Een oude Maya-techniek zou de groei van planten op Mars kunnen bevorderen, zo beweert een onderzoek

Door Janine

Vroeg of laat zullen mensen naar Mars gaan. Misschien zal de missie niet in de nabije toekomst plaatsvinden, maar het staat vast dat het koloniseren van de rode planeet een van de doelstellingen van ruimtevaartorganisaties is. De vraag is: wat zullen toekomstige kolonisten eten? Leveringen vanaf de aarde zijn allesbehalve duurzaam, en dus blijft er maar één optie over: voedsel direct op Mars verbouwen, met enige hulp van oude Maya-praktijken.

De Maya's en de landbouw op Mars

PLOS ONE/Gonçalves et al./2024

De voedselvoorziening en de landbouw op Mars zijn verre van een ondergeschikt probleem, maar uiterst belangrijke kwesties. Met name een onderzoek van Wageningen University & Research in Nederland heeft mogelijk de eerste stappen gezet om het probleem op te lossen. De onderzoekers hebben in feite een moderne versie van een oude Maya-techniek overgenomen, genaamd intercropping of tussenteelt, en zijn begonnen met het telen van tomaten, erwten en wortels in dezelfde potten.

De resultaten, gepubliceerd in PLOS ONE, waren verrassend. Tomaten geteeld door middel van tussenteelt verdubbelden hun productie vergeleken met individueel geteelde tomaten, met grotere vruchten en in minder tijd. Hetzelfde gebeurde niet met erwten, die een onveranderde opbrengst behielden, en wortelen, die daarentegen een lagere opbrengst vertoonden. Terwijl aan de ene kant intercropping veelbelovende resultaten oplevert, is het aan de andere kant essentieel om zorgvuldig gewassen, grond en additieven te kiezen.

Verbouwen op Marsgrond: is dat mogelijk?

PLOS ONE/Gonçalves et al./2024

Bij het experiment van de onderzoekers van de Nederlandse universiteit waren in deze eerste fase drie soorten gewassen betrokken. Zoals we al zeiden, zijn de grondsoort en eventuele toevoegingen even belangrijk. Om de bodem van Mars te simuleren, ontwikkelden wetenschappers een bodem die bestaat uit regoliet, zonder organisch materiaal, waaraan ze vervolgens bacteriën en voedingsstoffen toevoegden. Een proces dat sterk lijkt op het proces dat toekomstige kolonisten zouden kunnen gebruiken om gewassen op Mars te verbouwen.

Als aanvoer vanaf de aarde moet worden uitgesloten vanwege de kosten en tijd die daarvoor nodig is, lijkt teelt op de rode planeet de enige optie. En intercropping, oftewel het gebruik van planten met complementaire eigenschappen, zou echt een levensvatbare toekomst kunnen vertegenwoordigen. Evenals een manier om het gebruik van water en voedingsstoffen te optimaliseren.

De nieuwe landbouw op Mars en de kunst van het kiezen van de juiste planten

PLOSE ONE/Gonçalves et al./2024 / 中国新闻网/Wikimedia Commons - CC BY 3.0 DEED

Uit de resultaten van hun experiment ontdekten de onderzoekers dat de tomatenplanten een concreet voordeel haalden uit de nabijheid van erwten. Deze laatste kunnen namelijk zeer efficiënt stikstof uit de lucht opnemen en omzetten in voedingsstoffen. Tegelijkertijd profiteerden de wortels niet alleen niet van de nabijheid van de erwten, maar werden ze er ook door geschaad, waarschijnlijk als gevolg van de concurrentie om licht. En we weten dat zonlicht op Mars niet in grote hoeveelheden beschikbaar is: ook in dit geval zal het nodig zijn om na te denken over duurzame alternatieven voor een menselijke kolonie.

Het succes van toekomstige missies naar de rode planeet hangt inderdaad ook af van het vermogen van de kolonisten om zelfvoorzienend te zijn. En deze capaciteit hangt op zijn beurt af van duurzame landbouw op Marsgrond, dat wil zeggen van de tussenteelt van de oude Maya’s. Naast het kiezen van de juiste gewassen om het project te starten, rest er vandaag nog maar één twijfel: niemand heeft de tomaten, erwten en wortelen geproefd. Wie weet hoe ze zullen smaken.

{ https://www.curioctopus.nl/ }

03-06-2024 om 22:37 geschreven door peter  

Venus had oorspronkelijk hetzelfde water als de aarde: eindelijk is ontdekt waarom het zo droog werd

Door Janine

Venus, onze dorre buur, was ooit rijk aan water. Maar waar is al het water gebleven? Een nieuwe studie heeft het antwoord gevonden.

Waarom is Venus een warme, droge planeet als er water is?

Waarom Venus van een planeet met water, zo warm en droog is geworden, is voor wetenschappers een mysterie. De oeroude aanwezigheid van water zou de planeet heet en vochtig moeten maken, maar toch is er geen spoor van waterdamp te vinden. Dit werd ontdekt door planeetwetenschappers van de University of Colorado Boulder en werpt een licht op waarom deze hete en onbewoonbare planeet is geworden wat hij nu is.

Men denkt dat Venus oorspronkelijk een vergelijkbare hoeveelheid water had als de aarde. Er is echter nog maar een honderdduizendste van over, volledig ingesloten in de atmosfeer, in plaats van verspreid in de oceanen, zeeën, ijs en lucht zoals op onze planeet. Dus waar is al het water gebleven? Een echt mysterie dat eindelijk ontrafeld lijkt te zijn.

De verantwoordelijke voor de dorre toestand van Venus

NASA/JPL/Wikimedia commons - Public domain

Eryn Cangi, co-hoofdauteur van het onderzoek en onderzoeker aan het Space and Atmospheric Physics Laboratory, legt uit: "Water is echt belangrijk voor leven. We moeten de omstandigheden begrijpen die vloeibaar water in het heelal ondersteunen en die mogelijk de huidige droge staat van Venus hebben veroorzaakt." Als we al het water op aarde op het oppervlak van onze planeet zouden gieten, zouden we een vloeibare laag hebben van ongeveer 3 kilometer. Als we hetzelfde zouden doen op Venus, zou de diepte slechts 3 centimeter zijn. Dat komt omdat de droge planeet 100.000 keer minder water heeft dan de aarde, ook al is hij even groot.

In wezen heeft het turbulente broeikaseffect van Venus het water letterlijk gekookt, waardoor stoom ontsnapte. Door middel van computersimulaties ontdekten de onderzoekers dat de waterstofatomen in de atmosfeer van Venus de ruimte in vliegen door “associatieve recombinatie”, een proces dat ervoor zorgt dat de planeet twee keer zoveel water verliest als eerder werd voorspeld. Met behulp van computermodellen stelden wetenschappers zich Venus voor als een enorm scheikundelaboratorium, waar ze reacties in de atmosfeer observeerden. Een molecuul genaamd HCO+, een ion dat bestaat uit een waterstof-, koolstof- en zuurstofatoom en dat wordt aangetroffen in de bovenste atmosfeer van de planeet, zou verantwoordelijk kunnen zijn voor het ontsnappen van water van Venus.

Dit is hoe Venus zo anders werd dan de aarde

NASA

Daarom kan deze ontdekking volgens Cangi onthullen waarom Venus zo anders werd dan de aarde, ook al waren de twee planeten oorspronkelijk bijna identiek: "We proberen te begrijpen welke kleine veranderingen zich op elke planeet voordeden om ze in deze zeer verschillende toestand te brengen." Volgens de wetenschappers veroorzaakten de machtige wolken koolstofdioxide in de atmosfeer een ongekend broeikaseffect in het hele zonnestelsel, waardoor de temperatuur steeg tot ongeveer 480°. Water werd stoom en het meeste daarvan kwam in de ruimte terecht. De rest verdween door HCO+, gevormd door de interactie tussen water en koolstofdioxide in de bovenste atmosferen van de planeet.

