SPACE/COSMOLOGY
CubeSats, the tiniest of satellites, are changing the way we explore the solar system
The Conversation
September 28, 2024
CubeSats, as depicted in this illustration, make it affordable for universities and private companies to launch a satellite into space. Victor Habbick Visions/Science Photo Library via Getty Images
Most CubeSats weigh less than a bowling ball, and some are small enough to hold in your hand. But the impact these instruments are having on space exploration is gigantic. CubeSats – miniature, agile and cheap satellites – are revolutionizing how scientists study the cosmos.
A standard-size CubeSat is tiny, about 4 pounds (roughly 2 kilograms). Some are larger, maybe four times the standard size, but others are no more than a pound.
As a professor of electrical and computer engineering who works with new space technologies, I can tell you that CubeSats are a simpler and far less costly way to reach other worlds.
Rather than carry many instruments with a vast array of purposes, these Lilliputian-size satellites typically focus on a single, specific scientific goal – whether discovering exoplanets or measuring the size of an asteroid. They are affordable throughout the space community, even to small startup, private companies and university laboratories.
Tiny satellites, big advantages
CubeSats’ advantages over larger satellites are significant. CubeSats are cheaper to develop and test. The savings of time and money means more frequent and diverse missions along with less risk. That alone increases the pace of discovery and space exploration.
CubeSats don’t travel under their own power. Instead, they hitch a ride; they become part of the payload of a larger spacecraft. Stuffed into containers, they’re ejected into space by a spring mechanism attached to their dispensers. Once in space, they power on. CubeSats usually conclude their missions by burning up as they enter the atmosphere after their orbits slowly decay.
Case in point: A team of students at Brown University built a CubeSat in under 18 months for less than US$10,000. The satellite, about the size of a loaf of bread and developed to study the growing problem of space debris, was deployed off a SpaceX rocket in May 2022.
A CubeSat can go from whiteboard to space in less than a year.
Smaller size, single purpose
Sending a satellite into space is nothing new, of course. The Soviet Union launched Sputnik 1 into Earth orbit back in 1957. Today, about 10,000 active satellites are out there, and nearly all are engaged in communications, navigation, military defense, tech development or Earth studies. Only a few – less than 3% – are exploring space.
That is now changing. Satellites large and small are rapidly becoming the backbone of space research. These spacecrafts can now travel long distances to study planets and stars, places where human explorations or robot landings are costly, risky or simply impossible with the current technology.
But the cost of building and launching traditional satellites is considerable. NASA’s lunar reconnaissance orbiter, launched in 2009, is roughly the size of a minivan and cost close to $600 million. The Mars reconnaissance orbiter, with a wingspan the length of a school bus, cost more than $700 million. The European Space Agency’s solar orbiter, a 4,000-pound (1,800-kilogram) probe designed to study the Sun, cost $1.5 billion. And the Europa Clipper – the length of a basketball court and scheduled to launch in October 2024 to the Jupiter moon Europa – will ultimately cost $5 billion.
These satellites, relatively large and stunningly complex, are vulnerable to potential failures, a not uncommon occurrence. In the blink of an eye, years of work and hundreds of millions of dollars could be lost in space.
NASA scientists prep the ASTERIA spacecraft for its April 2017 launch. NASA/JPL-Caltech
Exploring the Moon, Mars and the Milky Way
Because they are so small, CubeSats can be released in large numbers in a single launch, further reducing costs. Deploying them in batches – known as constellations – means multiple devices can make observations of the same phenomena.
For example, as part of the Artemis I mission in November 2022, NASA launched 10 CubeSats. The satellites are now trying to detect and map water on the Moon. These findings are crucial, not only for the upcoming Artemis missions but to the quest to sustain a permanent human presence on the lunar surface. The CubeSats cost $13 million.
The MarCO CubeSats – two of them – accompanied NASA’s Insight lander to Mars in 2018. They served as a real-time communications relay back to Earth during Insight’s entry, descent and landing on the Martian surface. As a bonus, they captured pictures of the planet with wide-angle cameras. They cost about $20 million.
CubeSats have also studied nearby stars and exoplanets, which are worlds outside the solar system. In 2017, NASA’s Jet Propulsion Laboratory deployed ASTERIA, a CubeSat that observed 55 Cancri e, also known as Janssen, an exoplanet eight times larger than Earth, orbiting a star 41 light years away from us. In reconfirming the existence of that faraway world, ASTERIA became the smallest space instrument ever to detect an exoplanet.
Two more notable CubeSat space missions are on the way: HERA, scheduled to launch in October 2024, will deploy the European Space Agency’s first deep-space CubeSats to visit the Didymos asteroid system, which orbits between Mars and Jupiter in the asteroid belt.
And the M-Argo satellite, with a launch planned for 2025, will study the shape, mass and surface minerals of a soon-to-be-named asteroid. The size of a suitcase, M-Argo will be the smallest CubeSat to perform its own independent mission in interplanetary space.
The swift progress and substantial investments already made in CubeSat missions could help make humans a multiplanetary species. But that journey will be a long one – and depends on the next generation of scientists to develop this dream.
Mustafa Aksoy, Assistant Professor of Electrical & Computer Engineering, University at Albany, State University of New York
This article is republished from The Conversation under a Creative Commons license. Read the original article.
ESO telescope captures the most detailed infrared map ever of our Milky Way
image:
This collage highlights a small selection of regions of the Milky Way imaged as part of the most detailed infrared map ever of our galaxy. Here we see, from left to right and top to bottom: NGC 3576, NGC 6357, Messier 17, NGC 6188, Messier 22 and NGC 3603. All of them are clouds of gas and dust where stars are forming, except Messier 22, which is a very dense group of old stars.
The images were captured with ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA) and its infrared camera VIRCAM. The gigantic map to which these images belong contains 1.5 billion objects. The data were gathered over the course of 13 years as part of the VISTA Variables in the Vía Láctea (VVV) survey and its companion project, the VVV eXtended survey (VVVX).
view moreCredit: ESO/VVVX survey
Astronomers have published a gigantic infrared map of the Milky Way containing more than 1.5 billion objects ― the most detailed one ever made. Using the European Southern Observatory’s VISTA telescope, the team monitored the central regions of our Galaxy over more than 13 years. At 500 terabytes of data, this is the largest observational project ever carried out with an ESO telescope.
“We made so many discoveries, we have changed the view of our Galaxy forever,” says Dante Minniti, an astrophysicist at Universidad Andrés Bello in Chile who led the overall project.
This record-breaking map comprises 200 000 images taken by ESO’s VISTA ― the Visible and Infrared Survey Telescope for Astronomy. Located at ESO’s Paranal Observatory in Chile, the telescope’s main purpose is to map large areas of the sky. The team used VISTA’s infrared camera VIRCAM, which can peer through the dust and gas that permeates our galaxy. It is therefore able to see the radiation from the Milky Way’s most hidden places, opening a unique window onto our galactic surroundings.
