Apollo Lunar Surface Experiments Research Articles

Tides and Volcanoes: A Historical Perspective

In this paper, we examine the origins and the history of the hypothesis for an influence of tidal forces on volcanic activity. We believe that exploring this subject through a historical perspective may help geoscientists gain new insights in a field of research so closely connected with the contemporary scientific debate and often erroneously considered as a totally separated niche topic. The idea of an influence of the Moon and Sun on magmatic processes dates back to the Hellenistic world. However, it was only since the late 19thcentury, with the establishment of volcano observatories at Mt. Etna and Vesuvius allowing a systematic collection of observations with modern methods, that the “tidal controversy” opened one of the longest and most important debates in Earth Science. At the beginning of the 20thcentury, the controversy assumed a much more general significance, as the debate around the tidal influence on volcanism developed around the formulation of the first modern theories on the origins of volcanism, the structure of the Earth’s interior and the mechanisms for continental drift. During the same period, the first experimental evidence for the existence of the Earth tides by Hecker (Beobachtungen an Horizontalpendeln über die Deformation des Erdkörpers unter dem Einfluss von Sonne und MondVeröffentlichung des Königl, 1907, 32), and the Chamberlin–Moulton planetesimal hypothesis (proposed in 1905 by geologist Thomas Chrowder Chamberlin and astronomer Forest Ray Moulton) about the “tidal” origin of the Solar System, influenced and stimulated new researches on volcano-tides interactions, such as the first description of the “lava tide” at the Kilauea volcano by Thomas Augustus Jaggar in 1924. Surprisingly, this phase of gradual acceptance of the tidal hypothesis was followed by a period of lapse between 1930 to late 1960. A new era of stimulating and interesting speculations opened at the beginning of the seventies of the 20thcentury thanks to the discovery of the moonquakes revealed by the Apollo Lunar Surface Experiment Package. A few years later, in 1979, the intense volcanism on the Jupiter’s moon Io, discovered by the Voyager 1 mission, was explained by the tidal heating produced by the Io’s orbital eccentricity. In the last part of the paper, we discuss the major advances over the last decades and the new frontiers of this research topic, which traditionally bears on interdisciplinary contributions (e.g., from geosciences, physics, astronomy). We conclude that the present-day debate around the environmental crisis, characterized by a large collection of interconnected variables, stimulated a new field of research around the complex mechanisms of mutual interactions among orbital factors, Milankovitch Cycles, climate changes and volcanism.

Cartography of the Apollo 12 landing site from photogrammetric analysis of surface imagery

This work represents an Apollo 12 landing site photogrammetric study based on the lunar surface imagery. A set of 303 photographs taken by the crew was used to build up a 3D scene of the landing site. The mapped area includes the Lunar Module (LM) vicinity, Apollo Lunar Surface Experiments Package (ALSEP) deployment site, Surveyor 3 landing site, and Surveyor Crater. The camera station map was composed, locations of artifacts on the lunar surface were accurately determined. Orientations of the LM and Surveyor 3 were found to an accuracy of about 0.5–1°. The depth of Surveyor Crater was determined to an accuracy better than 1 ​m. The map and coordinates are in a good agreement with image data and Digital Terrain Models (DTMs) from Lunar Reconnaissance Orbiter (LRO).

Availability of previously lost data and metadata from the Apollo Lunar Surface Experiments Package (ALSEP)

Fourteen types of geophysical instruments deployed at the Apollo 12, 14, 15, 16, and 17 sites by the astronauts for long-term observation were collectively called the Apollo Lunar Surface Experiments Package (ALSEP). These instruments were active from the times of their deployment (November 1969–December 1972) to September 1977. At the conclusion of the experiments, the raw instrument data received from the Moon prior to March 1976 were left unarchived. Portions of the data processed by the principal investigators (PIs) of these experiments had been archived at the NASA Space Science Data Coordinated Archive (NSSDCA) in various formats. The unarchived data, residing then on open-reel magnetic tapes, became lost in the decades since, along with much of the metadata (the supporting documents for these data). We have recently recovered 440 of the previously lost tapes, containing raw ALSEP instrument data from April through June of 1975. Here we describe the data extracted from these tapes and summarize the data products generated for archiving at the NASA Planetary Data System (PDS) and NSSDCA, along with their historical narrative. In addition, we have reformatted many of the datasets delivered to NSSDCA by the PIs in the 1970s for archiving at the PDS. Finally, we have compiled an online searchable repository of ALSEP-related documents by optically scanning tens of thousands of pages of them kept at the Lunar and Planetary Institute in Texas.

