommunications Radio System architecture for NASA missions to provide the desired software abstraction and flexibility while minimizing the resources necessary to support the architecture.     

An overview of LITE: NASA's Lidar In-space Technology Experiment

The Lidar In-space Technology Experiment (LITE) is a three-wavelength backscatter lidar developed by NASA Langley Research Center to fly on the Space Shuttle. LITE flew on Discovery in September 1994 as part of the STS-64 mission. The goals of the LITE mission were to validate key lidar technologies for spaceborne applications, to explore the applications of space lidar, and to gain operational experience which will benefit the development of future systems on free-flying satellite platforms. The performance of the LITE instrument was excellent, resulting in the collection of over 40 GBytes of data. These data present us with our first highly detailed global view of the vertical structure of cloud and aerosol from the Earth's surface through the middle stratosphere. This paper will discuss the LITE instrument, the LITE mission, and briefly present some results from the Experiment. These preliminary results highlight the benefits to be obtained from long duration satellite lidars     

One summer at NASA's John C. Stennis Space Center

The test stands at SSC are enormous structures, each with several hundred - even thousands - of sensors. With such a high sensor count and variety it is incredibly difficult to do anything useful with the influx of data in real time beyond recording it for future examination. However, it would be ideal if the test controller could not only view all of the data in an intuitive and information rich environment but also have the complementary sensor data fused together to provide more robust information. Enter the integrated intelligent health management system (IIHMS). The IIHMS is a collection of smart sensors, each aware of the local process they are measuring, controlled by an expert system with a global view of the entire system. The long-range goal is to develop an expert system to provide the test controller with a fully immersed environment in which to monitor the condition of every system component and receive advice on anomalies and proper courses of action. The IIHMS is now termed intelligent system health management (ISHM). Dave was assigned the hardware design of a smart temperature sensor that would form the foundation layer of the IIHMS; Don was responsible for the firmware that would add the intelligence to Dave's hardware by enabling it to monitor the health (i.e., quality) of the sensor and the quality of measurements in real time; Jon was left the task of designing the link between the smart sensor and the expert system. This work discusses the summer experience of the authors at SSC.     

The development of an intelligent user interface for NASA's scientific databases

The National Space Science Data Center (NSSDC) has initiated an Intelligent Data Management (IDM) research effort which has as one of its components, the development of an Intelligent User Interface (IUI). The intent of the IUI effort is to develop a friendly and intelligent user interface service that is based on expert systems and natural language processing technologies. This paper presents the design concepts, development approach and evaluation of performance of a prototype Intelligent User Interface Subsystem (IUIS) supporting an operational database.     

变装大师

年轻人皮斯塔肖(达那·卡维饰)出生于魔法师家庭,天生就有着活灵活现模仿他人、乔装改扮的本领。然而,他父亲的老仇敌找上门来,将其父绑走,利用其家族的变装能力骗取全世界的奇珍异宝。     

NASA's alphasat propagation terminals: Milan,Italy, and Edinburgh,Scotland

Since May of 2014, NASA's Glenn Research Center has operated measurement campaigns for the Alphasat Aldo Paraboni Propagation Experiment alongside the European community of propagation experimenters. Presently, three NASA stations have been deployed to distinct climatological regions across Europe. NASA's participation in the campaign began in 2014 through a collaborative effort with the Politecnico di Milano (POLIMI) to jointly operate a 20/40 GHz ground terminal at the POLIMI campus in Milan, Italy. Subsequently, a single‐channel 40 GHz terminal was deployed to Edinburgh, Scotland in March 2016 in collaboration with Heriot‐Watt University (HWU). A third terminal was deployed to NASA's Madrid Deep Space Communications Complex (MDSCC) in March 2017 with NASA'S Jet Propulsion Laboratory (JPL), also observing the 40 GHz beacon. In addition, a fourth station is planned for deployment to Andøya, Norway by early 2019 in collaboration with the Norwegian Defence Research Establishment (FFI). This paper will detail the design and results of the two most established terminals, Milan and Edinburgh, which together comprise 11 station years of propagation measurements.     

NASA's advanced tracking and data relay satellite system for theyears 2000 and beyond

An advanced tracking and data relay satellite system (ATDRSS) reference architecture that embodies many of the system features and technological enhancements considered essential is presented and described. The architectural and user service features of the existing TDRSS are reviewed, and certain evolutionary features that will take place by the mid-1990s are discussed. NASA's projected user service requirements for the first decade at the next century, which are the principal drivers for the ATDRSS architecture, are described, including such aspects as the real-time data rates and the quantity of simultaneous services that must be supported. The discussion of the ATDRSS reference architecture covers rationale, technology considerations, and key features of the future ATDRSS user service. A status summary of the ATDRSS program is given     

1.6 W hybrid master oscillator power amplifier withα-DFB-laser as master oscillator at 1057 nm

A hybrid master oscillator power amplifier is realised on a small area less than 100 mm² combining an α-DFB-laser as master oscillator and a broad area laser as power amplifier. A quasi-cw output power of P=1.6 W at the wavelength) λ=1057 nm is achieved with a beam quality factor M² less than 2 and a spectral width less than 6 pm     

Analysis of monolithic integrated master oscillator poweramplifiers

An analysis of a novel, monolithic integrated master oscillator power amplifier (M-MOPA) is presented. The M-MOPA consists of a DBR master oscillator which injects power into a linear chain of amplifiers and detuned second-order grating output couplers. The analysis self-consistently includes amplified spontaneous emission buildup and residual reflections throughout the amplifier stages. It predicts that output powers in excess of 1 W can be expected from a single-lateral-mode waveguide multistage amplifier less than 1 cm in length, injected with less than 15 mW of input power. In addition to the signal gain of >25 dB, the signal-to-noise ratio at 1-W output exceeds 15 dB. Because of the small reflections associated with the grating output couplers, and gain saturation by the injected signal, the amplifier self-oscillation threshold is suppressed to current densities above 15 kA/cm²