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Sullivan, R. J.

Publications and source records attributed to Sullivan, R. J..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

The Sedimentary History of Mars as Observed by Rovers

Mars has a sedimentary history that spans billions of years. Orbital images have allowed for the identification of vast regional sedimentary deposits that can be traced over 100s of kilometers and are 100s of meters thick including localized alluvial, deltaic, and lacustrine deposits. Detections of secondary minerals in these deposits from orbital spectroscopy suggest the aqueous history of early Mars varied as a function of space and time. Orbital observations, however, provide a simplified and incomplete picture of Mars’ sedimentary history because measurements for inferring sediment transport and deposition, such as lithology, grain size, and internal structures, and measurements for inferring sediment source and aqueous alteration, such as outcrop-scale mineralogic and geochemical composition and diagenetic features, cannot be identified from orbit. Rover observations have significantly enhanced our view of ancient and modern sedimentary environments on Mars, resulting in detailed reconstructions of paleo-environments and habitability.

Rampe, E. B.↗
NASA NTRS2016

Opportunity Microscopic Imager Results from the Western Rim of Endeavour Crater

The Athena science payload on the Mars Exploration Rovers (MER Spirit and Opportunity) includes the Microscopic Imager (MI), a fixed focus close-up camera mounted on the instrument arm. The MI acquires images at a scale of 31 micrometers/pixel over a broad spectral range (400 to 700 nm) using only natural illumination of target surfaces. Radio signals from Spirit have not been received since March 2010, so attempts to communicate with that rover ceased in mid-2011. The Opportunity MI optics were contaminated by a global dust storm in 2007. That contamination continues to reduce the contrast of MI images, and is being monitored by occasionally imaging the sky.

Herkenhoff, K. E.↗
NASA NTRS2014

Noachian Impact Breccias on the Rim of Endeavour Crater, Mars: Opportunity APXS Results

Mars Exploration Rover Opportunity has been investigating the geology of Meridiani Planum since January 2004, and is currently approx. 3830% into its primary mission. Opportunity reached the rim of 22 km diameter Endeavor crater at Spirit Point on the south end of Cape York on sol 2681 and began exploring the geology of Endeavour rim. She left Cape York on sol 3316 and arrived at the next rim remnant to the south, Solander Point, on sol 3387 to begin geological investigations at the contact and up onto Murray Ridge. The Burns fm. of Meridiani Planum lies near the top of the plains-forming unit of western Sinus Meridiani and onlaps onto the Endeavour rim rocks (hereafter rim rocks). Endeavour crater would have excavated approx. 4 km into the existing stratigraphy. Thus, the ejecta that form the rim rocks offer windows into the deeper lithologies of Sinus Meridiani. Here we discuss the polymict breccias of the Shoemaker fm. on Cape York and the breccias from Murray Ridge, with a focus on compositions determined by the Alpha Particle X-Ray Spectrometer (APXS).

Mittlefehldt, D. W.↗
NASA NTRS2013

Mars Hand Lens Imager (MAHLI) efforts and observations at the “Rocknest” Eolian sand shadow in Curiosity’s Gale Crater field site

The Mars Science Laboratory (MSL) mission is focused on assessing the past or present habitability of Mars, through interrogation of environment and environmental records at the Curiosity rover field site in Gale crater. The MSL team has two methods available to collect, process and deliver samples to onboard analytical laboratories, the Chemistry and Mineralogy instrument (CheMin) and the Sample Analysis at Mars (SAM) instrument suite. One approach obtains samples by drilling into a rock, the other uses a scoop to collect loose regolith fines.