Dezelfde molecule kan ook een belangrijke rol hebben gespeeld bij het verdwijnen van water van Mars. Op Venus wordt de molecule continu geproduceerd, maar de ionen leven niet lang: de elektronen splitsen ze in twee delen, waarvan er één door de ruimte raast. Waarschijnlijk is de hoeveelheid van de molecule nooit gedetecteerd bij gebrek aan geschikte apparatuur.

{ https://www.curioctopus.nl/ }

03-06-2024 om 22:28 geschreven door peter  

The China National Space Administration said the lander used its onboard camera during its powered descent to detect obstacles autonomously and select a safe landing site. Chang’e-6 captured video imagery during the final phase of the lander’s descent and transmitted the views back to Earth. One video frame shows the shadow of the lander itself moments before touchdown.

Chang’e-6 is built to collect samples using a drill and a robotic arm. It’s also expected to gather scientific data about its surroundings using a radon detector, a negative-ion detector and a mini-rover. During surface operations, data and telemetry are being relayed between Chang’e-6 and Earth via China’s Queqiao-2 satellite.

Up to 2 kilograms (4.4 pounds) of lunar samples will be stowed inside the lander’s “ascender” stage. The rocket-powered ascender will then lift off from the surface and transfer the samples to the Chang’e-6 orbiter, which is currently in lunar orbit. Following the model set by Chang’e-5, the orbiter will head back toward Earth and release the sample capsule for atmospheric re-entry and touchdown in Inner Mongolia.

The moon’s south polar region is of particular interest because it’s thought to harbor reserves of water ice that could support lunar settlement. Studying fresh samples from the South Pole-Aitken Basin could help scientists and mission planners learn more about the region’s resources.

Chang’e-6 is the latest spacecraft in an international armada of moon landers — including Russia’s Luna 25, iSpace’s Hakuto-R and Astrobotic’s Peregrine, which were unsuccessful, plus more fruitful missions such as India’s Chandrayaan-3, Japan’s SLIM and Intuitive Machines’ Odysseus.

Coming attractions include NASA’s VIPER rover, which is currently due to be delivered to the moon late this year; and China’s Chang’e-7 mission, which features a hopping probe and is set for launch in 2026. Looking further ahead, China aims to send astronauts to the lunar surface by 2030 — not long after NASA’s Artemis 3 crewed lunar landing, currently scheduled for 2026.

{ https://www.universetoday.com/ }

03-06-2024 om 20:47 geschreven door peter  

China lands Chang'e 6 sample-return probe on far side of the moon, a lunar success (video)

China has landed on the moon's mysterious far side — again.

The robotic Chang'e 6 mission touched down inside Apollo Crater, within the giant South Pole-Aitken basin, at 6:23 a.m. Beijing Time on Sunday (June 2) , according to Chinese space officials. It was 6:23 p.m. EDT (2223 GMT) on June 1 at the time of the landing. The probe "successfully landed in the pre-selected area," China's space agency said.

The China National Space Administration (CNSA) now has two far-side landings under its belt — this one and Chang'e 4, which dropped a lander-rover combo onto the gray dirt in January 2019. No other country has done it once.

newspress collage ovcjawo88 1717320280587

© Provided by The UBJ

• Read more:
  The space race for the moon's water
  What you need to know about NASA and China's space race

And Chang'e 6 will make further history for China, if all goes according to plan: The mission aims to scoop up samples and send them back to Earth, giving researchers their first-ever up-close looks at material from this part of the moon.

"The Chang'e-6 mission is the first human sampling and return mission from the far side of the moon," CNSA officials said in a translated statement. (To be clear: Chang'e 6 is a robotic, not crewed, mission.) "It involves many engineering innovations, high risks and great difficulty." 

• Related: China's Chang'e 6 mission has a big lunar mystery to solve

Sampling a new environment

Chang'e 6 launched on May 3 with a bold and unprecedented task: haul home samples from the moon's far side, which always faces away from us. (The moon is tidally locked to Earth, completing one rotation on its axis in roughly the same amount of time it takes to orbit our planet. So observers here on Earth always see the same side of our natural satellite.)

Every lunar surface mission before Chang'e 4 targeted the near side, largely because that area is easier to explore. It's harder to communicate with robots operating on the far side, for example; doing so generally requires special relay orbiters, which China launched ahead of both Chang'e 4 and Chang'e 6. China's newest moon relay satellite, called Queqiao-2, aided the Chang'e 6 landing, CNSA officials said.

Chang'e 6 arrived in lunar orbit about four days after liftoff. It spent the next few weeks scrutinizing its planned landing site and gearing up for today's big event, which went according to plan: Chang'e 6's lander came down softly in Apollo Crater, leaving the mission's orbiter, with its attached Earth-reentry module, circling the moon.

The lander will spend the next few days studying its surroundings and collecting about 4.4 pounds (2 kilograms) of lunar dirt and rock. Some of these samples will be scooped from the surface and some will be dug from up to 6.5 feet (2 meters) underground, using Chang'e 6's onboard drill.

This material will then be launched into lunar orbit by a rocket that rode down with the lander. The sample container will rendezvous with the Chang'e 6 orbiter, then make the long trek back to Earth, eventually touching down here under parachutes on June 25.

Chang'e 6 is also carrying a tiny moon rover and has a variety of scientific experiments onboard the lander.

Scientists will study the returned material in detail, seeking insights about the moon's history and evolution and clues about why the lunar far side is so different than the near. The dark volcanic seas known as maria are common on the near side, for example, but are rare on the far side, for reasons that remain mysterious.

Researchers will doubtless compare the Chang'e 6 material to the samples collected on the moon's near side by Chang'e 5, which came down to Earth in December 2020. (Chang'e 5 and Chang'e 6 are sister missions, with virtually identical architectures.)

• Related: The moon: Everything you need to know

Big lunar dreams

{ https://www.space.com/ }

03-06-2024 om 01:41 geschreven door peter  

There was a time when maps of the Moon were created from telescopic observations and drawings. Indeed Sir Patrick Moore created maps of the Moon that were used during the historic Apollo landings. Now researchers have enhanced a technique to create accurate maps from existing satellite images. Their approach uses a technique called ‘shape-from-shading’ and involves analyzing shadows to estimate the features and shape of the terrain. Future lunar missions will be able to use the maps to identify hazards on the surface making them far safer. 

Researchers at the Brown University in Rhode Island have helped refine a process used to map the surface of the Moon making it more accurate than ever before. In their paper, published in the Planetary Science Journal and authored by Benjamin Boatwright and team details the enhancements to the mapping technique. It can generate detailed models of the Moon’s surface to highlight craters, ridges and slopes from composites of 2D images. 

Highly detailed maps are of crucial importance to lunar missions and help the planners to identify the safest place to land. They can also use them to identify areas of particular interest that require further study enabling the whole mission to be far more efficient. Missions such as the Artemis project will benefit when it heads for the south pole of the Moon, an area which is not well mapped. High resolution maps of the area will aid the autonomous landing systems to avoid hazards. 

Creating the maps is a time consuming job and is difficult to be accurate when lighting levels on target area are poor. The interpretation of shadows has been less than effective until now with the team addressing the issues. In their paper, the team explain how advanced computer algorithms can automate a lot of the process and improve the resolution of the generated models. Their new software gives lunar astronomers the necessary tools and information to create larger more detailed maps of the surface. 

To allow lunar scientists to create a map from images requires at least two images of the same area. Each image must be perfectly aligned with its counterpart so that features in one are in exactly the same place in the other. Until now, the technology has not been able to take multiple images of an area and create a perfect map. Boatwright said ‘We implemented an image alignment algorithm where it picks out features in one image and tries to find those same features in the other and then line them up, so that you’re not having to sit there manually tracing interest points across multiple images, which takes a lot of hours and brain power.’

Along with the image alignment algorithm, the researchers created quality control algorithms and filters to remove poor quality images from the alignment process. By only inputing good quality images to the process means the output will be of far higher quality. It is a similar model that astronomical imaging employs when processing multiple images through stacking and alignment techniques. 

