Tag Archives: #moon

Lunar Samples Solve Mystery Of the Moon’s Supposed Magnetic Shield (Planetary Science)

Rochester geophysicists’ latest findings will inform the next generation of moon exploration.

In 2024, a new age of space exploration will begin when NASA sends astronauts to the moon as part of their Artemis mission, a follow-up to the Apollo missions of the 1960s and 1970s.

Some of the biggest questions that scientists hope to explore include determining what resources are found in the moon’s soil and how those resources might be used to sustain life.

In a paper published in the journal Science Advances, researchers at the University of Rochester, leading a team of colleagues at seven other institutions, report their findings on a major factor that influences the types of resources that may be found on the moon: whether or not the moon has had a long-lived magnetic shield at any point in its 4.53 billion-year history.

The presence or absence of a shield matters because magnetic shields protect astronomical bodies from harmful solar radiation. And the team’s findings contradict some longstanding assumptions.

“This is a new paradigm for the lunar magnetic field,” says first author John Tarduno, the William R. Kenan, Jr., Professor of Geophysics in the Department of Earth and Environmental Sciences and dean of research for Arts, Sciences & Engineering at Rochester.

Did the moon ever have a magnetic shield?

For years, Tarduno has been a leader in the field of paleomagnetism, studying the development of Earth’s magnetic shield as a means to understanding planetary evolution and environmental change.

Earth’s magnetic shield originates deep within the planet’s core. There, swirling liquid iron generates electric currents, driving a phenomenon called the geodynamo, which produces the shield. The magnetic shield is invisible, but researchers have long recognized that it is vital for life on Earth’s surface because it protects our planet from solar wind—streams of radiation from the sun.

But has Earth’s moon ever had a magnetic shield?“This is a new paradigm for the lunar magnetic field.”

While the moon has no magnetic shield now, there has been debate over whether or not the moon may have had a prolonged magnetic shield at some point in its history.

“Since the Apollo missions, there has been this idea that the moon had a magnetic field that was as strong or even stronger than Earth’s magnetic field at around 3.7 billion years ago,” Tarduno says.

The belief that the moon had a magnetic shield was based on an initial dataset from the 1970s that included analyses of samples collected during the Apollo missions. The analyses showed that the samples had magnetization, which researchers believed was caused by the presence of a geodynamo.

But a couple of factors have since given researchers pause.

“The core of the moon is really small and it would be hard to actually drive that kind of magnetic field,” Tarduno explains. “Plus, the previous measurements that record a high magnetic field were not conducted using heating experiments. They used other techniques that may not accurately record the magnetic field.”

When lunar samples meet lasers

Inset image shows close-up detail of lunar glass subsample in the quartz square tubing and being analyzed by a magnetometer.
A subsample of lunar glass is placed in 2-by-2 millimeter fused quartz square tubing (inset) then analyzed using the lab’s superconducting quantum interference device (SQUID) magnetometer. The results provide information about the moon’s soil—and may help inform a new wave of lunar experiments. (University of Rochester photos / J. Adam Fenster)

Tarduno and his colleagues tested glass samples gathered on previous Apollo missions, but used CO2 lasers to heat the lunar samples for a short amount of time, a method that allowed them to avoid altering the samples. They then used highly sensitive superconducting magnetometers to more accurately measure the samples’ magnetic signals.

“One of the issues with lunar samples has been that the magnetic carriers in them are quite susceptible to alteration,” Tarduno says. “By heating with a laser, there is no evidence of alteration in our measurements, so we can avoid the problems people may have had in the past.”

The researchers determined that the magnetization in the samples could be the result of impacts from objects such as meteorites or comets—not the result of magnetization from the presence of a magnetic shield. Other samples they analyzed had the potential to show strong magnetization in the presence of a magnetic field, but didn’t show any magnetization, further indicating that the moon has never had a prolonged magnetic shield.

“If there had been a magnetic field on the moon, the samples we studied should all have acquired magnetization, but they haven’t,” Tarduno says. “That’s pretty conclusive that the moon didn’t have a long-lasting dynamo field.”

Lack of magnetic shield means an abundance of elements

Astronaut collects lunar samples with a parked lunar roving vehicle in the background.
The belief that the moon had a magnetic shield was based on an initial dataset from the 1970s that included analyses of lunar samples collected during the Apollo missions. (Photo credit: Flickr/NASA Johnson)

Without the protection of a magnetic shield, the moon was susceptible to solar wind, which may have caused a variety of volatiles—chemical elements and compounds that can be easily evaporated—to become implanted in the lunar soil. These volatiles may include carbon, hydrogen, water, and helium 3, an isotope of helium that is not present in abundance on Earth.

“Our data indicates we should be looking at the high end of estimates of helium 3 because a lack of magnetic shield means more solar wind reaches the lunar surface, resulting in much deeper reservoirs of helium 3 than people thought previously,” Tarduno says.

The research may help inform a new wave of lunar experiments based on data that will be gathered by the Artemis mission. Data from samples gathered during the mission will allow scientists and engineers to study the presence of volatiles and better determine if these materials can be extracted for human use. Helium 3, for instance, is currently used in medical imaging and cryogenics and is a possible future fuel source.

A lack of magnetic shielding also means that ancient lunar soils may hold records of past solar wind emissions. Analyzing cores of soil samples could therefore provide scientists with a better understanding of the evolution of the sun.