This gigantic dataset [1] covers an area of the sky equivalent to 8600 full moons, and contains about 10 times more objects than a previous map released by the same team back in 2012. It includes newborn stars, which are often embedded in dusty cocoons, and globular clusters –– dense groups of millions of the oldest stars in the Milky Way. Observing infrared light means VISTA can also spot very cold objects, which glow at these wavelengths, like brown dwarfs (‘failed’ stars that do not have sustained nuclear fusion) or free-floating planets that don’t orbit a star.
The observations began in 2010 and ended in the first half of 2023, spanning a total of 420 nights. By observing each patch of the sky many times, the team was able to not only determine the locations of these objects, but also track how they move and whether their brightness changes. They charted stars whose luminosity changes periodically that can be used as cosmic rulers for measuring distances [2]. This has given us an accurate 3D view of the inner regions of the Milky Way, which were previously hidden by dust. The researchers also tracked hypervelocity stars — fast-moving stars catapulted from the central region of the Milky Way after a close encounter with the supermassive black hole lurking there.
The new map contains data gathered as part of the VISTA Variables in the Vía Láctea (VVV) survey [3] and its companion project, the VVV eXtended (VVVX) survey. “The project was a monumental effort, made possible because we were surrounded by a great team,” says Roberto Saito, an astrophysicist at the Universidade Federal de Santa Catarina in Brazil and lead author of the paper published today in Astronomy & Astrophysics on the completion of the project.
The VVV and VVVX surveys have already led to more than 300 scientific articles. With the surveys now complete, the scientific exploration of the gathered data will continue for decades to come. Meanwhile, ESO’s Paranal Observatory is being prepared for the future: VISTA will be updated with its new instrument 4MOST and ESO's Very Large Telescope (VLT) will receive its MOONS instrument. Together, they will provide spectra of millions of the objects surveyed here, with countless discoveries to be expected.
Notes
[1] The dataset is too large to release as a single image, but the processed data and objects catalogue can be accessed in the ESO Science Portal.
[2] One way to measure the distance to a star is by comparing how bright it appears as seen from Earth to how intrinsically bright it is; but the latter is often unknown. Certain types of stars change their brightness periodically, and there is a very strong connection between how quickly they do this and how intrinsically luminous they are. Measuring these fluctuations allows astronomers to work out how luminous these stars are, and therefore how far away they lie.
[3] Vía Láctea is the Latin name for the Milky Way.
More information
This research was presented in a paper entitled “The VISTA Variables in the Vía Láctea eXtended (VVVX) ESO public survey: Completion of the observations and legacy” published in Astronomy & Astrophysics (https://doi.org/10.1051/0004-6361/202450584). Data DOI: VVV, VVVX.
The team is composed of R. K. Saito (Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, Brazil [UFSC]), M. Hempel (Instituto de Astrofísica, Dep. de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Providencia, Chile [ASTROUNAB] and Max Planck Institute for Astronomy, Heidelberg, Germany), J. Alonso-García (Centro de Astronomía, Universidad de Antofagasta, Antofagasta, Chile [CITEVA] and Millennium Institute of Astrophysics, Providencia, Chile [MAS]), P. W. Lucas (Centre for Astrophysics Research, University of Hertfordshire, Hatfield, United Kingdom [CAR]), D. Minniti (ASTROUNAB; Vatican Observatory, Vatican City, Vatican City State [VO] and UFSC), S. Alonso (Departamento de Geofísica y Astronomía, CONICET, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Rivadavia, Argentina [UNSJ-CONICET]), L. Baravalle (Instituto de Astronomía Teórica y Experimental, Córdoba, Argentina [IATE-CONICET]; Observatorio Astronómico de Córdoba, Universidad Nacional de Córdoba, Argentina [OAC]), J. Borissova (Instituto de Física y Astronomía, Universidad de Valparaíso, Valparaíso, Chile [IFA-UV] and MAS), C. Caceres (ASTROUNAB), A. N. Chené (Gemini Observatory, Northern Operations Center, Hilo, USA), N. J. G. Cross (Wide-Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), F. Duplancic (UNSJ-CONICET), E. R. Garro (European Southern Observatory, Vitacura, Chile [ESO Chile]), M. Gómez (ASTROUNAB), V. D. Ivanov (European Southern Observatory, Garching bei München [ESO Germany]), R. Kurtev (IFA-UV and MAS), A. Luna (INAF – Osservatorio Astronomico di Capodimonte, Napoli, Italy [INAF- OACN]), D. Majaess (Mount Saint Vincent University, Halifax, Canada), M. G. Navarro (INAF – Osservatorio Astronomico di Roma, Italy [INAF-OAR]), J. B. Pullen (ASTROUNAB), M. Rejkuba (ESO Germany), J. L. Sanders (Department of Physics and Astronomy, University College London, London, United Kingdom), L. C. Smith (Institute of Astronomy, University of Cambridge, Cambridge, United Kingdom), P. H. C. Albino (UFSC), M. V. Alonso (IATE-CONICET and OAC), E. B. Amôres (Departamento de Física, Universidade Estadual de Feira de Santana, Feira de Santana, Brazil), E. B. R. Angeloni (Gemini Observatory/NSF’s NOIRLab, La Serena, Chile [NOIRLab]), J. I. Arias (Departamento de Astronomía, Universidad de La Serena, La Serena, Chile [ULS]), M. Arnaboldi (ESO Germany), B. Barbuy (Universidade de São Paulo, São Paulo, Brazil), A. Bayo (ESO Germany), J. C. Beamin (ASTROUNAB and Fundación Chilena de Astronomía, Santiago, Chile), L. R. Bedin (Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, Padova, Italy [INAF-OAPd]), A. Bellini (Space Telescope Science Institute, Baltimore, USA [STScI]), R. A. Benjamin (Department of Physics, University of Wisconsin-Whitewater, Whitewater, USA), E. Bica (Departamento de Astronomia, Instituto de Física, Porto Alegre, Brazil [IF – UFRGS]), C. J. Bonatto (IF – UFRGS), E. Botan (Instituto de Ciências Naturais, Humanas e Sociais, Universidade Federal de Mato Grosso, Sinop, Brazil), V. F. Braga (INAF-OAR), D. A. Brown (Vatican Observatory, Tucson, USA), J. B. Cabral (IATE-CONICET and Gerencia De Vinculación Tecnológica, Comisión Nacional de Actividades Espaciales, Córdoba, Argentina), D. Camargo (Colégio Militar de Porto Alegre, Ministério da Defesa, Exército Brasileiro, Brazil), A. Caratti o Garatti (INAF- OACN), J. A. Carballo-Bello (Instituto de Alta Investigación, Universidad