To evaluate the accuracy of their work, the team compared the output from existing maps of the Moon to look for errors. To their delight, they found that maps created using their enhanced ‘shape-from-shading’ technique was more precise compared to those acquired during traditional techniques. 

Source : 

• New technique from Brown University researchers offers more precise maps of the Moon’s surface

{ https://www.universetoday.com/ }

03-06-2024 om 01:01 geschreven door peter  

The Sun's Magnetic Field Starts Just Beneath the Surface, New Study Reveals

The Sun's magnetic field, which drives solar storms and solar wind, doesn't originate deep within the Sun after all.

BY KIONA SMITH

Handout/Getty Images News

University of Edinburgh mathematician Geoffrey Vasil and his colleagues published their work in the journal Nature.

SHALLOW, NO DIVING

Vasil and his colleagues used a computer simulation to model how plasma flows in the outer layers of the Sun, called the convective zone: a 124,000-mile-deep sea of roiling plasma, heated from below by the Sun’s thermonuclear core. Specifically, they were interested in what happened in the top 20,000 miles or so of the plasma.

Massachusetts Institute of Technology mathematician Keaton Burns, a coauthor on the study, designed the program, called the Dedalus Project, to be very good at simulating how fluids flow, from the movements of liquid inside a cell to the circulation of Earth’s oceans and atmosphere. And the Sun, although we tend to picture it as a big ball of fire, is actually a big ball of super-hot gas.

Physicists know that the magnetic field is driven by an enormous dynamo: physical mass in motion, whose mechanical energy becomes electrical energy.

“One of the basic ideas for how to start a dynamo is that you need a region where there’s a lot of plasma moving past other plasma, and that shearing motion converts kinetic energy into magnetic energy,” explains Burns in a recent statement.

Most astrophysicists are convinced that process happens more than 125,000 miles deep inside the Sun, at the very bottom of the convection layer. That explanation makes sense in a lot of ways, but simulations based on it don’t actually produce results that look much like the churning, roiling plumes of plasma in the Sun’s outer layers — or the pattern of sunspots (dark, relatively cool patches of the Sun’s surface, where magnetic field lines meet and tangle) that astronomers actually see on the Sun’s surface. The real Sun is much more turbulent than most simulations suggest. And in simulations of a magnetic field coming from deep within the Sun, sunspots tend to gather near the Sun’s poles; on the real Sun, most sunspots form near the equator.

Knowing more about how the Sun’s magnetic field works could help scientists make predictions about the kinds of solar activity that produced stunning auroras — and briefly stalled spring planting on some farms by disrupting navigation systems on tractors and other equipment — earlier in May.

JUST BENEATH THE SURFACE OF THE SUN

Vasil and his colleagues’ simulations showed that the Sun’s outermost reaches are made of layers of plasma, which normally rotate past each other (picture an onion; now picture an onion 865,000 miles wide and made of super-hot gas with a giant thermonuclear reactor running at its center). But tiny changes in how one layer flowed past the next — like a little plume or a slight eddy — could create an instability that fed on itself and rapidly grew into major turbulence.

“It doesn’t take much to trigger an instability! If a system is unstable, it is like a pencil balanced on its point — any slight breeze is enough to knock it over,” co-author Daniel Lecoanet, an assistant professor of Engineering Sciences and Applied Mathematics at Northwestern University, tells Inverse. “The outer part of the Sun is convective, which is kind of like it is boiling. These roiling motions are definitely enough to seed the instability.”

Most of the instabilities that eventually formed got their start thanks to powerful winds in the interior of the Sun, which move at different speeds depending on how deep into the Sun you go. As you sink deeper into the Sun, the winds get stronger — until about 21,000 miles below the outer edge, when they suddenly slow down.

“The difference in wind speed at the surface vs. deeper into the Sun is a source of energy that can drive instability,” says Lecoanet. That energy is eventually converted into the Sun’s magnetic field.

And in Vasil and his colleagues’ simulations, those instabilities in the outer layers of the simulated Sun eventually produced a pattern of magnetic field lines and sunspots that looked remarkably like the real thing.

“Our work provides strong evidence that the solar cycle starts near the surface of the Sun in the equatorial region,” says Lecoanet.

PREDICTING SOLAR STORM SEASONS

Eventually, Vasil and his colleagues hope their work will help astrophysicists forecast how active the next solar cycle will be, similar to the way that meteorologists predict how active the coming hurricane season will be.

“This work is not trying to make predictions about individual solar storms,” says Lecoanet.

At the moment, NOAA’s Space Weather Prediction Center can predict the severity of a solar storm a few days in advance, around the time a huge belch of plasma called a coronal mass ejection leaves the Sun’s surface. But we don’t have a good way to predict what the next few years hold; some solar cycles are more active than others, and knowing what’s coming could help us prepare.

“We want to forecast if the next solar cycle will be particularly strong, or maybe weaker than normal,” says Lecoanet. “The previous models (assuming the solar magnetic field is generated deep within the Sun) have not been able to make accurate forecasts of if the next solar cycle will be strong or weak. We are hoping to make predictions of if a cycle will have a lot of solar storms or not a lot.”

{ https://www.inverse.com/ }

02-06-2024 om 01:14 geschreven door peter  

Under the SPRINT program, Aurora has been tasked with delivering DARPA an aircraft capable of demonstrating a range of key technological capabilities. The agency says this will “enable a transformational combination of aircraft speed and runway independence.”

Aurora’s demonstrator will be a fan-in-wing design, which achieves low-drag flight thanks to an innovative wing body platform that blends the best capabilities in current vertical take-off and landing (VTOL) technology with high speed.

Aurora’s aircraft will help advance the SPRINT program’s objectives of attaining “game-changing capability for air mobility and Special Operations Forces (SOF) missions,” the company said in a recent statement on its website.

WHAT THE NEW IMAGES REVEAL

In Aurora’s latest artist concept images, the experimental aircraft’s fan-in-wing (FIW) design is revealed. It features a trio of lift fans and a more streamlined composite exterior.

“The choice of three lift fans reflects the team’s strategy to simplify the demonstrator and streamline its path to flight test,” the company says, with the fans designed to be scaled to provide additional fans as may be needed for future aircraft based on the new design.

Above: Fan configuration shown in recent artist’s concept images of the X-plane, currently under development by Aurora for DARPA’s SPRINT program

(Credit: Aurora Flight Sciences/Boeing).

Previously, Aurora has already demonstrated the use of fan systems in the development of its Excalibur Unmanned Aerial System (UAS), which employs jet power to drive three electric “louvered lift” fans for vertical takeoff and landing. On the new X-plane, the fan configurations will be retractable within the wings during primary flight mode operations.

Although the current X-plane design is an uncrewed demonstrator, Aurora says this offers advantages during the testing phase by reducing risks while allowing the FIW technologies it demonstrates to be carried over and scaled to aircraft designs featuring traditional crewed configurations.

SETTING THE PACE FOR ‘SPRINT’

Additionally, the new images reveal elements of the aircraft that will serve as crucial components for meeting the SPRINT program’s objectives. These include a body capable of 450-knot cruise speeds, short take-off and vertical landing (STOVL) capabilities, and seamless transitions between vertical and horizontal flight modes.

Above: Updated artist’s concept imagery of the Aurora X-plane, currently in development for DARPA’s SPRINT program

(Credit: Aurora Flight Sciences/Boeing).

Larry Wirsing, vice president of aircraft development at Aurora Flight Sciences, said that the company’s work with DARPA on its SPRINT program offers “an exciting opportunity to continue our history of advancing technology demonstrator programs that enable new capabilities for the U.S. military.”

According to current timelines, Aurora and Boeing anticipate their primary design review will likely conclude within the next 12 months, after which the X-plane’s first official flight will take place in approximately 36 months.

• Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.

