Apollo Missions Research Articles

A 2-year locomotive exploration and scientific investigation of the lunar farside by the Yutu-2 rover.

The lunar nearside has been investigated by many uncrewed and crewed missions, but the farside of the Moon remains poorly known. Lunar farside exploration is challenging because maneuvering rovers with efficient locomotion in harsh extraterrestrial environment is necessary to explore geological characteristics of scientific interest. Chang’E-4 mission successfully targeted the Moon’s farside and deployed a teleoperated rover (Yutu-2) to explore inside the Von Kármán crater, conveying rich information regarding regolith, craters, and rocks. Here, we report mobile exploration on the lunar farside with Yutu-2 over the initial 2 years. During its journey, Yutu-2 has experienced varying degrees of mild slip and skid, indicating that the terrain is relatively flat at large scales but scattered with local gentle slopes. Cloddy soil sticking on its wheels implies a greater cohesion of the lunar soil than encountered at other lunar landing sites. Further identification results indicate that the regolith resembles dry sand and sandy loam on Earth in bearing properties, demonstrating greater bearing strength than that identified during the Apollo missions. In sharp contrast to the sparsity of rocks along the traverse route, small fresh craters with unilateral moldable ejecta are abundant, and some of them contain high-reflectance materials at the bottom, suggestive of secondary impact events. These findings hint at notable differences in the surface geology between the lunar farside and nearside. Experience gained with Yutu-2 improves the understanding of the farside of the Moon, which, in return, may lead to locomotion with improved efficiency and larger range.

Characterization of novel lunar highland and mare simulants for ISRU research applications

Lunar regolith is the most critical material for the in-situ resource utilization in the crewed Moon exploration missions. This natural material can be utilized for the additive manufacturing of concrete or ceramic parts on the Moon's surface to support permanent human presence on the surface of Earth's natural satellite. Due to the scarcity of regolith on Earth, its simulants are used in lab research to prepare the technology for Moon missions. The present study is devoted to the characterization of lunar regolith simulant material, recently developed by the University of Central Florida, that is considered as a suitable material for regolith-focused additive manufacturing technologies. This paper describes the characterization of the LHS-1 and LMS-1 simulants using XRF, XRD, SEM, EDX, DTA, TGA, UV/Vis/NIR spectroscopy, and Laser diffractometry methods to provide data on their mineral, chemical, and fractional composition, as well as, on their morphology and optical properties. The results were compared to the data of the previously developed simulants and the original lunar samples delivered by Apollo and Luna missions. It was found that LHS-1 and LMS-1 simulants well mimic the primary properties of the original lunar regolith and can be potentially used for ISRU research tasks.

Far Beyond the Moon: A History of Life Support Systems in the Space Age by David P. D. Munns and Kärin Nickelsen (review).