Recent Progress in Lunar Laser Ranging at Grasse Laser Ranging Station

AbstractBased on a fully passive space segment, the lunar laser ranging experiment is the last of the Apollo Lunar Surface Experiments Package to operate. Observations from the Grasse lunar laser ranging station have been made on a daily basis since the first echoes obtained in 1981. In this paper, first, we review the principle and the technical aspects of lunar laser ranging. We then give a brief summary of the progress made at the Grasse laser ranging facility (Observatoire de la Côte d'Azur, Calern Plateau on the French Riviera) since the first echoes. The current performance, driven by the use of an infrared wavelength laser, is presented in the last section for the year 2018.

Coordinates and Maps of the Apollo 17 Landing Site

AbstractWe carried out an extensive cartographic analysis of the Apollo 17 landing site and determined and mapped positions of the astronauts, their equipment, and lunar landmarks with accuracies of better than ±1 m in most cases. To determine coordinates in a lunar body‐fixed coordinate frame, we applied least squares (2‐D) network adjustments to angular measurements made in astronaut imagery (Hasselblad frames). The measured angular networks were accurately tied to lunar landmarks provided by a 0.5 m/pixel, controlled Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) orthomosaic of the entire Taurus‐Littrow Valley. Furthermore, by applying triangulation on measurements made in Hasselblad frames providing stereo views, we were able to relate individual instruments of the Apollo Lunar Surface Experiment Package (ALSEP) to specific features captured in LROC imagery and, also, to determine coordinates of astronaut equipment or other surface features not captured in the orbital images, for example, the deployed geophones and Explosive Packages (EPs) of the Lunar Seismic Profiling Experiment (LSPE) or the Lunar Roving Vehicle (LRV) at major sampling stops. Our results were integrated into a new LROC NAC‐based Apollo 17 Traverse Map and also used to generate a series of large‐scale maps of all nine traverse stations and of the ALSEP area. In addition, we provide crater measurements, profiles of the navigated traverse paths, and improved ranges of the sources and receivers of the active seismic experiment LSPE.

REVISED COORDINATES FOR APOLLO HARDWARE

Abstract. The Narrow Angle Camera (NAC) on the Lunar Reconnaissance Orbiter provides direct imaging, at pixel scales of 0.5 to 1.0 meter, of anthropogenic equipment left on the Moon. We identified the descent stages of the lunar modules, central stations of the Apollo Lunar Surface Experiments Package, Laser Ranging Retroreflectors (LRRRs), and Lunar Roving Vehicles in each NAC image of the Apollo landing sites. The pixel coordinates of those objects were then converted to latitude and longitude coordinates using SPICE routines in the U.S. Geological Survey Integrated System for Imagers and Spectrometers. For images that contained an LRRR, pointing information was updated to match the well known LRRR coordinates. Final coordinates for each object are reported as averages from multiple images. NAC observations allow refinement of the locations of these objects and result in a more accurate geodetic referencing at these historic sites. Additionally, the anthropogenic coordinate analysis enables realistic error estimates for NAC derived coordinates for features anywhere on the Moon.

Mapping the Apollo 17 landing site area based on Lunar Reconnaissance Orbiter Camera images and Apollo surface photography

Newly acquired high resolution Lunar Reconnaissance Orbiter Camera (LROC) images allow accurate determination of the coordinates of Apollo hardware, sampling stations, and photographic viewpoints. In particular, the positions from where the Apollo 17 astronauts recorded panoramic image series, at the so‐called “traverse stations”, were precisely determined for traverse path reconstruction. We analyzed observations made in Apollo surface photography as well as orthorectified orbital images (0.5 m/pixel) and Digital Terrain Models (DTMs) (1.5 m/pixel and 100 m/pixel) derived from LROC Narrow Angle Camera (NAC) and Wide Angle Camera (WAC) images. Key features captured in the Apollo panoramic sequences were identified in LROC NAC orthoimages. Angular directions of these features were measured in the panoramic images and fitted to the NAC orthoimage by applying least squares techniques. As a result, we obtained the surface panoramic camera positions to within 50 cm. At the same time, the camera orientations, North azimuth angles and distances to nearby features of interest were also determined. Here, initial results are shown for traverse station 1 (northwest of Steno Crater) as well as the Apollo Lunar Surface Experiment Package (ALSEP) area.