“With the background provided by our research, scientists can more properly think about the next set of lunar experiments to perform,” Tarduno says. “These experiments may focus on current lunar resources and how we could use them and also on the historical record of what is trapped in the lunar soil.”

Featured image: The lunar glass samples tested by Rochester scientists were gathered during NASA’s 1972 Apollo 16 mission. (University of Rochester photo / J. Adam Fenster)


Reference: John A. Tarduno et al, Absence of a long-lived lunar paleomagnetosphere, Science Advances (2021). DOI: 10.1126/sciadv.abi7647


Provided by University of Rochester

NASA Identifies Likely Locations of the Early Molten Moon’s Deep Secrets (Planetary Science)

Shortly after it formed, the moon was covered in a global ocean of molten rock (magma). As the magma ocean cooled and solidified, dense minerals sank to form the mantle layer, while less-dense minerals floated to form the surface crust. Later intense bombardment by massive asteroids and comets punched through the crust, blasting out pieces of mantle and scattering them across the lunar surface.

Recently, a pair of NASA studies identified the most likely locations to find pieces of mantle on the surface, providing a map for future lunar sample return missions such as those under NASA’s Artemis program. If collected and analyzed, these fragments from deep within the moon can provide a better understanding of how the moon, the Earth, and many other solar system worlds evolved.

“This is the most up-to-date evaluation of the evolution of the lunar interior, synthesizing numerous recent developments to paint a new picture of the history of the mantle and how and where it may have been exposed on the lunar surface,” said Daniel Moriarty of NASA’s Goddard Space Flight Center, Greenbelt, Maryland and the University of Maryland, College Park.

Magma oceans evolve as they cool down and dense materials sink while light materials rise. The formation of magma oceans and their evolution are thought to be common processes among rocky planets and moons throughout our solar system and beyond. Earth’s moon is the most accessible and well-preserved body to study these fundamental processes.

“Understanding these processes in more detail will have implications for important follow-up questions: How does this early heating affect the distribution of water and atmospheric gases of a planet? Does water stick around, or is it all boiled away? What are the implications for early habitability and the genesis of life?” adds Moriarty, lead author of the papers, published August 3 in Nature Communications and January 2021 in the Journal of Geophysical Research.

Large rocky objects such as planets, moons, and large asteroids can form magma oceans with the heat generated as they grow. Our solar system formed from a cloud of gas and dust that collapsed under its own gravity. As this happened, dust grains smacked into each other and stuck together, and over time this process snowballed into larger and larger conglomerations, eventually forming asteroid and planet-sized bodies. These collisions generated a tremendous amount of heat. Also, the building blocks of our solar system contained a variety of radioactive elements, which released heat as they decayed. In larger objects, both processes can release enough heat to form magma oceans.

However, the details of how magma oceans evolve as they cool and how the various minerals in them crystalize are uncertain, which affects what scientists think mantle rocks may look like and where they could be found on the surface.

“The bottom line is that the evolution of the lunar mantle is more complicated than originally thought,” said Moriarty. “Some minerals that crystallize and sink early are less dense than minerals that crystallize and sink later. This leads to an unstable situation with light material near the bottom of the mantle trying to rise while heavier material closer to the top descends. This process, called ‘gravitational overturn,” does not proceed in a neat and orderly fashion, but becomes messy, with lots of mixing and unexpected stragglers left behind.”

The team reviewed the most recent laboratory experiments, lunar sample analysis, and geophysical and geochemical models to develop their new understanding of how the lunar mantle evolved as it cooled and solidified. They used this new understanding as a lens to interpret recent observations of the lunar surface from NASA’s Lunar Prospector and Lunar Reconnaissance Orbiter spacecraft, and NASA’s moon Mineralogy Mapper instrument on board India’s Chandrayaan-I spacecraft. The team generated a map of likely mantle locations using moon Mineralogy Mapper data to assess mineral composition and abundance, integrated with Lunar Prospector observations of elemental abundances, including markers of the last remaining liquid at the end of lunar magma ocean crystallization, and imagery and topography data from Lunar Reconnaissance Orbiter.

At around 1,600 miles (about 2,600 kilometers) across, the South Pole—Aitken basin is the largest confirmed impact structure on the moon, and therefore is associated with the deepest depth of excavation of all lunar basins, so it’s the most likely place to find pieces of mantle, according to the team.

For years, scientists have been puzzled by a radioactive anomaly in the northwest quadrant of the South Pole—Aitken Basin on the lunar farside. The team’s analysis demonstrates that the composition of this anomaly is consistent with the “sludge” that forms in the uppermost mantle at the very end of magma ocean crystallization. Because this sludge is very dense, scientists have previously assumed that it should completely sink into the lower mantle early in lunar history.

“However, our more nuanced understanding from recent models and experiments indicates that some of this sludge gets trapped in the upper mantle, and later excavated by this vast impact basin,” said Moriarty. “Therefore, this northwest region of the South Pole—Aitken Basin is the best location to access excavated mantle materials currently on the lunar surface. Interestingly, some of these materials may also be present around the proposed Artemis and VIPER landing sites around the lunar South Pole.”

