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At least 847 records · Page 47

Complex Role of Secondary Electron Emissions in Dust Grain Charging in Space Environments: Measurements on Apollo 11 and 17 Dust Grains

Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions. Knowledge of the dust grain charges and equilibrium potentials is important for understanding of a variety of physical and dynamical processes in the interstellar medium (ISM), and heliospheric, interplanetary, planetary, and lunar environments. The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. It has been well recognized that the charging properties of individual micron/submicron size dust grains are expected to be substantially different from the corresponding values for bulk materials and theoretical models. In this paper we present experimental results on charging of individual dust grains selected from Apollo 11 and Apollo 17 dust samples by exposing them to mono-energetic electron beams in the 10- 400 eV energy range. The charging rates of positively and negatively charged particles of approximately 0.2 to 13 microns diameters are discussed in terms of the secondary electron emission (SEE) process, which is found to be a complex charging process at electron energies as low as 10-25 eV, with strong particle size dependence. The measurements indicate substantial differences between dust charging properties of individual small size dust grains and of bulk materials.

Abbas, M. M.↗

Assessment of Scheduling and Plan Execution of Apollo 14 Lunar Surface Operations

Although over forty years have passed since first landing on the Moon, there is not yet a comprehensive, quantitative assessment of Apollo extravehicular activities (EVAs). Quantitatively evaluating lunar EVAs will provide a better understanding of the challenges involved with surface operations. This first evaluation of a surface EVA centers on comparing the planned and the as-ran timeline, specifically collecting data on discrepancies between durations that were estimated versus executed. Differences were summarized by task categories in order to gain insight as to the type of surface operation activities that were most challenging. One Apollo 14 EVA was assessed utilizing the described methodology. Selected metrics and task categorizations were effective, and limitations to this process were identified.

Marquez, Jessica J.↗

Was Project Management Life Really Better in Apollo?

This slide presentation discusses the question of "Was Project Management Life Really Better in Apollo?" Was money really flowing freely all through Apollo? Are we wallowing in nostalgia and comparing current circumstances to a managerial time which did not exist? This talk discusses these and other questions as background for you as today s project managers. There are slides showing the timelines from before the speech that Kennedy gave promising to land a man on the moon, to the early 60's, when the manned space center prepared the preliminary lunar landing mission design, an NASA organization chart from 1970, various photos of the rockets, and the astronauts are presented. The next slides discuss the budgets from the 1960's to the early 1970's. Also the results of a survey of 62 managers, who were asked "What problems pose the greatest obstacles to successful project performance?"

Source record↗

Analysis of Microgravity Experiments Conducted on the Apollo Spacecraft

This Technical Memorandum (TM) discusses the microgravity experiments carried out during the later missions of the Apollo program. Microgravity experiments took place during the Apollo 14, 16, and 17 missions and consisted of four experiments in various materials processing concentrations with two of the four experiments taking place over the course of two missions. Experiments consist of composite casting, electrophoresis, heat flow and convection, and liquid transfer. This TM discusses the background, the workup, execution, and results of each experiment. In addition, the historical significance of each experiment to future applications/NASA programs is discussed.

Sharpe, R. J.↗

Restoration and PDS Archive of Apollo Lunar Rock Sample Data

In 2008, scientists at the Johnson Space Center (JSC) Lunar Sample Laboratory and Image Science & Analysis Laboratory (under the auspices of the Astromaterials Research and Exploration Science Directorate or ARES) began work on a 4-year project to digitize the original film negatives of Apollo Lunar Rock Sample photographs. These rock samples together with lunar regolith and core samples were collected as part of the lander missions for Apollos 11, 12, 14, 15, 16 and 17. The original film negatives are stored at JSC under cryogenic conditions. This effort is data restoration in the truest sense. The images represent the only record available to scientists which allows them to view the rock samples when making a sample request. As the negatives are being scanned, they are also being formatted and documented for permanent archive in the NASA Planetary Data System (PDS) archive. The ARES group is working collaboratively with the Imaging Node of the PDS on the archiving.

