The purpose of this blog is the creation of an open, international, independent and free forum, where every UFO-researcher can publish the results of his/her research. The languagues, used for this blog, are Dutch, English and French.You can find the articles of a collegue by selecting his category. Each author stays resposable for the continue of his articles. As blogmaster I have the right to refuse an addition or an article, when it attacks other collegues or UFO-groupes.
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Deze blog is opgedragen aan mijn overleden echtgenote Lucienne.
In 2012 verloor ze haar moedige strijd tegen kanker!
In 2011 startte ik deze blog, omdat ik niet mocht stoppen met mijn UFO-onderzoek.
BEDANKT!!!
Een interessant adres?
UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN - DE ALLERLAATSTE NIEUWTJES
UFO's of UAP'S in België en de rest van de wereld Ontdek de Fascinerende Wereld van UFO's en UAP's: Jouw Bron voor Onthullende Informatie!
Ben jij ook gefascineerd door het onbekende? Wil je meer weten over UFO's en UAP's, niet alleen in België, maar over de hele wereld? Dan ben je op de juiste plek!
België: Het Kloppend Hart van UFO-onderzoek
In België is BUFON (Belgisch UFO-Netwerk) dé autoriteit op het gebied van UFO-onderzoek. Voor betrouwbare en objectieve informatie over deze intrigerende fenomenen, bezoek je zeker onze Facebook-pagina en deze blog. Maar dat is nog niet alles! Ontdek ook het Belgisch UFO-meldpunt en Caelestia, twee organisaties die diepgaand onderzoek verrichten, al zijn ze soms kritisch of sceptisch.
Nederland: Een Schat aan Informatie
Voor onze Nederlandse buren is er de schitterende website www.ufowijzer.nl, beheerd door Paul Harmans. Deze site biedt een schat aan informatie en artikelen die je niet wilt missen!
Internationaal: MUFON - De Wereldwijde Autoriteit
Neem ook een kijkje bij MUFON (Mutual UFO Network Inc.), een gerenommeerde Amerikaanse UFO-vereniging met afdelingen in de VS en wereldwijd. MUFON is toegewijd aan de wetenschappelijke en analytische studie van het UFO-fenomeen, en hun maandelijkse tijdschrift, The MUFON UFO-Journal, is een must-read voor elke UFO-enthousiasteling. Bezoek hun website op www.mufon.com voor meer informatie.
Samenwerking en Toekomstvisie
Sinds 1 februari 2020 is Pieter niet alleen ex-president van BUFON, maar ook de voormalige nationale directeur van MUFON in Vlaanderen en Nederland. Dit creëert een sterke samenwerking met de Franse MUFON Reseau MUFON/EUROP, wat ons in staat stelt om nog meer waardevolle inzichten te delen.
Let op: Nepprofielen en Nieuwe Groeperingen
Pas op voor een nieuwe groepering die zich ook BUFON noemt, maar geen enkele connectie heeft met onze gevestigde organisatie. Hoewel zij de naam geregistreerd hebben, kunnen ze het rijke verleden en de expertise van onze groep niet evenaren. We wensen hen veel succes, maar we blijven de autoriteit in UFO-onderzoek!
Blijf Op De Hoogte!
Wil jij de laatste nieuwtjes over UFO's, ruimtevaart, archeologie, en meer? Volg ons dan en duik samen met ons in de fascinerende wereld van het onbekende! Sluit je aan bij de gemeenschap van nieuwsgierige geesten die net als jij verlangen naar antwoorden en avonturen in de sterren!
Heb je vragen of wil je meer weten? Aarzel dan niet om contact met ons op te nemen! Samen ontrafelen we het mysterie van de lucht en daarbuiten.
04-11-2023
NASA’s Lucy Spacecraft Finds a Surprise During Its Dinkinesh Asteroid Flyby
NASA/Goddard/SwRI/ASU
NASA’s Lucy Spacecraft Finds a Surprise During Its Dinkinesh Asteroid Flyby
The discovery of a second, smaller asteroid helped test Lucy’s systems.
NASA’s Lucy spacecraft delivered an extra-special data package when it flew past asteroid Dinkinesh in the main asteroid belt between Mars and Jupiter on Wednesday.
Dinkinesh was a trial target for the mission’s terminal tracking system as it flies toward a collection of ancient asteroids near Jupiter called the Trojans. Up until Wednesday, Dinkinesh was considered the smallest asteroid in the main belt to ever get an up-close spacecraft visit. But Dinkinesh was usurped when a tiny moonlet appeared orbiting around it.
DINKINESH AND ITS MOONLET
Lucy principal investigator Hal Levison calls the finding “marvelous.” According to an announcement from NASA published Thursday, the team had some suspicions about a second rock. Dinkinesh changed brightness in the weeks prior to Lucy’s flyby, a hint that, as the spacecraft crept closer, a moonlet was creating noticeable shadows as it passed in front of the larger object.
NASA’s Lucy spacecraft took this image of asteroid Dinkinesh and its small satellite on Wednesday, November 1, 2023, with its Long-Range Reconnaissance Imager (L’LORRI) instrument.
The finding offers bonus science to what was otherwise a test-heavy rendezvous. Dinkinesh is interesting because of its location and diminutive size, at just half a mile across at its widest. The smaller asteroid is a measly 0.15 miles across, roughly the size of half a city block. In the coming weeks, Lucy’s team will download even more data from the encounter. And someday, this could add nuance to what’s already known about the main asteroid belt.
TESTING OUT LUCY’S ABILITY TO LOCK ONTO A TARGET
The goal of the game was to test out Lucy’s systems. When the spacecraft launched in 2021, Lucy was set to test its systems on another main belt asteroid, Donaldjohanson. Last year, the Lucy team realized the spacecraft would fly near Dinkinesh, so they rerouted to get really close. This second testing opportunity provides a more robust evaluation of how well the spacecraft can lock onto a target, a critical feature of the mission that will be doing all of its science while careening past the elusive Trojans at 15,000 miles per hour. }The Trojans are a strange lot. They orbit the Sun inside Jupiter’s orbit, just ahead and behind the gas giant as two grand swarms. Lucy will spend the great majority of its time flying through space, weaving through the inner Solar System, and getting just moments to take imagery and data on each one. Wednesday’s flyby is giving the team confidence that Lucy is prepped for what lies ahead for this decade.
NASA has released footage showing a massive 'canyon of fire' about twice the size of the US shooting out from the sun on Halloween day.
The feature was a tremendous explosion of radiation that measured 6,200 miles wide and 62,000 miles long - large enough for the American Space Agency's Perseverance rover to see it on Mars, which is 145.59 million miles away.
The plasma ravine was around double the size of the entire United States and 50 times longer than the largest-known crater in our solar system, the Red Planet's Valles Marineris.
The video shows thefilament slowing formingon the sun's southeastern limb and accelerating until it bursts, releasing electrified gas toward the ‘Earth-strike-zone.'
NASA has released footage showing a massive 'canyon of fire' about twice the size of the US shooting out from the sun on Halloween day
The culprit is sunspot AR3477, which released an M flare that can cause brief radio blackouts that affect Earth's polar regions.
However, EarthSky reports that the sunspot also released eight C flares in the last 24 hours.
On November 1, AR3477 shot an M1.2 flare that caused radio blackouts over the South Indian Ocean.
And the flare released last month could impact Earth on November 4.
NASA's probe, SDO, was recently named the fastest artificial object in history.
It was large enough for the American Space Agency's Perseverance rover to see it on Mars , which is 145.59 million miles away
The feature was a tremendous explosion of radiation that measured 6,200 miles wide and 62,000 miles long
The craft hit a record speed of 394,736 miles per hour (mph) last month, twice as fast as a bolt of lightning or 200 times the speed of a rifle bullet.
The achievement was made during its 17th sun swing on September 27, breaking its distance record by skimming just 4.51 million from the solar surface.
SDO launched on August 12, 2018, to study the sun.
In 2021, the probe uncovered the source in the sun, which produces solar energetic particles that threaten crewed spaceflight, near-Earth satellites and airplanes.
A team of US researchers analyzed the composition of particles that flew towards Earth in 2014 and found the same 'fingerprint' of plasma located low in the sun's chromosphere - its second-most outer layer.
The solar energetic particles are released from the sun at high speed during storms in its atmosphere.
The team behind the new study said the new information could be used to predict better when a major solar storm will hit and act faster to mitigate the risks.
Astronomers have long suspected that the Moon formed roughly 4.5 billion years ago when a hefty planet-in-the-making called Theia collided with a young Earth. Now, researchers have found evidence that massive blobs deep within Earth are actually relics from long-lost Theia. If true, other planets may also be filled with parts of their ancient foes.
Scientists call Theia’s strike the Giant Impact. This was probably the last major event during Earth’s accretion phase when it was growing larger and regularly getting bombarded by space material. The Giant Impact is time zero on the clock for Earth and the Moon. This is why Qian Yuan, a geodynamicist at the California Institute of Technology who is interested in what makes some planets friendly to life, led a team of researchers to look into this ancient phase.
“So far, Earth is still the only habitable planet, but we do not know why Earth is habitable and others are not. As a modeler, I believe that the initial condition is crucially important, and it is widely believed that the Moon's formation set the initial condition of Earth,” Yuan tells Inverse.
The Giant Impact would have infused parts of Theia’s mantle into Earth’s mantle.
HONGPING DENG, HANGZHOU SPHERE STUDIO, CHINA
The middle layer of our planet, called the mantle, is an important part of the habitability question. It’s intrinsic to the carbon cycle, for instance, which is required to form complex molecules like proteins and DNA. Carbon is continually exchanged between the ocean’s surface waters and the atmosphere and can also be released in grand displays like volcanic eruptions. Sitting atop the mantle is the crust, which has evolved over time from supercontinents to the seven land masses where you find humans and many other terrestrial creatures living today.
Just below the mantle, there’s Earth’s outer liquid core. This powers the magnetic field that cocoons our planet from cosmic radiation that would pose a threat to life. Two blobs near the boundary between the mantle and the outer core, some 2,900 km below the surface, maybe Theia relics, according to simulations run by the team of astronomers. They published their findings on Wednesday in the journal Nature.
A previous study, published in Nature in 2016, showed these two continent-sized anomalies at the base of the mantle via seismic images. To create these images, seismologists use waves generated from earthquakes, which have traveled through the center of Earth, Edward Garnero, a geophysicist at Arizona State University, who was the lead author of the 2016 Nature study and a co-author of the new work, tells Inverse.
“In a similar way to ultrasound or MRI machines, we study recordings of the waves after they have traveled through structures or reflected off of them to identify anomalies. In this way, ‘pictures’ of the interior are computed, just like X-ray images,” Garnero says.
Another study, published in the journal Geochemistry in 2019, suggests that Theia’s collision would not have mixed ancient isotopes effectively due to its “hit-and-run” or “merger” nature.