de Tarapacá, Arica, Chile [IAI-UTA]), M.Catelan (Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile [Instituto de Astrofísica UC]; MAS and Centro de Astro-Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile [AIUC]), C. Chavero (OAC and Consejo Nacional de Investigaciones Científica y Técnicas, Ciudad Autónoma de buenos Aires, Argentina [CONICET]), M. A. Chijani (ASTROUNAB), J. J. Clariá (OAC and CONICET), G. V. Coldwell (UNSJ-CONICET), C. Contreras Peña (Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea and Research Institute of Basic Sciences, Seoul National University, Seoul, Republic of Korea), C. R. Contreras Ramos (Instituto de Astrofísica UC and MAS), J. M. Corral-Santana (ESO Chile), C. C. Cortés (Departamento de Tecnologías Industriales, Faculty of Engineering, Universidad de Talca, Curicó, Chile), M. Cortés-Contreras (Departamento de Física de la Tierra y Astrofísica & Instituto de Física de Partículas y del Cosmos de la UCM, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Madrid, Spain), P. Cruz (Centro de Astrobiología, CSIC-INTA, Madrid, Spain [CAB]), I. V. Daza-Perilla (CONICET; IATE-CONICET and Facultad de Matemática, Astronomía, Física y Computación, Universidad Nacional de Córdoba, Córdoba, Argentina), V. P. Debattista (University of Central Lancashire, Preston, United Kingdom), B. Dias (ASTROUNAB), L. Donoso (Instituto de Ciencias Astronómicas, de la Tierra y del Espacio, San Juan, Argentina), R. D’Souza (VO), J. P. Emerson (Astronomy Unit, School of Physical and Chemical Sciences, Queen Mary University of London, London, United Kingdom), S. Federle (ESO Chile and ASTROUNAB), V. Fermiano (UFSC), J. Fernandez (UNSJ-CONICET), J. G. Fernández-Trincado (Instituto de Astronomía, Universidad Católica del Norte, Antofagasta, Chile [IA-UCN]), T. Ferreira (Department of Astronomy, Yale University, New Haven, USA), C. E. Ferreira Lopes (Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama, Copiapó, Chile [INCT] and MAS), V. Firpo (NOIRLab), C. Flores-Quintana (ASTROUNAB and MAS), L. Fraga (Laboratorio Nacional de Astrofísica, Itajubá, Brazil), D.Froebrich (Centre for Astrophysics and Planetary Science, School of Physics and Astronomy, University of Kent, Canterbury, United Kingdom), D. Galdeano (UNSJ-CONICET), I. Gavignaud (ASTROUNAB), D. Geisler (Departamento de Astronomía, Universidad de Concepción, Chile [UdeC]; Instituto Multidisciplinario de Investigación y Postgrado, Universidad de La Serena, Chile [IMIP-ULS] and ULS), O. E.Gerhard (Max Planck Institute for Extraterrestrial Physics, Germany [MPE]), W. Gieren (UdeC), O. A. Gonzalez (UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, United Kingdom), L. V. Gramajo (OAC and CONICET), F. Gran (Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France [Lagrange]), P. M. Granitto (Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas, Rosario, Argentina), M. Griggio (INAF-OAPd; Dipartimento di Fisica, Università di Ferrara, Ferrara, Italy and STScI), Z. Guo (IFA-UV and MAS), S. Gurovich (IATE-CONICET and Western Sydney University, Kingswood, Australia), M. Hilker (ESO Germany), H. R. A. Jones (CAR), R. Kammers (UFSC), M. A. Kuhn (CAR), M. S. N. Kumar (Centro de Astrofísica da Universidade do Porto, Porto, Portugal), R. Kundu (Miranda House, University of Delhi, India and Inter University centre for Astronomy and Astrophysics, Pune, India), M. Lares (IATE-CONICET), M. Libralato (INAF-OAPd), E. Lima (Universidade Federal do Pampa, Uruguaiana, Brazil), T. J. Maccarone (Department of Physics & Astronomy, Texas Tech University, Lubbock, USA), P. Marchant Cortés (ULS), E. L. Martin (Instituto de Astrofisica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, San Cristóbal de la Laguna, Spain), N. Masetti (Istituto Nazionale di Astrofisica, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Bologna, Italy and ASTROUNAB), N. Matsunaga (Department of Astronomy, Graduate School of Science, The University of Tokyo, Japan), F. Mauro (IA-UCN), I. McDonald (Jodrell Bank Centre for Astrophysics, The University of Manchester, UK [JBCA]), A. Mejías (Departamento de Astronomía, Universidad de Chile, Las Condes, Chile), V. Mesa (IMIP-ULS; Association of Universities for Research in Astronomy, Chile, Grupo de Astrofísica Extragaláctica-IANIGLA; CONICET, and Universidad Nacional de Cuyo, Mendoza, Argentina), F. P. Milla-Castro (ULS), J. H. Minniti (Department of Physics and Astronomy, Johns Hopkins University, Baltimore, USA), C. Moni Bidin (IA-UCN), K. Montenegro (Clínica Universidad de los Andes, Santiago, Chile), C. Morris (CAR), V. Motta (OAC), F. Navarete (SOAR Telescope/NSF’s NOIRLab, La Serena, Chile), C. Navarro Molina (Centro de Docencia Superior en Ciencias Básicas, Universidad Austral de Chile, Puerto Montt, Chile), F. Nikzat (Instituto de Astrofísica UC and MAS), J. L. NiloCastellón (IMIP-ULS and ULS), C. Obasi (IA-UCN and Centre for Basic Space Science, University of Nigeria, Nsukka, Nigeria), M. Ortigoza-Urdaneta (Departamento de Matemática, Universidad de Atacama, Copiapó, Chile), T. Palma (OAC), C. Parisi (OAC and IATE-CONICET), K. Pena Ramírez (NSF NOIRLab/Vera C. Rubin Observatory, La Serena, Chile), L. Pereyra (IATE-CONICET), N. Perez (UNSJ-CONICET), I. Petralia (ASTROUNAB), A. Pichel (Instituto de Astronomía y Física del Espacio, Ciudad Autónoma de Buenos Aires, Argentina [IAFE-CONICET]), G. Pignata (IAI-UTA), S. Ramírez Alegría (CITEVA), A. F. Rojas (Instituto de Astrofísica UC, Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Santiago, Chile and CITEVA), D. Rojas (ASTROUNAB), A. Roman-Lopes (ULS), A. C. Rovero (IAFE-CONICET), S. Saroon (ASTROUNAB), E. O. Schmidt (OAC and IATE-CONICET), A. C. Schröder (MPE), M. Schultheis (Lagrange), M. A. Sgró (OAC), E. Solano (CAB), M. Soto (INCT), B. Stecklum (Thüringer Landessternwarte, Tautenburg, Germany), D. Steeghs (Department of Physics, University of Warwick, UK), M. Tamura (Department of Astronomy, Graduate School of Science, University of Tokyo; Astrobiology Center, Tokyo, Japan, and National Astronomical Observatory of Japan, Tokyo, Japan), P. Tissera (Instituto de Astrofísica UC and AIUC), A. A. R. Valcarce (Departamento de Física, Universidad de Tarapacá, Chile), C. A. Valotto (IATE-CONICET and OAC), S. Vasquez (Museo Interactivo de la Astronomía, La Granja, Chile), C. Villalon (IATE-CONICET and OAC), S. Villanova (UdeC), F. Vivanco Cádiz (ASTROUNAB), R. Zelada Bacigalupo (North Optics, La Serena, Chile), A. Zijlstra (JBCA and School of Mathematical and Physical Sciences, Macquarie University, Sydney, Australia), and M. Zoccali (Instituto de Astrofísica UC and MAS).