Garcia, P. A.↗

In-Situ XRF Measurements in Lunar Surface Exploration Using Apollo Samples as a Standard

Samples collected during the Apollo lunar surface missions were sampled and returned to Earth by astronauts with varying degrees of geological experience. The technology used in these EVAs, or extravehicular activities, included nothing more advanced than traditional terrestrial field instruments: rock hammer, scoop, claw tool, and sample bags. 40 years after Apollo, technology is being developed that will allow for a high-resolution geochemical map to be created in the field real-time. Handheld x-ray fluorescence (XRF) technology is one such technology. We use handheld XRF to enable a broad in-situ characterization of a geologic site of interest based on fairly rapid techniques that can be implemented by either an astronaut or a robotic explorer. The handheld XRF instrument we used for this study was the Innov-X Systems Delta XRF spectrometer.

Young, Kelsey E.↗

Inhalation Toxicity of Ground Lunar Dust Prepared from Apollo-14 Soil

Within the decade one or more space-faring nations intend to return humans to the moon for more in depth exploration of the lunar surface and subsurface than was conducted during the Apollo days. The lunar surface is blanketed with fine dust, much of it in the respirable size range (<10 micron). Eventually, there is likely to be a habitable base and rovers available to reach distant targets for sample acquisition. Despite designs that could minimize the entry of dust into habitats and rovers, it is reasonable to expect lunar dust to pollute both as operations progress. Apollo astronauts were exposed briefly to dust at nuisance levels, but stays of up to 6 months on the lunar surface are envisioned. Will repeated episodic exposures to lunar dust present a health hazard to those engaged in lunar exploration? Using rats exposed to lunar dust by nose-only inhalation, we set out to investigate that question.

James, John T.↗

Apollo Video Photogrammetry Estimation of Plume Impingement Effects

Each of the six Apollo mission landers touched down at unique sites on the lunar surface. Aside from the Apollo 12 landing site located 180 meters from the Surveyor III lander, plume impingement effects on ground hardware during the landings were largely not an issue. The Constellation Project's planned return to the moon requires numerous landings at the same site. Since the top few centimeters are loosely packed regolith, plume impingement from the lander ejects the granular material at high velocities. With high vacuum conditions on the moon (10 (exp -14) to 10 (epx -12) torr), motion of all particles is completely ballistic. Estimates from damage to the Surveyor III show that the ejected regolith particles to be anywhere 400 m/s to 2500 m/s. It is imperative to understand the physics of plume impingement to safely design landing sites for the Constellation Program.

Immer, Christopher↗

Magnesium and Silicon Isotopes in HASP Glasses from Apollo 16 Lunar Soil 61241

The high-Al (>28 wt %), silica-poor (<45 wt %) (HASP) feldspathic glasses of Apollo 16 are widely regarded as the evaporative residues of impacts in the lunar regolith [1-3]. By virtue of their small size, apparent homogeneity, and high inferred formation temperatures, the HASP glasses appear to be good samples in which to study fractionation processes that may accompany open system evaporation. Calculations suggest that HASP glasses with present-day Al2O3 concentrations of up to 40 wt% may have lost 19 wt% of their original masses, calculated as the oxides of iron and silicon, via evaporation [4]. We report Mg and Si isotope abundances in 10 HASP glasses and 2 impact-glass spherules from a 64-105 m grain-size fraction taken from Apollo 16 soil sample 61241.

Herzog, G. F.↗

Apollo Lunar Sample Photograph Digitization Project Update

This is an update of the progress of a 4-year data restoration project effort funded by the LASER program to digitize photographs of the Apollo lunar rock samples and create high resolution digital images and undertaken by the Astromaterials Acquisition and Curation Office at JSC [1]. The project is currently in its last year of funding. We also provide an update on the derived products that make use of the digitized photos including the Lunar Sample Catalog and Photo Database[2], Apollo Sample data files for GoogleMoon[3].