Qian Yuan and team’s simulation. This shows the 24 hours following Theia’s impact.
In the new study, researchers simulated how the mantle would have sloshed about over the last 4.5 billion years and what the cataclysmic 24 hours looked like after the Giant Impact.
Theia was a protoplanet, so its abundance of material would have separated into layers. Theia also had a mantle, and the simulation work shows that Theia’s mantle material (TMM) could have sunk into Earth’s own mantle after the Giant Impact. The “mostly molten” TMM may have later solidified and sunk down to Earth’s lowermost mantle, the study says. Other work, like a study published in Nature in 2012, suggests that some ancient accreted material, which predates the 4.5 billion year benchmark that usually serves as the start of Earth’s clock, may have survived the convection of Earth’s mantle.
Some of this material may have been what Theia captured from the protoplanetary disk, the dusty puff where the entire Solar System originated.
On the left: Theia’s impact with Earth 4.5 billion years ago. On the right, a modern understanding of the two blobs Theia left behind.
HERNÁN CAÑELLAS
Yuan is still researching these relics, looking into the subsequent influences of the deep Theia blobs on the tectonic evolution of Earth's surface. And by doing so, aims to tie the epic past to the modern day.
Has the mystery of how the moon formed finally been solved? Our lunar satellite was propelled into orbit IMMEDIATELY after a giant impact between Earth and a Mars-sized planet 4.5 billion years ago, study claims
Has the mystery of how the moon formed finally been solved? Our lunar satellite was propelled into orbit IMMEDIATELY after a giant impact between Earth and a Mars-sized planet 4.5 billion years ago, study claims
Scientists suspect moon was created when a planet called Theia struck Earth
But the nature of collision and what happened after has been subject to debate
Some believe collision created debris which coalesced into the moon over time
In a new study, researchers ran the most detailed supercomputer simulations yet
Findings suggest the moon was placed into orbit around Earth immediately
It's a question that has puzzled scientists for hundreds of years – how exactly did our moon form?
Since the 1970s, astronomers have suspected that the moon was created when a giant protoplanet called Theia struck Earth.
However, the nature of this collision and what happened immediately after has been subject to debate.
Some scientists believe that the collision created a vast cloud of debris, which coalesced into the moon over time.
However, in a new study, researchers from the University of Durham claim that the giant impact immediately placed the moon into orbit around Earth.
Vincent Eke, co-author of the study, said: 'This formation route could help explain the similarity in isotopic composition between the lunar rocks returned by the Apollo astronauts and Earth's mantle.
'There may also be observable consequences for the thickness of the lunar crust, which would allow us to pin down further the type of collision that took place.'
In a new study, researchers from the University of Durham claim that the giant impact immediately placed the moon into orbit around Earth (artist's impression pictured)
The Moon theories
Astronomers have long suspected that the moon was created when a giant protoplanet called Theia struck the newly formed Earth - a theory first put forward in the 1970s.
It says the huge collision created a vast cloud of debris, which coalesced into the moon.
However, until now, astronomers have not been able to explain how this left the moon and Earth chemically identical.
Later, two hypotheses arose that could explain why the moon is Earth's chemical clone, but they predict radically different masses for Theia.
In one scenario, two half-Earths merged to form the Earth-moon system.
But the second hypothesis suggests Theia was a small, high-velocity projectile that smacked into a large and fast-spinning young Earth.
About 4.45 billion years ago, 150 million years after the solar system formed, Earth was hit by a Mars-sized object called Theia.
The collision created the moon, but debate has raged about exactly what happened during this event - and the question of why the moon and Earth are so similar in their composition has remained a mystery.
In the study, the researchers set out to explain the Moon's origin story once and for all.
The team used the SWIFT open-source simulation code, run on the DiRAC Memory Intensive service ('COSMA'), to create the most detailed supercomputer simulations yet.
This allowed them to simulate hundreds of different impacts, varying the angle and speed of the collision as well as the masses and spins of the two colliding bodies.
While previous studies have used lower-resolution simulations, the extra computational power revealed important new aspects.
For example, only the high-resolution simulations produced the Moon-like satellite, and the extra detail showed how its outer layers were richer in material originating from Earth.
If much of the Moon formed immediately following the giant impact, this could mean that less material became molten during formation than previously thought, according to the researchers.
Depending on how this molten rock solidified, these theories should predict different internal structures for the Moon.
The researchers suggest that the moon formed following a giant impact between Earth and a Mars-sized planet
The computer simulations indicate that the collision formed the moon almost immediately, and went straight into orbit around Earth
Jacob Kegerreis, who led the study, said: 'This opens up a whole new range of possible starting places for the Moon's evolution'
The simulations also revealed that even when a satellite passes so close to the Earth that it might be expected to be torn apart by tidal forces from Earth's gravity, the satellite can not only survive, but also be pushed into a wider, safer orbit.
Jacob Kegerreis, who led the study, said: 'This opens up a whole new range of possible starting places for the Moon's evolution.
'We went into this project not knowing exactly what the outcomes of these very high-resolution simulations would be.
So, on top of the big eye-opener that standard resolutions can give you wrong answers, it was extra exciting that the new results could include a tantalisingly Moon-like satellite in orbit.'
The researchers hope the findings will encourage further research into the Moon's composition and internal structure.
'The many upcoming lunar missions should reveal new clues about what kind of giant impact led to the Moon, which in turn will tell us about the history of Earth itself,' the team concluded.
About 4.45 billion years ago, 150 million years after the solar system formed, Earth was hit by a Mars-size object called Theia.
The collision created the moon, but debate has raged exactly what happened during this event - and a mystery has persisted on why the moon and Earth are so similar in their composition.
The impact of Theia with Earth was so violent, the resulting debris cloud mixed thoroughly before settling down and forming the moon.
This cloud would have been composed of some Earth material, explaining the similarity between Earth and the moon, and other material.
The colliding body is sometimes called Theia, after the mythical Greek Titan who was the mother of Selene, the goddess of the Moon.
But one mystery has persisted, revealed by rocks the Apollo astronauts brought back from the moon - why are the moon and Earth so similar in their composition?
Several different theories have emerged over the years to explain the similar fingerprints of Earth and the moon.
Perhaps the impact created a huge cloud of debris that mixed thoroughly with the Earth and then later condensed to form the moon.
Or Theia could have, coincidentally, been isotopically similar to young Earth.
A third possibility is that the moon formed from Earthen materials, rather than from Theia, although this would have been a very unusual type of impact.
A giant collision between the ancient protoplanet Theia and the proto-Earth about 4.5 billion years ago may have formed Earth’s Moon as well as two continent-sized regions — formally known as large low-velocity provinces — within Earth’s mantle, according to a research team led by Caltech scientists.
Yuan et al. suggest that LLVPs are remnants of the ancient protoplanet Theia that violently collided with Earth billions of years ago in the same giant impact that created our Moon.
Image credit: Hernán Cañellas.
In the 1980s, scientists discovered two continent-sized blobs of unusual material deep near the center of the Earth: one beneath the African continent and one beneath the Pacific Ocean.
Each blob is twice the size of the Moon and likely composed of different proportions of elements than the mantle surrounding it.
Where did these strange blobs — formally known as large low-velocity provinces (LLVPs) — come from?
“Terrestrial planet formation concludes with a number of giant impacts among Moon- and Mars-sized planetary embryos,” said Caltech researcher Qian Yuan and colleagues.
“The well-studied giant-impact scenario involves a protoplanet, Theia, colliding with proto-Earth.”
In the study, the authors used computer simulations to propose an explanation for LLVPs.
The material in these regions has been suggested to be between 2.0 and 3.5% denser than the surrounding mantle.
The simulations show that LLVPs may represent buried relics of Theia mantle material that was preserved in proto-Earth’s mantle after the Moon-forming giant impact.
These Theia relics are proposed to have been tens of kilometers across, and the authors suggest that they sunk to the lower region of the mantle and accumulated to form dense blobs above the Earth’s core.
“A logical consequence of the idea that the LLVPs are remnants of Theia is that they are very ancient,” said Dr. Paul Asimow, also of Caltech.
“It makes sense, therefore, to investigate next what consequences they had for Earth’s earliest evolution, such as the onset of subduction before conditions were suitable for modern-style plate tectonics, the formation of the first continents, and the origin of the very oldest surviving terrestrial minerals.”
“Our findings challenge the traditional notion that the giant impact led to the homogenization of the early Earth,” said Professor Hongping Deng, a researcher at the Shanghai Astronomical Observatory.
“Instead, the Moon-forming giant impact appears to be the origin of the early mantle’s heterogeneity and marks the starting point for the Earth’s geological evolution over the course of 4.5 billion years.”
“The Moon appears to have materials within it representative of both the pre-impact Earth and Theia, but it was thought that any remnants of Theia in the Earth would have been ‘erased’ and homogenized by billions of years of dynamics (e.g., mantle convection) within the Earth,” said Arizona State University’s Professor Steven Desch.
“This is the first study to make the case that distinct ‘pieces’ of Theia still reside within the Earth, at its core-mantle boundary.”
“It appears that Earth’s blobs are remnants of a planetary collision that formed our Moon,” said Arizona State University’s Professor Ed Garnero.
“In other words, the massive blobs currently inside Earth, deep beneath our feet, are extraterrestrial. Earth not only has ‘blobs,’ Earth has extraterrestrial blobs!”
“Through precise analysis of a wider range of rock samples, combined with more refined giant impact models and Earth evolution models, we can infer the material composition and orbital dynamics of the primordial Earth, Gaia, and Theia,” Dr. Yuan said.
An illustration of Earth's layers. The mantle is in bright red.
Shutterstock
“This allows us to constrain the entire history of the formation of the inner Solar System.”
“This research even provides inspiration for understanding the formation and habitability of exoplanets beyond our Solar System,” Professor Deng said.
Deze verbeterde afbeelding van Jupiters maan Ganymedes werd verkregen door de JunoCam-imager aan boord van NASA’s Juno-ruimtevaartuig tijdens de vlucht van de missie op 7 juni 2021 langs de ijzige maan. Gegevens van deze pas werden gebruikt om de aanwezigheid van zouten en organische materialen op Ganymedes te detecteren.
Gegevens verzameld door NASAJuno’s missie suggereert dat het zoute verleden mogelijk aan de oppervlakte komt JupiterDe grootste maan.
NASA’s Juno-missie ontdekte minerale zouten en organische verbindingen op het oppervlak van Jupiters maan Ganymede. Gegevens voor deze ontdekking werden verzameld door de Jovian InfraRed Auroral Mapper (JIRAM) spectrometer aan boord van het ruimtevaartuig tijdens een vlucht langs de ijzige maan. De resultaten, die wetenschappers zouden kunnen helpen de oorsprong van Ganymede en de samenstelling van zijn diepe oceanen beter te begrijpen, werden op 30 oktober in het tijdschrift gepubliceerd. Natuur astronomie.