Featured image: The thorium concentration across the vast South Pole – Aitken Basin on the lunar farside reveals the distribution of mantle materials violently ejected during the basin-forming impact. Here, thorium abundance is represented by a rainbow color scale, with high-thorium areas shown in red, trending to purple and grey with lower abundances. Two craters in the northwestern region of the basin exhibit especially high thorium abundance (indicated in red on the map), suggesting the presence of abundant mantle materials currently exposed on the surface. Credit: NASA/LRO/Lunar Prospector/D. Moriarty


References: (1) Daniel P. Moriarty et al, The search for lunar mantle rocks exposed on the surface of the Moon, Nature Communications (2021). DOI: 10.1038/s41467-021-24626-3 (2) D. P. Moriarty et al, Evidence for a Stratified Upper Mantle Preserved Within the South Pole‐Aitken Basin, Journal of Geophysical Research: Planets (2020). DOI: 10.1029/2020JE006589


Provided by NASA’s Goddard Space Flight Center

NASA Study Highlights Importance of Surface Shadows in Moon Water Puzzle (Planetary Science)

The shadows cast by the roughness of the Moon’s surface create small cold spots for water ice to accumulate even during the harsh lunar daytime.

Scientists are confident that water ice can be found at the Moon’s poles inside permanently shadowed craters – in other words, craters that never receive sunlight. But observations show water ice is also present across much of the lunar surface, even during daytime. This is a puzzle: Previous computer models suggested any water ice that forms during the lunar night should quickly burn off as the Sun climbs overhead.

“Over a decade ago, spacecraft detected the possible presence of water on the dayside surface of the Moon, and this was confirmed by NASA’s Stratospheric Observatory for Infrared Astronomy [SOFIA] in 2020,” said Björn Davidsson, a scientist at NASA’s Jet Propulsion Laboratory in Southern California. “These observations were, at first, counterintuitive: Water shouldn’t survive in that harsh environment. This challenges our understanding of the lunar surface and raises intriguing questions about how volatiles, like water ice, can survive on airless bodies.”

This illustration zooms in on the area of detail indicated in the previous photo, showing how shadows enable water ice to survive on the sunlit lunar surface. When shadows move as the Sun tracks overhead, the exposed frost lingers long enough to be detected by spacecraft. Credit: NASA/JPL-Caltech

In a new study, Davidsson and co-author Sona Hosseini, a research and instrument scientist at JPL, suggest that shadows created by the “roughness” of the lunar surface provide refuge for water ice, enabling it to form as surface frost far from the Moon’s poles. They also explain how the Moon’s exosphere (the tenuous gases that act like a thin atmosphere) may have a significant role to play in this puzzle.

Water Traps and Frost Pockets

Many computer models simplify the lunar surface, rendering it flat and featureless. As a result, it’s often assumed that the surface far from the poles heats up uniformly during lunar daytime, which would make it impossible for water ice to remain on the sunlit surface for long.

So how is it that water is being detected on the Moon beyond permanently shadowed regions? One explanation for the detection is that water molecules may be trapped inside rock or the impact glass created by the incredible heat and pressure of meteorite strikes. Fused within these materials, as this hypothesis suggests, the water can remain on the surface even when heated by the Sun while creating the signal that was detected by SOFIA.

But one problem with this idea is that observations of the lunar surface show that the amount of water decreases before noon (when sunlight is at its peak) and increases in the afternoon. This indicates that the water may be moving from one location to another through the lunar day, which would be impossible if they are trapped inside lunar rock or impact glass.

https://eyes.nasa.gov/apps/orrery/#/moon

Click on this interactive visualization of the Moon and take it for a spin. The “HD” button in the lower right offers for more detailed textures. The full interactive experience is at Eyes on the Solar System.

Davidsson and Hosseini revised the computer model to factor in the surface roughness apparent in images from the Apollo missions from 1969 to 1972, which show a lunar surface strewn with boulders and pockmarked with craters, creating lots of shady areas even near noon. By factoring this surface roughness into their computer models, Davidsson and Hosseini explain how it’s possible for frost to form in the small shadows and why the distribution of water changes throughout the day.

Because there is no thick atmosphere to distribute heat around the surface, extremely cold, shaded areas, where temperatures may plummet to about minus 350 degrees Fahrenheit (minus 210 degrees Celsius), can neighbor hot areas exposed to the Sun, where temperatures may reach as high as 240 Fahrenheit (120 Celsius).

As the Sun tracks through the lunar day, the surface frost that may accumulate in these cold, shaded areas is slowly exposed to sunlight and cycled into the Moon’s exosphere. The water molecules then refreeze onto the surface, reaccumulating as frost in other cold, shaded locations.

“Frost is far more mobile than trapped water,” said Davidsson. “Therefore, this model provides a new mechanism that explains how water moves between the lunar surface and the thin lunar atmosphere.”

A Closer Look

While this isn’t the first study to consider surface roughness when calculating lunar surface temperatures, previous work did not take into account how shadows would affect the capability of water molecules to remain on the surface during daytime as frost. This new study is important because it helps us to better understand how lunar water is released into, and removed from, the Moon’s exosphere.

“Understanding water as a resource is essential for NASA and commercial endeavors for future human lunar exploration,” Hosseini said. “If water is available in the form of frost in sunlit regions of the Moon, future explorers may use it as a resource for fuel and drinking water. But first, we need to figure out how the exosphere and surface interact and what role that plays in the cycle.”