Edgett, K. S.↗
NASA NTRS2007

Mars Exploration Rover Pancam Multispectral Imaging of Rocks, Soils, and Dust at Gusev Crater and Meridiani Planum

Multispectral imaging from the Panoramic Camera (Pancam) instruments on the Mars Exploration Rovers Spirit and Opportunity has provided important new insights about the geology and geologic history of the rover landing sites and traverse locations in Gusev crater and Meridiani Planum. Pancam observations from near-UV to near-IR wavelengths provide limited compositional and mineralogic constraints on the presence abundance, and physical properties of ferric- and ferrous-iron bearing minerals in rocks, soils, and dust at both sites. High resolution and stereo morphologic observations have also helped to infer some aspects of the composition of these materials at both sites. Perhaps most importantly, Pancam observations were often efficiently and effectively used to discover and select the relatively small number of places where in situ measurements were performed by the rover instruments, thus supporting and enabling the much more quantitative mineralogic discoveries made using elemental chemistry and mineralogy data. This chapter summarizes the major compositionally- and mineralogically-relevant results at Gusev and Meridiani derived from Pancam observations. Classes of materials encountered in Gusev crater include outcrop rocks, float rocks, cobbles, clasts, soils, dust, rock grindings, rock coatings, windblown drift deposits, and exhumed whitish/yellowish salty soils. Materials studied in Meridiani Planum include sedimentary outcrop rocks, rock rinds, fracture fills, hematite spherules, cobbles, rock fragments, meteorites, soils, and windblown drift deposits. This chapter also previews the results of a number of coordinated observations between Pancam and other rover-based and Mars-orbital instruments that were designed to provide complementary new information and constraints on the mineralogy and physical properties of martian surface materials.

Bell, J. F., III↗
NASA NTRS2005

The Mars Hand Lens Imager (MAHLI) for the 209 Mars Science Laboratory

The MArs Hand Lens Imager (MAHLI) is a small, RGB-color camera designed to examine geologic material at 12.5-75 microns/pixel resolution at the Mars Science Laboratory (MSL) landing site. MAHLI is a PI-led investigation competitively selected by NASA in December 2004 as part of the science payload for the MSL rover launching in 2009. The instrument is being fabricated by, and will be operated by, Malin Space Science Systems of San Diego, California.

Edgett, K. S.↗
NASA NTRS2005

The Mast Cameras and Mars Descent Imager (MARDI) for the 2009 Mars Science Laboratory

Based on operational experience gained during the Mars Exploration Rover (MER) mission, we proposed and were selected to conduct two related imaging experiments: (1) an investigation of the geology and short-term atmospheric vertical wind profile local to the Mars Science Laboratory (MSL) landing site using descent imaging, and (2) a broadly-based scientific investigation of the MSL locale employing visible and very near infra-red imaging techniques from a pair of mast-mounted, high resolution cameras. Both instruments share a common electronics design, a design also employed for the MSL Mars Hand Lens Imager (MAHLI) [1]. The primary differences between the cameras are in the nature and number of mechanisms and specific optics tailored to each camera s requirements.

Malin, M. C.↗
NASA NTRS2000

Degradation and Deformation of Scarps and Slopes on Io: New Results

Initial analysis of degradational processes on scarps and slopes on Io using just-acquired images by the Galileo SSI team. Among other results, is evidence for sublimation, sapping, and perhaps "glacial" flow of interstitial volatiles in relief-forming materials.

Moore, J. M.↗
NASA NTRS1992

Characterization of Martian near-subsurface materials by determination of cohesion and angle of internal friction

Back-analysis (reconstruction) of the stability of thirty avalanche chutes was performed in the very limited areas where high resolution imaging overlapped with available 1:500 K topographic map coverage. A new technique was developed to incorporate the third dimension (width) of an avalanche chute in stability back-analysis in order to yield unambiguous values of cohesion and angle of internal friction. The procedure is based upon extending the ordinary method of slices to three dimensions, in order to construct avalanche chute cross-sections whose widths and depths vary as a function of gradient, gravity, density of material, and phi and c. Applying the technique to the well documented slide at Lodalen, Norway as a test produces excellent correspondence with reality. Generally, the technique reveals that the width:depth ratio of any avalanche chute decreases with increasing contrast between the average slope angle and the angle of internal friction. Applying this technique to the martian avalanche chute yields results consistent with indications from earlier work, but with greater certainty. Values of cohesion and angle of internal friction identify the materials at the time of failure as moderately cohesive debris. If Sharp's identification of these features as avalanche chutes is correct, then the results here imply that weathering processes have had a significant effect to depths of tens of meters (where failure has occured) below the martian surface. It is also implied that on relatively steep slopes within Valles Marineris, sizable, unaltered, unmantled bedrock exposures for high resolution spectral and spatial scanning by Mars Observer may be scarce.