{ https://thedebrief.org/category/space/ }

02-06-2024 om 00:56 geschreven door peter  

De grootste astronomische ontdekkingen aller tijden

©Getty Images

De grootste astronomische ontdekkingen aller tijden
Het heelal heeft ons mensen al sinds we op planeet aarde rondlopen, gefascineerd. Er wordt dan ook al duizenden jaren studie gedaan naar dat donkere gat met al die lichtpuntjes. Van de oude Assyriërs, Grieken en de grootste geesten van de Renaissance tot de miljardair ruimteverkenners van de 21e eeuw. Er is ongelooflijk veel tijd, moeite en geld gestoken in het beter begrijpen van onze hemelse omgeving. En toch, ondanks alle grote stappen die zijn gezet om het universum te begrijpen, wordt geschat dat 95% daarvan nog steeds onontdekt is.

Desalniettemin weten we al aardig wat over het heelal. Benieuwd naar de grootste ontdekkingen? LEES dan verder!

©Getty Images

Wat is dat toch?
Het heelal is voor ons nog altijd een behoorlijk mysterie. Moet je nagaan wat onze voorvaderen daarover moeten hebben gedacht.

©Getty Images

Wat is dat toch?
De sterren waren direct verbonden met de religies van de prehistorie. Oude volkeren begonnen hemellichamen al snel te zien als wezens die verantwoordelijk waren voor aardse gebeurtenissen zoals regen, wind en stormen. Sommige van 's werelds vroegste bouwwerken en monumenten werden waarschijnlijk gebouwd als centra van aanbidding in overeenstemming met hemelse gebeurtenissen zoals de zonsverduistering en lente-equinox.

©Getty Images

Babylonische astronomie
De eerste schriftelijke astronomische waarnemingen verschijnen in Babylonische spijkerschriftteksten die rond 1500 voor Christus zijn geschreven. De vroegste planetaire waarneming werd vastgelegd in de 'Enuma Anu Enlil'. Daarin werd de beweging van Venus in de loop van 21 jaar gevolgd.

©Public Domain

De eerste sterrencatalogus
Gan De, een vroege voorvechter van Chinese astrologie, wordt gecrediteerd met het produceren van de eerste uitgebreide sterrencatalogus ter wereld, ergens in de 4e eeuw v.Chr., eeuwen voordat de Griekse astronomie Hipparchus zijn eigen atlas samenstelde.

©Getty Images

Eerste waargenomen komeet
Een van de meest bekende hemelse gebeurtenissen over de hele wereld, het passeren van de komeet van Halley werd voor het eerst vastgelegd in een Chinese tekst die teruggaat tot 240 v.Chr., en vervolgens opnieuw door de Babyloniërs in 164 v.Chr.. De komeet van Halley passeert de aarde op zo'n afstand dat hij elke 75 jaar met het blote oog zichtbaar is.

©Public Domain

De eerste heliocentrische theorie
Meer dan een millennium voordat Nicolaus Copernicus zijn heliocentrische theorie aan de wereld introduceerde, veronderstelde de oude Griekse astronoom Aristarchus, ergens tussen de 3e en 4e eeuw v.Chr., dat de zon en niet de aarde het centrum van het universum was.

©Getty Images

Ptolemaeus' Almagest
In de 2e eeuw n.Chr. introduceerde de Griekse astronoom Ptolemaeus de 'Almagest'. Die beschreef een enorm invloedrijke, zij het onnauwkeurige, geocentrische theorie van het universum. Dit idee dat de aarde het centrum van het universum was, zou meer dan duizend jaar heersen, tot de Italiaanse Renaissance.

©Getty Images

Astronomy through the Dark Ages
Terwijl de westerse vooruitgang in de astronomie tijdens de donkere Middeleeuwen bijna tot stilstand kwam, bleven astronomen in de Aziatische en Arabische wereld het veld verder pushen, nieuwe meetinstrumenten creëren en verbeteren en enorme, prachtige observatoria bouwen.

©Getty Images

De heliocentrische theorie van Copernicus
In 1543 publiceerde Copernicus zijn heliocentrische theorie, die de Copernicaanse revolutie ontketende. Het was de eerste keer in meer dan duizend jaar dat een heliocentrische theorie werd geponeerd, en hoewel het niet onmiddellijk werd aanvaard, onderschreven veel astronomen na Copernicus zijn theorieën en verbeterden ze totdat ze als feit werden geaccepteerd.

©Getty Images

Uraniborg
Een tijdgenoot en tegenstander van Copernicus, Tycho Brahe, die de heliocentrische theorie verwierp, boekte wel onschatbare vooruitgang met betrekking tot de posities van sterren met behulp van zijn enorme observatorium, Uraniborg. Uraniborg, gebouwd op het toenmalige Deense eiland Hven, was een van de grootste en belangrijkste observatoria die in gebruik was vóór de uitvinding van de telescoop.

©Getty Images

De sterrencatalogus van Tycho Brahe
In Uraniborg werkte Brahe aan zijn sterrencatalogus, waarvan de definitieve versie uit meer dan 1.000 sterren bestond. De catalogus van Brahe, die aan het einde van de 16e eeuw werd voltooid, maar pas in 1627 werd gepubliceerd, bevatte gegevens die tot 10 keer nauwkeuriger waren dan voorheen.

©Getty Images

De manen van Galileo
Een van Galileo's grootste prestaties, bereikt met de hulp van zijn telescoop in 1610, was de eerste waarneming van de vier grootste manen van Jupiter, gezamenlijk bekend als de Galileïsche manen. Dit was de eerste keer dat satellieten van een andere planeet werden waargenomen.

©Public Domain

De afstand tussen de aarde en Mars
In 1672 berekende de Italiaanse astronoom Giovanni Cassini, met de hulp van zijn assistent Jean Richer, de afstand van de aarde tot Mars. Dit was de eerste bewezen afstand van de aarde naar een andere planeet, en speelde een belangrijke rol bij het bepalen van de ware grootte van ons zonnestelsel.

©Getty Images

De sterren zijn niet vast op hun plaats
Edmond Halley, een Engelse wetenschapper en astronoom, was de eerste die zich realiseerde dat de verre sterren aan de hemel bewegende en dynamische objecten waren, terwijl hij hedendaagse kaarten en sterposities vergeleek met de posities die waren opgenomen in de 'Almagest' van Ptolemaeus. Daarin werd nog aangenomen dat sterren niet bewegende, statische objecten waren. Er werd een komeet naar Halley vernoemd.

©Getty Images

De ontdekking van Uranus
De Engelse astronoom William Herschel ontdekte de eerste 'nieuwe' planeet, Uranus, in 1781. Er waren al eerder waarnemingen van Uranus gedaan, maar tot de 18e eeuw werd ten onrechte aangenomen dat Uranus een verre ster was en geen planeet in ons eigen zonnestelsel.

©Public Domain

Het bestaan ​​van andere sterrenstelsels

Het twistpunt van het Grote Debat van 1920 tussen de Amerikaanse astronomen Harlow Shapley en Heber Curtis was hoe groot het universum eigenlijk was. Centraal in dit argument stond de Grote Spiraalnevel. Shapley betoogde dat deze nevel een kleine, relatief dichtbij gelegen wolk van gas en stof was.

©Getty Images

Het bestaan ​​van andere sterrenstelsels
Curtis beweerde echter correct dat de Grote Spiraalnevel, nu bekend als de Andromedanevel, in feite een massief en onafhankelijk sterrenstelsel was, vele lichtjaren verwijderd van ons eigen Melkwegstelsel.

©Getty Images

Het heelal breidt zich uit
In de jaren twintig werd een van de meest schokkende en revolutionaire ontdekkingen over de aard van de ruimte gedaan. De wet van Hubble-Lemaître, eerst verondersteld door de Belgische priester en astronoom Georges Lemaître en later bevestigd door Edwin Hubble, had bewezen dat het universum zelf in een constante staat van verandering en uitbreiding verkeert. De wet van Hubble-Lemaître vertelt ons dat de snelheid waarmee een hemellichaam van ons af beweegt recht evenredig is met zijn afstand tot de aarde.

