Engineering Papers⌕ Search

Engineering topics

Jordan, R.

Publications and source records attributed to Jordan, R..

33 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

The "Myth" of the Minimum SAR Antenna Area Constraint

A design constraint traceable ot the early days of spaceborne Synthetic Aperture Radar (SAR) is known as the minimum antenna area constraint for SAR. In this paper, it is confirmed that this constraint strictly applies only to the case where both the best possible resolution and the widest possible swath are the design goals. SAR antennas with area smaller than the constraint allows are shown to be possible, have been used on spaceborne SAR missions in the past, and should permit further, lower-cost SAR mission in the future.

Freeman, A.↗
NASA NTRS1995

(abstract) SIR-C/X-SAR: A Multifaceted Radar

The Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SAR-C/X-SAR) was a joint US/German/Italian project, with flights aboard the shuttle Endeavor in April and October 1994. SIR-C/X-SAR is the first spaceborne multifrequency, multipolarization radar. The SIR-C and the X-SAR were designed to operate in conjunction with each other, collecting data over common sites. Scientists around the world are using the data in conjunction with ground measurements to conduct experiments relating to Earth's ecology, geology, hydrology, and oceanography. In addition, the data are the most comprehensive set yet available for engineering characterization of spaceborne SAR capabilities relative to various radar phenomenology and methodology. Preliminary results show changes between missions in vegetation, ice, snow, flooding, and volcano activity.

imaging↗
NASA NTRS1984

Topography of the shield volcano, Olympus Mons on Mars

Olympus Mons, one of the largest known shield volcanoes in the solar system, covers an area of more than 3.2 x 10 to the 5th sq km and has a diameter of more than 600 km, excluding its vast aureole deposits. The structure is five times larger than the largest shield volcano on the earth. It is situated on the north-west flank of the Tharsis volcanic region, a broad topographic rise on the Martian surface. The volcano has three physical subdivisions: the summit caldera, the terraced upper flanks, and the lower flanks, which terminate in a scarp 2-10 km high that nearly surrounds the structure. A large block of images of the Tharsis region, including Olympus Mons, was obtained by the Viking mission. A topographic map of Olympus Mons is presented here, which has been compiled using various combinations of stereo pairs of these images, together with stereoscopic perspective views generated by image processing techniques.

Wu, S. S. C.↗
NASA NTRS1982

Photogrammetric application of Viking orbital photography

The paper describes special techniques for the photogrammetric compilation of topographic maps and profiles from stereoscopic photographs taken by the two Viking Orbiter spacecraft. These techniques were developed because the extremely narrow field of view of the Viking cameras rules out compilation by conventional photogrammetric methods. The techniques adjust for internal consistency the Supplementary Experimental Data Record and the computation of geometric orientation parameters of the stereo models. A series of contour maps of Mars is being compiled by these new techniques using a wide variety of Viking Orbiter photographs.

Wu, S. S. C.↗
NASA NTRS1978

The Seasat-A synthetic aperture radar design and implementation

The Seasat-A Synthetic Aperture Imaging Radar System is the first imaging radar system intended to be used as a scientific instrument designed for orbital use. The requirement of the radar system is to generate continuous radar imagery with a 100 kilometer swath with 25 meter resolution from an orbital altitude of 800 kilometers. These requirements impose unique system design problems and a description of the implementation will be given. The end-to-end data system will be described, including interactions of the spacecraft, antenna, sensor, telemetry link, recording subsystem, and data processor. Some of the factors leading to the selection of critical system parameters will be listed. The expected error sources leading to degradation of image quality will be described as well as estimates given of the expected performance from data obtained during ground testing of the completed subsystems.

Jordan, R.↗
NASA NTRS1974

Atlas of Surveyor 5 television data

This atlas is a compendium of the Surveyor 5 television mosaics. It it divided into two main sections. The first consists of improved mosaics of panoramas and basic cartographic data used in investigating surface detail, and the second contains individual frame data, including photoindex mosaics and tabulations in which individual frames are identified. A short section containing a set of special-purpose mosaics assembled by the staff of the Jet Propulsion Laboratory is also included. For more details about the Surveyor 5 mission, television data, or science results, a brief bibliography is included.

