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NASA NTRSDate not supplied

Green Run Modal Test of the NASA Space Launch System Core Stage

The Core Stage of the new NASA Space Launch System (SLS) is a 212-foot-tall rocket assembly—consisting primarily of two cryogenic propellant tanks, an engine section, and four RS-25 rocket engines—that will send crew and large payloads to the moon and beyond for NASA’s Artemis program. Prior to SLS assembly, the Core Stage completed a series of structural and functional tests in the B-2 Test Stand at Stennis Space Center, designated Green Run. The goal of Green Run was to verify analytical models, confirm proper subsystem operation, and test-fire all four RS-25 engines of the Core Stage. In January 2020, Green Run testing began with an experimental modal analysis test, performed by the Marshal Space Flight Center modal test team. A free-boundary test condition of the Core Stage was simulated as close as possible by suspending the massive launch vehicle from the B-2 Test Stand crane. Modal excitation was provided by a pair of 250-lb electro-dynamic shakers for multi-shaker random vibration testing, as well as a 12-pound instrumented hammer for impact testing. Modal response was measured with 550 accelerometer channels distributed on both the Core Stage and the B-2 Test Stand derrick crane. Following one very long day of testing, frequency response functions were calculated from the measured time histories in the target mode frequency range of 5 Hz to 15 Hz, and mode shapes, frequencies, and damping values were successfully estimated. The case-study presented in this paper will discuss Green Run, the SLS Core Stage, the modal test setup and execution, as well as a brief overview of the test results. Challenges associated with testing such a large, suspended structure in an outdoor environment will be discussed as well.

Space Launch System↗
NASA NTRS1975

Magnetostatic potential theory and the lunar magnetic dipole field

The lunar magnetic dipole moment is discussed. It is proposed that if a primordial core magnetic field existed, it would give rise to a present day nonzero external dipole magnetic field. This conclusion is based on the assumption that the lunar mantle is at least slightly ferromagnetic, and thus would maintain a permanent magnetization after the disappearance of the core magnetic field. Using a simple mathematical model of the moon, calculations are performed which support this hypothesis.

Goldstein, M. L.↗
NASA NTRS1979

Mercury - A post-Mariner 10 assessment

The paper reviews the analyses of the imagery since the Mariner 10 flight, and considers the implications for the surface evolution of the terrestrial planets. Mercury is probably differentiated into a large iron-rich core and a thin silicate mantle. It differs from the moon by having (1) large areas of old intercrater plains, (2) a wide-spread distribution of lobate scarps, and (3) a similar albedo between young smooth plains and the older mercurian highlands. The origin of Mercury's plains and lobate scarps is discussed, and it is concluded that the crater diameter density distribution on the moon, Mars, and Mercury indicates that all the terrestrial planets experienced intense bombardment early in their histories, and that the objects responsible for this bombardment probably belonged to the same population(s).

Storm, R. G.↗
NASA NTRS1982

The accretional heating of the terrestrial planets - A review

Accretional heating in forming planets results from the transfer of kinetic energy of objects striking the proto-planet surface. By accounting for all energy transfer for every cratering event it is theoretically possible to determine the thermal state of newly-formed planets. Various models of the thermodynamics of planetary formation are presented, ranging from the simple to the complex. Few definite conclusions can be drawn from the theoretical models, except that larger terrestrial planets were melted by their formation, cores being formed during formation. Mars may have been extensively heated, core formation in that case being contemporaneous with accretion. Mercury was unlikely to have been subject to much bombardment by planetesimals from other zones, and its core may not have its origin in accretional heat. The moon may have been completely or slightly melted, depending on the nature of the late formation of the earth and Venus.