To test this theory, Hosseini is leading a team to develop ultra-miniature sensors to measure the faint signals from water ice. The Heterodyne OH Lunar Miniaturized Spectrometer (HOLMS) is being developed to be used on small stationary landers or autonomous rovers – like JPL’s Autonomous Pop-Up Flat Folding Explorer Robot (A-PUFFER), for example – that may be sent to the Moon in the future to make direct measurements of hydroxyl (a molecule that contains one hydrogen atom and an oxygen atom).

Hydroxyl, which is a molecular cousin of water (a molecule with two hydrogen atoms and one oxygen atom), can serve as an indicator of how much water may be present in the exosphere. Both water and hydroxyl could be created by meteorite impacts and through solar wind particles hitting the lunar surface, so measuring the presence of these molecules in the Moon’s exosphere can reveal how much water is being created while also showing how it moves from place to place. But time is of the essence to make those measurements.

“The current lunar exploration by several nations and private companies indicates significant artificial changes to the lunar environment in the near future,” said Hosseini. “If this trend continues, we will lose the opportunity to understand the natural lunar environment, particularly the water that is cycling through the Moon’s pristine exosphere. Consequently, the advanced development of ultra-compact, high-sensitivity instruments is of critical importance and urgency.”

The researchers point out that this new study could help us better understand the role shadows play in the accumulation of water ice and gas molecules beyond the Moon, such as on Mars or even on the particles in Saturn rings.

The study, titled “Implications of surface roughness in models of water desorption on the Moon”, was published in the Monthly Notices of the Royal Astronomical Society on August 2, 2021.

Featured image: The Moon is covered with craters and rocks, creating a surface “roughness” that casts shadows, as seen in this photograph from the 1972 Apollo 17 mission. Image Credit:  NASA


Provided by Jet Propulsion Laboratory

Dated One of the Oldest Craters on the Moon (Planetary Science)

A new analysis of a sample of lunar rock collected by astronauts on the Apollo 17 mission reveals that the Serenity basin is even older than previously thought. The formation of this large crater, estimated thanks to new dating techniques and numerical simulations, dates back to 4.2 billion years ago, even before the intense late bombardment that produced many of the impact craters on the Moon.

Even with the naked eye, the Moon shows more or less dark areas which, when observed in more detail, tell the billions of years of history of our natural satellite. While on Earth the meteorological phenomena, water and tectonic activity tend to erase the signs of the celestial bodies that have affected it during its long history, the absence of these elements on the Moon forever preserves the memory of each impact on its surface. Now, by studying a sample of the lunar soil brought back to Earth in 1972 by astronauts from the Apollo 17 mission , the latest in the historic NASA series, an international team of researchers has refined the estimate of the age of the crater known as the Serenitatis basin , or basin. of Serenity, created by an impact 4.2 billion years ago .

Since the first observations, the Serenity basin – which includes the most famous sea ​​of ​​Serenity , the landing site not only of Apollo 17 but also of the Soviet robotic mission Luna 21 in 1973 – has been considered one of the oldest of the great craters on the face of the Moon turning towards our planet. Estimating its age through the analysis of the rocks collected by astronauts was one of the scientific objectives of the Apollo 17 mission – the one that, among the six landed on the lunar surface, brought back most of the samples, over one hundred kilos. In the past, analysis of the samples from this mission had associated most of them with a more recent impact, linked to the formation of the nearby Imbrium basin, whose material would have been thrown over great distances, covering much of the ‘near face’ of the Moon. This mixing complicates the determination of the actual age of the Serenity basin, initially indicating a value of approximately 3.8–3.9 billion years.

The new study, based in particular on a rock collected by astronauts at Station 8 on the route of their second extravehicular activity, now pushes this estimate back by 300 million years . The results of the research, led by the Open University (UK) and with the participation of researchers from the University of Portsmouth (UK), the Royal Ontario Museum, the University of Toronto and the Université de Sherbrooke (Canada), Swedish Museum of Natural History (Sweden) and Curtin University (Australia), have been published in Nature Communications Earth and Environment .

“We have long observed this fascinating specimen and tried to unravel its complex radiogenic ages,” says lead author Ana Černok of the Open University, Royal Ontario Museum and the University of Toronto. “It has been difficult to establish the exact link of the samples with the Serenitatis basin since the Apollo 17 collection was reported, because it was not easy to distinguish between the samples formed by the Imbrium event and those formed by Serenitatis.”

The Geoscience Atom Probe Facility at Curtin University, used in this study. Credits: Curtin University

To obtain accurate dating of the sample, the team used an innovative technique from materials science, atomic probe tomography , along with numerical simulations of the impacts. The combination of these methods made it possible to link the microscopic-scale study of a small sample of the moon to the moment when, billions of years ago, a celestial body hit the surface of the Moon. «The dating techniques (uranium-lead geochronology) have suggested that this sample of the Serenitatis basin on the Moon is very old, about 4.2 billion years, that is, only about 350 million years younger than the entire Solar System, making it a precious sample for knowing the primordial evolution of the Moon and the origin of our planet “, explains the co-authorKatarina Miljkovic , associate professor at Curtin University.

In the history of the Earth-Moon system, this result indicates that the crater may even precede the beginning of the ‘ late heavy bombardment – in English late heavy bombardment (LHB), or the time during which the planets of the inner solar system were subjected to numerous impacts from asteroids and comets, which is between 4.1 and 3.8 billion years ago. Alternatively, the new measure could call into question the very duration of the Lhb, in support of a more prolonged period whose very early stages could coincide with the formation of the Serenitatis basin.

