Engineering topics

Engel, J. L.

Publications and source records attributed to Engel, J. L..

4 records

NASA NTRS1981

Multispectral scanner, thematic mapper, and beyond

The capabilities and functions of the Landsat D multispectral scanner (MSS) and thematic mapper (TM) are explored as a basis for improvements to satisfy increasing user demands. The MSS is an object-space line scanner for gathering data in four spectral bands ranging from 0.5-1.1 micron. In a 705 km near-polar sunsynchronous orbit, the MSS will generate 185 x 185 km imagery with 80 x 80 m ground resolution, mapping the entire earth every 16 days. Photomultiplier tubes are used for four of the bands and the other employs Si photodiodes. A calibration light source provides in orbit calibration during every reverse scan period of a pivotal on-board mirror. The TM collects data in seven bands from 0.45-12.5 microns, yielding a ground resolution of 30 x 30 m in six bands for reflected sunlight and 120 x 120 m for the 10.4-12.5 thermal bands. The addition of 16 Si detectors for 0.9-1.1 micron viewing for agricultural purposes, as well as higher resolution, is discussed.

Jones, C. R.↗

NASA NTRS1980

Thematic Mapper - An interim report on anticipated performance

The requirements and design concept of the Thematic Mapper are briefly reviewed. Emphasis is placed on the anticipated on-orbit performance based on subsystem and system level test results obtained from Engineering Model and Protoflight Model hardware. The anticipated performance of the Thematic Mapper is discussed in four key areas: spectral response, radiometric sensitivity, square-wave response, and band-to-band registration.

Engel, J. L.↗

NASA NTRS1978

Viking infrared thermal mapper

The infrared thermal mapper (IRTM) was designed to measure the emitted and reflected radiance of Mars. Carried by the Viking Orbiter, the IRTM contains four small Cassegrainian telescopes which each image the same, seven circular areas. There is a total of twenty-eight channels in four surface and one atmospheric thermal bands from 6 to 30 microns and a broad solar reflectance band. All channels are sampled simultaneously, using the spacecraft scanning capability to map the radiance over small and large areas of the planet. All channels use thermopile detectors; spectral passbands are determined by a combination of interference filters, detector lense materials, antireflection coatings, and restrahlen optics.

Chase, S. C., Jr.↗

NASA NTRS1976

Thematic mapper critical elements breadboard program

A 40.6 cm bidirectional scan mirror assembly, a scan line corrector and a silicon photodiode array with integral preamplifier input stages were designed, fabricated, and tested to demonstrate performance consistent with requirements of the Hughes thematic mapper system. The measured performance met or exceeded the original design goals in all cases with the qualification that well defined and well understood deficiencies in the design of the photodiode array package will require the prescribed corrections before flight use.

Dale, C. H., Jr.↗