Ransford, G. A.↗
NASA NTRS2010

Space Operations for a New Era of Exploration Launch Vehicles

NASA's Constellation Program is depending on the Ares Projects to deliver the crew and cargo launch capabilities needed to send human explorers to the Moon and beyond. Ares I and V will provide the core space launch capabilities needed to continue providing crew and cargo access to the International Space Station (ISS), and to build upon the U.S. history of human space exploration. Since 2005, Ares has made substantial progress on designing, developing, and testing the Ares I crew launch vehicle and has continued its in-depth studies of the Ares V cargo launch vehicles. The combined Ares I/Ares V architecture has been designed to reduce the complexity and labor intensity of ground operations for America's next journeys beyond low-Earth orbit (LEO). A deliberate effort is being made to ensure a high level of system operability to significantly increase safety and system availability as well as reduce recurring costs for this new launch vehicle. The Ares Projects goal is to instill operability as part of the vehicles requirements development, design, and operations. This simplicity will come from using simpler, proven engine designs, as in the case of the J-2X upper stage engine and RS-68 engine; improving existing hardware, as in the case of the Shuttle-heritage 5-segment solid rocket motor; and using common propulsion and instrument unit elements between Ares I and Ares V. Furthermore, lessons learned while developing Ares I will be applied directly to Ares V operations. In 2009, the Ares Projects plan to conduct the first flight test of Ares I, designated Ares I-X. Ares I-X preparations have already prompted changes to the vehicle stacking and launch infrastructure at Kennedy Space Center (KSC), including removing Shuttle-specific fixtures from the Vehicle Assembly Building (VAB) to accommodate Ares I-style stacking operations, new firing room computers and infrastructure in the VAB Launch Control Center, and new lightning protection system towers at Launch Complex 39B to accommodate the greater height of Ares I-X. In addition to lessons learned from the stacking of Ares I-X, the flight test itself promises to yield important data and operations lessons for assembling, launching, and flying Ares I.

Cook, Stephen A.↗
NASA NTRS2014

Identification of New Lithic Clasts in Lunar Breccia 14305 by Micro-CT and Micro-XRF Analysis

From 1969 to 1972, Apollo astronauts collected 382 kg of rocks, soils, and core samples from six locations on the surface of the Moon. The samples were initially characterized, largely by binocular examination, in a custom-built facility at Johnson Space Center (JSC), and the samples have been curated at JSC ever since. Despite over 40 years of study, demand for samples remains high (~500 subsamples per year are allocated to scientists around the world), particularly for plutonic (e.g., anorthosites, norites, etc.) and evolved (e.g., granites, KREEP basalts) lithologies. The reason for the prolonged interest is that as new scientists and new techniques examine the samples, our understanding of how the Moon, Earth, and other inner Solar System bodies formed and evolved continues to grow. Scientists continually clamor for new samples to test their emerging hypotheses. Although all of the large Apollo samples that are igneous rocks have been classified, many Apollo samples are complex polymict breccias that have previously yielded large (cm-sized) igneous clasts. In this work we present the initial efforts to use the non-destructive techniques of micro-computed tomography (micro-CT) and micro x-ray fluorescence (micro-XRF) to identify large lithic clasts in Apollo 14 polymict breccia sample 14305. The sample in this study is 14305,483, a 150 g slab of regolith breccia 14305 measuring 10x6x2 cm (Figure 1a). The sample was scanned at the University of Texas High-Resolution X-ray CT Facility on an Xradia MicroXCT scanner. Two adjacent overlapping volumes were acquired at 49.2 micrometer resolution and stitched together, resulting in 1766 slices. Each volume was acquired at 100 kV accelerating voltage and 98 mA beam current with a 1 mm CaF2 filter, with 2161 views gathered over 360deg at 3 seconds acquisition time per view. Micro-XRF analyses were done at Washington University in St. Louis, Missouri on an EDAX Orbis PC micro-XRF instrument. Multiple scans were made at 40 kV accelerating voltage, 800 mA beam current, 30 μm beam diameter, and a beam spacing of 30-120 micrometer. The micro-CT scan of 14305,483 (Figure 2) was able to identify several large lithic clasts (approx. 1 cm) within the interior of the slab. These clasts will be exposed by band-sawing or chipping of the slab, and their composition more fully characterized by subsequent micro-XRF analysis. In addition to lithic clasts, the micro-CT scans identified numerous mineral clasts, including many FeNi metal grains, as well as the prominent fractures within the slab. The micro-XRF analyses (Figure 1b,c) of the slab surfaces revealed the bulk chemical compositions (qualitative) of the different clast types observed. In particular, by looking at the ratios of major elements (e.g. Ca:Mg:Fe), differences among the many observed clast types are readily observed. Moreover, several clasts not apparent to the naked eye were revealed in the K:Al:Si ratio map. The scans are also able to identify small grains of Zr- and P-rich minerals (not shown), which could in turn yield important age dates for the samples.

Zeigler, Ryan A.↗
NASA NTRS1991

The moon

Moon research is reviewed for the 1987-1990 time period. Particular attention is given to lunar meteorites, remote sensing and photogeology, impact cratering and impact breccias, soils, cores, and regolith breccias, mare magmatism, origin of the crust, bulk composition and origin of the moon.