The new-technique analysis of a long-studied lunar sample also offers a new key to studying the atomic-scale processes occurring in minerals hit by extreme astronomical impacts. The distribution of the atoms in the analyzed sample, Miljkovic points out, shows that it “underwent not one, but two impact events. The second impact transported the sample close to its resting place where it was collected by the astronauts ».

Featured image: The Serenity basin, one of the oldest craters on the near side of the Moon, landing site for the Apollo 17 mission. Credits: Wikipedia


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Queqiao: The Bridge Between Earth and the Far Side of the Moon (Astronomy)

Researchers explain the design of the relay communication satellite that enabled us to peek at the hidden face of the moon

Because of a phenomenon called gravitational locking, the Moon always faces the Earth from the same side. This proved useful in the early lunar landing missions in the 20th century, as there was always a direct line of sight for uninterrupted radiocommunications between Earth ground stations and equipment on the Moon. However, gravitational locking makes exploring the hidden face of the moon–the far side–much more challenging, because signals cannot be sent directly across the Moon towards Earth.

Still, in January 2019, China’s lunar probe Chang’e-4 marked the first time a spacecraft landed on the far side of the Moon. Both the lander and the lunar rover it carried have been gathering and sending back images and data from previously unexplored areas. But how does Chang’e-4 probe communicate with the Earth? The answer is Queqiao, a relay communications satellite, explains Dr. Lihua Zhang from DFH Satellite Co., Ltd., China.

As explained by Dr. Zhang in a review paper recently published in Space: Science & Technology, Queqiao is an unprecedented satellite designed specifically for one purpose: to act as a bridge between Chang’e-4 probe and the Earth. Queqiao was launched in 2018 and put into orbit around a point ‘behind’ the Moon. This point is known as the Earth-Moon Libration point 2, where a special case of gravitational balance allows Queqiao to maintain an orbit such that it has almost constant direct line of sight with both the far side of the Moon and the Earth. Getting the satellite into this peculiar orbit required careful planning and maintenance management, and the success of this operation set a precedent for future attempts at putting satellites in orbit around other Earth-Moon libration points.

From its stable place in space, Queqiao helped guide the soft-landing and surface operations of Chang’e-4 probe and has been our intermediary with it ever since. The satellite is equipped with two different kinds of antennas: a parabolic antenna and several spiral antennas. The former, which has a large diameter of 4.2 m, was designed to send and receive signals on the X band (7-8GHz) to and from the rover and lander on the surface of the Moon. Its large size is related the expected noise levels and the low intensity of the transmissions that are sent by surface equipment.

On the other hand, the spiral antennas operate on the S band (2-4 GHz) and communicate with Earth ground stations, forwarding commands to the lunar surface equipment and exchanging telemetry and tracking data. Most notably, all these different links can transmit and receive simultaneously, making Queqiao highly versatile. The review paper addresses other important design considerations for Queqiao and future relay satellites, such as the use of regenerative forwarding, the various link data rates involved, and data storage systems for when no Earth ground station is accessible.

Over two years of exploration, a great amount of data has been received from the rover and lander through Queqiao. “Scientists in both China and other countries have conducted analysis and research based on the retrieved data, and they have produced valuable scientific results. The longer the operational life of Queqiao, the more scientific outcomes will be achieved,” remarks Dr. Zhang. Based on current predictions, Queqiao should be operable on mission orbit for at least five years.

Dr. Zhang also addressed the prospects for future lunar missions and how relay communication systems should evolve to support them. Many unexplored areas on the Moon, such as the largest crater at the South Pole, call for multiple relay satellites to maintain constant communication links, which poses an expensive and time-consuming challenge. But what if relay satellites were suitable for more than a single mission? “A sustainable communication and navigation infrastructure should be established to benefit all lunar missions rather than dealing with each mission independently,” comments Dr. Zhang, “This infrastructure should adopt an open and extensible architecture and provide flexible, interoperable, cross-supportable, and compatible communications services, which are critical to the success of future lunar explorations.” It’s likely that future endeavors on the far side of the Moon will be a test on how well we can cooperate to unveil the secrets of our natural satellite.

Featured image: The far side of the Moon always faces away from the Earth, making communications from lunar equipment there much more challenging. Fortunately, relay communication satellites can act as a bridge or stepping stone between transmission from the far side towards Earth ground stations. © Space: Science & Technology


Reference


Provided by Cactus Communications

Researchers Prepare To Send Fungi For A Ride Around the Moon (Astronomy / Biology)

Microbiologists at the U.S. Naval Research Laboratory are preparing experimental samples of fungi to send for a ride around the moon tentatively scheduled for later in 2021 or early 2022.

The experiment aims to provide insight into fungi’s natural defenses against radiation, a phenomenon that could prove useful for future space exploration and sustained life in space.

“During this past year, we successfully completed the Scientific Verification Test to ensure the experiment is working in our lab, which is the first step of this project,” said Zheng Wang, NRL microbiologist and the principal investigator on this project. “Additionally, since October 2020 we have accomplished Experimental Verification Test at Kennedy Space Center, which mimics the flight environment for about two months.”

Fungi have natural mechanisms to protect from and repair DNA damage caused by radiation. Those mechanisms enable the fungi to withstand several hundred times more radiation than humans. This experiment will study the melanin in fungi (which may assist in protecting them from damage), as well as DNA repair pathways (which repair damage once it occurs). The fungus used for this experiment will be Aspergillus niger, a black mold commonly used in laboratories and industry and also one of the predominant fungi detected on the International Space Station (ISS). 