Ganymedes, groter dan de planeet Mercurius, is de grootste manen van Jupiter en is lange tijd van groot belang geweest voor wetenschappers vanwege de enorme binnenoceaan van water verborgen onder de ijskoude korst. Eerdere spectroscopische waarnemingen door NASA’s Galileo-ruimtevaartuig, de Hubble-ruimtetelescoop en de Very Large Telescope van het European Southern Observatory hebben de aanwezigheid van zouten en organische materialen aangetoond, maar de ruimtelijke resolutie van die waarnemingen was te laag om vast te stellen.
Op 7 juni 2021 kwam NASA’s Juno-ruimtevaartuig dichter bij Jupiters met ijs bedekte maan Ganymede dan enig ruimtevaartuig in meer dan twintig jaar. Minder dan een dag later maakte Juno zijn 34ste scheervlucht langs Jupiter. Deze animatie biedt een ‘ruimtevaartuigkapitein’-weergave van elke vlucht. Voor beide werelden werden JunoCam-beelden orthografisch geprojecteerd op een digitale bol en gebruikt om vluchtanimaties te maken. Er zijn kunstmatige frames toegevoegd om benaderings- en vertrekbeelden van zowel Ganymede als Jupiter te bieden. Krediet: NASA/Laboratorium voor straalaandrijving-California Institute of Technology/SwRI/MSSS
Juno’s nauwe benadering en de resultaten ervan
Op 7 juni 2021 vloog Juno over Ganymede (zie video hierboven) op een hoogte van minstens 650 mijl (1.046 kilometer). Kort na het tijdstip van de dichtste nadering maakte het JIRAM-instrument infraroodbeelden en infraroodspectra (in wezen chemische vingerafdrukken van materialen, gebaseerd op de manier waarop ze licht reflecteren) van het oppervlak van de maan. JIRAM, gebouwd door de Italiaanse ruimtevaartorganisatie Agenzia Spaziale Italiana, is ontworpen om infrarood licht (onzichtbaar voor het blote oog) op te vangen dat diep uit Jupiter komt, om de weerlaag te onderzoeken tot een diepte van 30 tot 45 mijl (50 tot 70 mijl). kilometer) hieronder. Gasreuzenwolken. Maar het instrument is ook gebruikt om inzicht te geven in de topografie van de manen Io, Europa, Ganymede en Callisto (gezamenlijk bekend als Satelliet). Manen van Galilea Voor hun ontdekker Galileo).
Verwerkte gegevens van de Jovian InfraRed Auroral Mapper (JIRAM) spectrometer aan boord van NASA’s Juno-missie worden over een mozaïek van optische beelden van de Galileo- en Voyager-ruimtevaartuigen van het agentschap heen gelegd die het gegroefde terrein op Jupiters maan Ganymede tonen.
Afbeelding tegoed: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM/Brown University
Ontdek andere Joviaanse werelden
Eerdere modellen van het magnetische veld van Ganymedes hebben vastgesteld dat het equatoriale gebied van de maan, tot ongeveer 40 graden noorderbreedte, beschermd is tegen energetische elektronen- en zware ionenbombardementen veroorzaakt door Het helse magnetische veld van Jupiter. Het is bekend dat de aanwezigheid van deze deeltjesstromen een negatieve invloed heeft op zouten en organisch materiaal.
Tijdens de vlucht van juni 2021 besloeg JIRAM een smal bereik van breedtegraden (10°N tot 30°N) en een groter bereik van lengtegraden (35°O tot 40°O) op het naar Jupiter gerichte halfrond.
“We vonden de grootste overvloed aan zouten en organische materialen in Donker en helder terrein “Op breedtegraden waar het magnetische veld beschermt”, zegt hoofdonderzoeker Scott Bolton van de Juno-missie van het Southwest Research Institute in San Antonio. “Dit suggereert dat we de overblijfselen zien van een diepe oceaanpekel die de oppervlakte van deze bevroren wereld heeft bereikt.”
Verwerkte gegevens van de Jovian InfraRed Auroral Mapper (JIRAM) spectrometer aan boord van NASA's Juno-missie worden over een mozaïek van optische beelden van de Galileo- en Voyager-ruimtevaartuigen van het agentschap heen gelegd die gegroefd terrein op Jupiters maan Ganymede tonen. NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM/Brown University
Ganymedes is niet de enige ondergrondse wereld waar Juno doorheen ging. De maan Europa, waarvan men denkt dat deze een oceaan onder zijn ijskoude korst heeft, kwam ook onder de aandacht van Juno, eerst in oktober 2021 (zie afbeelding hierboven) en vervolgens in september 2022. En nu krijgt Io de flyby-behandeling. De volgende nadering van deze met vulkanen gevulde wereld is gepland voor 30 december, wanneer het ruimtevaartuig een bereik zal bereiken van binnen 932 mijl (1.500 kilometer) van het oppervlak van Io.
Referentie:
“Zouten en organische stoffen op het oppervlak van Ganymede gecontroleerd door de JIRAM-spectrometer aan boord van Juno” door Federico Tosi, Alessandro Mora, Alessandra Cofano, Francesca Zambon, Christopher R. Glenn, Mauro Ciarniello, Jonathan I. Lunin, Giuseppe Piccione, Cristina Bellacci, Roberto Sordini, Alberto Adriani, Scott J. Bolton, Candace J. Hansen, Tom A. Nordheim, Alessandro Moirano, Livio Agostini, Francesca Altieri, Sean M. Brooks, Andrea Cicchetti, Bianca Maria Dinelli, Davide Grassi, Alessandra Migliorini, Maria Luisa Morricone, Raffaella Nochesi, Pietro Scarica, Giuseppe Sindoni, Stefania Stefani en Diego Torini, 30 oktober , 2023, Natuur astronomie. doi: 10.1038/s41550-023-02107-5
NASA’s Jet Propulsion Laboratory (JPL), een divisie van het California Institute of Technology in Pasadena, Californië, beheert de Juno-missie voor hoofdonderzoeker Scott Bolton van het Southwest Research Institute in San Antonio. Juno maakt deel uit van NASA’s New Frontiers Program, dat wordt beheerd in het Marshall Space Flight Center van NASA in Huntsville, Alabama, voor het Science Mission Directorate van het agentschap in Washington. De Italiaanse ruimtevaartorganisatie (ASI) financierde de Jovian InfraRed Auroral Mapper. Lockheed Martin Space in Denver bouwde en exploiteert het ruimtevaartuig.
In een nieuwe verkenning heeft Juno, een sonde van de NASA, een belangrijke ontdekking gedaan door mineralen en organische verbindingen op het oppervlak van de grootste maan van Jupiter en de grootste in ons zonnestelsel, Ganymedes, te observeren.
Deze gegevens werden verzameld tijdens een scheervlucht van de sonde dicht bij de bevroren maan en onthulden de aanwezigheid van ammoniumzouten, gehydrateerd natriumchloride, natriumbicarbonaat en mogelijke alifatische aldehyden, wat suggereert dat Ganymedes deze materialen tijdens zijn vorming heeft kunnen accumuleren. Deze ontdekking biedt waardevolle inzichten in de oorsprong van de maan en de samenstelling van zijn diepe oceaan.
Informatie verzameld door Juno onthulde ook dat gebieden beschermd door het magnetische veld van Jupiter de hoogste concentraties van zouten en organische verbindingen vertoonden. Deze bevinding draagt bij aan het begrip van de processen die Ganymedes in de loop van de tijd hebben gevormd en aan mogelijke oceanische omgevingen op andere hemellichamen.
Ganymedes is de grootste maan van Jupiter en staat bekend om het herbergen van een intern oceaan onder zijn bevroren korst, wat het tot een interessant onderzoeksobject maakt voor wetenschappers.
Study: Asteroid Impact-Generated Dust Played Key Role in Dinosaur-Killing Mass Extinction
Asteroid Impact-Generated Dust Played Key Role in Dinosaur-Killing Mass Extinction
About 66 million years ago, a massive asteroid crashed into Earth near the site of the small town of Chicxulub in what is now Mexico. The impact eradicated roughly 75% of the animal and plant species on Earth, including whole groups like non-avian dinosaurs and ammonites. Fine silicate dust from pulverized rock generated by the impact played a dominant role in global climate cooling and the disruption of photosynthesis following the event, according to new research.
This painting depicts an asteroid slamming into tropical, shallow seas of the sulfur-rich Yucatan Peninsula in what is today southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 65 million years ago, is believed to have caused the extinction of the dinosaurs and many other species on Earth. Shown in this painting are pterodactyls, flying reptiles with wingspans of up to 50 feet, gliding above low tropical clouds.
Image credit: Donald E. Davis / NASA.
The Chicxulub impact has long been thought to have triggered a global winter 66 million years ago, which led to the demise of the dinosaurs and around 75% of species on Earth.
However, what effect the various types of debris ejected from the crater had on the climate is debated, and exactly what caused the mass extinction remains unclear.
Previous research has suggested that sulfur released during the impact and soot from post-impact wildfires constituted the main drivers of an impact winter, but the size of silicate dust particles ejected into the atmosphere has not been considered to be a major contributor.
“The Chicxulub asteroid impact event 66 million years ago showcases a unique opportunity to examine the rate, magnitude and mechanisms of extreme and abrupt climate change in Earth’s history,” said Dr. Cem Berk Senel, a researcher at the Royal Observatory of Belgium and Vrije Universiteit Brussel, and his colleagues.
“The 45-60° inclined impact of a 10- to 15-km-sized carbonaceous chondrite on the Yucatán Peninsula in Mexico triggered a chain reaction of events ultimately responsible for the end-Cretaceous mass extinction and the demise of 75% of species, including the iconic non-avian dinosaurs.”
“Yet the climatic consequences of the various debris injected into the atmosphere following the Chicxulub impact remain unclear, and the exact killing mechanisms of the mass extinction remain poorly constrained.”
To evaluate the roles of sulfur, soot and silicate dust on the post-impact climate, Dr. Senel and co-authors produced paleoclimate simulations based on an analysis of fine-grained material emplaced at a well-preserved impact deposit from a site in North Dakota, the United States.
They found that the size distribution of silicate debris (approximately 0.8-8 micrometers) revealed a larger contribution of fine dust than previously appreciated.
They inputted the measured size distribution into a climate model and estimated that such fine dust could have remained in the atmosphere for up to 15 years after the event, contributing to global cooling the Earth’s surface by as much as 15 degrees Celsius.
They suggest that dust-induced changes in solar radiation may also have shut down photosynthesis for almost two years post-impact.
“Our simulations of the atmospheric injection of such a plume of micrometer-sized silicate dust suggest a long atmospheric lifetime of 15 years, contributing to a global-average surface temperature falling by as much as 15 degrees Celsius,” the authors said.