©Getty Images

De ontdekking van donkere energie
Wat deze expansie voortstuwde, was echter nog onbekend in de tijd van Lemaître en Hubble. Pas in 1998 ontdekten wetenschappers donkere energie. Het universum bestaat voor 69% uit donkere energie. In tegenstelling tot materie en donkere materie, lijkt donkere energie gelijkmatig over het universum te zijn verspreid, en is zwaartekracht afstotend. Dat betekent dat de energie naar buiten duwt, waardoor alles in het universum verder uit elkaar wordt geduwd. Tot op de dag van vandaag blijft donkere energie een van de grootste mysteries van het universum.

©Getty Images

Kosmische magnetron achtergrond
Een van de belangrijkste vorderingen bij het in kaart brengen van de geschiedenis van het universum was de ontdekking van de kosmische microgolfachtergrond van het universum. In 1963 ontdekten natuurkundigen Arno Penzias en Robert Wilson de achtergrondstraling die in alle uithoeken van het universum aanwezig is en fungeert als een voetafdruk voor de kosmische gebeurtenissen die eraan voorafgingen. Deze ontdekking was instrumenteel in de brede acceptatie van de oerknaltheorie.

©Getty Images

De ontdekking van het eerste zwarte gat
Astronomen ontdekten het eerste zwarte gat in 1964 in een diep deel van het sterrenbeeld Zwaan, na onderzoek naar onverwachte röntgenstraling in de ruimte. Het zwarte gat kreeg de naam Cygnus-X en bewees voor het eerst de theorie van Albert Einstein over zwarte gaten van bijna 50 jaar eerder.

©Getty Images

Verkenning van Mars
De Sovjet Mars 3 rover, gelanceerd in 1971, was de eerste sonde die met succes op Mars landde, hoewel de verbinding minder dan een minuut daarna verbrak. Vijf jaar later, in 1976, landde NASA met succes de Viking I en Viking II rovers op de rode planeet. Deze twee rovers stuurden in de loop van vier jaar meer dan 52.000 beelden van het oppervlak van Mars naar de aarde.

©Getty Images

Ondergang van de dinosaurussen uitgelegd
In 1980 was de Amerikaanse Nobelprijswinnaar Luis Alvarez, met de hulp van zijn zoon, geoloog Walter Alvarez, en een team van nucleaire chemici, de eerste die stelde dat een enorme asteroïde die in botsing kwam met de aarde leidde tot het uitsterven van de dinosauriërs en een einde maakte aan het Krijt. Enkele jaren later, in de jaren negentig, werd de Chicxulub-krater, met een diameter van 180 kilometer, ontdekt in Mexico. Tegenwoordig wordt algemeen aangenomen dat de Chicxulub-krater de plek is waar de legendarische asteroïde was ingeslagen.

©Getty Images

Eerste planeet gevonden buiten ons zonnestelsel
In 1992 ontdekte een team van astronomen dat werkte vanuit het beroemde Arecibo-observatorium, twee exoplaneten buiten ons melkwegstelsel. Dit waren de eerste planeten buiten ons eigen zonnestelsel die ooit werden waargenomen, maar zeker niet de laatste. Er zijn inmiddels meer dan 4.000 exoplaneten ontdekt.

©Getty Images

Water op Mars
Er werd lang gedacht dat Mars een ongelooflijk droge planeet was, verstoken van water. Echter veranderde de perceptie in 2012 toen NASA's Curiosity-rover bewijs vond van een enorm waterbed dat bevroren was onder het oppervlak van Mars. Sindsdien zijn er talloze andere ontdekkingen van water gedaan en wetenschappers zijn het er nu over eens dat minstens een derde van Mars bedekt is met bevroren water.

©Getty Images

Een tweede aarde
Een van de meest prikkelende vragen van ruimteverkenning is of er planeten zijn die zo op de aarde lijken dat ze leven zouden kunnen ondersteunen. In 2015 kondigde NASA aan dat ze een zeer aardachtige planeet hadden gevonden, bekend als Kepler-452b, in een baan rond een ster die veel op onze zon lijkt. Hoewel de samenstelling van de atmosfeer van de exoplaneet onbekend is, is het wel bekend dat hij op een bewoonbare afstand van zijn thuisster ligt en een rotsachtig oppervlak heeft.

©Getty Images

Een oceaan op Europa
Een internationaal gezamenlijk onderzoeksteam onder leiding van NASA kondigde in 2019 aan dat er waterdamp was gedetecteerd in de atmosfeer van de maan Europa, een van de 79 manen van Jupiter. Deze ontdekking ondersteunde de lang gekoesterde theorie dat er zich een enorme oceaan verbergt onder het oppervlak van deze maan, waarvan veel wetenschappers denken dat het een 24 kilometer diepe ijslaag is.

Zie ook:

• Duizelingwekkend mooie ruimtefoto's van NASA

Bronnen:

• (European Space Agency)
• (NASA)
• (Futurism)

{ https://www.msn.com/nl-be/feed?ocid=msedgntp&pc=acts }

01-06-2024 om 23:13 geschreven door peter  

China's secret space plane has released another unknown object over Earth

Related stories: 

• China has launched a secret robot to the far side of the moon, new Chang'e 6 photos reveal

Meanwhile, the U.S. military's X-37B space plane is also in Earth's orbit. The craft launched on Dec. 28 on a SpaceX Falcon Heavy rocket. The fact that the two missions are operating simultaneously is "probably no coincidence," Space Force Chief of Space Operations B. Chance Saltzman told Air & Space Forces magazine. 

Perhaps unsurprisingly, China's state-run media outlets have not indicated any military applications for the space plane. "After operating in orbit for a period of time, the experimental spacecraft will return to the designated landing site in China," Xinhua reported, according to Gizmodo. "During this period, it will carry out reusable technology verification and space science experiments as planned, providing technical support of the peaceful use of space."

Reusable space planes have many potential commercial and scientific applications, including carrying passengers and launching satellites more efficiently. Nevertheless, the Space Force will continue to monitor the Shenlong mission until it returns to Earth.

{ https://www.livescience.com/ }

01-06-2024 om 15:52 geschreven door peter  

The team’s discovery seems to be linked to the concept of disappearing stars. Over the last few years, it has become evident that some stars seem to just vanish from view, neither passing through the planetary nebula phase nor going supernova. The discovery of supermassive stars undergoing complete collapse without supernova now provides a good explanation for the phenomenon. 

The team reached their conclusion when they explored an object known as VFTS 243; a binary system which includes a star thought to be 25 times more massive than the Sun and a blackhole 10 times more massive than the Sun. Both objects orbit a common centre of gravity over a period of 10.4 days and lie in the Tarantula Nebula in the Large Magellanic Cloud – 160,000 light years away. The binary system is not the first of its kind to be discovered, such systems have been known about for decades. 

Studying the system revealed the orbit was almost circular. Given that one of the stars had collapsed into a black hole, the nearly circular orbit and the lack of any evidence of an explosion all point to a star that collapsed completely. The complete collapse meant that all matter from the star collapsed into the blackhole and no material escaped out as a supernova. Could it be then that the team have finally revealed the mechanism by which massive stars have been vanishing? It certainly looks like it but further observations of binary systems with stars and black holes is required to confirm. 

Source : 

• Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243

{ https://www.universetoday.com/ }

01-06-2024 om 15:02 geschreven door peter  

Dr. Swindle follows this with, “There are two basic types of motivation. One is that we’re planning on bringing all these rock samples, and we’re going to be interested in knowing how they’ve interacted with the atmosphere, but we can’t figure that out without knowing the composition of the atmosphere in detail. So, we need an atmospheric sample to know what the rocks might have been exchanging elements and isotopes with. But we’d also like to have a sample of the Martian atmosphere to answer some basic questions about processes that have occurred, or are occurring, on Mars. For example, Martian meteorites contain trapped atmospheric noble gases, like krypton and xenon. But it appears that there are at least two different “atmospheric” components in those meteorites.”