“We are looking at fungi that are extremely resistant to radiation and trying to figure out why,” said Jillian Romsdahl, a microbiologist and NRC postdoctoral fellow on the project. “But we are also looking at a bigger question of how biological systems adapt to deep space, which has implications for people trying to travel to Mars or further.”

The researchers are preparing four different samples of Aspergillus niger — one wild type strain and three mutated strains that were genetically engineered in the laboratory. One mutated strain is defective in making melanin, so it can be compared to the wild type strain that does produce melanin. 

The other two mutated strains will be deficient in DNA repair pathways. Wang’s group wants to know how important those DNA pathways are in protecting the fungal cells against damage caused by radiation. They also want to know if the radiation stimulates new DNA pathways not yet discovered.

During the actual experiment, the fungal samples will be stored in NASA’s Orion capsule and launched into space, where it will travel around the moon for three weeks. Once complete, NASA will return the specimens to NRL for analysis.

Researchers plan to compare the samples to look for changes to the DNA and other biomolecules. The fungal cells will undergo a thorough analysis of morphological, physiological, and chemical changes.

Long-term, researchers hope to use the knowledge gained to investigate new ways to prevent radiation damage to humans and equipment in space. 

The NRL team is investigating these research questions from other angles as well. Wang’s research group was recently selected by NASA to study how melanized fungal cells adapt to Mars-like conditions using NASA’s Antarctic balloon platform. The team is also collaborating with DoD’s Space Testing Program and ISS National Laboratory to send fungal samples to the International Space Station to study how microgravity and radiation alter production of beneficial biomaterials and biomolecules. 

“Fungi are great at adapting”, Wang said. If we can harness their natural defense mechanisms, we could leverage biological systems to develop protective mechanisms for equipment or astronauts. As a DoD lab, NRL is in a great position for this. We have the facilities and the capabilities.”

Zachary Schultzhaus, a former Jerome and Isabella Karle Distinguished Scholar Fellow and another researcher on the project, said he believes it is also feasible to grow fungus in space to produce different molecules for therapeutic applications, like medicine or vitamins. Instead of carrying all of the food and medicine needed for a mission, astronauts could produce it on demand. He hopes to delve deeper into the idea once this current research project concludes. 

NRL’s work on investigating the roles of melanin and DNA repair on adaptation and survivability of fungi in deep space is funded by NASA, and is scheduled to continue through 2022. 

Featured image: Drs. Zachary Schultzhaus (left), Zheng Wang (center), and Jillian Romsdahl (right) from the U.S. Naval Research Laboratory’s fungal biology research team observe a fungal agar plate in Washington, D.C., Nov. 13, 2019. The fungus Aspergillus niger, along with its three mutant strains, are slated to rotate the moon on NASA’s Orion Space Capsule in 2021 so researchers can improve their understanding of the fungi’s natural and adapted defenses against radiation. (U.S. Navy photo by Sarah Peterson)


Provided by US Naval Research Laboratory

Moon Mission Delays Could Increase Risks From Solar Storms (Astronomy)

Planned missions to return humans to the Moon need to hurry up to avoid hitting one of the busiest periods for extreme space weather, according to scientists conducting the most in-depth ever look at solar storm timing.

Scientists at the University of Reading studied 150 years of space weather data to investigate patterns in the timing of the most extreme events, which can be extremely dangerous to astronauts and satellites, and even disrupt power grids if they arrive at Earth.

The researchers found for the first time that extreme space weather events are more likely to occur early in even-numbered solar cycles, and late in odd-numbered cycles – such as the one just starting. They are also more likely during busy periods of solar activity and in bigger cycles, mirroring the pattern for moderate space weather.

The findings, published in the journal Solar Physics, could have implications for the NASA-led Artemis mission, which plans to return humans to the moon in 2024, but which could be delayed to the late 2020s.

Professor Mathew Owens, a space physicist at the University of Reading, said: “Until now, the most extreme space-weather events were thought to be random in their timing and thus little could be done to plan around them.

“However, this research suggests they are more predictable, generally following the same ‘seasons’ of activity as smaller space-weather events. But they also show some important differences during the most active season, which could help us avoid damaging space-weather effects.  

“These new findings should allow us to make better space weather forecasts for the solar cycle that is just beginning and will run for the decade or so. It suggests any significant space missions in the years ahead – including returning astronauts to the Moon and later, onto Mars – will be less likely to encounter extreme space-weather events over the first half of the solar cycle than the second.”

Extreme space weather is driven by huge eruptions of plasma from the Sun, called coronal mass ejections, arriving at Earth, causing a global geomagnetic disturbance.

Previous research has generally focused on how big extreme space weather events can be, based on observations of previous events. Predicting their timing is far more difficult because extreme events are rare, so there is relatively little historic data in which to identify patterns.

In the new study, the scientists used a new method applying statistical modelling to storm timing for the first time. They looked at data from the past 150 years – the longest period of data available for this type of research – recorded by ground-based instruments that measure magnetic fields in the Earth’s atmosphere, located in the UK and Australia.

The Sun goes through regular 11-year cycles of its magnetic field, which is seen in the number of sunspots on its surface. During this cycle the Sun’s magnetic north and south poles switch places. Each cycle includes a solar maximum period, where solar activity is at its greatest, and a quiet solar minimum phase.