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
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Journal
Astronomy and Astrophysics
Chinese scientists analyze first lunar farside samples collected from the other half of the moon
Chinese Academy of Sciences Headquarters
image:
The Topographic Map illustrates the landing sites of the Chang'E Missions, Apollo Missions, and Luna Missions.
view moreCredit: Image by NAOC
A Chinese team of scientists has undertaken a study of lunar samples retrieved by the Chang'E-6 mission. These are the first samples studied from the farside of the Moon. They mark a significant milestone in lunar exploration science and technical exploration capability. The study was published in the journal National Science Review on September 17, 2024.
"As the first lunar sample obtained from the far side of the Moon, the Chang'E-6 sample will provide an unparalleled opportunity for lunar research," said Prof. Chunlai Li, National Astronomical Observatories of the Chinese Academy of Sciences. This unique sample helps to advance the understanding of several key aspects of lunar science, including the Moon's early evolution; the variability of volcanic activities between the nearside and farside; the impact history of the inner solar system; the record of galactic activity preserved in the lunar weathering layer; the lunar magnetic field and its anomalies and duration; and the composition and structure of the lunar crust and mantle. "These insights are expected to lead to new concepts and theories regarding the origin and evolution of the Moon, and refine its use as an interpretive paradigm for the evolution of the terrestrial planets," said Li.
Adding together the lunar samples gathered from the six Apollo missions, three Luna missions, and the Chang'E-5 mission, scientists have collected a total of 382.9812 kg of lunar samples. These lunar samples have provided scientists with critical information on the formation and evolutionary history of the Moon. "Returned lunar samples are essential to planetary science research, as they provide key laboratory data to link orbital remote sensing observations to actual surface ground truth," said Li. The samples have contributed to the development of hypotheses, such as the Moon's giant impact into early Earth origin, the Lunar Magma Ocean, and the Late Heavy Bombardment. These earlier studies of lunar samples, all of them collected from the lunar nearside, have significantly advanced the discipline of planetary science. From a sampling perspective, the farside has remained unexplored until now.
"Nearside samples alone, without adequate sampling from the entire lunar surface, especially from the farside, cannot fully capture the geologic diversity of the entire Moon. This limitation hampers our understanding of the Moon's origin and evolution," said Li. Scientists gained the much-needed farside lunar samples when the Chang'E-6 mission collected 1935.3 grams of lunar samples from the South Pole-Aitken basin on June 25, 2024.
The samples were gathered from the lunar surface using drilling and scooping techniques. The team analyzed the samples' physical, mineralogical, petrographic, and geochemical properties. Their analysis showed that the collected samples reflect a mixture of "local" basaltic material and "foreign" non-mare material. The rock fragments in the Chang'E-6 samples are mainly basalt, breccia, and agglutinates. The primary constituent minerals of the soils are plagioclase, pyroxene, and ilmenite, with very low olivine abundance. The lunar soil in the Chang'E-6 samples is mostly a mixture of local basalts and non-basaltic ejecta materials.
The lunar surface is divided into three very distinct geochemical provinces based on variations in geochemical characterization and petrologic evolutionary history. These are the Procellarum KREEP Terrane (PKT), the Feldspathic Highland Terrane (FHT), and the South Pole-Aitken Terrane (SPAT).
"These local mare basalts document the volcanic history of lunar farside, while the non-basaltic fragments may offer critical insights into the lunar highland crust, South Pole-Aitken impact melts, and potentially the deep lunar mantle, making these samples highly significant for scientific research," said Li.
The lunar samples collected from the nearside by the Apollo, Luna, and Chang'E-5 missions included samples from the PKT and the FHT. Until now, no samples had been collected from the unique SPAT on the lunar farside. Scientists believe the South Pole-Aitken basin was formed 4.2 to 4.3 billion years ago in the Pre-Nectarian period. It is the largest confirmed impact basin in the Solar System.
The research is funded by the Key Research Program of the Chinese Academy of Sciences.
The research team includes: Chunlai Li, Jianjun Liu, Qin Zhou, Xin Ren, Bin Liu, Dawei Liu, Xingguo Zeng, Wei Zuo, Guangliang Zhang, Hongbo Zhang, Saihong Yang, Xingye Gao, Yan Su, and Weibin Wen, from the National Astronomical Observatories of the Chinese Academy of Sciences, Beijing; Hao Hu and Qiong Wang from the Lunar Exploration and Space Engineering Center, Beijing; Meng-Fei Yang and Xiangjin Deng from the Beijing Institute of Spacecraft System Engineering, Beijing; and Ziyuan Ouyang from the National Astronomical Observatories of the Chinese Academy of Sciences, Beijing, and also the Institute of Geochemistry of the Chinese Academy of Sciences, Guiyang.
Journal
National Science Review
Article Title
Nature of the lunar farside samples returned by the Chang'E-6 mission
This rocky planet around a white dwarf resembles Earth — 8 billion years from now
Existence of Earth-like planet around dead sun offers hope for our planet's ultimate survival
University of California - Berkeley
image:
Images of the area of the microlensing event, indicated by perpendicular white lines, years before the event (a), shortly after peak magnification of the background star in 2020 (b) and in 2023 after its disappearance (c). The planetary system with a white dwarf, an Earth-like planet and a brown dwarf cannot be seen; the point of light in (c) is from the background source star that is no longer magnified.
view moreCredit: OGLE, CFHT, Keck Observatory
The discovery of an Earth-like planet 4,000 light years away in the Milky Way galaxy provides a preview of one possible fate for our planet billions of years in the future, when the sun has turned into a white dwarf, and a blasted and frozen Earth has migrated beyond the orbit of Mars.
This distant planetary system, identified by University of California, Berkeley, astronomers after observations with the Keck 10-meter telescope in Hawaii, looks very similar to expectations for the sun-Earth system: it consists of a white dwarf about half the mass of the sun and an Earth-size companion in an orbit twice as large as Earth’s today.
That is likely to be Earth’s fate. The sun will eventually inflate like a balloon larger than Earth's orbit today, engulfing Mercury and Venus in the process. As the star expands to become a red giant, its decreasing mass will force planets to migrate to more distant orbits, offering Earth a slim opportunity to survive farther from the sun. Eventually, the outer layers of the red giant will be blown away to leave behind a dense white dwarf no larger than a planet, but with the mass of a star. If Earth has survived by then, it will probably end up in an orbit twice its current size.
The discovery, to be published this week in the journal Nature Astronomy, tells scientists about the evolution of main sequence stars, like the sun, through the red giant phase to a white dwarf, and how it affects the planets around them. Some studies suggest that for the sun, this process could begin in about 1 billion years, eventually vaporizing Earth's oceans and doubling Earth's orbital radius — if the expanding star doesn't engulf our planet first.
Eventually, about 8 billion years from now, the sun's outer layers will have dispersed to leave behind a dense, glowing ball — a white dwarf — that is about half the mass of the sun, but smaller in size than Earth.
