Gravity Study Shows Why the Moon's Two Sides Look So Different
The moon's near side, at left, and far side are seen in a combination of undated images from observations made by NASA's Lunar Reconnaissance Orbiter.
WASHINGTON (Reuters) — An exhaustive examination of lunar gravity using data obtained by two NASA robotic spacecraft is offering new clues about why the two sides of the moon — the one perpetually facing Earth and the other always facing away — look so different.
The data from the U.S. space agency's GRAIL, or Gravity Recovery and Interior Laboratory, mission indicates that the moon's deep interior has an asymmetrical structure, apparently caused by intense volcanism on its nearside billions of years ago that helped shape its surface features.
The researchers discovered that the lunar nearside flexes slightly more than the farside during its elliptical orbit around Earth thanks to our planet's gravitational influence — a process called tidal deformation. This indicates differences in the two sides of the lunar interior, they said, specifically in the geological layer called the mantle.
'Our study shows that the moon's interior is not uniform: the side facing Earth — the nearside — is warmer and more geologically active deep down than the farside,' said Ryan Park, supervisor of the Solar System Dynamics Group at NASA's Jet Propulsion Laboratory in California and lead author of the study published on May 14 in the journal Nature.
The moon's nearside is covered by vast plains, called mare, formed from molten rock that cooled and solidified billions of years ago. Its farside has much more rugged terrain, with few plains.
Some scientists have hypothesized that intense volcanism within the nearside that caused radioactive, heat-generating elements to accumulate on that side of the mantle drove the surface differences observed today. The new findings offer the strongest evidence yet to support this notion.
The researchers estimated that the nearside mantle on average is about 100 C-200 C hotter than the farside, with the thermal difference perhaps sustained by radioactive decay of the elements thorium and titanium on the nearside.
'The moon's nearside and farside look very different, as shown by differences in topography, crustal thickness and the amount of heat-producing elements inside,' Park said.
The moon's diameter of about 3,475 kilometers is a bit more than a quarter of Earth's diameter. The lunar mantle is the layer located beneath the crust and above the core, spanning a depth about 35 kilometers-1,400 kilometers under the surface. The mantle makes up roughly 80% of the moon's mass and volume and is composed mostly of the minerals olivine and pyroxene, similar to Earth's mantle.
'The fact that the detected asymmetry in the mantle matches the pattern of the surface geology — for instance, differences in the abundance of the approximately 3-4 billion-year-old mare basalts [volcanic rock] between the nearside and the farside — suggests that processes which drove ancient lunar volcanism are active today,' said Caltech computational planetary scientist and study coauthor Alex Berne, affiliated with the Jet Propulsion Laboratory working on the design of gravity sensors for missions to the outer solar system.
The researchers spent years analyzing data from GRAIL's Ebb and Flow spacecraft, which orbited the moon from December 2011 to December 2012.
'Our study delivers the most detailed and accurate gravitational map of the moon to date,' Park said.
'This enhanced gravity map is a critical foundation for developing lunar Positioning, Navigation and Timing systems, which are essential for the success of future lunar exploration missions. By improving our understanding of the moon's gravity field, it contributes to establishing a precise lunar reference frame and time system, enabling safer and more reliable navigation for spacecraft and surface operations,' Park added.
The same approach employed here using gravity data to assess the lunar interior, the researchers said, could be applied to other bodies in the solar system such as Saturn's moon Enceladus and Jupiter's moon Ganymede, two worlds of interest in the search for potential life beyond Earth.
In the meantime, the new findings add to the understanding of Earth's eternal companion.
'The moon plays a vital role in stabilizing Earth's rotation and generating ocean tides, which influence natural systems and daily rhythms,' Park said. 'Our knowledge of the moon has expanded through human and robotic missions that have revealed details about its surface and interior, yet many questions about its deep structure and history remain. As our closest neighbor, the moon continues to be an important focus of scientific discovery.'