Batson, R. M.↗
NASA NTRS1974

Elevation profiles of the moon

Five MHz radar data obtained from the Apollo 17 mission are used to determine elevation profiles of the moon. A change in range of one quarter of a wavelength (15 m for the 5 MHz radar) changes the round-trip radar range one half wavelength or 180 deg, thus allowing determination of the relative surface profile or slope with a high degree of precision. The technique of deriving the range or altimetry measurement from the range-Doppler data record on film yields a better understanding of the range accuracy. The presence of fade intervals can be observed directly and their effect on the profile measurement reduced to a minimum. The maria used to generate the center of maria are Western Procellarum, Serenitatis, and Crisium. The location of the center of mare relative to the center of figure and center of mass is identified.

Brown, W. E., Jr.↗
NASA NTRS1973

Photogrammetric evaluation of Mariner 9 photography

Some attempts to produce, with an AP/C analytical plotter, stereo models using Mariner 9 pictures are reported. The first attempt using geometrically uncorrected mission test video system (MTVS) imagery failed; the second, using corrected reduced data record (RDR) pictures also failed, probably because they were reconstructed through a vidicon display which introduces additional distortion. By using images obtained from RDR tape data through the Optronics Photowrite device, models were successfully obtained.

Wu, S. S. C.↗
NASA NTRS1973

Apollo lunar sounder experiment

The four basic data products from the ALSE are sounding, profiling, imaging, and noise measurements. Attention was concentrated on the first three products, and both theory and preliminary results are presented. Background information is presented on the experiment and on the data products. Preliminary examples of the types of analyses that can be performed and the conclusions to which they can lead are included. Preliminary analysis of the data for subsurface features was successful in indicating with a high probability the capability of the ALSE to achieve its fundamental goal of substrate sounding. The imagery and profiling data are useful immediately for geologic interpretation, as demonstrated.

Phillips, R. J.↗
NASA NTRS1973

The Apollo 17 Lunar Sounder

The Apollo Lunar Sounder Experiment, a coherent radar operated from lunar orbit during the Apollo 17 mission, has scientific objectives of mapping lunar subsurface structure, surface profiling, surface imaging, and galactic noise measurement. Representative results from each of the four disciplines are presented. Subsurface reflections have been interpreted in both optically and digitally processed data. Images and profiles yield detailed selenomorphological information. The preliminary galactic noise results are consistent with earlier measurements by other workers.

Phillips, R. J.↗
NASA NTRS1972

Photogrammetry of Apollo 15 photography, part C

In the Apollo 15 mission, a mapping camera system and a 61 cm optical bar, high resolution panoramic camera, as well as a laser altimeter were used. The panoramic camera is described, having several distortion sources, such as cylindrical shape of the negative film surface, the scanning action of the lens, the image motion compensator, and the spacecraft motion. Film products were processed on a specifically designed analytical plotter.

Wu, S. S. C.↗
NASA NTRS1972

Photogrammetry using Apollo 16 orbital photography, part B

Discussion is made of the Apollo 15 and 16 metric and panoramic cameras which provided photographs for accurate topographic portrayal of the lunar surface using photogrammetric methods. Nine stereoscopic models of Apollo 16 metric photographs and three models of panoramic photographs were evaluated photogrammetrically in support of the Apollo 16 geologic investigations. Four of the models were used to collect profile data for crater morphology studies; three models were used to collect evaluation data for the frequency distributions of lunar slopes; one model was used to prepare a map of the Apollo 16 traverse area; and one model was used to determine elevations of the Cayley Formation. The remaining three models were used to test photogrammetric techniques using oblique metric and panoramic camera photographs. Two preliminary contour maps were compiled and a high-oblique metric photograph was rectified.

Wu, S. S. C.↗