“Simulated changes in photosynthetic active solar radiation support a dust-induced photosynthetic shut-down for almost 2 years post-impact.”
“We suggest that, together with additional cooling contributions from soot and sulfur, this is consistent with the catastrophic collapse of primary productivity in the aftermath of the Chicxulub impact.”
The results appear in the journal Nature Geoscience.
C.B. Senel et al. Chicxulub impact winter sustained by fine silicate dust. Nat. Geosci, published online October 30, 2023; doi: 10.1038/s41561-023-01290-4
The Crab Nebula – otherwise known as the first object on Charles Messier’s list of non-cometary objects or M1 for short – has never really failed to visually underwhelm me! I have spent countless hours hunting down this example of a supernova remnant and found myself wondering why I have bothered. Yet here I am, after decades of looking at it, and I still find it one of the most intriguing objects in the sky.
Never has this interest been piqued more than right now after another mirror-smashing beauty of an image from the James Webb Space Telescope, and it’s already found its way to my mobile phone wallpaper!
The NASA/ESA/CSA James Webb telescope was launched back in December 2021, and from its position 1.5 million km away, it orbits the Sun, giving us a brand new window out into the Universe. Using its Near-Infrared Camera (NIRCAM) and the Mid-Infrared Instrument (MIRI) JWST has been exploring the Crab Nebula, the remains of a star whose explosion was recorded back in 1054. The object, which is 6,500 light years away, can be seen in small amateur telescopes and is without doubt one of the most studied supernova remnants of all.
Despite being the target of many, many observations, there are still plenty of unanswered questions about the nature of the star that exploded, the mechanics of the explosion itself, and the composition of the ejecta. Using JWSTs infrared capabilities, the image of the Crab reveals red/orange filaments of dust around the central region. The filaments weave an intricate pattern over the whole nebula, but it’s the core that has received more attention.
Compare and contrast the Hubble version on the left with the new, Webb version on the right. Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)
It has been known that there is a pulsar at the core of the nebula, and it’s this pulsar that is the true remains of the progenitor star. When it went ‘supernova,’ the core collapsed to form the ultra-dense rotating object that, if you happen to be in the right place in space (hey, that rhymes), then you will see a pulse of radiation as it rotates. The infrared images from JWST reveal synchrotron emissions, which are a direct result of the rapidly rotating pulsar. As the pulsar rotates, the magnetic field accelerates particles in the nebula to astonishingly high speeds such that they emit synchrotron radiation. As a fabulously lucky quirk of nature, the radiation is particularly obvious in infrared, making it ideal for JWST.
Not only has JWST detected synchrotron radiation, but it has also mapped out locations of dust particles and even… locations where dust particles are forming. It’s fabulous to think that an object that was discovered almost a thousand years ago is still surprising us. That’s one of the things I love about astronomy: you think you have seen it all, but there is always more to learn. Over the coming years, teams of astronomers using both HST and JWST will continue to probe the depths of the Crab Nebula, and maybe one day, all of its secrets will finally be revealed.
The blue areas on this map of Mars are regions where NASA missions have detected subsurface water ice (from the equator to 60 degrees north latitude). Scientists can use the map – part of the Subsurface Water Ice Mapping project – to decide where the ... Credit: NASA/JPL-Caltech/Planetary Science Institute.
Water will be one of the most important resources for human explorers on Mars. They’ll need it for drinking, propellant, breathing, and more. It makes sense to land near a spot where there’s water ice close to the surface.
NASA has released a new map of Mars’s northern hemisphere showing all the places where subsurface water ice has been detected, some of which are surprisingly close to the equator, as well as surprisingly close to the surface. This map could decide the first human landing site.
Earlier and later HiRISE images of a fresh meteorite crater 12 meters, or 40 feet, across located within Arcadia Planitia on Mars show how water ice excavated at the crater faded with time. The images, each 35 meters, or 115 feet across, were taken in November 2008 and January 2009. Credit: NASA/JPL-Caltech/University of Arizona
Early on during the Mars Reconnaissance Orbiter (MRO) mission, which arrived at Mars in 2006, scientists started finding evidence of subsurface water ice being exposed from recent impacts, showing up as bright white in the high-resolution images from the new spacecraft. While scientists were fairly certain there was ice below the surface at high latitudes of Mars, they were surprised to find that the ice was also present closer to the equator.
But whenever you’re looking for exposed subsurface ice on the Red Planet, you have to look fast. It doesn’t take long for ice — or water – to sublimate away because of the thin atmosphere on Mars.
The ice-exposing impact crater at the center of this image is an example of what scientists look for when mapping places where future astronauts should land on Mars. It’s one of several such impacts incorporated into the latest version of a series of NASA-funded maps of subsurface water ice on the Red Planet.
Credit: NASA/JPL-Caltech/University of Arizona
Scientists have now combined data from several NASA missions, including MRO, 2001 Mars Odyssey, and the now-inactive Mars Global Surveyor. The project is called SWIM, Subsurface Water Ice Mapping. The project has just released its fourth set of maps, and NASA and JPL say these are the most detailed water ice maps since the project began in 2017.
Using a mix of data sets, scientists have identified the likeliest places to find Martian ice that could be accessed from the surface by future missions.
“These ice-revealing impacts provide a valuable form of ground truth in that they show us locations where the presence of ground ice is unequivocal,” said Gareth Morgan, SWIM’s co-lead at the Planetary Science Institute, in a JPL press release. “We can then use these locations to test that our mapping methods are sound.”
These Mars global maps show the likely distribution of water ice buried within the upper 3 feet (1 meter) of the planet’s surface and represent the latest data from the SWIM project. Buried ice will be a vital resource for astronauts on Mars, serving … Credit: NASA/JPL-Caltech/PSI
The new maps reveal what scientists believe are masses of subsurface frozen water along Mars’ mid-latitudes. The northern mid-latitudes are especially attractive because a thicker atmosphere exists there than most other regions on the planet. A thicker atmosphere would aid in slowing down an incoming spacecraft. NASA says the ideal astronaut landing sites would be a sweet spot at the southernmost edge of this region – far enough north for ice to be present but close enough to the equator to ensure the warmest possible temperatures for astronauts in an icy region.
“If you send humans to Mars, you want to get them as close to the equator as you can,” said Sydney Do, JPL’s SWIM project manager. “The less energy you have to expend on keeping astronauts and their supporting equipment warm, the more you have for other things they’ll need.”
The HiRISE camera on NASA’s Mars Reconnaissance Orbiter took this image of a new, 8-meter (26-foot)-diameter meteorite impact crater in the topographically flat, dark plains within Vastitas Borealis, Mars, on November 1, 2008. The crater was made sometime after Jan. 26, 2008. Bright water ice was excavated by, and now surrounds, the crater. This entire image is 50 meters (164 feet) across. Credit: NASA/JPL-Caltech/University of Arizona
Back in 2009, data from several instruments on MRO detected and confirmed highly pure, bright ice exposed in new craters, ranging from 1.5 feet to 8 feet deep, at five different Martian sites. Scientists said they were able to figure out, given how long it took that ice to fade from view, that the ice was about 99 percent pure ice.
Over the years, MRO’s wonderful, high-resolution camera, HiRISE (High-Resolution Imaging Science Experiment) has continued to study fresh impact craters, where meteoroids may have excavated chunks of ice. For the latest maps for the SWIM project, HiRISE data was incorporated to provide the most detailed perspective of the ice’s boundary line as close to the equator as possible. Another instrument on MRO, the Context Camera, which provides a big-picture, background view of the terrain, provides data that further refines the northern hemisphere maps.
Detailed image of large-scale crater floor polygons, caused by desiccation process, with smaller polygons caused by thermal contraction inside. The central polygon is 160 metres in diameter, smaller ones range 10 to 15 metres in width and the cracks are 5-10 metres across. Credit: NASA/JPL
In addition to ice-exposing impacts, scientists also look for “polygon terrain,” where the seasonal expansion and contraction of subsurface ice causes the ground to form polygonal cracks. Seeing these polygons extending around fresh, ice-filled impact craters is yet another indication there’s more ice hidden beneath the surface at these locations.
“The amount of water ice found in locations across the Martian mid-latitudes isn’t uniform; some regions seem to have more than others, and no one really knows why,” said Nathaniel Putzig, SWIM’s other co-lead at the Planetary Science Institute. “The newest SWIM map could lead to new hypotheses for why these variations happen.”
In this artist’s concept, NASA astronauts drill into the Martian subsurface. The agency has created new maps that show where ice is most likely to be easily accessible to future astronauts.
Credit: NASA
He added that it could also help scientists tweak models of how the ancient Martian climate evolved over time, leaving larger amounts of ice deposited in some regions and lesser amounts in others.
SWIM’s scientists hope the project will serve as a foundation for a proposed future mission, called Mars Ice Mapper. This would be an orbiter with a powerful subsurface radar that could search for near-surface ice beyond where HiRISE has confirmed its presence.
This artist’s rendering shows the star HR 8799 and one of its four planets, HR 8799c. It illustrates the system at an early stage of evolution. It also shows the star's dusty disk and rocky inner planets. Credit: Dunlap Institute for Astronomy & Astrophysics
When the JWST activated its penetrating infrared eyes in July 2022, it faced a massive wish-list of targets compiled by an eager international astronomy community. Distant, early galaxies, nascent planets forming in dusty disks, and the end of the Universe’s dark ages and its first light were on the list. But exoplanets were also on the list, and there were thousands of them beckoning to be studied.
But one distant solar system stood out: HR 8799, a system about 133 light-years away.
Why this system over others? 15 years ago astronomers discovered three exoplanets orbiting the star. Not long after they announced a fourth, all detected with direct imaging. They’re all massive planets on wide orbits, which are rare. The HR 8799 system is also young, another important point.
The fact that they were discovered 15 years ago is also important; it means we have observations of these planets that span a lengthy time. This type of data is critical to understanding other solar systems because the duration of the data paints a more complete picture.
However, it also poses more questions and whets our appetite for more answers.
That’s why the JWST observed the system recently. Its MIRI instrument and its coronagraph can perform the kind of high-contrast imaging needed to understand the system better.
HR 8799 is 1.5 times more massive than the Sun and is almost five times more luminous. It’s also surrounded by a debris disk and is only about 30 million years old. Young solar systems are important because they can reveal the intricate details behind planet formation, one of the things the JWST was built to focus on.
The four planets are HR 8799 b, c, d, and e. They’re all massive planets, between 5.7 and 9.1 Jupiter masses, barely below the point where deuterium fusion takes place, making them brown dwarfs. They range from 16 to 71 astronomical units away from the star, and have orbits from about 45 to about 460 years. All four of them have radii of about 1.2 Jupiter radii.
A portrait of the HR8799 planetary system as imaged by the Hale Telescope. A fourth planet was eventually discovered. Credit: NASA/JPL-Caltech/Palomar Observatory.