Reviewed by: Far Beyond the Moon: A History of Life Support Systems in the Space Age by David P. D. Munns and Kärin Nickelsen Jordan Bimm (bio) Far Beyond the Moon: A History of Life Support Systems in the Space Age By David P. D. Munns and Kärin Nickelsen. Pittsburgh: University of Pittsburgh Press, 2021. Pp. 206. Make no mistake, this is a book about shit in space. The sanitized title and cover design don't do justice to what's inside this important and far-ranging history of human waste's various roles in sealed artificial environments designed for space travel. The problem of what to do with astronaut poo has been there since the start of human spaceflight, and coauthors David Munns and Kärin Nickelsen note that sixty-plus years later, a long-term sustainable solution remains elusive. From stick-on poop collection bags to vacuum-assisted commodes to aquarium-like algae habitats converting solid waste into (theoretically) edible food, the array of [End Page 302] engineering and life sciences approaches examined ranges from simple and pragmatic to complex and far-future directed. The first book-length historical treatment of the topic, this frank, unflinching look at an unglamorous, sometimes embarrassing, yet absolutely essential aspect of space technology aims to remove what the authors convincingly argue has been a limiting stigma. We need to talk about shit in space, and Far Beyond the Moon is a thought-provoking conversation starter. The book moves mostly chronologically through a selection of little-known but fascinating American and Soviet projects from the 1960s to the 1990s, emblematic of the work trajectories on this issue, and evocative of themes the authors want to highlight. These include how waste is conceptualized; talked about (or not); incorporated into ecological and technological schemata; collected, stored, or processed; and finally centered in totalizing visions of environment and environmentalism extending far beyond tiny space cabins to experimental megastructures and the entire Earth. The result is an illuminating history of the space race and its aftermath from the new perspective of sanitary engineering. First, the authors dispel the notion that NASA only began work on the problems of long-term living in space in the 1970s, with Skylab extending post-Apollo missions from days to months (ch. 1). Munns and Nickelsen delve into the lesser-known history of NASA's life science research in the 1960s, and of work managing closed systems carried out between the Agency's Ames and Langley centers, as well as in the U.S. Air Force, and at private defense contractors Lockheed, Boeing, and General Electric. Next, the book focuses on fecal bags and the Algatron, two technologies developed in the 1960s representing vastly different approaches to dealing with astronaut poop (ch. 2). The stowable fecal bag used on NASA's famed Apollo missions was straightforward but also messy, smelly, and not reusable. In contrast, the Algatron—an experimental system developed at Berkeley with USAF funding but never flown in space—used algae cultures to endlessly recycle human waste into purified water and food. The book then pivots to the Soviet 1960s space program and ambitious human experiments at the Krasnoyarsk Institute, where scientists sealed test-subjects inside prototype closed ecological systems called "planet-ships" (ch. 3). Started in 1962, these culminated in a year-long experiment in 1967, when three subjects attempted to live and work in close quarters, growing hydroponic crops and recycling their waste with a system similar to the Algatron. Next, the authors take readers into the 1970s and waste-centric critiques of Gerard K. O'Neill's utopian plans for massive cylindrical space settlements, and then into the 1980s to real-life problems with space shuttle toilets and important links between astronaut psychology and hygiene in orbit (ch. 4). Their final chapter focuses on the best-known episode covered in the book, the infamous Biosphere 2 experiments in the early 1990s. Small groups attempted to live inside a giant sealed ecosystem [End Page 303] constructed in Arizona, with controversial results. Munns and Nickelsen place this project—often understood in terms of ecology—squarely within their history of spaceflight and sanitation. Historians of technology will find...

Retrieval of Lunar Surface Dielectric Constant Using Chandrayaan-2 Full-Polarimetric SAR Data

For more than four decades, it has been known that the dielectric constant of the lunar surface can be retrieved from the Fresnel reflection coefficients. However, theoretical models have met with limited success in validating laboratory test results from the Apollo missions to date. This paper is the first study to focus on the use of high-resolution full-polarimetric synthetic aperture radar datasets for the retrieval of the dielectric constant of the lunar surface from the Fresnel reflection coefficients. We initially show that it is possible to retrieve the lunar dielectric constant via the classical Freeman-Durden Decomposition (FDD). The performance of the FDD algorithm is found to be unacceptable over regions with surface slopes and craters, and for sub-surface soil samples. Accurate estimation is not possible by simply replacing the volume scattering model in the FDD with popular and widely used volume scattering models. Therefore, a model-based three-component decomposition (TCD) algorithm for a robust retrieval of the lunar dielectric constant is proposed. The proposed TCD algorithm implements an efficient branching condition combined with double unitary matrix rotations and provides exceptionally accurate dielectric constant estimation. The proposed TCD algorithm is validated by using L band full-polarimetric datasets acquired by the Chandrayaan-2 mission over Apollo 12, Apollo 15, and Apollo 17 landing sites. Comparisons are also made with other three-component decomposition algorithms. Excellent agreement between the estimated values by the proposed TCD algorithm and the reference values for the dielectric constant, available from the literature, has been observed.

