Apollo Lunar Surface Experiments Package 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.

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.

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.

Lunar Seismology

The past 4 years have marked the beginning of a new era in lunar exploration. With the successful landing of instruments on the lunar surface by unmanned spacecrafts of the Luna, Ranger, and Surveyor series, and finally the first manned landing on the moon in July 1969, as part of the Apollo program, direct measurements of the physical and chemical properties of the moon have become a reality.Thus far we have had the opportunity to record data from two lunar seismic stations installed by the astronauts during Apollo missions 11 and 12 as part of an integrated set of geophysical experiments called ALSEP (Apollo lunar surface experiments package). The combined recording time from these stations was 13 months at the time of this writing, but there was no overlap in operation to permit recording the same event at two stations. Results from the analysis of these data have been presented by the seismic experiment team in six papers [Latham et al., 1969, 1970a, b, c, d; Ewing et al., 1970].

Lunar Surface Magnetometer

The lunar surface magnetometer is one of five instruments in the Apollo lunar surface experiments package (ALSEP). It measures three components of the vector magnetic field in the range 0 to 400ϒ with a resolution of 0.2ϒ and a frequency response from dc to 3 Hz. This instrument also has a gradient measuring capability, making it an automatic magnetic observatory on the lunar surface. The magnetometer experiment deployed by Astronauts Conrad and Bean on Apollo 12 has measured a steady magnetic field of approximately 36ϒ on the lunar surface. During each lunar day-night period the magnetic fields in the geomagnetic tail, transition zone, and interplanetary region are superimposed upon this steady field. Measurements of the induced lunar magnetic field will permit the interior electrical conductivity and temperature to be calculated.