Apollo measurements of lunar dust amidst geology priorities

Geology dominated the science of the six successful Apollo lunar sampling expeditions. About 380 kg of rocks and soils were collected in 2400 samples, along with many thousands of documenting photos. Lunar dust shrouding Moonscapes, obscuring and coating rock samples, was a nuisance for geologist-advisers and plagued each astronaut with its inescapable presence, sticking to every surface. Lunar dust was judged by Apollo 17 geologist-astronaut Harrison Schmitt as ‘No. 1 environmental problem on the Moon.’ As fine as talcum powder but more abrasive than sandpaper, dust jeopardised vacuum sealing of sample containers to preserve rocks free from terrestrial contamination, just as later at Houston it jeopardised long-term archives of lunar samples. Yet the only one type of Apollo experiment to measure dust and its movements in situ was a matchbox-sized Dust Detector Experiment (DDE) weighing 270 g deployed on Apollo 11, 12, 14 and 15 Apollo Lunar Surface Experiment Packages (ALSEPs), which transmitted DDE data to Earth every 54 s between 21 July 1969 and 30 September 1977. This report by the Australian inventor and Principal Investigator of the minimalist DDE, designed to hitch-hike, outlines its discoveries of basic characteristics of movements and stickiness of lunar dust. Unexpected realities include effects of (1) an out-gassing aura metres in extent surrounding an astronaut and (2) contamination and heating effects of ‘collateral dust,’ lunar surface dust kicked up and splashed by astronauts on experiments and rock samples. Some interpretations of DDE data presented in Apollo-era literature are challenged and alternative interpretations are presented, with two Apollo-era dust discoveries not referenced for 40 years. Little-known potential contamination of Apollo experiments, Moon rock samples and photographic validity is discussed, together with ongoing discoveries of the basics of dust such as dynamic behaviour and long-term accretion.

Mission interplanetary: Using radioisotope power to explore the solar system

The exploration of space both by humans and robots has been greatly enhanced and, in many cases, enabled by the use of radioisotope power sources (RPSs) to power and/or heat scientific instruments. Radioisotope power sources have enabled such breakthrough missions as the Pioneer flights to Jupiter, Saturn and beyond; the Voyager flights to Jupiter, Saturn, Uranus, Neptune, and beyond; the Apollo lunar surface experiments; the Viking Lander studies of Mars; the Galileo spacecraft that orbited Jupiter; the Ulysses mission to study the polar regions of the Sun; the Cassini spacecraft orbiting Saturn; and the recently launched New Horizons spacecraft to Pluto. Radioisotope heater units have enhanced or enabled the Apollo Early Scientific Experiment Package and the Mars exploration rover missions (Sojourner, Spirit and Opportunity). Since 1961, the United States has successfully flown 41 radioisotope thermoelectric generators (RTGs) to provide electrical power for 23 space missions.

Taking science to the moon: lunar experiments and the Apollo Program

How did science get aboard the Apollo rockets, and what did scientists do with the space allotted to them? This volume describes, from the perspective of NASA headquarters, the struggles that took place to include science payloads and lunar exploration as part of the Apollo program. Author Donald A. Beattie - who served at NASA from 1963 to 1973 in several management positions and finally as programme manager, Apollo Lunar Surface Experiments - supplies a detailed, insider's view of the events leading up to the acceptance of science activities on all the Apollo missions. Beattie tells this story within the context of what we knew about the moon in the 1960s, the ongoing programmes that looked ahead to the first successful landing, and the objections that had to be overcome within NASA's entrenched engineering culture. Beattie concentrates on activities directly related to science, including behind-the-scenes controversies. He also discusses the important contributions of some of the lesser-known participants and contractors, who he says played a much larger role than previous books on the programme have acknowledged. The book provides the early history of on-site lunar experiments, raising important questions about a shift in NASA policy which led to some of the most dramatic planetary-science developments of our time.