Warren, Paul H.↗
NASA NTRS1982

The evolution of the moon - A finite element approach

The present lunar evolution model analyzes the thermal history of a self-gravitating spherical planetary body, including the effects of viscous dissipation, internal melting, adiabatic gradient, core formation, variable viscosity, radioactive nucleide decay, and a depth-dependent initial temperature profile, together with physical parameters corresponding to the moon. Although no initial basalt ocean is assumed, partial melting is observed early in the model moon's history. This is suggested to be related to the formation of the basalt maria. The model's present lithospheric thickness is 600 km, with core-mantle temperatures close to 1600 K and surface heat flux of 25.3 mW/sq m. The finite element method is judged to be applicable to the problem of planetary evolution, although faster solution algorithms will be required for the examination of a sufficient number of models.

Chacko, S.↗
DOE OSTI2023

TFR-2577 MARVEL Fuel and Core System (FCS)

This document contains the Level 3 requirements associated with the three subsystems of the Fuel and Core System (FCS) in the Microreactor Applications Research Validation and Evaluation (MARVEL) project: Fuel Subsystem (FS), Core Support Structures Subsystem (CSS), Stationary Core Reflector Subsystem (SCR). These subsystems interface directly with the MARVEL Reactor Structure (MRS) to produce and transfer thermal energy generated through nuclear fission.

99 GENERAL AND MISCELLANEOUS↗
NASA NTRS1977

Mercury

Prior to the flight of the Mariner 10 spacecraft, Mercury was the least investigated and most poorly known terrestrial planet (Kuiper 1970, Devine 1972). Observational difficulties caused by its proximity to the Sun as viewed from Earth caused the planet to remain a small, vague disk exhibiting little surface contrast or details, an object for which only three major facts were known: 1. its bulk density is similar to that of Venus and Earth, much greater than that of Mars and the Moon; 2. its surface reflects electromagnetic radiation at all wavelengths in the same manner as the Moon (taking into account differences in their solar distances); and 3. its rotation period is in 2/3 resonance with its orbital period. Images obtained during the flyby by Mariner 10 on 29 March 1974 (and the two subsequent flybys on 21 September 1974 and 16 March 1975) revealed Mercury's surface in detail equivalent to that available for the Moon during the early 1960's from Earth-based telescopic views. Additionally, however, information was obtained on the planet's mass and size, atmospheric composition and density, charged-particle environment, and infrared thermal radiation from the surface, and most significantly of all, the existence of a planetary magnetic field that is probably intrinsic to Mercury was established. In the following, this new information is summarized together with results from theoretical studies and ground-based observations. In the quantum jumps of knowledge that have been characteristic of "space-age" exploration, the previously obscure body of Mercury has suddenly come into sharp focus. It is very likely a differentiated body, probably contains a large Earth-like iron-rich core, and displays a surface remarkably similar to that of the Moon, which suggests a similar evolutionary history.

Gault, D. E.↗
NASA NTRS1981

The free librations of a dissipative moon

It is noted that dissipation in the moon produces a small offset (approximately 0.23 arcsec) of the moon's rotation axis from the plane defined by the ecliptic and lunar orbit normals. Both solid body tidal friction and viscous fluid friction at a core-mantle interface are thought to be plausible mechanisms. The merits of both are discussed, and it is found that solid friction requires a low lunar tidal Q (approximately 28), whereas turbulent fluid friction requires a core with a radius of approximately 330 km to cause the signature observed by lunar laser ranging. Large (approximately 0.4-8.0 arcsec) free librations of the lunar figure have also been detected through laser ranging. Both a very recent impact on the moon and fluid turbulence in the lunar core are considered plausible mechanisms for generating these librations.

Yoder, C. F.↗
NASA NTRS2012

Gravity Recovery and Interior Laboratory (GRAIL) Mission: Mission Status and Initial Science Results

The Gravity Recovery and Interior Laboratory (GRAIL) Mission is a component of the NASA Discovery Program. GRAIL is a twin-spacecraft lunar gravity mission that has two primary objectives: to determine the structure of the lunar interior, from crust to core; and to advance understanding of the thermal evolution of the Moon. GRAIL launched successfully from the Cape Canaveral Air Force Station on September 10, 2011, executed a low-energy trajectory to the Moon, and inserted the twin spacecraft into lunar orbit on December 31, 2011 and January 1, 2012. A series of maneuvers brought both spacecraft into low-altitude (55-km), near-circular, polar lunar orbits, from which they perform high-precision satellite-to-satellite ranging using a Ka-band payload along with an S-band link for time synchronization. Precise measurements of distance changes between the spacecraft are used to map the lunar gravity field. GRAIL completed its primary mapping mission on May 29, 2012, collecting and transmitting to Earth >99.99% of the possible data. Spacecraft and instrument performance were nominal and has led to the production of a high-resolution and high-accuracy global gravity field, improved over all previous models by two orders of magnitude on the nearside and nearly three orders of magnitude over the farside. The field is being used to understand the thickness, density and porosity of the lunar crust, the mechanics of formation and compensation states of lunar impact basins, and the structure of the mantle and core. GRAIL s three month-long-extended mission will initiate on August 30, 2012 and will consist of global gravity field mapping from an average altitude of 22 km.