For the study, the researchers proposed several benefits of returning a Mars atmospheric sample to Earth, including atmospheric samples being among the NASA Perseverance (Percy) rover sample tubes, gaining insight into potential solar gar within the Martian interior, evolutionary trends in atmospheric compositions, nitrogen cycling, and sources of methane on Mars. For the Percy atmospheric sample, also known as Sample No.1 “Roubion”, the study notes how this sample was obtained after Percy tried to collect a rock core sample but ended up collecting atmospheric gases instead. Additionally, the study proposes the lack of leakage the sample tube will experience while awaiting its return to Earth and the gases present within the sample are ideal for analysis once returned to Earth, as well. But aside from the Percy rover sample, how else could a Martian atmosphere sample be obtained?

“At least two other ideas for collecting a sample of Martian atmosphere have been suggested,” Dr. Swindle tells Universe Today. “One is to fly a spacecraft through the Martian atmosphere, collect a sample as it goes through, then return it to Earth. The other is to have a sample return “cannister” (it doesn’t have to be any bigger than a Perseverance tube) that has valves and a (Martian) air compressor. You could land it on the surface of Mars, open the valve to the atmosphere, turn on the compressor, and get a sample that has hundreds or thousands of times as much Martian atmosphere as a volume that is just sealed without compression, as Perseverance has done, and hopefully will do again.”

Dr. Swindle and Dr. Young both mention the Sample Collection for Investigation of Mars (SCIM) mission, which was proposed in 2002 by a team of NASA and academic researchers with the goal of collecting atmospheric samples at an altitude of 40 kilometers (25 miles) above the Martian surface and return them to Earth for further analysis. While SCIM was selected as a semi-finalist for the 2007 Mars Scout Program, it was unfortunately not selected for further development, and both Dr. Young and Dr. Swindle tell Universe Today there are currently no atmospheric sample missions being planned aside from the Percy rover sample. Therefore, what follow-up studies from this research are currently underway or being planned?

Dr. Swindle and Dr. Young both mention how efforts are being made to collect small quantities of atmospheric gas due to the small size of the sample tubes, with Dr. Swindle telling Universe Today, “A big set of questions right now is how good a sealed Perseverance tube would be at containing an atmospheric sample. How good is the seal? Might the tube spring a leak on a hard landing? Would some molecules in the Martian atmosphere stick to the coatings of the tubes? There’s been some activity on all of these questions, and so far, the answers have all been good – it looks like those Perseverance tubes may do well, even though they weren’t really designed with atmospheric sampling in mind.”

As noted, the purpose of obtaining and returning an atmospheric sample from Mars could help scientists better understand the formation and evolution of the Red Planet. While present-day Mars is a very cold and dry world with an atmosphere that is a fraction of the Earth’s atmosphere, with liquid water being unable to exist on the surface, along with no active volcanism, as well. However, significant evidence obtained from landers, rovers, and orbiters over the last several decades point to a much different Mars billions of years ago after it first formed. This included an active interior that produced a magnetic field that shielded the surface from harmful solar and cosmic radiation, a much thicker atmosphere being replenished from active volcanism, and flowing liquid water, all of which potentially led to the existence of some forms of life on the surface.

However, given Mars’ small size (half of Earth), this means its internal heat cooled off much faster (possibly over millions of years), resulting in volcanism becoming inactive and the dissipation of the magnetic field the interior activity was driving, the latter of which led to harmful solar and cosmic radiation stripping the atmosphere, with the surface liquid water evaporating to space along with it. Therefore, do Dr. Young and Dr. Swindle believe life ever existed on Mars, and will we ever find it?

Dr. Young tells Universe Today, “I really don’t know.  I think microbial life sometime in the past, or even now, is a reasonable hypothesis but we don’t have enough information.”

Dr. Swindle also echoes his uncertainty whether life ever existed on Mars, but elaborates by telling Universe Today, “If there hasn’t, why did life start so early on Earth, but didn’t start on Mars, which had a similar climate at the time. If there has been, how similar is it to life on Earth? Since Earth and Mars are always exchanging rocks because of impacts, is life on Earth related to life on Mars? If it has existed, it will be tough to find. But an atmospheric sample could help. For instance, there seems to be methane in the Martian atmosphere. Most, but not all, of the methane in Earth’s atmosphere is biological, and analyzing the relative ratios of the isotopes of carbon or hydrogen is one of the best ways to figure that out.”

When will we obtain an atmospheric sample of Mars and what will it teach us about the formation and evolution of the Red Planet in the coming years and decades? Only time will tell, and this is why we science!

• As always, keep doing science & keep looking up!

{ https://www.universetoday.com/ }

01-06-2024 om 14:42 geschreven door peter  

POSTED BY CAROLYN COLLINS PETERSEN

Io Has Been Volcanically Active for its Entire History

Jupiter’s moon Io is a volcanic powerhouse. It’s the most geologically active world in the Solar System, sporting more than 400 spouting volcanoes and vents on its surface. Has it always been this way? A team of planetary scientists says yes, and they have the chemical receipts to prove it.

In a recent paper, the team headed by CalTech scientist Katherine de Kleer cites data from millimeter observations of elemental isotopes found in Io’s eruptions. They found that chemicals like chlorine and sulfur exist in higher quantities at Io than in comparable places in the Solar System. Analysis shows that Io hasn’t just started erupting lately—it’s been going on for most of its history. And, it’s so volcanic that it practically resurfaces itself every million years or so.

The discovery of volcanism on Io was one of the major results of the Voyager mission. As the two spacecraft swept past Jupiter in 1979, their images revealed Io’s volcanic features and plumes. Since that time, the Galileo, Cassini-Huygens, New Horizons, and Juno missions also sent images. The Jovian system and its moons are also frequent targets for ground- and space-based observatories, including Hubble Space Telescope and JWST.

Facts about Io

Io is the fourth-largest Jovian moon and is one of the four Galilean satellites. It orbits closest to Jupiter and gets pulled by a gravitational tug-of-war between Jupiter and the other Galilean moons. The result is a process called “tidal heating” deep inside Io, produced by friction. That generates heat, which melts Io’s interior, and opens up vents so that the heat and melted material can escape to the surface.

This little moon is mostly silicate rock atop an iron or iron sulfide core. The surface is scarred with volcanoes and deformed by compressional forces beneath the crust. The most obvious features are the volcanic mountains, plumes, and lava flows. Currently, Io’s volcanoes resurface the landscape at a rate of about 0.1 to 1.0 cm per year. They also paint its surface in an amazing array of colors. During the Voyager 2 flyby, people often compared its appearance to a pizza. The colors come mainly from sulfur and sulfurous compounds deposited across the landscape.

Normally, geologists would look at its surface and count craters to get an idea of its age. But, since volcanic flows erase craters, there’s no easy visual way to determine how long volcanic features have been around. However, it turns out that abundances of certain isotopes of sulfur and other elements could provide a good record the history of volcanism on Io.

Analyzing Io’s Chemistry

Io has probably lost mass to space throughout its history. de Kleer and her colleagues point out that its supply of volatile elements should be highly enriched in heavy stable isotopes. That’s because atmospheric escape processes generally favor the loss of lighter isotopes. They suggest that stable isotope measurements of volatile elements, such as sulfur and chlorine, could give accurate details about the history of volcanism at Io. So, it makes sense, then, to do a thorough chemical analysis of Io’s volcanic emissions now and extrapolate back.

Understanding Io’s current chemistry, requires, among other things, a good idea of its mass-loss history. Io’s mass loss occurs because of collisions between atmospheric molecules and energetic particles trapped in Jupiter’s magnetosphere. If this continued over Io’s history, then its chemistry should provide evidence of the volcanic past. In their paper, the team discusses the assumptions they made, including estimates of Io’s initial inventory of sulfur, as well as possible early mass-loss rates that could affect its current abundances of sulfur and chlorine—two elements that help determine past and present volcanism.