Carl Nelson Cederstrand (1927–2022): A Biophysicist, an Innovator and a Wonderful Person

We provide a glimpse of the personal and professional life of Carl Nelson Cederstrand, most of the personal part is contributed by the daughter Laura Cederstrand (LC), and his research part in the Life Sciences is provided by Govindjee, his early collaborator and friend. Carl is remembered for his critical contributions to the discovery, in 1957, of the Emerson Enhancement Effect that led to the current Z-Scheme of photosynthesis, and later to the absorption and fluorescence spectroscopy of algae through his design and construction of a unique spectrophotometer, at the University of Illinois at Urbana Champaign (UIUC). After receiving his PhD at UIUC, he worked at Beckman Instrument’s research division in California, where he designed an oxygen analyser that went to the Moon as part of one of the Apollo missions. Carl is best known for designing many infrared and ultraviolet detectors and creatively applying these in various ways in the life sciences, for which he is listed as inventor in nearly a dozen patents. Above all, Carl is remembered for his inventions that have significantly impacted many areas of the life sciences. We have included here his great insight into and fascination with MG cars. We end this Tribute to Carl with a reminiscence by his wife Darlene Kelly, and our summary of his personal family life.

Nasa's Space Launch System Will Lift Off: But with rival rockets readying for flight, the ultimate value of SLS is murky

Inside the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida―a cavernous structure built in the 1960s for constructing the Apollo program's Saturn V rockets and, later, for preparing the space shuttle―the agency's next big rocket is taking shape.

Mineral chemistry and 3D tomography of a Chang’E 5 high-Ti basalt: implication for the lunar thermal evolution history

In December 2020, Chang’E-5 (CE-5), China’s first lunar sample return mission, successfully collected samples totaling 1731 g from the northern Oceanus Procellarum. The landing site was located in a young mare plain, a great distance from those of Apollo and Luna missions. These young mare basalts bear critical scientific significance as they could shed light on the nature of the lunar interior (composition and structure) as well as the recent volcanism on the Moon. In this article, we investigated a CE-5 basalt sample (CE5C0000YJYX065) using a combination of state-of-art techniques, including high resolution X-ray tomographic microscopy (HR-XTM), energy dispersive X-ray spectroscopy (EDS)-based scanning electron microscope (SEM), and electron probe microanalysis (EPMA) to reveal its 3D petrology and minerology. Our results show that this sample has a fine- to medium-grained subophitic texture, with sparse olivine phenocrysts setting in the groundmass of pyroxene, plagioclase, ilmenite and trace amounts of other phases. It has an extremely high ilmenite modal abundance (17.8 vol%) and contains a significant amount (0.5 vol%) of Ca-phosphate grains. The mineral chemistry is in excellent agreement with that of Apollo and Luna high-Ti basalts. The major phase pyroxenes also display strong chemical zoning with compositions following the trends observed in Apollo high-Ti basalts. Based on current data, we came to the conclusion that CE5C0000YJYX065 is a high-Ti mare basalt with a rare earth element (REE) enriched signature. This provides a rigid ground-truth for the geological context at the CE-5 landing site and clarifies the ambiguity inferred from remote sensing surveys.

Chemical heterogeneities reveal early rapid cooling of Apollo Troctolite 76535

The evolution of the lunar interior is constrained by samples of the magnesian suite of rocks returned by the Apollo missions. Reconciling the paradoxical geochemical features of this suite constitutes a feasibility test of lunar differentiation models. Here we present the results of a microanalytical examination of the archetypal specimen, troctolite 76535, previously thought to have cooled slowly from a large magma body. We report a degree of intra-crystalline compositional heterogeneity (phosphorus in olivine and sodium in plagioclase) fundamentally inconsistent with prolonged residence at high temperature. Diffusion chronometry shows these heterogeneities could not have survived magmatic temperatures for >~20 My, i.e., far less than the previous estimated cooling duration of >100 My. Quantitative modeling provides a constraint on the thermal history of the lower lunar crust, and the textural evidence of dissolution and reprecipitation in olivine grains supports reactive melt infiltration as the mechanism by which the magnesian suite formed.