Neumann, Gregory A.↗
NASA NTRS1984

On the Apollo subsatellite evidence for a lunar core

Two independent techniques used to infer the electrical conductivity of the interior of the Moon are discussed. The first is the measurement of an incident spectrum of electromagnetic waves in the solar wind near the Moon and the separate measurement of the incident plus reflected spectrum on the surface of the Moon. The second is the measurement of the distortion of the ambient magnetic field of the geomagnetic tail lobes by the conducting Moon. The size of the conducting region was found to be greater than 400 km in radius.

Russell, C. T.↗
NASA NTRS1993

Expectations for the Martian core magnetic field

In the traditional view of planetary magnetism, a planet either has a core dynamo (Earth, Jupiter, Saturn, Uranus, Neptune, maybe Mercury) or does not (Mars, Venus, Moon...) I argue that this view is simplistic in two respects. First, mantle convection in terrestrial planets is invariably ata high enough Rayleigh number that it is time variable; this leads to the intermittent arrival of mantle 'cold fingers' at the core-mantle boundary promoting at least local core convection and dynamo action even when the planetary core is stably stratified on average. Thus, I predict an intermittent dynamo regime in addition to the simple dynamo-on (Earth) and dynamo-off regimes. Second, the mantle convection-driven horizontal temperature gradients just below the core-mantle boundary can lead to unstable flows that will convert thermoelectric or electrochemical toroidal fields into externally detectable poloidal fields, even when a dynamo is not possible. It is likely that Mars possesses an interesting core magnetic field of the latter kind, complex but with a dipole that might be approximately aligned with the rotation axis and a surface field of a few to tens of gammas.

Stevenson, D. J.↗
NASA NTRS1983

Experimental investigation of the partitioning of phosphorus between metal and silicate phases - Implications for the earth, moon and eucrite parent body

An experimental study is reported of the partitioning of Phosphorus between solid metal and basaltic silicate liquid as a function of temperature and oxygen fugacity and of the implications for the earth, moon and eucrite parent body (EPB). The relationship established between the partition coefficient and the fugacity is given at 1190 C by log D(P) = -1.12 log fO2 - 15.95 and by log D(P) = -1.53 log fO2 17.73 at 1300 C. The partition coefficient D(P) was determined, and it is found to be consistent with a valence state of 5 for P in the molten silicate. Using the determined coefficient the low P/La ratios of the earth, moon, and eucrites relative to C1 chondrites can be explained. The lowering of the P/La ratio in the eucrites relative to Cl chondrite by a factor of 40 can be explained by partitioning P into 20-25 wt% sulfur-bearing metallic liquid corresponding to 5-25% of the total metal plus silicate system. The low P/La and W/La ratios in the moon may be explained by the partitioning of P and W into metal during formation of a small core by separation of liquid metal from silicate at low degrees of partial melting of the silicates. These observations are consistent with independent formation of the moon and the earth.