"We do not currently have a consensus whether Earth could avoid being engulfed by the red giant sun in 6 billion years," said study leader Keming Zhang, a former doctoral student at the University of California, Berkeley, who is now an Eric and Wendy Schmidt AI in Science Postdoctoral fellow at UC San Diego. "In any case, planet Earth will only be habitable for around another billion years, at which point Earth's oceans would be vaporized by runaway greenhouse effect — long before the risk of getting swallowed by the red giant."
The planetary system provides one example of a planet that did survive, though it is far outside the habitable zone of the dim white dwarf and unlikely to harbor life. It may have had habitable conditions at some point, when its host was still a sun-like star.
"Whether life can survive on Earth through that (red giant) period is unknown. But certainly the most important thing is that Earth isn't swallowed by the sun when it becomes a red giant," said Jessica Lu, associate professor and chair of astronomy at UC Berkeley. “This system that Keming's found is an example of a planet — probably an Earth-like planet originally on a similar orbit to Earth — that survived its host star's red giant phase.”
Microlensing makes star brighten a thousandfold
The far-away planetary system, located near the bulge at the center of our galaxy, came to astronomers' attention in 2020 when it passed in front of a more distant star and magnified that star's light by a factor of 1,000. The gravity of the system acted like a lens to focus and amplify the light from the background star.
The team that discovered this "microlensing event" dubbed it KMT-2020-BLG-0414 because it was detected by the Korea Microlensing Telescope Network in the Southern Hemisphere. The magnification of the background star — also in the Milky Way, but about 25,000 light years from Earth — was still only a pinprick of light. Nevertheless, its variation in intensity over about two months allowed the team to estimate that the system included a star about half the mass of the sun, a planet about the mass of Earth and a very large planet about 17 times the mass of Jupiter — likely a brown dwarf. Brown dwarfs are failed stars, with a mass just shy of that required to ignite fusion in the core.
The analysis also concluded that the Earth-like planet was between 1 and 2 astronomical units from the star — that is, about twice the distance between the Earth and sun. It was unclear what kind of star the host was because its light was lost in the glare of the magnified background star and a few nearby stars.
To identify the type of star, Zhang and his colleagues, including UC Berkeley astronomers Jessica Lu and Joshua Bloom, looked more closely at the lensing system in 2023 using the Keck II 10-meter telescope in Hawaii, which is outfitted with adaptive optics to eliminate blur from the atmosphere. Because they observed the system three years after the lensing event, the background star that had once been magnified 1,000 times had become faint enough that the lensing star should have been visible if it was a typical main-sequence star like the sun, Lu said.
But Zhang detected nothing in two separate Keck images.
"Our conclusions are based on ruling out the alternative scenarios, since a normal star would have been easily seen," Zhang said. "Because the lens is both dark and low mass, we concluded that it can only be a white dwarf."
"This is a case of where seeing nothing is actually more interesting than seeing something," said Lu, who looks for microlensing events caused by free-floating stellar-mass black holes in the Milky Way.
Finding exoplanets through microlensing
The discovery is part of a project by Zhang to more closely study microlensing events that show the presence of a planet, in order to understand what types of stars exoplanets live around.
"There is some luck involved, because you'd expect fewer than one in 10 microlensing stars with planets to be white dwarfs," Zhang said.
The new observations also allowed Zhang and colleagues to resolve an ambiguity regarding the location of the brown dwarf.
“The original analysis showed that the brown dwarf is either in a very wide orbit, like Neptune's, or well within Mercury’s orbit. Giant planets on very small orbits are actually quite common outside the solar system,” Zhang said, referring to a class of planets called hot Jupiters. “But since we now know it is orbiting a stellar remnant, this is unlikely, as it would have been engulfed.”
The modeling ambiguity is caused by so-called microlensing degeneracy, where two distinct lensing configurations can give rise to the same lensing effect. This degeneracy is related to the one Zhang and Bloom discovered in 2022 using an AI method to analyze microlensing simulations. Zhang also applied the same AI technique to rule out alternative models for KMT-2020-BLG-0414 that may have been missed.
"Microlensing has turned into a very interesting way of studying other star systems that can't be observed and detected by the conventional means, i.e. the transit method or the radial velocity method," Bloom said. "There is a whole set of worlds that are now opening up to us through the microlensing channel, and what's exciting is that we're on the precipice of finding exotic configurations like this."
One purpose of NASA's Nancy Grace Roman Telescope, scheduled for launch in 2027, is to measure light curves from microlensing events to find exoplanets, many of which will need follow up using other telescopes to identify the types of stars hosting the exoplanets.
"What is required is careful follow up with the world's best facilities, i.e. adaptive optics and the Keck Observatory, not just a day or a month later, but many, many years into the future, after the lens has moved away from the background star so you can start disambiguating what you're seeing," Bloom said.
Zhang noted that even if Earth gets engulfed during the sun's red giant phase in a billion or so years, humanity may find a refuge in the outer solar system. Several moons of Jupiter, such as Europa, Callisto and Ganymede, and Enceladus around Saturn, appear to have frozen water oceans that will likely thaw as the outer layers of the red giant expand.
"As the sun becomes a red giant, the habitable zone will move to around Jupiter and Saturn's orbit, and many of these moons will become ocean planets," Zhang said. "I think, in that case, humanity could migrate out there."
Other co-authors are Weicheng Zang and Shude Mao of Tsinghua University in Beijing, China, who co-authored the first paper about KMT-2020-BLG-0414; former UC Berkeley doctoral student Kareem El-Badry, now an assistant professor at the California Institute of Technology in Pasadena; Eric Agol of the University of Washington in Seattle; B. Scott Gaudi of The Ohio State University in Columbus; Quinn Konopacky of UC San Diego; Natalie LeBaron of UC Berkeley; and Sean Terry of the University of Maryland in College Park.
Journal
Nature Astronomy
Article Title
An Earth-Mass Planet and a Brown Dwarf in Orbit Around a White Dwarf
Article Publication Date
26-Sep-2024
Research sheds light on large-scale cosmic structures
The Hebrew University of Jerusalem
image:
Velocity streamlines within the reconstructed volume, with colored envelopes associated with the prominent nearby basins of attraction. The map and streamlines have been cropped to the region covered by Cosmicflows-4 data. The streamlines within a given basin converge onto the region of high concentration of galaxies.
view moreCredit: Daniel Pomarède
A new study has mapped out the gravitational “basins of attraction” in the local Universe, offering fresh insights into the large-scale cosmic structures that shape the movement of galaxies. Using advanced data from the Cosmicflows-4 compilation of distances and velocities of roughly 56,000 galaxies, the international research team applied cutting-edge algorithms to identify regions where gravity dominates, such as the Sloan Great Wall and the Shapley Supercluster. This research suggests that our Milky Way most probably resides within the larger Shapley basin, shifting our understanding of cosmic flows and the role of massive structures in shaping the Universe's evolution.