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yomiuri Shimbun
7 hours ago
- Yomiuri Shimbun
Ancient Proteins Found in Fossils up to 24 Million Years Old
WASHINGTON (Reuters) — Scientists in recent years have made progress in finding ancient DNA in fossils, gaining insight into organisms that lived long ago. But the oldest DNA obtained so far dates back about two million years. Proteins, a cell's molecular machinery, also offer valuable information and have the virtue of surviving much longer, as new research shows. Scientists have now extracted and sequenced proteins from dental fossils of extinct rhinoceroses, elephants and hippopotamuses, including from a rhino tooth 21-24 million years old. Separate research teams found protein fragments in fossils from vastly different environments — the frigid High Arctic of Canada and a scorching rift valley in Kenya. 'Together, these complementary projects demonstrate that proteins — fundamental building blocks of living organisms that preserve information about evolutionary history — can be found in ancient fossils the world over,' said Harvard University evolutionary biologist Daniel Green, lead author of the Kenya fossils study published in the journal Nature. This opens a new frontier for probing the deep evolutionary past, including the human lineage and perhaps even dinosaurs. 'Ancient proteins can tell us about an organism's evolutionary history by providing molecular data from specimens too old for DNA preservation. This allows researchers to clarify evolutionary relationships across the tree of life, even for species that went extinct millions of years ago,' said Ryan Sinclair Paterson, a postdoctoral researcher at the University of Copenhagen's Globe Institute and lead author of the Canada fossil study in Nature. DNA and proteins are fragile and degrade over time, but proteins are more resilient. The oldest-known DNA is from organisms that lived in Greenland two million years ago. Until now, the oldest-known proteins preserved well enough to offer insight on evolutionary relationships were about four million years old, from the Canadian Arctic. The new research pushes the boundaries of ancient protein research, a field called paleoproteomics, back by millions of years. Proteins were obtained from teeth of five rhino, elephant and hippo species that lived 1.5–18 million years ago in Kenya's Turkana region. The proteins showed the ties between the ancient animals and their modern-day relatives. Proteins also were extracted from a fragment of a tooth of an extinct rhino unearthed at a site called Haughton Crater in Nunavut, Canada's northernmost territory, that was up to 24 million years old. They showed how this species fit into the rhino family tree. Haughton Crater's cold and dry conditions were considered ideal for preserving proteins. Preservation in the hot climate of Turkana was more unexpected. DNA and proteins, fundamental molecules in biology, possess distinct structures and functions. Deoxyribonucleic acid is the blueprint for life, bearing instructions for an organism's development, growth and reproduction. Proteins perform numerous functions based on instructions from DNA. 'Proteins are encoded by our genetic code, DNA, so protein sequences reveal information about relatedness between different individuals, and biological sex, among other things,' Green said. The scientists extracted peptides — chains of organic compounds called amino acids that combine to form proteins — found inside tooth enamel. 'Some proteins help build teeth, the hardest and most durable structures in animal bodies,' Green added. 'Enamel is mostly rock: a mineral called hydroxyapatite. But its formation is biologically mediated by proteins that guide both shape and hardness over time. Because these proteins become entombed deep within enamel mineral, we have some reason to expect that protein fragments can be preserved over many millions of years,' Green said. Homo sapiens appeared about 300,000 years ago. Ancient proteins previously have been found in the teeth of some extinct species in the human evolutionary lineage, called hominins. The Turkana region has yielded important hominin fossils. 'Hominins have evolutionary origins and/or diversification in the area where our samples derive, so our results have promise in future exploration of the enamel proteome [set of proteins] of our evolutionary ancestors from the Turkana Basin of Kenya,' said study coauthor Timothy Cleland, a physical scientist at the Smithsonian Museum Conservation Institute in Maryland. The proteins studied came from large-bodied species dating to the age of mammals that followed the demise of the dinosaurs that had dominated during the preceding Mesozoic era, which ended 66 million years ago. Green said that in the new research the number of detectable proteins declined in progressively older fossils. But Green did not rule out finding proteins dating to the age of dinosaurs, saying, 'Newer and better methods for extracting and detecting ancient proteins could, perhaps, push paleoproteomics into the Mesozoic.'
Yomiuri Shimbun
7 hours ago
- Yomiuri Shimbun
Denmark Aims to Host Most Powerful Quantum Computer
STOCKHOLM/COPENHAGEN (Reuters) — The Novo Nordisk Foundation and Denmark's state-owned credit fund said on July 17 they will invest in what they say will be the world's most powerful quantum computer, aiming to revolutionize areas such as drug discovery and materials science. Quantum computing holds the promise of carrying out calculations that would take today's systems millions of years and could unlock discoveries in medicine, chemistry and many other fields where near-infinite seas of possible combinations of molecules confound classical computers. The Novo Nordisk Foundation, the non-profit which controls pharmaceutical giant Novo Nordisk, and Denmark's Export and Investment Fund, said in a statement they would invest €80 million ($92.93 million) in the initiative called QuNorth. Microsoft, which has its largest quantum lab in Denmark, will provide software and Atom Computing will build the quantum computer. The computer will be named Magne, inspired by Norse mythology where Magne, the son of Thor, is known for his immense strength. Construction will begin in autumn and the computer is expected to be ready by the end of next year. The quantum computer will start operating with 50 logical qubits, Jason Zander, Microsoft's executive vice president, told Reuters. A qubit, short for quantum bit, is the basic unit of information in a quantum computer and a logical qubit is a virtual qubit built from many physical qubits to reliably process quantum information. Last November, Microsoft and Atom created 24 logical qubits, the highest number ever created. 'When we get to about 50 logical qubits, that's when we start hitting true quantum advantage,' Zander said. 'I get to the point where I can run something on a quantum computer that I could not run on a classic computer.' 'When the machine gets up to 100 [logical qubits], we can start doing science problems, get up to a couple 100s, we can start doing some chemistry and starting to answer things, and then when all the way up to 1,000, now you are solving everything,' Zander said.
NHK
3 days ago
- NHK
More than 20% of NASA employees opt to leave agency: US media
US media outlets say nearly 4,000 employees have applied to leave the NASA space agency under a program by President Donald Trump's administration to cut federal spending. CBS News and other media have reported that 3,870 staff, or over 20 percent of NASA's workforce, have applied to leave. The agency employs about 18,000 people. The reports said the deadline for applications for the deferred resignation program was on Friday. The Trump administration says NASA will face a 24-percent year-on-year reduction in the budget for the fiscal year that begins in October. About 360 current and former employees of the agency published an open letter on Monday last week to voice their opposition to the spending cuts. The "Voyager Declaration" says, "The last six months have seen rapid and wasteful changes which have undermined our mission and caused catastrophic impacts on NASA's workforce."