Massive giant planets that follow large orbits greater than 5 AU are rare. So every instance of these types of planets is important. MIRI’s high contrast imaging can open up a new window on these types of systems and allowing scientists to characterize them more fully. Mid-infrared observations of the system have been difficult up until now. Not only that, but the JWST’s angular resolution makes the observations even more powerful.
What did the JWST find?
“Overall, the MIRI images of the HR 8799 system yield a very different vision than in the near IR, with the clear detection of the four planets, together with a localized but extended central emission,” the authors write.
The JWST was able to refine what we already know about some aspects of this system. The main objective of this work was to characterize the planetary atmospheres better.
While there has been some uncertainty around the nature of the planets, and if they are brown dwarfs, the JWST observations put that idea to rest. “Their colors indicate that these four giant planets differ from field brown dwarfs,” the authors write.
An artist’s depiction of the relative sizes of the Sun, a low-mass star, a brown dwarf, Jupiter, and the Earth. While there was some initial uncertainty over the nature of the planets around HR 8799, the JWST images confirmed them as planets rather than brown dwarfs. Image Credit: Jupiter: NASA,ESA,and A. Simon (NASA,GSFC); Sun and Low-Mass Star: NASA,SDO; Brown Dwarf: NASA,ESA,and JPL-Caltech; Earth: NASA; Infographic: NASA and E. Wheatley (STScI)
Their temperatures range from 900 K to 1300 K, with HR 8799 b being fainter and cooler. The JWST measurement’s shows that planet b’s temperature is lower than previous observations showed, an indication of the telescope’s greater power. MIRI also identified two atmospheric chemicals unequivocally: H2O and CO. The authors say there’s a debatable detection of methane, and that’s additional evidence that they’re planets not brown dwarfs. Brown dwarfs always show the signature for methane at these temperatures.
The JWST’s MIRI instrument was built with different filters. They were partly designed to investigate the presence of ammonia, which is a solid biosignature on terrestrial planets. Unfortunately, these four planets are a little too hot for ammonia to stand out. “As a result, the current data cannot conclude on the detectability of the ammonia feature in the HR 8799 planets,” the paper states. If it had detected ammonia, it would be headline news.
This is one of the JWST’s MIRI images of HR 8799 and its four planets. It won’t grace the cover of a magazine; it’s a scientific image. Image Credit: Boccaletti et al. 2023.
The HR 8799 system is also noteworthy for its debris disk. It’s unusual in that it has two belts. Researchers have wondered if the inner edge of the outer belt was caused by a fifth planet with a mass between Jupiter’s and Saturn’s. Others thought it might be a dust clump.
But the JWST shows that it’s a background object, and seems to have ended the debate. “With a new data point, 4.44 years apart from the former detection, we can now safely conclude that this is a background object,” the authors write.
The powerful filters on the JWST’s MIRI instrument ended the debate about a potential fifth planet at HR 8799. This MIRI image helped determine that the object is in fact a background object. Image Credit: Boccaletti et al. 2023.
This was the JWST’s first look at a young exoplanetary system with its MIRI instrument, including its filters and its coronagraph. “The MIRI instrument onboard JWST is now offering high-contrast imaging capacity at mid-IR wavelengths, thereby opening a completely new field of investigation to characterize young exoplanetary systems,” the authors explain.
As such, the main thrust of the work was to test the observations and different algorithms to determine how to best use it in future work, and how to interpret the results. For example, measuring a planet’s flux successfully means accounting for how the coronagraph attenuates the images, depending on a planet’s position.
These observations contribute to using the instrument more effectively. Ironically, MIRI’s coronagraph can be so sensitive that understanding its images of young stellar systems can be challenging. The use of the instrument is only in its infancy, and the coronagraphs extreme sensitivity “can make the detection and the interpretation of young system observations very challenging, not mentioning the confusion related to background galaxies,” the authors write.
The authors point out that there’s still room for improvement, and these results will only lead to improved future results.
Planet formation is a little like making a cake. If you haven't yet added an emulsifier, you will find that the liquids and fats separate in the bowl. Something like this happened when big celestial bodies in our Solar System were forming billions of years ago. Scientists now think Mars was once covered in a global magma ocean, and eventually, gravity began to separate the different stuff within this gooey ultra-hot blob into layers.
Data from NASA’s Mars InSight mission suggests that its center is more decadent than expected. Rather than one single, sizable liquid iron core, there’s evidence that it's much smaller but topped with a coating of molten rock.
LISTENING TO A CRASH
On Wednesday, the journal Nature published two papers based on data from Insight, which listened keenly to Mars’ interior rumblings beginning in 2018 until dust blanketed the stationary lander’s solar panels, cutting off its energy supply and forcing the mission to end in 2022.
The Red Planet is only the third celestial body, after Earth and the Moon, to have its interior significantly examined via seismological waves, the same science that tracks earthquakes on Earth. On Mars, tremors are called marsquakes. These perturbations come from internal activity or when a meteorite smacks into the planet’s surface, and they give scientists an idea about what is sitting in the middle of the planet, deep below any probe could survive. Waves travel differently depending on what they move through, and thanks to one particular meteorite strike, scientists have reimagined what lies deep beneath Mars’ surface.
The two new studies focused on a strike from a meteor that smacked into Mars almost on the opposite side to where Insight was located. The September 2021 event created waves that sliced through the planet and skimmed across the top of Mars's center. This reading, paired with other marsquake data, reveals that the iron core of Mars is smaller than previously estimated, owing to the coating of a molten rock layer.
Two new studies published on October 25, 2023 suggest that Mars’ liquid iron core (center) is surrounded by a 93-mile-thick (150 km) molten rock layer.
A critical aspect of the new work is the P wave that propagated through Mars. In seismology, there are two main types of waves. Imagine a slinky on a table, and you're holding one end. Push it, and the coil will compress and travel, known as a P wave. The meteorite impact was almost on the other side of Mars to where the InSight probe was stationed, so the lander picked up this P wave after it hit the molten rock layer on top of the iron liquid core.
Other marsquakes that happened much closer to Insight produced S waves. If instead of pushing a slinky, you move the end side to side, you create a vertical wiggle known as an S wave. Altogether, P wave and S wave data show that Mars's iron liquid iron core is actually much smaller than previously predicted, as it’s surrounded by a 93-mile-thick liquid layer made of silicate.
A UNIQUE POSSIBILITY
Molten rock touching molten iron “appears to be unique,” Amir Khan, a geophysicist at Eidgenössische Technische Hochschule Zurich and lead author of one of the two studies, says in a Nature article describing the research. “You have this peculiarity of liquid–liquid layering, which is something that doesn’t exist on the Earth.”
The second study suggests there was an ancient, global magma ocean on Mars, a time in the planet’s ancient past when heavy iron gravitationally separated from the lighter silicates and formed the liquid iron core that has fascinated scientists since InSight’s surveys began.
Scientists think Mars’ core is entirely covered by the molten rock, but the estimate is based on the serendipitous blows that meteorites dealt to Mars while InSight was online. There’s no future seismological survey planned for Mars to add further checks, but at the very least, what scientists have learned with the lander will inform missions to other worlds in our Solar System.
NASA heeft een prachtige opname gepresenteerd in de ‘Astronomische Afbeelding van de Dag‘ van Komeet Encke, de tweede periodieke asteroïde ooit ontdekt in de geschiedenis, na de Komeet Halley, naast de emissienevel die officieel bekendstaat als IC 410.
Encke (2P/Encke) staat bekend om zijn korte omlooptijd onder de kometen die door ons zonnestelsel reizen, en heeft slechts 3,3 jaar nodig om een volledige omloop om de zon te voltooien en zichtbaar te worden.
Bovendien is deze komeet nauw verbonden met ten minste twee jaarlijkse meteorietenregens op aarde, de Noordelijke en Zuidelijke Tauriden, die beide eind oktober en begin november plaatsvinden.
Op de afbeelding is de schoonheid van Komeet Encke te zien, met zijn groene kleur, in de buurt van een jonge sterrenhoop en wolken in de emissienevel IC 410.
NASA benadrukt een indrukwekkende opname van een komeet naast een nevel
Mars’ liquid iron alloy core is surrounded by a layer of fully molten silicate (magma) about 150 km thick, according to a pair of papers published in the journal Nature.
An artist’s depiction of a liquid silicate layer wrapped around the Martian core.
Image credit: IPGP-CNES.
In 2021, an analysis of seismic data gathered by the Seismic Experiment for Interior Structure (SEIS) instrument onboard NASA’s InSight lander suggested the presence of a large but low-density core, composed of liquid iron and lighter elements such as sulfur, carbon, oxygen and hydrogen.
However, these results suggest that the core has a higher proportion of lighter elements than is feasible according to estimates of the abundances of these elements early in Mars’ formation history.
In the two new studies, the authors analyzed the latest batch of seismic data from InSight in combination with first principles simulations and geophysical models to produce their estimates for the size and composition of the Martian core.
They found that the liquid iron core of Mars is surrounded by an approximately 150 km-thick layer of near-molten silicate rock, the top of which was previously misinterpreted as the surface of the core.
This decrease in core radius implies a higher density than estimated in the earlier InSight study.
“The blanket not only insulates the heat coming from the core and prevents the core from cooling, but also concentrates radioactive elements whose decay generates heat,” said University of Maryland’s Professor Vedran Lekic.
“And when that happens, the core is likely to be unable to produce the convective motions that would create a magnetic field — which can explain why Mars currently doesn’t have an active magnetic field around it.”
Without a functional protective magnetic field around itself, a terrestrial planet such as Mars would be extremely vulnerable to harsh solar winds and lose all the water on its surface, making it incapable of sustaining life.
“This difference between Earth and Mars could be attributed to differences in internal structure and the different planetary evolution paths the two planets took,” Professor Lekic said.
“The thermal blanketing of Mars’ metallic core by the liquid layer at the base of the mantle implies that external sources are necessary to generate the magnetic field recorded in the Martian crust during the first 500 to 800 million years of its evolution,” said Dr. Henri Samuel of the French National Center for Scientific Research.
“These sources could be energetic impacts or core motion generated by gravitational interactions with ancient satellites which have since then disappeared.”
The findings support theories that Mars was at one time a molten ocean of magma that later crystallized to produce a layer of silicate melt enriched in iron and radioactive elements at the base of the Martian mantle.
The heat emanating from the radioactive elements would then have dramatically altered the thermal evolution and cooling history of the Red Planet.
“These layers, if widespread, can have pretty big consequences for the rest of the planet,” Professor Lekic said.
“Their existence can help tell us whether magnetic fields can be generated and maintained, how planets cool over time, and also how the dynamics of their interiors change over time.”