Link to pictures:
https://drive.google.com/drive/folders/1_QNJizSqkx3swEpG7OXrTE0E2z4Pjim4?usp=sharing
Video: https://youtu.be/xleH4wCyQtQ
Credit: Daniel Pomarède
A team of international researchers has taken a significant step forward in understanding the vast structure of the Universe, identifying key gravitational regions known as "basins of attraction." The research, led by Dr. Valade during his doctoral work under the supervision of Prof. Yehuda Hoffman from Hebrew University and Prof. Noam Libeskind from AIP Potsdam. The work also involved contributions from Dr. Pomarede from the University of Paris-Saclay, Dr. Pfeifer from AIP Potsdam, and Prof. Tully and Dr. Kourkchi from the University of Hawaii.
Understanding the Structure of the Universe
The study is based on the widely accepted Lambda Cold Dark Matter (ΛCDM) standard model of cosmology, which suggests that the Universe's large-scale structure emerged from quantum fluctuations during the early stages of cosmic inflation. These minute fluctuations in density evolved over time, forming the galaxies and clusters we observe today. As these density perturbations grew, they attracted surrounding matter, creating regions where gravitational potential minima, or "basins of attraction," formed.
Innovative Approach Using Cosmicflows-4 Data
Utilizing the latest data from the Cosmicflows-4 (CF4) compilation the team employed a Hamiltonian Monte Carlo algorithm to reconstruct the large-scale structure of the Universe up to a distance corresponding to roughly a billion light years. This method allowed the researchers to provide a probabilistic assessment of the Universe's gravitational domains, identifying the most significant basins of attraction that govern the movement of galaxies.
Key Findings: Laniakea and Shapley Basins of Attraction
Earlier catalogues had suggested that the Milky Way Galaxy was part of a region called the Laniakea Supercluster. However, the new CF4 data offers a slightly different perspective, indicating that Laniakea might be part of the much larger Shapley basin of attraction, which encompasses an even greater volume of the local Universe.
Among the newly identified regions, the Sloan Great Wall stands out as the largest basin of attraction, with a volume of about half a billion cubic lightyears, more than twice the size of the Shapley basin, which was previously considered the largest. These findings provide an unprecedented look into the gravitational landscape of the local Universe, offering new insights into how galaxies and cosmic structures evolve and interact over time.
A Leap Forward in Cosmological Research
This research offers a deeper understanding of the Universe’s intricate gravitational dynamics and the forces that have shaped its structure. The identification of these basins of attraction is a significant advancement in cosmology, potentially reshaping our understanding of cosmic flows and large-scale structures.
This research is important because it deepens our understanding of the large-scale structure of the Universe and the gravitational forces that shape it. By mapping out the basins of attraction—regions where gravity pulls galaxies and matter—the study reveals how massive cosmic structures influence the movement and formation of galaxies over time. Understanding these dynamics not only helps us better grasp the Universe’s past and its ongoing evolution, but also provides valuable insights into fundamental cosmological questions, such as the distribution of dark matter and the forces driving cosmic expansion. This knowledge has the potential to refine our models of the Universe and guide future astronomical research.
Journal
Nature Astronomy
Caption
Envelopes of the prominent basins of attractions superimposed on probable centers of convergence of the streamlines. The distribution of the points reflects the uncertainty in the determination of basins of attraction and their centers.
Credit
Daniel Pomarède
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Identification of basins of attraction in the local universe
Article Publication Date
27-Sep-2024
Our cosmic neighborhood may be 10x larger
University of Hawaii at Manoa
image:
Galaxy motions converge into colored basins of attraction. The Milky Way is shown as the red dot.
view moreCredit: University of Hawaiʻi
A team of international researchers guided by astronomers at University of Hawaiʻi Institute for Astronomy is challenging our understanding of the universe with groundbreaking findings that suggest our cosmic neighborhood may be far larger than previously thought. The Cosmicflows team has been studying the movements of 56,000 galaxies, revealing a potential shift in the scale of our galactic basin of attraction.
A decade ago, the team concluded that our galaxy, the Milky Way, resides within a massive basin of attraction called Laniākea, stretching 500 million light-years across. However, new data suggests that this understanding may only scratch the surface. There is now a 60% probability that we are part of an even grander structure, potentially 10 times larger in volume, centered on the Shapley concentration—a region packed with an immense amount of mass and gravitational pull. The findings were recently published in Nature Astronomy.
“Our universe is like a giant web, with galaxies lying along filaments and clustering at nodes where gravitational forces pull them together,” said UH Astronomer R. Brent Tully, one of the study’s lead researchers. “Just as water flows within watersheds, galaxies flow within cosmic basins of attraction. The discovery of these larger basins could fundamentally change our understanding of cosmic structure.”
Vast cosmos
The universe’s origins date back 13 billion years when tiny differences in density began to shape the cosmos, growing under the influence of gravity into the vast structures we see today. But if our galaxy is part of a basin of attraction much larger than Laniākea, which means immense heaven in the Hawaiian language, it would suggest that the initial seeds of cosmic structure grew far beyond current models.
“This discovery presents a challenge: our cosmic surveys may not yet be large enough to map the full extent of these immense basins,” said UH astronomer and co-author Ehsan Kourkchi. “We are still gazing through giant eyes, but even these eyes may not be big enough to capture the full picture of our universe.”
Gravitational forces
The researchers evaluate these large-scale structures by examining their impact on the motions of galaxies. A galaxy between two such structures will be caught in a gravitational tug-of-war in which the balance of the gravitational forces from the surrounding large-scale structures determines the galaxy’s motion. By mapping the velocities of galaxies throughout our local universe, the team is able to define the region of space where each supercluster dominates.
The researchers are set to continue their quest to map the largest structures of the cosmos, driven by the possibility that our place in the universe is part of a far more expansive and interconnected system than ever imagined.
The international team is composed of UH astronomers Tully and Kourkchi, Aurelien Valade, Noam Libeskind and Simon Pfeifer (Leibniz Institut für Astrophysik Potsdam), Daniel Pomarede (University of Paris-Saclay) and Yehuda Hoffman (Hebrew University).
Laniākea Supercluster
Laniākea, an immense supercluster of galaxies, including our own.
Credit
University of Hawaiʻi
Journal
Nature Astronomy
Article Title
Identification of Basins of Attraction in the Local Universe
Article Publication Date
27-Sep-2024
A new birthplace for asteroid Ryugu
Samples of asteroid Ryugu have once again caused a surprise - and call into question previous ideas about the formation of carbon-rich asteroids.
Max Planck Institute for Solar System Research
image:
About two million years after the formation of the Solar System, the first carbonaceous chondrites made of dust, chondrules, early condensates and iron-nickel grains agglomerated outside the orbit of the still young Jupiter. About two million years later, the CI chondrites were formed by photoevaporation. They incorporated a particularly large number of iron-nickel grains.
view more
Credit: MPS (Fridolin Spitzer)
In December 2020 the space probe Hayabusa 2 brought samples of asteroid Ryugu back to Earth. Since then, the few grams of material have been through quite a lot. After initial examinations in Japan, some of the tiny, jet-black grains traveled to research facilities around the world. There they were measured, weighed, chemically analyzed and exposed to infrared, X-ray and synchroton radiation, among other things. At the MPS, researchers examine the ratios of certain metal isotopes in the samples, as in the current study. Scientists refer to isotopes as variants of the same element that differ only in the number of neutrons in the nucleus. Investigations of this kind can help to understand where in the Solar System Ryugu was formed.
