2,939 research outputs found
Interagency telemetry arraying for Voyager-Neptune encounter
The reception capability of the Deep Space Network (DSN) has been improved over the years by increasing both the size and number of antennas at each complex to meet spacecraft-support requirements. However, even more aperture was required for the final planetary encounters of the Voyager 2 spacecraft. This need was met by arraying one radio astronomy observatory with the DSN complex in the United States and another with the complex in Australia. Following a review of augmentation for the Uranus encounter, both the preparation at the National Radio Astronomy (NRAO) Very Large Array (VLA) and the Neptune encounter results for the Parkes-Canberra and VLA-Goldstone arrays are presented
Testing methods and techniques: A compilation
Mechanical testing techniques, electrical and electronics testing techniques, thermal testing techniques, and optical testing techniques are the subject of the compilation which provides technical information and illustrations of advanced testing devices. Patent information is included where applicable
Imaging the first light: experimental challenges and future perspectives in the observation of the Cosmic Microwave Background Anisotropy
Measurements of the cosmic microwave background (CMB) allow high precision
observation of the Last Scattering Surface at redshift 1100. After the
success of the NASA satellite COBE, that in 1992 provided the first detection
of the CMB anisotropy, results from many ground-based and balloon-borne
experiments have showed a remarkable consistency between different results and
provided quantitative estimates of fundamental cosmological properties. During
2003 the team of the NASA WMAP satellite has released the first improved
full-sky maps of the CMB since COBE, leading to a deeper insight into the
origin and evolution of the Universe. The ESA satellite Planck, scheduled for
launch in 2007, is designed to provide the ultimate measurement of the CMB
temperature anisotropy over the full sky, with an accuracy that will be limited
only by astrophysical foregrounds, and robust detection of polarisation
anisotropy. In this paper we review the experimental challenges in high
precision CMB experiments and discuss the future perspectives opened by second
and third generation space missions like WMAP and Planck.Comment: To be published in "Recent Research Developments in Astronomy &
Astrophysics Astrophysiscs" - Vol I
Sensors Workshop summary report
A review of the efforts of three workshops is presented. The presentation describes those technological developments that would contribute most to sensor subsystem optimization and improvement of NASA's data acquisition capabilities, and summarizes the recommendations of the sensor technology panels from the most recent workshops
Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4
Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences
System analysis and integration studies for a 15-micron horizon radiance measurement experiment
Systems analysis and integration studies for 15-micron horizon radiance measurement experimen
Coherent Receiver Arrays for Astronomy and Remote Sensing
Monolithic Millimeter-wave Integrated Circuits (MMICs) provide a level of integration that makes possible
the construction of large focal plane arrays of radio-frequency detectorsâeffectively the first âRadio
Camerasââand these will revolutionize radio-frequency observations with single dishes, interferometers,
spectrometers, and spacecraft over the next two decades. The key technological advances have been
made at the Jet Propulsion Laboratory (JPL) in collaboration with the Northrop Grumman Corporation
(NGC). Although dramatic progress has been made in the last decade in several important areas, including
(i) packaging that enables large coherent detector arrays, (ii) extending the performance of amplifiers
to much higher frequencies, and (iii) reducing room-temperature noise at high frequencies, funding to
develop MMIC performance at cryo-temperatures and at frequencies below 150GHz has dropped nearly
to zero over the last five years. This has severely hampered the advance of the field. Moreover, because
of the high visibility of < 150GHz cryogenic detectors in astrophysics and cosmology, lack of progress in
this area has probably had a disproportionate impact on perceptions of the potential of coherent detectors
in general.
One of the prime objectives of the Keck Institute for Space Studies (KISS) is to select crucial areas of
technological development in their embryonic stages, when relatively modest funding can have a highly
significant impact by catalyzing collaborations between key institutions world-wide, supporting in-depth
studies of the current state and potential of emerging technologies, and prototyping development of key
componentsâall potentially leading to strong agency follow-on funding.
The KISS large program âCoherent Instrumentation for Cosmic Microwave Background Observationsâ
was initiated in order to investigate the scientific potential and technical feasibility of these âRadio
Cameras.â This opens up the possibility of bringing support to this embryonic area of detector development
at a critical phase during which KISS can catalyze and launch a coherent, coordinated, worldwide
effort on the development of MMIC Arrays. A number of key questions, regarding (i) the importance and
breadth of the scientific drivers, (ii) realistic limits on sensitivity, (iii) the potential of miniaturization into
receiver âmodules,â and (iv) digital signal processing, needed to be studied carefully before embarking on
a major MMIC Array development effort led by Caltech/JPL/NGC and supported by KISS, in the hope
of attracting adequate subsequent government funding. For this purpose a large study was undertaken
under the sponsorship and aegis of KISS. The study began with a workshop in Pasadena on âMMIC
Array Receivers and Spectrographsâ (July 21â25, 2008)1, immediately after an international conference
âCMB Component Separation and the Physics of Foregroundsâ (July 14â18, 2008)2 that was organized in
conjunction with the MMIC workshop. There was then an eight-month study period, culminating in a
final âMMIC 2Workshopâ (March 23â27, 2009).3 These workshops were very well attended, and brought
together the major international groups and scientists in the field of coherent radio-frequency detector
arrays. A notable aspect of the workshops is that they were well attended by young scientistsâthere
are many graduate students and post-doctoral fellows coming into this area. The two workshops focused
both on detailed discussions of key areas of interest and on the writing of this report. They were
conducted in a spirit of full and impartial scrutiny of the pros and cons of MMICs, in order to make an
objective assessment of their potential. It serves no useful purpose to pursue lines of technology development
based on unrealistic and over-optimistic projections. This is crucially important for KISS, Caltech,
and JPL which can only have real impact if they deliver on the promise of the technologies they develop.