Previous research has shown moderate space weather is more likely during the solar maximum than the period around the solar minimum, and more likely during cycles with a larger peak sunspot number. However, this is the first study that shows the same pattern is also true of extreme events.

The major finding, though, was that extreme space weather events are more likely to occur early in even-numbered solar cycles, and late in odd-numbered cycles, such as cycle 25, which began in December 2019.

The scientists believe this could be because of the orientation of the Sun’s large-scale magnetic field, which flips at solar maximum so it is pointing opposite to Earth’s magnetic field early in even cycles and late in odd cycles. This theory will need more investigation.

This new research on space weather timing allows predictions to be made for extreme space weather during solar cycle 25. It could therefore be used to plan the timing of activities that could be affected by extreme space weather, such as power grid maintenance on Earth, satellite operations, or major space missions.

The findings suggest that any major operations planned beyond the next five years will have to make allowances for the higher likelihood of severe space weather late in the current solar cycle between 2026 and 2030.

major solar eruption in August 1972, between NASA’s Apollo 16 and 17 missions, was strong enough that it could have caused major technical or health problems to astronauts had it occurred while they were en route or around the Moon.


Provided by University of Reading

Measuring the Moon’s Nano Dust is No Small Matter (Planetary Science)

Like a chameleon of the night sky, the Moon often changes its appearance. It might look larger, brighter or redder, for example, due to its phases, its position in the solar system or smoke in Earth’s atmosphere. (It is not made of green cheese, however.)

Another factor in its appearance is the size and shape of moon dust particles, the small rock grains that cover the moon’s surface. Researchers at the National Institute of Standards and Technology (NIST) are now measuring tinier moon dust particles than ever before, a step toward more precisely explaining the Moon’s apparent color and brightness. This in turn might help improve tracking of weather patterns and other phenomena by satellite cameras that use the Moon as a calibration source.

NIST researchers and collaborators have developed a complex method of measuring the exact three-dimensional shape of 25 particles of moon dust collected during the Apollo 11 mission in 1969. The team includes researchers from the Air Force Research Laboratory, the Space Science Institute and the University of Missouri-Kansas City.

These researchers have been studying moon dust for several years. But as described in a new journal paper, they now have X-ray nano computed tomography (XCT), which allowed them to examine the shape of particles as small as 400 nanometers (billionths of a meter) in length.

The research team developed a method for both measuring and computationally analyzing how the dust particle shapes scatter light. Follow-up studies will include many more particles, and more clearly link their shape to light scattering. Researchers are especially interested in a feature called “albedo,” moonspeak for how much light or radiation it reflects.

The recipe for measuring the Moon’s nano dust is complicated. First you need to mix it with something, as if making an omelet, and then turn it on a stick for hours like a rotisserie chicken. Straws and dressmakers’ pins are involved too.

“The procedure is elaborate because it is hard to get a small particle by itself, but one needs to measure many particles for good statistics, since they are randomly distributed in size and shape,” NIST Fellow Ed Garboczi said.

“Since they are so tiny and because they only come in powders, a single particle needs to be separated from all the others,” Garboczi continued. “They are too small to do that by hand, at least not in any quantity, so they must be carefully dispersed in a medium. The medium must also freeze their mechanical motion, in order to be able to get good XCT images. If there is any movement of the particles during the several hours of the XCT scan, then the images will be badly blurred and generally not usable. The final form of the sample must also be compatible with getting the X-ray source and camera close to the sample while it rotates, so a narrow, straight cylinder is best.”

The procedure involved stirring the Apollo 11 material into epoxy, which was then dripped over the outside of a tiny straw to get a thin layer. Small pieces of this layer were then removed from the straw and mounted on dressmakers’ pins, which were inserted into the XCT instrument.

The XCT machine generated X-ray images of the samples that were reconstructed by software into slices. NIST software stacked the slices into a 3D image and then converted it into a format that classified units of volume, or voxels, as either inside or outside the particles. The 3D particle shapes were identified computationally from these segmented images. The voxels making up each particle were saved in separate files that were forwarded to software for solving electromagnetic scattering problems in the visible to the infrared frequency range.

The results indicated that the color of light absorbed by a moon dust particle is highly sensitive to its shape and can be significantly different from that of spherical or ellipsoidal particles of the same size. That doesn’t mean too much to the researchers — yet.

“This is our first look at the influence of actual shapes of lunar particles on light scattering and focuses on some fundamental particle properties,” co-author Jay Goguen of the Space Science Institute said. “The models developed here form the basis of future calculations that could model observations of the spectrum, brightness and polarization of the moon’s surface and how those observed quantities change during the moon’s phases.”

The authors are now studying a wider range of moon dust shapes and sizes, including particles collected during the Apollo 14 mission in 1971. The moon dust samples were loaned to NIST by NASA’s Curation and Analysis Planning Team for Extraterrestrial Materials program.