To get that history, team used the Atacama Large Millimeter Array to observe gases in Io’s atmosphere. The goal was to measure SO2, SO, NaCl, and KCl in various forms and determine the ratios of ³⁴S to ³²S and ³⁷Cl to ³⁵Cl. After analyzing the data, the team found that Io has lost at least 94 to 99 percent of its available sulfur over time. In addition, the measurements show enriched levels of chlorine. This probably indicates that Io has been volcanically active throughout time. It’s also possible that this tiny moon has experienced higher rates of outgassing and mass loss early in its history. More measurements should help scientists constrain Io’s volcanic activity even more tightly.

For More Information

• Isotopic Evidence of Long-lived Volcanism on I
• Violent Volcanoes Have Wracked Jupiter’s Moon Io for Billions of Years

{ https://www.universetoday.com/ }

01-06-2024 om 01:45 geschreven door peter  

POSTED BY MATT WILLIAMS

Pluto Has an Ocean of Liquid Water Surrounded by a 40-80 km Ice Shell

On July 14th, 2015, the New Horizons spacecraft conducted the first-ever flyby of Pluto, which once was (and to many, still is) the ninth planet of the Solar System. While the encounter was brief, the stunning images and volumes of data it obtained revealed a stunningly vibrant and dynamic world. In addition to Pluto’s heart, floating ice hills, nitrogen icebergs, and nitrogen winds, the New Horizons data also hinted at the existence of an ocean beneath Pluto’s icy crust. This effectively made Pluto (and its largest moon, Charon) members of the “Ocean Worlds” club.

Almost a decade after that historic encounter, scientists are still making discoveries from New Horizons data. In a new paper, planetary scientists Alex Nguyen and Dr. Patrick McGovern used mathematical models and images to learn more about the possible ocean between Pluto’s icy surface and its silicate and metallic core. According to their analysis, they determined that Pluto’s ocean is located beneath a surface shell measuring 40 to 80 km (25 to 50 mi), an insulating layer thick enough to ensure that an interior ocean remains liquid.

Nguyen is a graduate student in Earth, environmental, and planetary sciences in Arts & Sciences at Washington University in St. Louis (WUSTL), while Dr. McGovern is a Senior Staff Scientist with the Lunar and Planetary Institute (LPI) in Houston. Their paper, “The role of Pluto’s ocean’s salinity in supporting nitrogen ice loads within the Sputnik Planitia basin,” recently appeared in the journal Icarus. The study is part of Nguyen’s Ph.D. research at Washington University, where he is an Olin Chancellor’s Fellow and a National Science Foundation Graduate Research Fellow.

For decades, planetary scientists assumed Pluto was far too cold to support an interior ocean. Pluto orbits well beyond the Solar System’s “Frost Line,” the boundary beyond which volatile elements (water, carbon dioxide, ammonia, etc.) become solid. With an average surface temperature of -229 °C (-380°F), even nitrogen and methane become as solid as rock. As Nguyen indicated in a recent interview with The Source (WUSTL’s news site), “Pluto is a small body. It should have lost almost all of its heat shortly after it was formed, so basic calculations would suggest that it’s frozen solid to its core.”

But thanks to New Horizons, scientists were presented with multiple lines of evidence that suggest Pluto likely has an interior ocean. This includes cryovolcanoes, such as those observed on Ceres, Europa, Ganymede, Enceladus, Titan, Triton, and other “Ocean Worlds.” While the existence of this ocean is still subject to debate, the theory is gaining acceptance to the point that it is considered a very real possibility. For their study, Nguyen and McGovern created mathematical models to explain the cracks and bulges in the ice covering Pluto’s Sputnik Planitia Basin.

Their results indicate that an ocean could exist beneath an icy shell 40 to 80 km (25 to 50 mi) thick, which would be sufficient to ensure that Pluto could maintain a liquid water ocean in its interior despite surface conditions. They also calculated the likely density or salinity of the ocean based on the surface features and determined that Pluto’s ocean could be up to 8% denser than Earth’s oceans. This salinity level would make Pluto’s ocean comparable to the Great Salt Lake, the Dead Sea, and other high-salinity bodies of water on Earth.

According to Nguyen, any variations in this density (greater or lower) would be evident from the cracks and fractures in the Sputnik Platina Basin. “We estimated a sort of Goldilocks zone where the density and shell thickness is just right,” he said. If the ocean were less dense, the ice shell would collapse, leading to many more fractures in the surface. If it were denser, the ice sheet would be more buoyed, which would be evident from there being fewer fractures. Unfortunately, it could be many decades before another spacecraft reaches Pluto to help confirm these findings. In the meantime, the case for Pluto’s interior ocean grows stronger!

Further Reading:

•  Washington University at St. Louis, Icarus

{ https://www.universetoday.com/ }

01-06-2024 om 01:37 geschreven door peter  

For the study, the researchers investigated water management requirements for a 100-person self-sustaining lunar base measured at 500 m x 100 x 6 m (1640 ft x 328 ft x 20 ft), including the location of the lunar base near water ice deposits, the technology required to convert the water ice to water vapor (since liquid water can’t exist on the Moon), and the technology required for water treatment and recovery that would result in safe consumption for the 100-person base. The study used the current water usage estimates for American households, which is approximately 100 gallons per day (GPD) per person, which includes cleaning, cooking, drinking, flushing toilets, and washing clothes.

Additionally, the researchers examined the amount of water required for agricultural, technical, and overall needs for the lunar base. Regarding the location of the lunar base, the researchers deduced that the best location for the base would be either near, or exactly on, the Shackleton-de Gerlache Ridge, which is located at 89.9°S 0.0°E, or almost directly on the lunar south pole. The reason this location is ideal for water ice deposits is because Shackleton Crater resides within a permanently shadowed region (PSR), meaning it is shrouded in permanent darkness due to the Moon’s small axial tilt, and water ice has potentially built up over billions of years.

In the end, the team concluded the water requirements for the 100-person lunar base for human, agricultural, and technical needs are 12.3, 72, and 2 acre-feet per year. For context, one acre-foot is equivalent to approximately 326,000 gallons, so a 100-person lunar base would need more than 4,000,000 gallons per year for human needs, more than 23,000,000 gallons per year for agricultural needs, and 652,000 gallons per year for technical needs. So, based on these findings, what were the most significant results from this study, and what follow-up studies are currently in the works or being planned?

Dr. Lee tells Universe Today, “There is good evidence that sufficient water exists on the Moon to support a permanent lunar colony, and the acquisition, treatment, and distribution of the lunar water can be achieved with current technology. An appropriate administrative structure will be necessary to oversee all aspects of lunar water. The relative scarcity and management of water on the Moon can potentially provide insight for improving the management of water on Earth. The next study for my group will be to investigate the ways in which the management of lunar water could help to improve terrestrial water management. However, the timeline for this research is yet to be determined.”

The study discusses in-situ resource utilization (ISRU), which is using available, on-site resources for both sustainability and survivability. In this case, using water ice deposits on the Moon, and specifically near the south pole of the Moon, to meet the water needs of a 100-person, self-sustaining lunar base. The potential for NASA using ISRU has gained considerable traction in the last few years since sending water from the Earth to the Moon could prove to be extremely costly. But aside from the financial risks, if a resupply mission gets delayed or fails on the way to the Moon, the crew could face significant danger. Therefore, learning to “live off the land” for a lunar base could prove to be a viable, long-term option for mitigating the need of resupply missions from Earth. But what additional importance could a self-sustaining moonbase also provide?

Dr. Lee tells Universe Today, “Over the years, there has been a groundswell of excitement at the prospect of colonizing Mars. Indeed, at present, we are conceivably able to mount a short-term human voyage to the Red Planet in which the astronauts would collect samples, conduct experiments, plant flags, and when the next launch window occurs, return to Earth. However, the permanent colonization of Mars is much more ambitious and challenging. Mars is much farther away than the Moon, requiring 9 months to get there and a round trip time of 21 months (a 3-month stay on Mars is needed until the next launch window arrives).”