“The discovery of this stratification in the Martian mantle opens new research horizons, since the seismic data recorded by the SEIS instrument of the InSight mission will now be reconsidered in the light of this new paradigm,” said ISAE-SUPAERO’s Dr. Mélanie Drilleau.
A. Khan et al. 2023. Evidence for a liquid silicate layer atop the Martian core. Nature 622, 718-723; doi: 10.1038/s41586-023-06586-4
H. Samuel et al. 2023. Geophysical evidence for an enriched molten silicate layer above Mars’s core. Nature 622, 712-717; doi: 10.1038/s41586-023-06601-8
The inner structure of Mars, revealed: NASA discovers a molten layer wrapped around the planet's core - in breakthrough that could provide key clues to its formation
The inner structure of Mars, revealed: NASA discovers a molten layer wrapped around the planet's core - in breakthrough that could provide key clues to its formation
The discovery suggests Mars' core is denser and smaller than previous estimates
It may help to explain how Mars evolved and became the barren planet it is today
Like Earth, much of Mars' rocky insides remain somewhat of a mystery because the planet's interior is inaccessible to humans.
But a major new breakthrough could yet provide new insights into how Mars formed, evolved and became the barren world it is today.
That's because two new studies have helped to uncover a previously unknown molten layer wrapped around the planet's core.
The scientists involved compared it to a 'heating blanket' and say the discovery suggests the Martian core is likely to be smaller and denser than previously thought.
Their findings have been described as 'the most accurate and precise estimates so far of Mars' core and mantle structure'.
The inside of Mars: Data from NASA's Insight lander has helped to discover a molten layer wrapped around the Red Planet's core
Cutting open the Red Planet: Scientists compared it to a 'heating blanket' and say the revelation suggests the Martian core is likely to be smaller and denser than previously thought
Mars is the fourth planet from the sun, with a 'near-dead' dusty, cold, desert world with a very thin atmosphere.
Mars is also a dynamic planet with seasons, polar ice caps, canyons, extinct volcanoes, and evidence that it was even more active in the past.
It is one of the most explored planets in the solar system and the only planet humans have sent rovers to explore.
One day on Mars takes a little over 24 hours and a year is 687 Earth days.
Facts and Figures
Orbital period: 687 days
Surface area: 55.91 million mi²
Distance from Sun: 145 million miles
Gravity: 3.721 m/s²
Radius: 2,106 miles
Moons: Phobos, Deimos
Vedran Lekic, a professor of geology at the University of Maryland and co-author of one of the new studies, said: 'The blanket not only insulates the heat coming from the core and prevents the core from cooling, but also concentrates radioactive elements whose decay generates heat.
'And when that happens, the core is likely to be unable to produce the convective motions that would create a magnetic field — which can explain why Mars currently doesn't have an active magnetic field around it.'
Experts believe Mars once had a similar magnetic field to Earth which shut down billions of years ago and left behind only patches of magnetism thanks to magnetised minerals in the Martian crust.
Without a protective shield surrounding it, the Red Planet would then have been extremely vulnerable to harsh solar winds, causing it to lose all water on its surface and making it incapable of sustaining life.
Lekic believes the difference in internal make-up between Earth and Mars is likely to explain why the two planets took very different evolutionary paths, leading to life forming on Earth around 3.7 billion years ago.
'The thermal blanketing of Mars' metallic core by the liquid layer at the base of the mantle implies that external sources are necessary to generate the magnetic field recorded in the Martian crust during the first 500 to 800 million years of its evolution,' said the paper's lead author Henri Samuel, of the French National Center for Scientific Research.
'These sources could be energetic impacts or core motion generated by gravitational interactions with ancient satellites which have since then disappeared.'
The researchers added that the results would help to further scientists' understanding of how terrestrial planets such as Mars and the Earth form, as well as revealing more about what they are made of.
The Red Planet's internal structure was originally mapped by NASA's InSight mission — a probe which landed on Mars in November 2018 and concluded its mission last year.
Conclusion: The new studies support theories that Mars was once a molten ocean of magma which later crystallised to produce a layer of silicate melt enriched in iron and radioactive elements at the base of the planet's mantle
However, scientists are still pouring over data from the mission.
This is what helped to uncover the existence of a thin layer of molten silicates – rock-forming minerals which make up the crust and mantle of both the Earth and Mars – surrounding the Red Planet's liquid iron core.
With the new discovery of this layer, the researchers concluded that Mars' core is likely to be both denser and smaller than previous estimates indicated.
This assumption is also backed up by geophysical data and analysis of Martian meteorites.
A separate new study led by researchers at ETH Zürich in Switzerland also suggests that the liquid iron core is in fact surrounded by a 93-mile (150km)-thick layer of near-molten silicate rock, the top of which was wrongly thought to be the surface of the core.
How Mars evolved: The heat coming from these radioactive elements would have dramatically altered the thermal evolution and cooling history of the Martian world, experts say
Analysis of measurements from InSight suggested in 2021 that Mars had a low-density core made up of liquid iron and lighter elements such as sulfur, carbon, oxygen and hydrogen.
However, this doesn't fit with estimates of how abundant such lighter elements were at the time the Red Planet was formed.
The new studies support theories that Mars was once a molten ocean of magma which later crystallised to produce a layer of silicate melt enriched in iron and radioactive elements at the base of the planet's mantle.
The heat coming from these radioactive elements would then have dramatically altered the thermal evolution and cooling history of the Martian world, experts say.
'These layers, if widespread, can have pretty big consequences for the rest of the planet,' Lekic said.
'Their existence can help tell us whether magnetic fields can be generated and maintained, how planets cool over time, and also how the dynamics of their interiors change over time.'
The two new studies have been published in the journal Nature here and here.
Tools: The InSight lander (pictured) had three key instruments
Three key instruments allowed the InSight lander to 'take the pulse' of the Red Planet:
Seismometer: The InSight lander carried a seismometer, SEIS, which listened to the pulse of Mars.
This recorded the waves travelling through the interior structure of a planet.
Studying seismic waves tells us what might be creating the waves.
On Mars, scientists suspect that the culprits may be marsquakes, or meteorites striking the surface.
Heat probe: InSight's heat flow probe, HP3, burrowed deeper than any other scoops, drills or probes on Mars before it.
It was tasked with investigating how much heat is still flowing out of Mars.
Radio antennas:Like Earth, Mars wobbles a little as it rotates around its axis.
To study this, two radio antennas, part of the RISE instrument, tracked the location of the lander very precisely.
This helped scientists test the planet's reflexes and gave them information about how the deep interior structure affects the planet's motion around the sun.
Why doesn’t Mars have a magnetic field? If it did, the planet would be protected from cosmic radiation and charged particles emitted by our Sun. With a magnetic field, perhaps the Red Planet wouldn’t be the dry, barren world it is today.
It has long been believed that Mars once had a global magnetic field like Earth does, but somehow the iron-core dynamo that generated it must have shut down billions of years ago.
But new seismic data from NASA’s InSight lander might change our understanding of Mar’s interior, as well as alter the view of how Mars evolved and changed over time. InSight’s data revealed the presence of a molten silicate layer overlying Mars’ metallic core. Scientists say this insulating layer is like a blanket that might prevent the core from producing a global magnetic field.
“The blanket not only insulates the heat coming from the core and prevents the core from cooling, but also concentrates radioactive elements whose decay generates heat,” said Vedran Lekic, a professor at the University of Maryland and co-author of a new paper published in Nature. “And when that happens, the core is likely to be unable to produce the convective motions that would create a magnetic field—which can explain why Mars currently doesn’t have an active magnetic field around it.”
Earth’s magnetic field comes from its core, where molten, electrically conducting iron flows beneath the crust. This magnetic field is global, meaning it surrounds the entire planet. Even though Mars is a rocky, terrestrial planet like Earth, Mars does not generate a magnetic field on its own, outside of relatively small patches of magnetized crust.
Without the protection a magnetic field provided, Mars’ atmosphere was stripped, and eventually, any water on the surface – even oceans – would have evaporated as water vapor in the atmosphere was lost to space, making it incapable of sustaining life.
InSight’s seismometer, SEIS, the Seismic Experiment for Interior Structure. Credit: NASA/JPL
NASA’s InSight mission deployed the first seismometer on the surface of Mars. It recorded “Marsquakes,” and it has also helped determine the layering and thickness of the planet’s crust, the structure of the mantle, and the size of Mars’ core and its composition. Data from InSight is helping planetary scientists to work out the internal structure of Mars. Lekic and his colleagues say that InSIght has now revealed, surprisingly, the molten silicate layer overlying the planet’s metallic core.
Silicates are rock-forming minerals that make up the crust and mantle of both Mars and Earth. The molten layer on Mars lies between the mantle and core. Earlier research with data from InSight revealed that the Martian core is molten but is larger than previously thought. With the discovery of this molten layer, the researchers say this explains “other geophysical data and analysis of Martian meteorites,” according to a press release from the University of Maryland.
They also theorize that Mars was at one time a molten ocean of magma that later crystallized to produce a layer of silicate melt enriched in iron and radioactive elements at the base of the Martian mantle. The heat emanating from the radioactive elements would then have dramatically altered the thermal evolution and cooling history of the red planet.
Mars’ interior as revealed by the NASA/DLR InSight lander. Image Credit: Cottar, Koelemeijer, Winterbourne, NASA
“These layers, if widespread, can have pretty big consequences for the rest of the planet,” Lekic said. “Their existence can help tell us whether magnetic fields can be generated and maintained, how planets cool over time, and also how the dynamics of their interiors change over time.”
The InSight lander mission officially ended in December 2022 after more than four years of collecting data on Mars. InSight was part of the overall effort to understand Mars and if it was habitable in the past. By probing the planet’s interior, it has revealed some of the planet’s geological history. Another finding by InSight’s magnetometer showed that the planet’s magnetic field may have been much stronger on the surface than orbital measurements showed, which strengthens the case for its potential ancient habitability.
As this new research indicates, analysis of the spacecraft’s observations continues.
“This new discovery of a molten layer is just one example of how we continue to learn new things from the completed InSight mission,” Lekic said. “We hope that the information we’ve gathered on planetary evolution using seismic data is paving the way for future missions to celestial bodies like the Moon and other planets like Venus.”
Io has 266 Active Volcanic Hotspots Linked by a Global Magma Ocean
Jupiter’s Io stands apart from the Solar System’s other moons, with its numerous volcanoes and its surface dominated by lava flows. Io’s surface volcanism was confirmed in 1979 when the Voyager spacecraft imaged it, but its volcanic nature isn’t duplicated anywhere else in our system. Tidal heating is behind the moon’s eruptive nature, driven by Jupiter’s powerful gravity, and by resonance with other moons. But is there a magma ocean inside Io?
A final answer to that question has been elusive, but new research supports the idea of a magma ocean.