Sullivan, R. J.↗
NASA NTRS1984

Considerations of and improvements to large-scale vegetation monitoring

The NOAA-7 polar orbiting sun-synchronous operational satellite carries the 5-channel advanced very high-resolution radiometer which acquires data globally at a spatial resolution of 4 km on a daily basis. These data provide a means for frequently monitoring global vegetation at continental scales. Techniques for compositing and cloud screening a green leaf density vegetation index product for Africa are presented for 9 sequential days beginning August 16, 1982 and are compared with a semi-operational vegetation index product produced by NOAA.

Gatlin, J. A.↗
NASA NTRS1983

Monitoring global vegetation using NOAA-7 AVHRR data

The NOAA-7 polar orbiting, sun-synchronous, operational satellite carries the 5 channel Advanced Very High Resolution Radiometer (AVHRR). Data are acquired globally at a resolution of 4 km on a daily basis. This data provides the means of frequently monitoring global vegetation on continental scales. Techniques for compositing and cloud screening a vegetation index for Africa are presented. The sample data set covers 9 days beginning August 16, 1983 and is compared with a semi-operational vegetation index product produced by NOAA.

Gatlin, J. A.↗
NASA NTRS1978

Noise spectra for monolithic detector arrays

Following a brief review of nonstationary processes, the paper deals with mixed stationary processes as they apply to the determination of the power density spectrum for monolithic detector arrays. A rather direct method is developed for realizing the noise power spectrum by transforming the corresponding autocorrelation function. Although the measurements presented pertain to a 96-element photodiode linear array, the method outlined should be applicable to any monolithic device. Theoretical and experimental results are provided.

Finkel, M. W.↗
NASA NTRS1973

Saturn orbiter mission study

A preliminary analysis of the important aspects of missions orbiting the planet Saturn is provided. Orbital missions to Saturn is given serious consideration for the 1980's, or after flybys by Pioneer 10/G and Mariner Jupiter-Saturn 1977. An attempt is made to characterize Saturn orbiters in detail so that comparisons with Jupiter missions can be made. The scientific objectives of Saturn exploration are grouped under four topics: (1) the atmosphere, (2) the magnetosphere, (3) the rings, and (4) the satellites.

Wells, W. C.↗
NASA NTRS1972

A performance application study of a jet-flap helicopter rotor

A performance study was made of the application of a jet-flap to a reaction-drive rotor for a heavy-lift helicopter mission and for a high-speed-helicopter maneuverability (200 knots, 2g) mission. The results of the study are as follows: As a result of the increase in maximum airfoil lift coefficient achieved by the jet-flap, rotor solidity is reduced with the jet-flap to approximately 59% of a nonjet-flap rotor. As a result of the saving in rotor solidity, and hence in rotor weight, the jet-flap configuration had a 21% higher productivity than a nonjet-flap configuration. Of the three propulsion systems studied utilizing a jet-flap (hot cycle, warm cycle, cold cycle) the hot cycle gave the largest increase in productivity. The 200 knot 2g mission is performed best with a warm cycle propulsion system. The jet-flap permits designing for a rotor blade loading coefficient C sub T/sigma = .170 at 2g without encountering blade stall. The jet-flap rotor permits a 200 knot 2g maneuver without suffering the penalty of an unreasonable rotor solidity that would be required by a nonjet-flap rotor.

Sullivan, R. J.↗
NASA NTRS1972

First generation atmospheric probes (10-BARS) for Uranus and Neptune

The feasibility of atmospheric entry probe missions to Uranus and Neptune is studied, and preliminary estimates of missions parameters are presented. Most of the study results are applicable, with only minor modifications, to Uranus-Neptune entry probes included on any type of outer planet mission. Trajectory dynamics is discussed first because it imposes some important constraints upon the total time available for data transmission, which in turn determines the descent rate. This last quantity provides important information for the design of the scientific payload.

Sullivan, R. J.↗