Ryugu's journey through the Solar System
Ryugu is a near-Earth asteroid: Its orbit around the Sun crosses that of Earth (without risk of collision). However, researchers assume that, like other near-Earth asteroids, Ryugu is not native to the inner Solar System, but travelled there from the asteroid belt located between the orbits of Mars and Jupiter. The actual birthplaces of the asteroid belt population are probably even further away from the Sun, outside the orbit of Jupiter.
Ryugu's “family relations” can help shed light on its origin and further evolution. To what degree does Ryugu resemble the representatives of well-known classes of meteorites? These are fragments of asteroids that have made their way from space to Earth. Investigations in recent years have yielded a surprise: Ryugu fits into the large crowd of carbon-rich meteorites, the carbonaceous chondrites, as expected. However, detailed studies of its composition assign it to a rare group: the so-called CI chondrites. These are also known as Ivuna-type chondrites, named after the Tanzanian location where their best-known representative was found. In addition to the Ivuna chondrite itself, only eight others of these exotic specimens have been discovered to date. As their chemical composition is similar to that of the Sun, they are considered to be particularly pristine material that was formed at the outermost edge of the Solar System. “So far, we had assumed that Ryugu's place of origin is also outside Saturn's orbit,” explains MPS scientist Dr. Timo Hopp, co-author of the current study, who has already led earlier investigations into Ryugu's isotopic composition.
The latest analyses by the Göttingen scientists now paint a different picture. For the first time, the team has investigated the ratios of nickel isotopes in four samples of the asteroid Ryugu and six samples of carbonaceous chondrites. The results confirm the close relationship between Ryugu and the CI chondrites. However, the idea of a common birthplace at the edge of the Solar System is no longer compelling.
A missing ingredient
What had happened? Until now, researchers had understood carbonaceous chondrites as mixtures of three “ingredients” that can even be seen with the naked eye in cross-sections. Embedded in fine-grained rock, round, millimeter-sized inclusions as well as smaller, irregularly shaped inclusions are densely packed together. The irregular inclusions are the first material to have condensed into solid clumps in the hot gas disk that once orbited the Sun. The round silicate-rich chondrules formed later. Until now, researchers have attributed differences in the isotopic composition between CI chondrites and other groups of carbonaceous chondrites to different mixing ratios of these three ingredients. CI chondrites, for example, consist predominantly of fine-grained rock, while their siblings are significantly richer in inclusions. However, as the team describes in the current publication, the results of the nickel measurements do not fit into this scheme.
The researchers' calculations now show that their measurements can only be explained by a fourth ingredient: tiny iron-nickel grains, which must also have accumulated during the formation of the asteroids. In the case of Ryugu and the CI chondrites, this process must have been particularly efficient. “Completely different processes must have been at work in the formation of Ryugu and the CI chondrites on the one hand and the other groups of carbonaceous chondrites on the other,” says Fridolin Spitzer from the MPS, first author of the new study, summarizing the basic idea.
According to the researchers, the first carbonaceous chondrites began to form around two million years after the formation of the Solar System. Attracted by the gravitational force of the still young Sun, dust and the first solid clumps made their way from the outer edge of the gas and dust disk into the inner Solar System, but encountered an obstacle along the way: the newly forming Jupiter. Outside its orbit, the heavier and larger clumps in particular accumulated - and thus grew into carbonaceous chondrites with their many inclusions. Towards the end of this development, after around two million years, another process gained the upper hand: under the influence of the Sun, the original gas gradually evaporated outside Jupiter's orbit leading to the accumulation of primarily dust and iron-nickel grains. This led to the birth of the CI chondrites.
“The results surprised us very much. We had to completely rethink - not only with regard to Ryugu, but also with regard to the entire group of CI chondrites,” says Dr. Christoph Burkhard from the MPS. The CI chondrites no longer appear as distant, somewhat exotic relatives of the other carbonaceous chondrites from the outermost edge of the Solar System, but rather as younger siblings that may have formed in the same region, but through a different process and later. “The current study shows how crucial laboratory investigations can be in deciphering the formation history of our Solar System,” says Prof. Dr. Thorsten Kleine, Director of the Department of Planetary Sciences at the MPS and co-author of the study.
Journal
Science Advances
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous condrites,
Article Publication Date
27-Sep-2024
Asteroid Ceres is a former ocean world that slowly formed into a giant, murky icy orb
The asteroid is believed to have a dirty, icy crust according to researchers at Purdue University and NASA
Purdue University
Since the first sighting of the first-discovered and largest asteroid in our solar system was made in 1801 by Giuseppe Piazzi, astronomers and planetary scientists have pondered the make-up of this asteroid/dwarf planet. Its heavily battered and dimpled surface is covered in impact craters. Scientists have long argued that visible craters on the surface meant that Ceres could not be very icy.
Researchers at Purdue University and the NASA's Jet Propulsion Lab (JPL) now believe Ceres is a very icy object that possibly was once a muddy ocean world. This discovery that Ceres has a dirty ice crust is led by Ian Pamerleau, PhD student, and Mike Sori, assistant professor in Purdue’s Department of Earth, Atmospheric, and Planetary Sciences who published their findings in Nature Astronomy. The duo along with Jennifer Scully, research scientist with JPL, used computer simulations of how craters on Ceres deform over billions of years.
“We think that there's lots of water-ice near Ceres surface, and that it gets gradually less icy as you go deeper and deeper,” Sori said. “People used to think that if Ceres was very icy, the craters would deform quickly over time, like glaciers flowing on Earth, or like gooey flowing honey. However, we've shown through our simulations that ice can be much stronger in conditions on Ceres than previously predicted if you mix in just a little bit of solid rock.”
The team’s discovery is contradictory to the previous belief that Ceres was relatively dry. The common assumption was that Ceres was less than 30% ice, but Sori’s team now believes the surface is more like 90% ice.
“Our interpretation of all this is that Ceres used to be an ‘ocean world’ like Europa (one of Jupiter's moons), but with a dirty, muddy ocean,’” Sori said. “As that muddy ocean froze over time, it created an icy crust with a little bit of rocky material trapped in it.”
Pamerleau explained how they used computer simulations to model how relaxation occurs for craters on Ceres over billions of years.
“Even solids will flow over long timescales, and ice flows more readily than rock. Craters have deep bowls which produce high stresses that then relax to a lower stress state, resulting in a shallower bowl via solid state flow," he said. "So the conclusion after NASA’s Dawn mission was that due to the lack of relaxed, shallow craters, the crust could not be that icy. Our computer simulations account for a new way that ice can flow with only a little bit of non-ice impurities mixed in, which would allow for a very ice-rich crust to barely flow even over billions of years. Therefore, we could get an ice-rich Ceres that still matches the observed lack of crater relaxation. We tested different crustal structures in these simulations and found that a gradational crust with a high ice content near the surface that grades down to lower ice with depth was the best way to limit relaxation of Cerean craters.”