NASA’s Juno mission has shifted its focus from Jupiter to the gas giant’s moons, beginning with the volcanic Io. It’s flybys are getting increasingly closer to the unique moon, and the decreasing distance is giving the spacecraft a better and better look. It’s identified 266 active volcanoes, and together, they’re evidence of a vast global ocean of magma according to new research.
A new study titled “Io’s polar volcanic thermal emission indicative of magma ocean and shallow tidal heating models” presented these results. The lead author is Ashley Gerard Davies from NASA’s Jet Propulsion Laboratory. “The extreme level of volcanic activity on Io, the most volcanically active object in the Solar System, is the result of tidally-induced internal heating,” the authors write. That’s not a new conclusion, but there’s more to the research.
Juno’s Jovial Infrared Auroral Mapper (JIRAM) instrument acquired the data behind this research. JIRAM is an image spectrometer, and was designed to probe Jupiter’s upper atmosphere in infrared, including the giant planet’s auroral regions. But now the focus has shifted to Io, and JIRAM is observing the moon’s widespread volcanic activity.
“Io is the most volcanic celestial body that we know of in our solar system,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “By observing it over time on multiple passes, we can watch how the volcanoes vary – how often they erupt, how bright and hot they are, whether they are linked to a group or solo, and if the shape of the lava flow changes,” Bolton said in May 2023 when Juno came within about 35,500 km (22,000 miles) of Io.
Since then, Juno has closed the distance even more, and its latest pass brought it to within 12,000 km (7500 miles.) But it’s not just the proximity that is driving more discoveries. Juno follows a polar orbit, while previous observations of Io have been mostly confined to an equatorial plane. Why does that matter?
Scientists have been studying Io intently, trying to discover what drives its volcanic nature. They’ve developed detailed models of the moon, but haven’t been able to test them as rigorously as they can now. “Models predict enhanced heat flow at Io’s poles if tidal heating is deep in the mantle, and at lower latitudes if heating is predominantly in the asthenosphere, or a magma ocean is present,” the authors explain.
But now scientists have Juno’s data to work with, and its polar orbit is giving researchers a more complete look at the moon.
This figure from the research shows four images of Io from JIRAM. Two are from perijove 10 and show the south polar region at a resolution of 112 km/pixel (a & c.) The other two (c & d) are from perijove 43 and show the north polar region at a resolution of 21 km/pixel. Image b and d are JIRAM data overlain on Galileo/Voyager images. This new data from Io’s poles is critical to understanding the moon’s nature. Image Credit: Davies et al. 2023.
“The distribution of Io’s volcanic activity likely reflects the position and magnitude of internal tidal heating,” the authors write. Now that JIRAM has provided polar data, researchers have complete, global near-infrared coverage that reveals the distribution and the magnitude of thermal emission from Io’s actively erupting volcanoes. With that data, the researchers can probe the moon’s interior and models developed to explain it.
“This result is consistent with models of a global magma ocean or tidal heating in the shallow asthenosphere.”
From “Io’s polar volcanic thermal emission indicative of magma ocean and shallow tidal heating models” by Davies et al. 2023
The research uncovered differences in energy output between the poles and the more equatorial regions, and between the poles themselves. “On average, Io’s polar volcanoes individually generate less energy than volcanoes at lower latitudes; and the south polar volcanoes generate less energy per volcano than the north polar volcanoes,” the researchers explain.
This figure from the research shows the hot spot detections. They range in colour and size from blue up to yellow. Each increasing size and corresponding colour indicates greater spectral radiance. Image Credit: Davies et al. 2023.
Why are these findings significant? It’s because of previously developed models.
“We show that the distribution of volcanic heat flow from 266 active hot spots is consistent with the presence of a global magma ocean, and/or shallow asthenospheric heating,” the authors write.
This isn’t the first study to suggest that Io has a magma ocean. Previous research from 2009 based on Galileo’s magnetometer data showed that the moon must have a magma ocean about 50 km (30 mi) below the surface. But Galileo only did one flyby of the moon, leaving room for some doubt to creep in. More recent analysis of the same data strengthened the same conclusion, showing that the magma ocean is 50 km thick.
But there was always a little doubt cast on those conclusions because they lacked global infrared data. Now that scientists have that data, the case for a magma ocean is solidifying
After DART Smashed Into Dimorphos, What Happened to the Larger Asteroid Didymos?
Asteroid Didymos (bottom left) and its moonlet, Dimorphos, about 2.5 minutes before the impact of NASA’s DART spacecraft. Credit: NASA/Johns Hopkins APL.
After DART Smashed Into Dimorphos, What Happened to the Larger Asteroid Didymos?
NASA’s DART mission (Double Asteroid Redirection Test) slammed into asteroid Dimorphos in September 2022, changing its orbital period. Ground and space-based telescopes turned to watch the event unfold, not only to study what happened to the asteroid, but also to help inform planetary defense efforts that might one day be needed to mitigate potential collisions with our planet.
Astronomers have continued to observe and study Dimorphos, well past the impact event. However, Dimorphos is the smaller asteroid in this binary system, and is just a small moon orbiting the larger asteroid Didymos.
The James Webb Space Telescope (JWST) is the only telescope capable of visually distinguishing between the two closely orbiting asteroids. Now, astronomers have made follow-on observations on the system with JWST to see what happened to Didymos after the dust cleared.
In a new preprint paper, a team of scientists, led by Andrew Rivkin, the Investigation Lead for DART, explain how they used two instruments on JWST to measure spectra of Didymos about two months after the DART impact. One of their biggest takeaways is that Didymos and Dimorphos appear to be of the same composition, which is that of an ordinary chondrite. That’s the class of stony meteorites which account for over 80% of total meteorite falls on Earth. This means DART’s test was an extremely good proxy for the type of asteroids that might pose a threat one day.
“One of the benefits of using the Didymos system was definitely that we thought it was representative of most of what’s out there in its properties,” Rivkin told Universe Today via email. “People working on planetary defense often note that the ‘asteroid picks us rather than the other way around,’ but showing that what we did at Dimorphos is broadly applicable is very important.”
For the new observations, the scientists used NIRSpec – the near infrared spectrometer — and MIRI, the mid-infrared instrument, on November 28, 2022.
At the time of the observations, the centers of Didymos and Dimorphos were never separated by more than 0.1” from each other, from JWST’s vantage point. But the team did take advantage of Dimorphos being occulted by Didymos during the MIRI observations.
Median averaged slice through the MIRI MRS IFU showing Didymos. Note that Dimorphos was being occulted by Didymos during the entire period of MIRI observations.Credit: Rivkin et al, 2023.
“Didymos is roughly five times larger in diameter than Dimorphos and therefore it has roughly 25 times the cross-sectional area as Dimorphos,” the researchers wrote. “This size difference between the components means that roughly 96% of flux from the system typically comes from Didymos.”
The researchers said several lines of evidence suggest that the asteroid and its moon have similar compositions and the team concludes they “can reasonably estimate the composition of Dimorphos specifically from measurements of the Didymos-dominated flux.”
This image from the DART spacecraft of the light from asteroid Didymos and its orbiting moonlet Dimorphos. Credit: NASA/JPL-Caltech/DART Navigation Team
Given how hard it is to distinguish between Didymos and Dimorphos in long-range observations, I asked Rivkin if they were able to see any noticeable changes in the observations of Didymos after the impact to Dimorphos, given all the dust and debris from the impact. The results seem to indicate Didymos escaped mostly unscathed from DART’s impact of the asteroid’s moon.
“We have a lot of new results from observations of the Didymos system that are getting published (including this pre-print paper led by Theodore Kareta) talking about the tail development and evolution. It shows that after 25 days or so there was no extra brightness from debris within the Didymos system, and so by November 2022, observations of the system (including the JWST ones!) are pretty much all Didymos again.”
Rivkin added that they’ve made some puzzling observations using polarized light that suggest perhaps the average particle size or the average reflectivity might have slightly changed on Didymos, but they are waiting for spring 2024 to get more observations.
Rivulets of melted rock line the fusion crust of melted rock on this small Chelyabinsk meteorite. Credit: Bob King
An interesting (and fun!) comparison that Rivkin and his team made is how similar in composition Didymos is to the Chelyabinsk meteor, the famous meteor that created a huge airburst event over Russia in February 2013. The Chelyabinsk meteor is thought to be the biggest natural space object to enter Earth’s atmosphere since the 1908 Tunguska event. So, it too serves as a very representative near-Earth asteroid.
“Yes, that comparison seemed particularly apt!” Rivkin said. “What Didymos and Dimorphos are composed of are very common among near-Earth asteroids, so even a randomly chosen meteorite would have a good chance of matching!”
Other asteroids that have been studied even more closely — such as Eros and Itokawa — also have similar compositions, Rivkin said, even though they likely don’t come from the same original object. But all the asteroids mentioned here are from the same class, S-type asteroids – siliceous or stony.
Eros was the first asteroid to be orbited by a spacecraft (NEAR in 2000), and the first asteroid to have a spacecraft land on it. It was also the first near-Earth asteroid (NEA) to be discovered, in 1898. Itokawa was visited by the JAXA Hayabusa mission, and was the first asteroid from which samples were captured and brought to Earth for analysis.
Detailed view of the rubble-pile asteroid 25143 Itokawa visited by the Japanese spacecraft Hayabusa in 2005. Credit: JAXA
Even though remote observations of distant objects like Didymos and Dimorphos are incredibly difficult – especially for precisely determining asteroid composition – Rivkin said he’s heartened by the success they’ve had.
“We’ve spent over 50 years trying to sort out some very detailed questions and how to approach them,” he said. “Studies like the JWST observations and all of the other great work done to observe Didymos over the years and the fact they agree on the big-picture story gives us a chance to step back and realize how far we’ve come in being able to remotely tell what something is made of.”
But the observations of Dimorphos and Didymos will continue, and astronomers are looking forward to learning even more soon. ESA’s Hera mission is scheduled to arrive at the Didymos system in late 2026, and the researchers said they’ll be able to follow up or extend several of the results they found with JWST.
Hera specifically will be able to image Didymos’ surface at higher spatial resolution than was possible from DART (as well as from LICIACube — the Light Italian CubeSat for Imaging of Asteroids, a cubesat that was part of the DART mission, which sent back images of the impact.) Hera will be able to perform a test of the regolith particle size inferences derived from mid-infrared spectroscopy and a do check on the measured thermal inertia.
“We look forward to Hera and future JWST measurements of additional S-complex asteroids to help us continue efforts to understand the population of potential asteroid impactors, for the science return and to help inform planetary defense efforts to mitigate potential collisions,” the researchers said.
