Engineering topics

Russell, E. E.

Publications and source records attributed to Russell, E. E..

6 records

NASA NTRS1992

Galileo Photopolarimeter/Radiometer experiment

The Photopolarimeter/Radiometer (PPR) is a remote sensing instrument on the Galileo Orbiter designed to measure the degree of linear polarization and the intensity of reflected sunlight in ten spectral channels between 410 and 945 nm to determine the physical properties of Jovian clouds and aerosols, and to characterize the texture and microstructure of satellite surfaces. The PPR also measures thermal radiation in five spectral bands between 15 and 100 microns to sense the upper tropospheric temperature structure. Two additional channels which measure spectrally integrated solar and solar plus thermal radiation are used to determine the planetary radiation budget components. The PPR photopolarimetric measurements utilize previously flown technology for high-precision polarimetry using a calcite Wollaston prism and two silicon photodiodes to enable simultaneous detection of the two orthogonal polarization components. The PPR radiometry measurements are made with a lithium tantalate pyroelectric detector utilizing a unique arrangement of radiometric stops and a scene/space chopper blade to enable a warm instrument to sense accurately the much colder scene temperatures.

Russell, E. E.↗

NASA NTRS1977

Orbiter Cloud Photopolarimeter for the Pioneer Venus mission

The Orbiter Cloud Photopolarimeter (OCPP) to be flown aboard the Pioneer Venus Orbiter spacecraft is described. This instrument, while in orbit about the planet Venus, will perform polarimetric and radiometric mapping of the Venus atmosphere in four spectral bands centered in the near ultraviolet, visible, and near infrared regions. Additionally, the instrument is equipped to provide moderate resolution imaging of the time varying cloud patterns in the near ultraviolet. In another mode of operation the instrument is capable of profiling the atmosphere at the limb of the planet to measure the particulate layering. Information resulting from these measurements is intended to provide an understanding of the global cloud dynamics and the atmospheric structure and composition on Venus. The basic operation and functional elements of the instrument are discussed. The optical configuration incorporating a polarization analyzing technique with improved accuracy is described. Long-term and short-term calibration techniques along with expected instrument performance characteristics are summarized.

Russell, E. E.↗

NASA NTRS1974

Study of spin-scan imaging for outer planets missions

The constraints that are imposed on the Outer Planet Missions (OPM) imager design are of critical importance. Imager system modeling analyses define important parameters and systematic means for trade-offs applied to specific Jupiter orbiter missions. Possible image sequence plans for Jupiter missions are discussed in detail. Considered is a series of orbits that allow repeated near encounters with three of the Jovian satellites. The data handling involved in the image processing is discussed, and it is shown that only minimal processing is required for the majority of images for a Jupiter orbiter mission.

Russell, E. E.↗

NASA NTRS1974

Study of spin-scan imaging for outer planets missions: Executive summary

The development and characteristics of spin-scan imagers for interplanetary exploration are discussed. The spin-scan imaging photopolarimeter instruments of Pioneer 10 and 11 are described. In addition to the imaging function, the instruments are also used in a faint-light mode to take sky maps in both radiance and polarization. The performance of a visible-infrared spin-scan radiometer (VISSR), which operates in both visible and infrared wavelengths, is reported.

Russell, E. E.↗

NASA NTRS1973

Pioneer imaging photopolarimeter optical system.

The imaging photopolarimeter aboard the Pioneer 10 spacecraft en route to the vicinity of Jupiter is described. This instrument is capable of moderate resolution spin-scan imaging and high precision polarimetric and photometric mapping of Jupiter in red and blue light. The field of view can be selectively changed from 0.50 mrad square to 40 mrad square to accommodate resolution and radiance combinations ranging from the zodiacal background to that of Jupiter. Optical materials were chosen to survive, with minimum degradation, the rigors of a nearly 2-year journey to Jupiter including transit through the Jovian trapped radiation belts. The optics are described in detail, and the operational system is outlined. The procedures for preflight and in-flight calibration are described, and some performance characteristics and preliminary flight results are presented.

Pellicori, S. F.↗

NASA NTRS1972

Outer planet Grand Tour missions photometry/polarimetry experiment critical components study

Work performed during this effort was limited to two primary areas of technical concern: optical design optimization, and sensor selection. An optical system concept was established, and various system components were evaluated through experimental test sequences. Photodetectors were investigated for the applicability in meeting OPGT requirements as constrained by the photometry/polarimetry team directives. The most promising (gallium arsenide PMT) was further experimentally tested to ascertain its behavior with respect to anticipated environmental conditions. Results of testing and summary of the preceding tradeoff study effort are presented.

Pellicori, S. F.↗