The Moon revisisted

The brightest and biggest object in our night sky, the Moon is the only other place in the solar system that humans have set foot – so far. It’s been nearly 50 years since NASA’s Apollo missions when humankind last walked on the Moon, but with the commencement of the Artemis programme, people are set […]

Temperature sensitivity analysis on mass-spring potential with electrostatic frequency reduction for lunar seismometers

A broadband seismometer has been identified as an important scientific instrument that can be deployed on the surface of Earth’s Moon in the near future. To achieve the goals of the International Lunar Network, this next generation of seismometers is required to achieve at least 2 × 10−10 ms−2 Hz−1/2 at 1 mHz, which are several orders of magnitude more sensitive at the same frequency than the ones deployed during the Apollo program; their goal is to capture the lunar seismic noise floor, observe the lunar normal modes, and record distant teleseisms from all over the Moon. The Electrostatic Frequency Reduction (EFR) technique has been employed in a seismometer design in our laboratory and can enhance the Moonquake measurement sensitivity covering a longer period down to 1 mHz. EFR has advantages over the traditional frequency reduction techniques since it can be autonomously tuned and lowers the resonance frequency without modifying the mechanical design of a capacitive readout seismometer, an approach desirable for spaceflight-qualified instrumentation. A drawback is that we have also found that the EFR as well as other frequency reduction techniques amplify the temperature sensitivity of a seismometer beyond the limit of a conventional temperature control system. Here, we describe quantitatively and analytically the temperature dependence of a spring suspended mass model of a seismometer and provide practical solutions to minimize the thermal effects on a lunar seismometer using the EFR technique. By choosing the materials for the seismometer housing and the spring suspension that could balance the shear modulus and thermal expansion coefficients, one could mitigate the thermal sensitivity of the seismometer using the EFR technique. These modifications allow us to approach the stringent requirements for instrument self-noise necessary for the science objective.

Numerical Simulations of the Apollo S‐IVB Artificial Impacts on the Moon

AbstractThe third stage of the Saturn IV rocket used in the five Apollo missions made craters on the Moon ∼30 m in diameter. Their initial impact conditions were known, so they can be considered controlled impacts. Here, we used the iSALE‐2D shock physics code to numerically simulate the formation of these craters, and to calculate the vertical component of seismic moment (∼4 × 1010 Nm) and seismic efficiency (∼10−6) associated with these impacts. The irregular booster shape likely caused the irregular crater morphology observed. To investigate this, we modeled six projectile geometries, with footprint area between 3 and 105 m2, keeping the mass and velocity of the impactor constant. We showed that the crater depth and diameter decreased as the footprint area increased. The central mound observed in lunar impact sites could be a result of layering of the target and/or low density of the projectile. Understanding seismic signatures from impact events is important for planetary seismology. Calculating seismic parameters and validating them against controlled experiments in a planetary setting will help us understand the seismic data received, not only from the Moon, but also from the InSight Mission on Mars and future seismic missions.