Todd, N. S.↗

Convective Heating Predictions of Apollo IV Flight Data

It has been more than 50 years since NASA engineers have attempted to design a manned space vehicle with the capability to return from beyond low Earth orbit. In this interval, our methodologies for designing the thermal protection system (TPS) to protect humans from the extremely high temperatures of re-entry have changed significantly. With these considerations in mind, we return to the Apollo IV (AS-501) flight data. This incredible data set allows us to assess the current tools and methodologies being used to design Orion MPCV. In particular, our ability to predict the aftbody separated region convective heating environments for MPCV is critical. The design uses reusable TPS in this area, whereas Apollo designers used ablative TPS which can withstand much more severe environments. This presentation will revisit the flight data, summarize the assumptions going into the analysis, present the results and draw conclusions regarding how accurately we can currently predict the heating in the aftbody separated region of a re-entry capsule.

White, Molly E.↗

13 Things That Saved Apollo 13

Perhaps, the most exciting rescue, terrestrial or extra-terrestrial, is the successful return of the Apollo 13 crew to Earth in April of 1970. The mission s warning system engineer, Jerry Woodfill, who remains a NASA employee after 47 years of government service has examined facets of the rescue for the past 42 years. He will present "13 Things That Saved Apollo 13" from the perspective of his real time experience as well as two score years of study. Many are recent discoveries never before published in mission reports, popular books or documentary and Hollywood movies depicting the rescue.

Woodfill, Jared↗

ArcGIS Digitization of Apollo Surface Traverses

The Apollo surface activities were documented in extraordinary detail, with every action performed by the astronauts while on the surface recorded either in photo, audio, film, or by written testimony [1]. The samples and in situ measurements the astronauts collected while on the lunar surface have shaped our understanding of the geologic history of the Moon, and the earliest history and evolution of the inner Solar System. As part of an ongoing LASERfunded effort, we are digitizing and georeferencing data from astronaut traverses and spatially associating them to available, co-registered remote sensing data. Here we introduce the products produced so far for Apollo 15, 16, and 17 missions.

Petro, N. E.↗

Thermal Analyses of Apollo Lunar Soils Provide Evidence for Water in Permanently Shadowed Areas

Thermally-evolved-gas analyses were performed on the Apollo lunar soils shortly after their return to Earth [1-8]. The analyses revealed the presence of water evolving at temperatures above 200 C. Of particular interest are samples that were collected from permanently-shadowed locations (e.g., under a boulder) with a second sample collected in nearby sunlight, and pairs in which one was taken from the top of a trench, and the second was taken at the base of the trench, where the temperature would have been -10 to -20 C prior to the disturbance [9]. These samples include 63340/63500, 69941/69961, and 76240/76280. At the time that this research was first reported, the idea of hydrated minerals on the lunar surface was somewhat novel. Nevertheless, goethite was observed in lunar breccias from Apollo 14 [10], and it was shown that goethite, hematite and magnetite could originate in an equilibrium assemblage of lunar rocks

Cooper, Bonnie L.↗

Indigenous Carbonaceous Phases Embedded Within Surface Deposits on Apollo 17 Volcanic Glass Beads

The assessment of indigenous organic matter in returned lunar samples was one of the primary scientific goals of the Apollo program. Prior studies of Apollo samples have shown the total amount of organic matter to be in the range of approx 50 to 250 ppm. Low concentrations of lunar organics may be a consequence not only of its paucity but also its heterogeneous distribution. Several processes should have contributed to the lunar organic inventory including exogenous carbonaceous accretion from meteoroids and interplanetary dust particles, and endogenous synthesis driven by early planetary volcanism and cosmic and solar radiation.