Space nuclear power - An overview

Nuclear power sources have enabled or enhanced some of the most challenging and exciting space missions yet conducted, including missions such as the Pioneer flights to Jupiter and Saturn; the Voyager flights to Jupiter, Saturn, Uranus, and Neptune; the Apollo lunar surface experiments; the Viking Lander studies of Mars; the Ulysses mission to study the polar regions of the sun; and the Galileo mission to orbit Jupiter. This article surveys the early missions and continues to the present Galileo and Ulysses missions and provides a summary of the power technology that was used in each mission. Current activities aimed at improving the specific power and efficiency of space nuclear power sources are summarized. In addition to radioisotope power sources, this article surveys the U.S. space nuclear reactor program focusing on the flight of the SNAP-lOA reactor and the technology developed in the SP-100 space nuclear reactor power system program. The general attributes of space nuclear power sources are described and possible future applications are identified.

Study of the Lunar Core by VLBI Observations of Artificial Radio Sources on the Moon

Differential VLBI technique can measure the variation in the angular distance between two artificial radio transmitters on the Moon with an accuracy of a few centimeters. We can observe the physical librations of the Moon through this technique since rotation of the Moon changes the angular distance. The gravitational field of the Moon can also be determined by observations of the angular distance between the radio source on the Moon and that on a lunar orbiter. Calculations show that this technique can determine the amplitude of the physical librations with an accuracy of 10-5 which are one or two orders higher than those obtained by using the Apollo Lunar Surface Experiments Package in 1970's. We can estimate the density and the radius of the lunar core through accurate amplitude and period of the librations together with seismic observations. The accuracy of determination of the lunar gravity harmonics of degree 2 derivable from the VLBI observations are in the range from 10-4 to 10-6. We are developing radio transmitters which will be put on the lunar surface by hard landing from the lunar orbiter.

Lunar baselines and libration from differential Vlbi observations of alseps

Differential very-long-baseline interferometric observations of signals from Apollo Lunar Surface Experiment Package telemetry transmitters will yield the relative projected positions of the transmitters with uncertainty of only 1-3 m, set mainly by uncertainty of the lunar ephemeris. Noise and systematic instrumental errors which in the past affected similar observations have been reduced to the equivalent of a few centimeters on the lunar surface by the development of a new type of differential receiver. Continued observations should yield a determination of the motion of the Moon about its center of mass with uncertainty less than 1 s of selenocentric arc. Improvements (by other means) in our knowledge of the Moon's orbital motion would allow a further order-of-magnitude refinement in the libration and relative position results obtainable by differential VLBI.

Electric potential of the Moon in the solar wind

Acceleration and detection of the lunar thermal ionosphere in the presence of the lunar electric field yields a value of at least +10 volts for the lunar electric potential for solar zenith angles between approximately 20° and 45° and in the magnetosheath or solar wind. An enhanced positive ion flux is observed with the Apollo Lunar Surface Experiments Package Suprathermal Ion Detector Experiment when a preacceleration voltage attains certain values. This enhancement is greater when the moon is in the solar wind as opposed to the magnetosheath.

Apollo 15 measurement of lunar surface brightness temperatures thermal conductivity of the upper 1 1/2 meters of regolith

In situ measurements of lunar surface brightness temperatures made as a part of the Apollo Lunar Surface Experiments Package at the Apollo 15 Hadley Rille landing site are reported. Data derived from 5 thermocouples of the Heat Flow Experiment, which are lying on or just above the surface, are used to examine the thermal properties of the upper 15 cm of the lunar regolith using eclipse and nighttime cool-down temperatures. Application of finite-difference techniques in modeling the lunar soil shows the thermocouple data are best fit by a model consisting of a low-density and low-thermal conductivity surface layer approximately 2 cm thick overlying a region increasing in conductivity and density with depth. Conductivities on the order of 1 × 10 −5 W/cm-°K are postulated for the upper layer, with conductivity increasing to the order of 1 × 10 −4 W/cm-°K at depths exceeding 20 cm. An increase in mean temperature with depth indicates that the ratio of radiative to conductive transfer at 350°K is 2.7 for at least the upper few centimeters of lunar soil; this value is nearly twice that measured for returned lunar fines. The thermal properties model deduced from Apollo 15 surface temperatures is consistent with earth-based microwave observations if electrical properties measured on returned lunar fines are assumed.

