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Fundamental methods of signal processing used in normal mesosphere stratosphere troposphere (MST) radar observations are described. Complex time series of received signals obtained in each range gate are converted into Doppler spectra, from which the mean Doppler shift, spectral width and signal-to-noise ratio (SNR) are estimated. These spectral parameters are further utilized to study characteristics of scatterers and atmospheric motions.
Magnetic shear was observed in several active regions prior to flaring activity. However, certain flares were observed with no apparent shear present. A more detailed investigation of such events is required.
The entire LDEF spacecraft was examined by M&D SIG for impact (i.e., craters greater than or = 0.5 mm and penetrations greater than or = 0.3 mm in diameter) and related features (e.g., debris, secondaries). During the various detailed surveys conducted at NASA Kennedy, approx. 5,000 impact related features were photodocumented, and their locations measured and recorded; an additional approx. 30,000 smaller features were counted. The equipment and techniques used by the M&D SIG permitted the determination and recording of the locations and diameters of the 5,000 imaged features. A variety of experimental and LDEF structural hardware was acquired by the M&D SIG and is presently being examined and curated at NASA Johnson.
The Magellan spacecraft has been systematically mapping the surface of Venus since September 15, 1990, using side-looking synthetic aperture radar imaging and nadir-pointed altimetry. Venus rotates slowly under the nearly polar mapping orbit, completing a full revolution in 243 days, one 'mapping cycle'. The altimeter collects a 10 km swath of altitude measurements each orbit. The groundtrack advances 21 km each orbit due to the rotation of Venus, leaving an 11 km gap of unmeasured terrain. To obtain global surface coverage by the altimeter, these gaps are eliminated by interleaving the swaths collected during the second mapping cycle with those from the first mapping cycle. Interleaving was put into effect by a propulsive maneuver, executed at the end of the first mapping cycle, on May 17, 1991. The orbit node was changed by +0.106 degrees, so that the cycle 2 groundtracks would bisect adjacent cycle 1 groundtracks. This paper describes the maneuver design and execution results, including the problem and solution of the groundtrack prediction to the end of the first mapping cycle.
The progress of research programs monitored by the Jet Propulsion Laboratory's Telecommunications and Mission Operations Directorate (TMOD) are presented in this quarterly document. Areas monitored include space communications, radio navigation, radio science, ground-based radio and radar astronomy, information systems, and all other communication and research technology activities for the Deep Space Network (DSN).
A new 16-bit 6-MHz compact, lightweight waveform digitizer module has been tested using actual 300-nm lidar atmospheric returns. The noise level of this digitizer was tested and found to be substantially below the ozone number density to be measured. The digitizer is inexpensive and compact enough to be deployed in UAV aircraft and spacecraft environments. With 16-bit digitizers a resolution of 0.046 mV/step can be achieved, substantially improving resolution over 12-bit systems. This digitizer will find widespread use in future DIAL receiver systems.
A 6-MHz 16-bit waveform digitizer was evaluated for use in atmospheric differential absorption lidar (DIAL) measurements of ozone. The digitizer noise characteristics were evaluated, and actual ozone DIAL atmospheric returns were digitized. This digitizer could replace computer-automated measurement and control (CAMAC)-based commercial digitizers and improve voltage accuracy.
This viewgraph presentation describes efforts at Kennedy Space Center (KSC) to develop spacecraft sensors and instruments which meet the expected needs of potential clients on a budget. Sensors are profiled, and the topics covered include systems health monitoring, smart structures, software algorithms, and testing.
This viewgraph presentation summarizes the characteristics required on sensors by consumers desiring access to space, a long term plan developed at KSC (Kennedy Space Center) to identify promising technologies for NASA's own future sensor needs, and the characteristics of several smart sensors already developed. Also addressed are the computer hardware and architecture used to operate sensors, and generic testing capabilities. Consumers desire sensors which are lightweight, inexpensive, intelligent, and easy to use.
The present invention comprises a method and apparatus that generates a waveform consisting of an arbitrary number of frequency sweeps combined from adding and subtracting mini frequency sweeps. Optimization routines determine the best combination order of frequency sweep to minimize or maximize design criteria such is aerodynamic surface deflection or maximum command rate of the wave form. The invention allows for arbitrary output timing, or commands per second issued for the desired waveform, arbitrary starting and ending frequencies and amplitudes, arbitrary number of frequency sweep components, arbitrary frequency sweep exponent, arbitrary amplitude sweep exponent, and arbitrary waveform length. For a given frequency range and sweep exponent, amplitude range and sweep exponent, desired total waveform time and number of frequency sweep components, the algorithm can determine the optimum arrangement of the components to minimize the maximum amplitude or rate.
Mossbauer spectrometers on the Spirit and Opportunity rovers have played a valuable role in identifying mineralogy at both the Gusev and Meridiani landing sites. Key to the application of Mossbauer results is the issue of how accurately the peak positions, on which the mineral identifications are based, can be determined. Remote Mossbauer spectroscopy has by necessity some unusual experimental constraints that may influence the confidence with which peak positions can be fit. We present here an analysis of the effects of variable temperature and short duration run times on spectral resolution.
A method and apparatus for an acquisition system includes a plurality of sensor input signal lines. At least one of the plurality of sensor input signal lines operatively connects to at least one of a plurality of amplifier circuits. At least one of the plurality of amplifier circuits operatively connects to at least one of a plurality of filter circuits.
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A LabVIEW-based system was recently caried aloft in a NASA DC-9.
The purpose of this article is to discuss several different types of software tools the Jet Propulsion Laboratory's (JPL) Measurement Technology Center (MTC) has used to develop such systems.
This paper describes recent work undertaken at the Jet Propulsion Laboratory in Pasadena, CA in the area of increased rover autonomy for planetary surface operations.
The Leaky Lamb Wave (LLW) technique is approaching a maturity level that is making it an attractive quantitative NDE tool for composites and bonded joints. Since it was first observed in 1982, the phenomenon has been studied extensively, particularly in composite materials.
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