Featured image: Colorized screenshots of the exact shapes of moon dust collected during the Apollo 11 mission. NIST researchers and collaborators developed a method of measuring these nanoscale particles as a prelude to studying their light-scattering properties. © Credit: E. Garboczi/NIST and A. Sharits/AFRL


Paper: S. Baidya, M. Melius, A.M. Hassan, A. Sharits, A.N. Chiaramonti, T. Lafarge, J.D. Goguen and E.J. Garboczi. Optical Scattering Characteristics of 3D Lunar Regolith Particles Measured using X-Ray Nano Computed Tomography. IEEE Geoscience and Remote Sensing Letters. Published online April 27, 2021. DOI: 10.1109/LGRS.2021.3073344


Provided by NIST

Galileo Will Help Lunar Pathfinder Navigate Around Moon (Astronomy)

ESA’s Lunar Pathfinder mission to the Moon will carry an advanced satellite navigation receiver, in order to perform the first ever satnav positioning fix in lunar orbit. This experimental payload marks a preliminary step in an ambitious ESA plan to expand reliable satnav coverage – as well as communication links – to explorers around and ultimately on the Moon during this decade.

Due for launch by the end of 2023 into lunar orbit, the public-private Lunar Pathfinder comsat will offer commercial data relay services to lunar missions – while also stretching the operational limits of satnav signals.

Galileo constellation © ESA

Navigation satellites like Europe’s Galileo constellation are intended to deliver positioning, navigation and timing services to our planet, so most of the energy of their navigation antennas radiates directly towards the Earth disc, blocking its use for users further away in space. 

“But this is not the whole story,” explains Javier Ventura-Traveset, leading ESA’s Galileo Navigation Science Office and coordinating ESA lunar navigation activities. “Navigation signal patterns also radiate sideways, like light from a flashlight, and past testing shows these antenna ‘side lobes’ can be employed for positioning, provided adequate receivers are implemented.”

Galileo ‘side lobe’ signals © ESA

Just like people or cars on the ground, satellites in low-Earth orbit rely heavily on satnav signals to determine their orbital position, and since ESA proved higher-orbit positioning was possible, a growing number of satellites in geostationary orbit today employ satnav receivers.

But geostationary orbit is 35 786 km up, while the Moon is more than ten times further away, at an average distance of 384 000 km. In 2019 however, NASA’s Magnetospheric Multiscale Mission acquired GPS signals to perform a fix and determine its orbit from 187 166 km away, close to halfway the Earth-Moon distance.

Lunar Pathfinder will relay signals from other Moon missions © ESA

Javier adds: “This successful experimental evidence provides us high confidence since the receiver we will embark on Lunar Pathfinder will have a significantly improved sensitivity, employ both Galileo and GPS signals and will also feature a high-gain satnav antenna.”

This high sensitivity receiver’s main antenna was developed through ESA’s General Support Technology Programme, with the receiver’s main unit developed through ESA’s Navigation Innovation and Support Programme, NAVISP.

The receiver project is led by ESA navigation engineer Pietro Giordano: “The high sensitivity receiver will be able to detect very faint signals, millions of times weaker than the ones received on Earth. The use of advanced on-board orbital filters will allow to achieve unprecedented orbit determination accuracy on an autonomous basis.”

Lunar Pathfinder’s receiver is projected to achieve positioning accuracy of around 100 m – more accurate than traditional ground tracking.

The availability of satnav will allow the performance of ‘Precise Orbit Determination’ for lunar satellites, notes Werner Enderle, Head of ESA’s Navigation Support Office: “Traditional orbit determination for lunar orbiting satellites is performed by radio ranging, using deep space ground stations. This Lunar Pathfinder demonstration will be a major milestone in lunar navigation, changing the entire approach. It will not only increase spacecraft autonomy and sharpen the accuracy of results, it will also help to reduce operational costs.”  

While lunar orbits are often unstable, with low-orbiting satellites drawn off course by the lumpy mass concentrations or ‘mascons’ making up the Moon , Lunar Pathfinder is planned to adopt a highly-stable ‘frozen’ elliptical orbit, focused on the lunar south pole – a leading target for future expeditions.

Lunar Pathfinder will focus coverage on the Moon’s south pole © ESA

Earth – and its satnav constellations – should remain in view of Lunar Pathfinder for the majority of testing. The main challlenge will be overcoming the limited geometry of satnav signals all coming from the same part of the sky, along with the low signal power.

Lunar Pathfinder’s demonstration that terrestrial satnav signals can be employed to navigate in lunar orbits will be an important early step in ESA’s Moonlight initiative. Supported through three ESA Directorates, Moonlight will go on to establish a Lunar Communication and Navigation Service.

 “Over this coming decade, ESA aims to contribute to building up a common communications and navigation infrastructure for all lunar missions based on dedicated lunar satellites,” explains Bernhard Hufenbach, managing commercialisation and innovation initiatives for space exploration at ESA.

“Moonlight will allow to support missions that cannot use Earth satnav signals, such as landers on the far side and is planning to cover the current gap towards the needs expressed by the Global Exploration community, targeting positioning accuracy below 50 metres.”

Extending satnav to the Moon © ESA

As well as facilitating lunar exploration, these satnav signals might one day become a tool for science in their own right, used, for example, to perform reflectometry across the lunar surface; sounding the scant dusty ‘exosphere’ that surrounds the Moon or by providing a common time reference signal across the Moon, to be used for fundamental physics or astronomy experiments.

So as well as marking a first in the history of satellite navigation, Javier notes that Lunar Pathfinder’s satnav experiment will have larger consequences: “This will become the first ever demonstration of GPS and Galileo reception in lunar orbit, opening the door to a complete way to navigate spacecraft in deep space, enabling human exploration of the Moon.”

Featured image: Lunar Ride and phone home service


Provided by ESA