Astronomers Want JWST to Study the Milky Way Core for Hundreds of Hours
This overview of the Milky Way's Galactic Center (GC) shows the region of the proposed JWST survey. Image Credit: NASA/JPL-Caltech/S. Stolovy (Spitzer Science Center/Caltech)
Astronomers Want JWST to Study the Milky Way Core for Hundreds of Hours
To understand the Universe, we need to understand the extreme processes that shape it and drive its evolution. Things like supermassive black holes (SMBHs,) supernovae, massive reservoirs of dense gas, and crowds of stars both on and off the main sequence. Fortunately there’s a place where these objects dwell in close proximity to one another: the Milky Way’s Galactic Center (GC.)
Astronomers know this, and they’ve studied the GC intensely. There are many unanswered questions in astronomy and astrophysics, and some of the answers are hidden in the densely-packed GC. But while its densely-packed nature make it an area practically begging to be studied, it also makes it difficult to study. Only the most powerful telescopes have the angular resolution to make sense of the Milky Way’s central region and its crowded constituents.
Fortunately, the James Webb Space Telescope has the angular resolution to make sense of the region. A new white paper lays out the case for a multi-epoch, large-area, multi-wavelength survey of the Milky Way’s inner 100 parsecs.
The paper is “The JWST Galactic Center Survey: A White Paper.” Over a hundred participants from more than 80 institutions around the world are listed authors, with Rainer Schodel from the Instituto de Astrofisica de Andalucia (CSIC), Granada, Spain listed as first author.
“JWST has the unique capability to provide us with the necessary, game-changing data,” the authors write. “As a community, we have identified the key unknowns that are limiting the potential of the Galactic Center as a laboratory for extreme astrophysics and understanding how galactic nuclei shape the galaxy population.”
These images from the white paper show how the JWST’s high angular resolution can help scientists figure out what’s going on in the GC. The left image was captured with the the ESO’s Vista Telescope in 2010. The middle image was captured in 2019 with the ESO’s VLT, and the image on the right is from the JWST. Image Credits: L: Minniti et al. 2010; M: Nogueras-Lara et al. 2019; R: JWS Proposal 1939, PI J. Lu.
What are the unknowns in this turbulent region? Sgr. A*, the SMBH at the heart of it all, draws matter inexorably towards itself, shredding stars that get too close and creating an enormous swirling mass of gas and dust. Vast gas clouds are caught up in it all, and out of these clouds, stars in their multitudes are born and then extinguished, many as ultra-powerful supernovae. The Milky Way’s nuclear star cluster is there, too, and is many times more massive than Sgr. A*, an anomaly in galaxies. And then there’s the nuclear bulge, where old, comparatively metal-rich stars congregate.
This image shows the Milky Way’s nuclear bulge and its nuclear star cluster (NSC.) The Milky Way is one of the few instances where evidence shows an NSC in a galaxy that also has an SMBH. Image Credit: Schoedel et al. 2008.
This survey, if it takes place, will help astrophysicists untangle some of nature’s most perplexing, stubborn questions. In their white paper, the multi-national team of astronomers lays out five key questions that the JWST can help address in an observing campaign focused on the GC:
What is the formation history of the Galactic Center and its relation to the overall formation history of the Milky Way?
How much stellar mass formed in the past ~30 Myr and what does this imply for the overall energetics of the GC?
What is the origin of, and environmental variation in, the stellar initial mass function?
Why is the star formation rate one to two orders of magnitude lower than predicted by standard star-formation-dense-gas relations?
What is the 3D structure of the interstellar medium (ISM) orbiting and fueling accretion and star formation at the Galactic Center?
This is an ambitious list of questions that helps define the current state of astronomy and astrophysics. Perhaps the only things not mentioned are dark matter and dark energy, and those two phenomena are outside of the JWST’s primary focus.
Success depends on being able to resolve more detail than previous studies of the region. “By being able to resolve physical processes down to size scales separating individual stars, the survey will provide a foundation for addressing key open questions in other fields,” the authors write. The GC is an extreme environment, and is often the case in science, understanding the extremes helps us understand nature’s boundaries.
“What drives the mass flows and energy cycles in extragalactic nuclei and high-z environments?” the authors ask. “What shapes star formation and the evolution of nuclear star clusters, nuclear stellar discs and their interaction with central black holes?” These are all compelling questions.
The proposed survey is designed to address them. As a multi-epoch survey, it would examine the GC in three separate epochs separated by 1, 5, and 10 years. It would observe the nuclear stellar disk and associated giant molecular clouds (GMCs) in the central molecular zone (CMZ,) a region containing about 60 million solar masses of star-forming gas. To see inside the region accurately, the survey would utilize the JWST’s NIRCam and its system of filters.
This image shows the Milky Way’s GC region and some of the objects of interest, including the nuclear star cluster and associated giant molecular clouds in the central molecular zone. Image Credit: Schodel et al. 2023.
One telescope can’t reveal everything, and the JWST won’t be alone in this survey. Success will rely on synergy with other telescopes. ALMA and the Hubble Space Telescope will be part of this observational coalition, as will future telescopes like the Roman Space Telescope, the ESO’s Extremely Large Telescope, and Japan’s JASMINE infrared astrometry mission.
“Together these surveys herald a revolution in the interpretation of current/future data, bring together research in different sub-fields, and answer key open science questions with enormous legacy potential,” Schodel and his colleagues write.
One of the questions the survey hopes to address is particularly fundamental in astrophysics: the Initial Mass Function (IMF.) The IMF describes how mass is distributed during star formation in a giant cloud of gas. The IMF is like an agglomeration of smaller sub-functions in star formation, and it also links individual star formation to larger issues of galaxy formation and evolution. “Thus, understanding the properties of the IMF and how it behaves in different environments has far-reaching implications for star formation theory and beyond,” the paper states.
The Milky Way’s galactic center is the only GC we can observe, and it’s been a tricky target. But the JWST has the power to probe this tumultuous astrophysical maelstrom more deeply than ever before. Along with the SMBH, the NSC, and gas clouds, there are other mysteries. The GC contains hundreds of mysterious magnetized radio filaments that are so far unexplained. Then there are the questions around stellar feedback and how it interacts with the Interstellar Medium (ISM) and how black hole feedback plays into it all.
If this survey takes place, it’ll provide answers that shift the horizon of our knowledge, and also highlight new questions. This survey will far surpass other GC surveys and observations. The authors claim that they can discern the proper motion for more than 10 million stars in the GC. “Such revolutionary data would enable exploring the GC kinematically down to almost solar mass main sequence stars,” the authors write, and that would be an enormous contribution.
As always, there will be surprises, and those surprises will almost certainly spread to scientific topics beyond the study of the GC. “The project proposed in this White Paper has implications for the entire GC community – and beyond,” the authors write.
NASA krijgt "wetenschappelijke schat" met buitenaardse bodemstalen niet open
NASA krijgt "wetenschappelijke schat" met buitenaardse bodemstalen niet open
Artikel van Wim De Maeseneer
"Een wetenschappelijke schat", zo noemde NASA de verzamelde bodemstalen van de planetoïde Bennu twee weken geleden. Op 11 oktober werden de eerste resultaten en foto's bekendgemaakt van het ruimtegruis dat 3 jaar onderweg is geweest.
NASA verklaarde toen dat de capsule nog niet werd geopend, omdat er zoveel zwart stof en steentjes aan de buitenkant van de capsule waren blijven hangen dat de wetenschappers zich daar eerst uitgebreid zouden over ontfermen.Nu blijkt dat NASA de capsule eigenlijk niet open krijgt. "Het team heeft 70,3 gram stenen en stof kunnen verzamelen, veel meer dan de 60 gram die we voor ogen hadden", zo staat te lezen op deblogvan NASA over de OSIRIS-REx-missie.
"Het goede nieuws is dat er nog veel meer stalen verzameld zijn. Maar na verschillende pogingen om de capsule te openen, ontdekte het team dat twee van de 35 sluitingen niet kunnen worden geopend met het voorziene gereedschap."
NASA zoekt nu andere manieren om de bodemstalen uit de capsule te halen, zonder ze te beschadigen en besmetten.
NASA krijgt "wetenschappelijke schat" met buitenaardse bodemstalen niet open
Voor alle duidelijkheid: de capsule met de bodemstalen was tijdens de terugkeer naar de aarde beschermd door nog een tweede omhulsel. Het ruimtegruis dat zich buiten de afgesloten capsule bevond, is dus niet per definitie onbruikbaar.
Zo veel ruimtegruis dat deksel eerst niet dicht kon
In oktober 2020 kon het onbemande OSIRIS-REx-ruimtetuig bodemstalen oppikken van de planetoïde Bennu, die op dat moment zo'n 330 miljoen kilometer van de aarde stond.-
Tegen de verwachting in konden veel meer steentjes en stof worden meegenomen. Zo veel dat het deksel eerst niet meer kon sluiten, waardoor een deel van de stalen verloren zijn gegaan. NASA verwacht dat er in totaal toch nog 250 gram ruimtegruis kon worden meegenomen.Bennu is een grote ruimterots die rond de zon draait en waarschijnlijk 4,5 miljard jaar geleden is ontstaan, in het prille begin van het zonnestelsel. Wetenschappers verwachten dat Bennu de bouwstenen bevat waaruit het zonnestelsel, en ook het leven op aarde, is opgebouwd. De eerste analyses van de bodemstalen tonen inderdaad aan dat er water- en koolstof zijn op Bennu.
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Over mijzelf
Ik ben Pieter, en gebruik soms ook wel de schuilnaam Peter2011.
Ik ben een man en woon in Linter (België) en mijn beroep is Ik ben op rust..
Ik ben geboren op 18/10/1950 en ben nu dus 75 jaar jong.
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![The NASA/ESA/CSA James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light. Similar to the Hubble optical wavelength image released in 2005, with Webb the remnant appears to consist of a crisp, cage-like structure of fluffy red-orange filaments of gas that trace doubly ionised sulphur (sulphur III). Within the remnant’s interior, yellow-white and green fluffy ridges form large-scale loop-like structures, which represent areas where dust particles reside. The area is composed of translucent, milky material. This material is emitting synchrotron radiation, which is emitted across the electromagnetic spectrum but becomes particularly vibrant thanks to Webb’s sensitivity and spatial resolution. It is generated by particles accelerated to extremely high speeds as they wind around magnetic field lines. The synchrotron radiation can be traced throughout the majority of the Crab Nebula’s interior. Locate the wisps that follow a ripple-like pattern in the middle. In the centre of this ring-like structure is a bright white dot: a rapidly rotating neutron star. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, following different directions that mimic the structure of the pulsar’s magnetic field. Note how certain gas filaments are bluer in colour. These areas contain singly ionised iron (iron II). [Image description: An oval nebula with a complex structure against a black background. On the oval's exterior lie curtains of glowing red and orange fluffy material. Interior to this outer shell lie large-scale loops of mottled filaments of yellow-white and green, studded with clumps and knots. Translucent thin ribbons of smoky white lie within the remnant’s interior, brightest toward its centre.]](https://www.universetoday.com/wp-content/uploads/2023/10/Crab-1.jpeg)