Participation in lunar data analysis

Since 1963 three Rangers, an Explorer, five Surveyors, five Lunar Orbiters, and nine Apollo lunar missions have acquired a vast amount of new scientific data. Encouraging and impressive as this new information is, it represents only a beginning of the analysis and assimilation of the data. New information will continue to be received from the Apollo Lunar Surface Experiment Packages, the Lunar Laser Ranging Experiment, and the orbiting subsatellite. During the next decade efforts must be devoted to the systematic analysis and interpretation of this growing storehouse of data.

Role of pressure transients in the detection and identification of lunar surface gas sources

The dynamic behavior of neutral gases emitted from lunar surface sources is investigated. Pressure transients to be expected from several types of possible lunar surface sources are constructed. An approximate method is developed to estimate the source-sensor separation distance and the amount of effluent release. The case for which the source location and effluent molecular weight can be determined from ancillary data is discussed. It is shown that, if such data are available, pressure transients detected by either Apollo lunar surface experiment package ion spectrometers or cold cathode gages can be used to determine the release rate and the total amount of effluent release from the source.

Very-long-baseline interferometry techniques applied to problems of geodesy, geophysics, planetary science, astronomy, and general relativity

Very-long-baseline interferometry (VLBI) techniques have already been used to determine the vector separations between antennas thousands of kilometers apart to within 2 m and the directions of extragalactic radio sources to 0.1", and to track an artificial satellite of the earth and the Apollo Lunar Rover on the surface of the moon. The relative locations of the Apollo Lunar Surface Experiment Package (ALSEP) transmitters on the lunar surface are being measured within 1 m, and the moon's libration is being measured to 1" of selenocentric arc. Attempts are under way to measure the solar gravitational deflection of radio waves more accurately than previously possible, by means of VLBI. A wide variety of scientific problems is being attacked by VLBI techniques, which may soon be two orders of magnitude more accurate than at present.

An experimental study of the seismic ringing of the moon

The seismic records obtained from the seismic station ALSEP (Apollo Lunar Surface Experiments Package) on the moon, due to the impact of the LM (Lunar Module) of the Apollo XII and the S-IVB rocket state of the Apollo XIII moon missions show the seismic signals decaying in amplitude slowly with time. The observed ringing phenomenon on these records along with the fact that the disturbances lasted for a long period were unexpected. Laboratory experiments on homogeneous spheres have produced this ‘ringing’. The physical explanation of this may be complicated, and it is quite possible that this observed ringing is due to the combined effect of the filtering, reflections and scattering of energy due to the curvature of the homogeneous (in the seismic sense) sphere. The explanation of the ‘ringing’ of the moon may very well lie in such a study.

The Apollo 15 lunar heat-flow measurement

The heat-flow experiment is one of the Apollo Lunar Surface Experiment Package (ALSEP) instruments that was emplaced on the lunar surface on Apollo 15. This experiment is designed to make temperature and thermal property measurements in the lunar subsurface so as to determine the rate of heat loss from the lunar interior through the surface. About 45 days (1 1/2 lunations) of data has been analyzed in a preliminary way. This analysis indicates that the vertical heat flow through the regolith at one probe site is 3.3 × 10−6 W/cm2 (±15%). This value is approximately one-half the Earth's average heat flow. Further analysis of data over several lunations is required to demonstrate that this value is representative of the heat flow at the Hadley Rille site. The mean subsurface temperature at a depth of 1 m is approximately 252.4K at one probe site and 250.7K at the other. These temperatures are approximately 35K above the mean surface temperature and indicate that conductivity in the surficial layer of the Moon is highly temperature dependent. Between 1 and 1.5m, the rate of temperature increase as a function of depth is 1.75K/m (±2%) at the probe 1 site. In situ measurements indicate that the thermal conductivity of the regolith increases with depth. Thermal-conductivity values between 1.4 × 10−4 and 2.5 × 10−4 W/cm K were determined; these values are a factor of 7 to 10 greater than the values of the surface conductivity. If the observed heat flow at Hadley Base is representative of the moonwide rate of heat loss (an assumption which is not fully justified at this time), it would imply that overall radioactive heat production in the Moon is greater than in classes of meteorites that have formed the basis of Earth and Moon bulk composition models in the past.