Gastrocnemius medialis contractile behavior during running differs between simulated Lunar and Martian gravities

The international partnership of space agencies has agreed to proceed forward to the Moon sustainably. Activities on the Lunar surface (0.16 g) will allow crewmembers to advance the exploration skills needed when expanding human presence to Mars (0.38 g). Whilst data from actual hypogravity activities are limited to the Apollo missions, simulation studies have indicated that ground reaction forces, mechanical work, muscle activation, and joint angles decrease with declining gravity level. However, these alterations in locomotion biomechanics do not necessarily scale to the gravity level, the reduction in gastrocnemius medialis activation even appears to level off around 0.2 g, while muscle activation pattern remains similar. Thus, it is difficult to predict whether gastrocnemius medialis contractile behavior during running on Moon will basically be the same as on Mars. Therefore, this study investigated lower limb joint kinematics and gastrocnemius medialis behavior during running at 1 g, simulated Martian gravity, and simulated Lunar gravity on the vertical treadmill facility. The results indicate that hypogravity-induced alterations in joint kinematics and contractile behavior still persist between simulated running on the Moon and Mars. This contrasts with the concept of a ceiling effect and should be carefully considered when evaluating exercise prescriptions and the transferability of locomotion practiced in Lunar gravity to Martian gravity.

Ewen A. Whitaker (1922–2016)

An amateur who devoted his life to studies of the Moon, Whitaker became one of the world's most renowned lunar specialists. His work directly contributed to mission planning for NASA’s Apollo program.

Safety considerations for SPIcDER: Spacesuit integrated carbon nanotube dust ejection/removal system

This paper presents a multi-tier safe implementation of the Spacesuit Integrated Carbon Nanotube Dust Ejection/Removal (SPIcDER) system. SPIcDER mitigates dust contamination of spacesuits and flexible surfaces during surface exploration of Moon and Mars. SPIcDER has Carbon nanotube (CNT) fibers embedded within the spacesuit outerlayer. These are energized using high voltage, low power, Alternating Current (AC) signals (∼350–1000 V). Laboratory experiments show the time-varying electric fields produced by SPIcDER repel the dust.This system mitigates astronaut exposures to lunar dust, and protects spacesuits and flexible surfaces from dust abrasion, wear and tear, and reduction in thermal performance. The adherence of lunar dust, and its entry into the habitable volume of habitats/landers, which was a major problem during Apollo missions, is also minimized.In this study, we review the primary health and safety aspects of SPIcDER for astronauts operating in these spacesuits. Simulation using ANSYS Maxwell® and preliminary experimental investigations were performed to conduct safety analysis and provide recommendations for implementation of SPIcDER for lunar mission operations.

Reconstruction of solar activity based on 14C and other isotope profiles in lunar regolith

The Moon might be considered as an integral detector of Galactic Cosmic Rays (GCR) as it contains on its surface cosmogenic isotopes produced by nuclear reactions. Since the retrieval of lunar regolith cores by Apollo missions, there were numerous attempts to measure concentrations and depth profiles of those isotopes and reconstruct the level of cosmic radiation at 1AU at various time scales, ranging from thousands to millions of years. The data also contains encoded levels of solar activity, as the Sun affects the differential flux of GCRs in a well-known manner. All those attempts showed that our nuclear interaction codes, GEANT4 for example, need corrections to describe the lunar data, be it tweaking of cross-sections or any other methods. There are also such archives on Earth: ice cores and trees. Based on terrestrial modulation potential reconstruction we try to calibrate GEANT4 code in a transparent manner, and also present our estimates on the solar activity on time scales of 0.02 and 3 Myrs. The estimates made using our calibration procedure show values consistent with modern understanding of history of solar modulation potential, and demonstrate the necessity to establish an agreed correction method for the analysis of lunar data. We also compare our results and method with another estimation of solar modulation potential during the last 1 Myr.

Jules Verne's Formulation of the Fermi Question

Abstract Jules Verne's novel Around the Moon envisions the circumlunar flight of a crewed projectile around the lunar farside ending with a safe return to Earth. The novel is justifiably famous, partly because of certain parallels it contains to the U.S. Apollo program a century later. What is less appreciated is that the novel contains a rather direct statement of what would later become known as the Fermi Question or Fermi Paradox.