Thomas-Keprta, K. L.↗

Base Flow Investigation of the Apollo AS-202 Command Module

In recent years, both Europe and the US are developing hypersonic research and operational vehicles. These include (re)entry capsules (both ballistic and lifting) and lifting bodies such as ExoMars, EXPERT, ARV, CEV and IXV. The research programs are meant to enable technology and engineering capabilities to support during the next decade the development of affordable (possibly reusable) space transportation systems as well as hypersonic weapons systems for time critical targets. These programs have a broad range of goals, ranging from the qualification of thermal protection systems, the assessment of RCS performances, the development of GNC algorithms, to the full demonstration of the performance and operability of the integrated vehicles. Since the aerothermodynamic characteristics influence nearly all elements of the vehicle design, the accurate prediction of the aerothermal environment is a prerequisite for the design of efficient hypersonic systems. Significant uncertainties in the prediction of the hypersonic aerodynamic and the aerothermal loads can lead to conservative margins in the design of the vehicle including its Outer Mould Line (OML), thermal protection system, structure, and required control system robustness. The current level of aerothermal prediction uncertainties results therefore in reduced vehicle performances (e.g., sub-optimal payload to mass ratio, increased operational constraints). On the other hand, present computational capabilities enable the simulation of three dimensional flow fields with complex thermo-chemical models over complete trajectories and ease the validation of these tools by, e.g., reconstruction of detailed wind tunnel tests performed under identified and controlled conditions (flow properties and vehicle attitude in particular). These controlled conditions are typically difficult to achieve when performing in flight measurements which in turn results in large associated measurement uncertainties. Similar problems arise when attempting to rebuild measurements performed in "hot" ground facilities, where the difficulty level is increased by the addition of the free-flow characterization itself. The implementation of ever more sophisticated thermochemical models is no obvious cure to the aforementioned problems since their effect is often overwhelmed by the large measurement uncertainties incurred in both flight and ground high enthalpy facilities. Concurrent to the previous considerations, a major contributor to the overall vehicle mass of re-entry vehicles is the afterbody thermal protection system. This is due to the large acreage (equal or bigger than that of the forebody) to be protected. The present predictive capabilities for base flows are comparatively lower than those for windward flowfields and offer therefore a substantial potential for improving the design of future re-entry vehicles. To that end, it is essential to address the accuracy of high fidelity CFD tools exercised in the US and EU, which motivates a thorough investigation of the present status of hypersonic flight afterbody heating. This paper addresses the predictive capabilities of after body flow fields of re-entry vehicles investigated in the frame of the NATO/RTO - RTG-043 Task Group and is structured as follows: First, the verification of base flow topologies on the basis of available wind-tunnel results performed under controlled supersonic conditions (i.e., cold flows devoid of reactive effects) is performed. Such tests address the detailed characterization of the base flow with particular emphasis on separation/reattachment and their relation to Mach number effects. The tests have been performed on an Apollo-like re-entry capsule configuration. Second, the tools validated in the frame of the previous effort are exercised and appraised against flight-test data collected during the Apollo AS-202 re-entry.

Walpot, Louis M. G.↗

Testing the Origins of Basalt Fragments fro Apollo 16

Several 2-4 mm regolith fragments of basalt from the Apollo 16 site were recently described by [1]. These included a high-Ti vitrophyric basalts (60603,10-16) and one very-low-titanium (VLT) crystalline basalt (65703,9-13). As Apollo 16 was the only highlands sample return mission distant from the maria, identification of basaltic samples at the site indicates input from remote sites via impact processes [1]. However, distinguishing between impact melt and pristine basalt can be notoriously difficult and requires significant sample material [2-6]. The crystal stratigraphy method utilizes essentially non-destructive methods to make these distinctions [7,8]. Crystal stratigraphy combines quantitative petrography in the form of crystal size distributions (CSDs) coupled with mineral geochemistry to reveal the petrogenetic history of samples. The classic CSD plot of crystal size versus population density can reveal insights on growth/cooling rates, residence times, and magma history which in turn can be used to evaluate basaltic vs impact melt origin [7-9]. Electron microprobe (EMP) and laser ablation (LA)-ICP-MS analyses of mineral phases complement textural investigations. Trace element variations document subtle changes occurring during the formation of the samples, and are key in the interpretation and preservation of this rare lunar sample collection.

Donohue, P. H.↗

Geologic Traverse Planning for Apollo Missions

The science on Apollo missions was overseen by the Science Working Panel (SWP), but done by multiple PIs. There were two types of science, packages like the Apollo Lunar Surface Experiment Package (ALSEP) and traverse science. Traverses were designed on Earth for the astronauts to execute. These were under direction of the Lunar Surface PI, but the agreed traverse was a cooperation between the PI and SWP. The landing sites were selected by a different designated committee, not the SWP, and were based on science and safety.

Lofgren, Gary↗