Newsom, H. E.↗
NASA NTRS1997

Planetary Geophysics and Tectonics

Research supported by grant NAGW-1928 has addressed a variety of problems related to planetary evolution. One important focus has been on questions related to the role of chemical buoyancy in planetary evolution with application to both Venus and the Moon. We have developed a model for the evolution of the Moon (Hess and Parmentier, 1995) in which dense, highly radioactive, late stage magma ocean cumulates sink forming a core. This core heats the overlying, chemically layered mantle giving rise to a heated, chemically well-mixed layer that thickens with time. This Mixed layer eventually becomes hot enough and thick enough that its top begins to melt at a pressure low enough that melt is buoyant, thus creating mare basalts from a high pressure source of the correct composition and at an appropriate time in lunar evolution. In work completed during the last year, numerical experiments on convection in a chemically stably stratified fluid layer heated from below have been completed. These results show us how to calculate the evolution of a mixed layer in the Moon, depending on the heat production in the ilmenite- cumulate core and the chemical stratification of the overlying mantle. Chemical stratification of the mantle after its initial differentiation is would trap heat in the deep interior and prevent the rapid rise of plumes with accompanying volcanism. This trapping of heat in the interior can explain the thickness of the lunar lithosphere as a function of time as well as the magmatic evolution. We show that heat transported to the base of the lithosphere at a rate determined by current estimates of radioactivity in the Moon would not satisfy constraints on elastic lithosphere thickness from tectonic feature associated with basin loading. Trapping heat at depth by a chemically stratified mantle may also explain the absence of global compressional features on the surface that previous models predict for an initially hot lunar interior. For Venus, we developed a model in which the chemical buoyancy of crust and a depleted mantle layer stabilizes the lithosphere for long periods of time and provides a mechanism of episodic planetary evolution (Parmentier and Hess, 1992). Continued thickening of a residual depleted mantle layer eventually suppresses pressure release melting and the creation of depleted mantle. Continued cooling then allows the lithosphere to become heavier than the underlying hotter, undepleted mantle. This repeated instability can occur on time scales appropriate for episodic global resurfacing on Venus. We have also examined the role of the gabbro-eclogite phase transformation on crust and lithosphere stability and as a mechanism of crustal recycling in the absence of plate tectonics. Our work thus far concentrates on the scale of instability that would occur due to cooling or crustal thickening associated with horizontal shortening. Whether repeated overturn can explain the evolution of Venus depends in part on whether sufficient heat transfer can occur between overturns and on constraints provided by understanding observed surface features and evolution.

Parmentier, E. M.↗
NASA NTRS2018

A Technology Architecture for Accessing the Oceans of Icy Worlds

The icy moon oceans beckon with ingredients that potentially may harbour extant life. Beginning with the Galileo and Cassini missions, measurements have revealed the presence of global oceans under the icy crust of several moons of Jupiter and Saturn. Among those moons, Europa and Enceladus have their ocean in contact with the rocky core, providing an environment similar to the conditions existing on the terrestrial sea-floor where life has developed at hydrothermal vents Accessing these oceans presents considerable difficulty due to a number of issues including the depth and composition of the icy crust, the time needed to travel through the crust, the power needed to propel a probe, communication of scientific and engineering data though the ice and back to Earth, entry and mobility in the ocean and autonomous operations for the life of the mission. A detailed trade space study was conducted to develop a technology architecture defining a system that would access an icy moon’s ocean. To specifically bound the architecture, Jupiter’s moon Europa was chosen as the target body though the work can apply to other bodies. The current understanding of the scientific properties of the ice crust and ocean was used to guide the development. A strawman scientific payload was devised to further develop a baseline set of requirements. Beginning with a launch and trajectory that can bring a system to Europa’s orbit, a complete trade space was developed outlining the engineering systems needed to access the ocean. The architecture was divided into specific phases for i) deorbit, descent and landing, ii) surface operations, iii) ice descent and iv) ocean access. The technical maturity of each of sub-system for the phases was assessed for systems that could be developed to a maturity ready for a preliminary design in less than ten years. Integrated system parameters on power, communication capacity, and mass were developed to further define the overall system. To constrain the design, a total time in the ice, from the ice crust surface to accessing the ocean was limited to three years, and 15Km of ice was baselined with a temperature profile through the ice estimated from the scientific literature.

Sengupta, Anita↗
NASA NTRSDate not supplied

From Apollo to Artemis: Opening and Processing Lunar Core 73002 for the ANGSA Program

The Apollo mission returned 382 kg of lunar material comprising rock, soil and core samples. Some of these samples were intentionally set aside after their return from the Moon for future study, including samples sealed on the lunar surface, frozen samples and samples stored under Helium. The Apollo Next Generation Sample Analysis (ANGSA) program was established to study thesesamples, in part to help bridge the gap between Apollo and the next generation of lunar science and exploration.Apollo 17 double drive tube core sample 73001/73002 was collected about 50 meters east of Lara Crater from a landslide deposit originating from South Massif. After separating the two halves, the lower drive tube 73001 was immediately sealed in a special vacuum container. Both drive tubes were then placed in an Apollo Lunar Sample Return Container (ALSRC) and returned to Earth under vacuum. Total sample weight and length of 73001/73002 is 1263.0 g and up to 60 cm, with the upper drive 73002 containing 429.7 g and 23 cm of material ( which was then compressed to 18.5 cm during extrusion in the lab). We will present the meticulous methods involved in preparing for, opening and processing lunar core 73002, the upper half of the double drive tube. This includes searching and locating procedures and tools, practicing assembly and extrusion in a mock-up, and finally opening and dissecting the core sample 73002. Challenges (both expected and unexpected) encountered along the way and lessons learned during this project will help pave the way towards improving future lunar sample return missions and advancing insight into the Moon’s history

C. H. Krysher↗