Sori is a planetary scientist whose focus is planetary geophysics. His team addresses questions about the planetary interiors, the connections between planetary interiors and surfaces, and those questions might be resolved with spacecraft missions. His work spans many solid bodies in the solar system, from the Moon and Mars to icy objects in the outer solar system.
“Ceres is the largest object in the asteroid belt, and a dwarf planet. I think sometimes people think of small, lumpy things as asteroids (and most of them are!), but Ceres really looks more like a planet,” Sori said. “It is a big sphere, diameter 950 kilometers or so, and has surface features like craters, volcanoes, and landslides.”
On Sept. 27, 2007, NASA launched the Dawn mission. This mission was the first and only spacecraft to orbit two extraterrestrial destinations — the protoplanet Vesta and Ceres. Although it was launched in 2007, Dawn didn’t reach Ceres until 2015. It orbited the dwarf planet until 2018.
“We used multiple observations made with Dawn data as motivation for finding an ice-rich crust that resisted crater relaxation on Ceres. Different surface features (e.g., pits, domes and landslides, etc.) suggest the near subsurface of Ceres contains a lot of ice,” Pamerleau said. “Spectrographic data also shows that there should be ice beneath the regolith on the dwarf planet and gravity data yields a density value very near that of ice, specifically impure ice. We also took a topographic profile of an actual complex crater on Ceres and used it to construct the geometry for some of our simulations.”
Sori says that because Ceres is the largest asteroid there was suspicion that it could have been any icy object based on some estimates of its mass made from the Earth. those factors made it a great choice for a spacecraft visit.
“To me the exciting part of all this, if we're right, is that we have a frozen ocean world pretty close to Earth. Ceres may be a valuable point of comparison for the ocean-hosting icy moons of the outer solar system, like Jupiter's moon Europa and Saturn's moon Enceladus,” Sori said. “Ceres, we think, is therefore the most accessible icy world in the universe. That makes it a great target for future spacecraft missions. Some of the bright features we see at Ceres' surface are the remnants of Ceres' muddy ocean, now mostly or entirely frozen, erupted onto the surface. So we have a place to collect samples from the ocean of an ancient ocean world that is not too difficult to send a spacecraft to.”
This research was supported by a NASA grant (80NSSC22K1062) in the Discovery Data Analysis Program.
About the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University
The Department of Earth, Atmospheric, and Planetary Sciences (EAPS) combines four of Purdue’s most interdisciplinary programs: Geology and Geophysics, Environmental Sciences, Atmospheric Sciences, and Planetary Sciences. EAPS conducts world-class research; educates undergraduate and graduate students; and provides our college, university, state and country with the information necessary to understand the world and universe around us. Our research is globally recognized; our students are highly valued by graduate schools and employers; and our alumni continue to make significant contributions in academia, industry, and federal and state government.
About Purdue University
Purdue University is a public research institution demonstrating excellence at scale. Ranked among top 10 public universities and with two colleges in the top four in the United States, Purdue discovers and disseminates knowledge with a quality and at a scale second to none. More than 105,000 students study at Purdue across modalities and locations, including nearly 50,000 in person on the West Lafayette campus. Committed to affordability and accessibility, Purdue’s main campus has frozen tuition 13 years in a row. See how Purdue never stops in the persistent pursuit of the next giant leap — including its first comprehensive urban campus in Indianapolis, the Mitch Daniels School of Business, Purdue Computes and the One Health initiative — at https://www.purdue.edu/president/strategic-initiatives.
Contributors:
Ian Pamerleau, PhD student with Purdue University’s Department of Earth, Atmospheric, and Planetary Sciences
Mike Sori, assistant professor with the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University
Written by Cheryl Pierce, lead marketing and public relations specialist for the Purdue University College of Science
Journal
Nature Astronomy
Article Title
An ancient and impure frozen ocean on Ceres implied by its ice-rich crust
A new method combining spatiotemporal decomposition and machine learning for the prediction of sunspot numbers and magnetic synoptic maps
image:
We are now entering the solar maximum of Solar Cycle 25. The cover features a time series of sunspot numbers over the past five solar cycles and their predicted results for the next 12 years, along with the magnetic synoptic maps and their predicted results for each solar maximum and minimum. The background of the cover consists of an image of solar extreme ultraviolet radiation and the magnetic field obtained by the potential field source surface model (from the Helioviewer Project), as well as the auroras on Earth associated with solar activities (from the International Space Station; NASA website).
view moreCredit: ©Science China Press
This study is led by Prof. Jiansen He’s team at Peking University and their cooperators from the Chinese Academy of Sciences, sheds light on the prediction of solar activities. The researchers analyze and discuss the potential laws in the spherical harmonic coefficients of solar synoptic magnetic maps. By combining machine learning, mode decomposition, and harmonic reconstruction methods, they achieve predictions for the sunspot numbers and solar magnetic synoptic maps for Solar Cycle 25.
The global spatiotemporal distribution of the solar magnetic field is a crucial factor in determining solar activity, which is closely connected to human society. The topology and complexity of the solar magnetic field are key to understanding solar eruptions and predicting solar activity levels. The study of the photospheric magnetic field’s evolution has a long history, and predicting solar magnetic activity remains a hot topic in the field. However, understanding the global spatiotemporal distribution of the solar magnetic field and how to predict its evolution remains an unresolved and challenging issue.
They first apply wavelet analysis to the spherical harmonic coefficients of synoptic maps, revealing complex short-period disturbances in the photospheric magnetic field around the solar maximum. Furthermore, the harmonic coefficient almost always reaches its peak simultaneously with sunspot numbers, suggesting a potential link to the Sun’s meridional circulation.
Next, the researchers construct a long short-term memory neural network (LSTM) model to predict sunspot numbers for Solar Cycle 25. According to the model, the peak sunspot number for Solar Cycle 25 is expected to occur around June 2024 within an 8-month window, with a peak intensity of 166.9±22.6. Therefore, Solar Cycle 25 is predicted to be stronger than Solar Cycle 24 but slightly weaker than Solar Cycle 23.
The researchers further apply an integrated method to predict the future 5-order magnetic synoptic maps. Using empirical mode decomposition (EMD), each harmonic coefficient is decomposed into several component series, which are then predicted using LSTM. The predicted low-order synoptic maps are reconstructed finally through spherical harmonics reconstruction. The predicted synoptic maps are validated to be consistent with known polarity laws, and quantitative analysis suggests a certain level of reliability.
Although there are still some deviations between the predicted maps and observations, this study fills a gap in the empirical prediction of the global distribution of solar magnetic fields, and offers valuable insights for the future solar observation programs.
See the article:
Prediction of solar activities: Sunspot numbers and solar magnetic synoptic maps
https://doi.org/10.1007/s11430-023-1354-4
Journal
Science China Earth Sciences