A broad range of opinions was evident at the start of the first workshop, but in the end a strong consensus
was achieved on the most important questions that had emerged. This report reflects the workshop
deliberations and that consensus.
The key scientific drivers for the development of the MMIC technology are: (i) large angular-scale Bmode
polarization observations of the cosmic microwave backgroundâhere MMICs are one of two key
technologies under development at JPL, both of which are primary detectors on the recently-launched
Planck mission; (ii) large-field spectroscopic surveys of the Galaxy and nearby galaxies at high spectral
resolution, and of galaxy clusters at low resolution; (iii) wide-field imaging via deployment as focal plane
arrays on interferometers; (iv) remote sensing of the atmosphere and Earth; and (v) wide-field imaging in
planetary missions. These science drivers are discussed in the report.
The most important single outcome of the workshops, and a sine qua non of this whole program,
is that consensus was reached that it should be possible to reduce the noise of individual HEMTs or
MMICs operating at cryogenic temperatures to less than three times the quantum limit at frequencies up
to 150 GHz, by working closely with a foundry (in this case NGC) and providing rapid feedback on the
performance of the devices they are fabricating, thus enabling tests of the effects of small changes in the
design of these transistors. This kind of partnership has been very successful in the past, but can now be
focused more intensively on cryogenic performance by carrying out tests of MMIC wafers, including tests
on a cryogenic probe station. It was felt that a properly outfitted university laboratory dedicated to this
testing and optimization would be an important element in this program, which would include MMIC
designs, wafer runs, and a wide variety of tests of MMIC performance at cryogenic temperatures.
This Study identified eight primary areas of technology development, including the one singled out
above, which must be actively pursued in order to exploit the full potential of MMIC Arrays in a timely
fashion:
1. Reduce the noise levels of individual transistors and MMICs to three times the quantum limit or
lower at cryogenic temperatures at frequencies up to 150 GHz.
2. Integrate high-performing MMICs into the building blocks of large arrays without loss of performance.
Currently factors of two in both noise and bandwidth are lost at this step.
3. Develop high performance, low mass, inexpensive feed arrays.
4. Develop robust interconnects and wiring that allow easy fabrication and integration of large arrays.
5. Develop mass production techniques suitable for arrays of differing sizes.
6. Reduce mass and power. (Requirements will differ widely with application. In the realm of planetary
instruments, this is often the most important single requirement.)
7. Develop planar orthomode transducers with low crosstalk and broad bandwidth.
8. Develop high power and high efficiency MMIC amplifiers for LO chains, etc.
Another important outcome of the two workshops was that a number of new collaborations were
forged between leading groups worldwide with the object of focusing on the development of MMIC
arrays
Research study of pressure instrumentation
To obtain a more vibration resistant pressure sensor for use on the Space Shuttle Main Engine, a proximity probe based, diaphragm type pressure sensor breadboard was developed. A fiber optic proximity probe was selected as the sensor. In combination with existing electronics, a thermal stability evaluation of the entire probe system was made. Based upon the results, a breadboard design of the pressure sensor and electronics was made and fabricated. A brief series of functional experiments was made with the breadboard to calibrate, thermally compensate, and linearize its response. In these experiments, the performance obtained in the temperature range of -320 F (liquid N2) to +200 F was comparable to that of the strain gage based sensor presently in use on the engine. In tests at NASA-Marshall Space Flight Center (MSFC), after some time at or near liquid nitrogen temperatures, the sensor output varied over the entire output range. These large spurious signals were attributed to condensation of air in the sensing gap. In the next phase of development of this sensor, an evaluation of fabrication techniques toward greater thermal and mechanical stability of the fiber probe assembly must be made. In addition to this, a positive optics to metal seal must be developed to withstand the pressure that would result from a diaphragm failure
Technology Needs Assessment of an Atmospheric Observation System for Multidisciplinary Air Quality/Meteorology Missions, Part 2
The technology advancements that will be necessary to implement the atmospheric observation systems are considered. Upper and lower atmospheric air quality and meteorological parameters necessary to support the air quality investigations were included. The technology needs were found predominantly in areas related to sensors and measurements of air quality and meteorological measurements
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