Cryogenic air purification for deep space exploration

Deep space exploration and settlement represents a new frontier for the progress of mankind. From the first stratospheric flight to the Apollo missions, to the International Space Station and in the near future sustainable life on the moon, the occupancy and duration of flights have risen dramatically. This has put increasing demands on life support system capabilities. Currently, adsorbent beds allow trapping of H2O and CO2 rejected by astronauts. Another possible means of trapping these compounds is based on cryogenic freezing. H2O, CO2 and VOC are simply sequestered by cooling the air below each molecule's dew point. Air Liquide has developed a versatile breadboard in collaboration with Airbus and ESA to assess several concepts and technologies for cryogenic trapping. A set of breadboards has been built to compare performance between using Counter-Flow and Regenerative Heat Exchangers/Crystallizers. In this paper we will recap main results obtained with the first prototype (MK I) and we will detail the new results obtained with the second prototype (MK II). While not all technological hurdles have been cleared to date, Cryogenic Air Purification appears as a promising path for next generation life support systems. Furthermore, the Technology could also be applicable to In Situ Resource Utilization, specifically Lunar water recovery and purification.

Chang’E-5 reveals the Moon's secrets to a longer life

The Moon is not only important because it enchants us in the night sky. The Earth-Moon system is critical for Earth's surface environment and even life, with lunar gravity controlling Earth's tides and rate of rotation. The origin of the Moon, from either a giant impact or a shrinking hot debris disk, remains debated and carries implications for either early Earth or even Earth's origin, respectively. The Apollo and Luna missions provided abundant samples informing the earliest lunar history, namely the evolution of the “lunar magma ocean,” where less dense plagioclase crystallized and floated up to the surface, lending most of the lunar surface its white appearance from this anorthositic crust, but the dark patches on the Moon—its “mare” basalts, named for the large “sea” of volcanic plains—record the rest of lunar history.

Characteristics of the lunar samples returned by the Chang'E-5 mission.

Forty-five years after the Apollo and Luna missions returned lunar samples, China's Chang’E-5 (CE-5) mission collected new samples from the mid-latitude region in the northeastern Oceanus Procellarum of the Moon. Our study shows that 95% of CE-5 lunar soil sizes are found to be within the range of 1.40–9.35 μm, while 95% of the soils by mass are within the size range of 4.84–432.27 μm. The bulk density, true density and specific surface area of CE-5 soils are 1.2387 g/cm3, 3.1952 g/cm3 and 0.56 m2/g, respectively. Fragments from the CE-5 regolith are classified into igneous clasts (mostly basalt), agglutinate and glass. A few breccias were also found. The minerals and compositions of CE-5 soils are consistent with mare basalts and can be classified as low-Ti/low-Al/low-K type with lower rare-earth-element contents than materials rich in potassium, rare earth element and phosphorus. CE-5 soils have high FeO and low Mg index, which could represent a new class of basalt.

Speaker tracking across a massive naturalistic audio corpus: Apollo-11

Apollo-11 was the first manned space mission to successfully bring astronauts to the moon. More than + 400 mission specialists/support team members were involved whose voice communications were captured using the SoundScriber multi-channel analog system. To ensure mission success, it was necessary for teams to engage, communicate, learn, address and solve problems in a timely manner. Hence, in order to identify each speaker’s role during Apollo missions and analyze group communication, we need to automatically tag and track speakers individually since manual annotation is costly and time consuming on a massive audio corpus. In this study, we focus on a subset of 100 h derived from the 10 000 h of the Fearless Steps Apollo-11 audio data. We use the concept of “Where’s Waldo” to identify all instances of our speakers-of-interest: (i) Three Astronauts; (ii) Flight Director; and (iii) Capsule Communicator. Analyzing the handful of speakers present in the small audio dataset of 100 h can be extended to the complete Apollo mission. This analysis provides an opportunity to recognize team communications, group dynamics, and human engagement/psychology. Identifying these personnel can help pay tribute to the hundreds of notable engineers and scientists who made this scientific accomplishment possible. Sponsored by NSF #2016725