NASA’s goal is to send humans to Mars through the agency’s Moon to Mars Architecture, which is an elaborate, years-long endeavor to develop the necessary technologies on the Moon for use during a crewed mission to the Red Planet. This includes science, infrastructure, transportation, habitation, and operations, just to name a few. However, as noted, while we can (possibly) send humans to the Red Planet for short-term stays with our current technology, a long-term human presence on Mars would require significantly more time and resources.  

Dr. Lee tells Universe Today, “Beyond low Earth orbit, the Moon is a logical next destination. Lunar colonization is technologically achievable, and in comparison to Martian colonization, it is far easier. Being capable of establishing a moonbase seems like an obvious prerequisite for establishing a Mars base. Furthermore, the Moon would be an excellent jumping off point for further Solar System colonization including potentially the eventual establishment of small colonies in the interiors of Near-Earth Asteroids. Additionally, some have suggested that the Moon is an ideal location from which the interception of Earth-bound asteroids could be conducted.”

This study comes as NASA’s Artemis program plans to land the first woman and person of color on the lunar surface in the next few years. The current landing sites of the Artemis missions are near the south pole to access nearby water ice deposits within the aforementioned PSRs and could be ideal to develop ISRU technologies that can also be used on future Mars crewed missions, as well. Therefore, what implications could this study have for the upcoming Artemis missions?

“Short term lunar visits, such as the planned Artemis missions would not require lunar water,” Dr. Lee tells Universe Today. “In these instances, sufficient water could be brought from Earth. However, if at some point in the future, a lunar colony were to become a priority, future Artemis missions could serve to provide valuable in situ information about the presence and abundance of lunar water, particularly at the lunar south pole and in proximity to the Shackleton Crater (an ideal area for a moonbase).”

How will water management play a role in a self-sustaining lunar base in the coming years and decades? Only time will tell, and this is why we science!

• As always, keep doing science & keep looking up!

{ https://www.universetoday.com/ }

01-06-2024 om 01:27 geschreven door peter  

The study, published in the journal Patterns, highlights the risks and challenges posed by this emerging behavior and calls for urgent action from policymakers and AI developers.

“AI developers do not have a confident understanding of what causes undesirable AI behaviors like deception,” Dr. Peter S. Park, the study’s lead author and an AI existential safety postdoctoral fellow at MIT, said in a press release. “But generally speaking, we think AI deception arises because a deception-based strategy turned out to be the best way to perform well at the given AI’s training task. Deception helps them achieve their goals.” 

The review meticulously analyzed various AI systems and found that many had developed deceptive capabilities due to their training processes. These systems ranged from game-playing AIs to more general-purpose models used in economic negotiations and safety testing environments.

One of the most striking examples cited in the study was Meta’s CICERO, an AI developed to play the game Diplomacy. Despite being trained to act honestly and maintain alliances with human players, CICERO frequently used deceptive tactics to win. 

This behavior included building fake alliances and backstabbing allies when it benefited its gameplay, leading researchers to conclude that CICERO had become a “master of deception.”​

“Despite Meta’s efforts, CICERO turned out to be an expert liar,” researchers wrote. “It not only betrayed other players but also engaged in premeditated deception, planning in advance to build a fake alliance with a human player to trick that player into leaving themselves undefended for an attack.”

Researchers found that other AI systems had developed the ability to cheat at different types of games. For instance, Pluribus, a poker-playing model created by Meta, demonstrated it could convincingly bluff in Texas hold ’em poker, successfully misleading professional human players about their hand strengths. 

In another example, AlphaStar, an AI system created by Google’s DeepMind to play the real-time strategy game Starcraft II, exploited the game’s “fog-of-war“ mechanics to feint attacks and deceive opponents to gain strategic advantages. 

“While it may seem harmless if AI systems cheat at games, it can lead to breakthroughs in deceptive AI capabilities that can spiral into more advanced forms of AI deception in the future,“ Dr. Park explained.

Indeed, during their review, researchers found that some AI systems had already learned methods of deception that extend far beyond the realm of games. 

In one instance, AI agents had learned to “play dead“ to avoid being detected by a safety test designed to eliminate faster-replicating AI variants. Such behavior can create a false sense of security among developers and regulators, potentially leading to severe consequences if these deceptive systems are deployed in real-world applications​​.

Another AI system trained on human feedback was found to have taught itself how to behave in ways that earned positive scores by tricking human reviewers into thinking an intended goal had been accomplished. 

The potential risks of AI deception are significant and multifaceted. Researchers note that in the near term, these systems could be used by malicious actors to commit fraud, manipulate financial markets, or interfere with elections. 

Moreover, as AI capabilities advance, there is an increasing concern among experts that humans may not be able to control these systems, posing existential threats to society.

Researchers call for robust regulatory frameworks and proactive measures to address these risks. This includes classifying deceptive AI systems as high risk, mandating transparency in AI interactions, and intensifying research into methods for detecting and preventing AI deception. 

While some progress has been made, such as the EU AI Act and President Joe Biden’s Executive Order on AI safety, enforcing these policies remains challenging due to the rapid pace of AI development and the lack of reliable techniques to manage these systems effectively​. 

Researchers argue that AI developers should be legally required to delay the deployment of AI systems until they are demonstrated to be trustworthy by reliable safety tests. Additionally, the deployment of new systems should be gradual so that emerging risks from deception can be properly assessed and mitigated. 

The study authors also stressed the importance of understanding why and how AI systems learn to deceive. Without this knowledge, creating adequate safeguards and ensuring that AI technologies benefit humanity without undermining trust and stability will be challenging.

As AI continues to evolve, the need for vigilance and proactive regulation becomes ever more critical. The findings of this review serve as a stark reminder of the potential dangers lurking within advanced AI systems and the urgent need for comprehensive strategies to mitigate these risks.

“Proactive solutions are needed, such as regulatory frameworks to assess AI deception risks, laws requiring transparency about AI interactions, and further research into detecting and preventing AI deception,“ researchers concluded. “Proactively addressing the problem of AI deception is crucial to ensure that AI acts as a beneficial technology that augments rather than destabilizes human knowledge, discourse, and institutions.”

• Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

{ https://thedebrief.org/category/tech/ }

01-06-2024 om 00:00 geschreven door peter  

We could float effortlessly in Pluto's subsurface ocean

Related: 

• Supervolcano eruption on Pluto hints at hidden ocean beneath the surface

Most strikingly, some scientists believe that Pluto holds cryovolcanoes that spew out water vapor or even solid water ice. That water has to come from somewhere — and a layer of liquid water beneath Pluto's crust would fit the description.

Researchers at Washington University in St. Louis and the Lunar and Planetary Institute in Houston set about constructing a model of what that liquid layer might look like. In particular, they wanted to match Sputnik Planitia — a heart-shaped lowland basin on Pluto's surface thought to be the aftermath of an impact. So, the researchers tried different configurations of ocean thickness and water density that would result in the Sputnik Planitia criss-crossed with cracks that New Horizons observed.

"We estimated a sort of Goldilocks zone where the density and shell thickness is just right," said Alex Nguyen, a graduate student at Washington University in St Louis and one of the authors, in a statement.

Their calculations indicated that a Plutonian ocean would most likely be around 25 to 50 miles (40 to 80 kilometers) thick, and about 8 percent denser than Earth seawater. That is about as dense as the Great Salt Lake. 

But the idea of a Plutonian ocean is still controversial. Scientists don't know enough about Pluto to know if the evidence really points to liquid water or if it's just circumstantial. Most recently, a study simulating the origin of Sputnik Planitia suggested that the heart-shaped basin was most likely to have formed if Pluto had a solid interior.

So, until a successor to New Horizons lets us revisit Pluto, what lies beneath the world's surface will remain cloaked in shadow.

Nguyen and co-author Patrick McGovern published their work in the journal Icarus on February 15.

{ https://www.space.com/ }

31-05-2024 om 23:30 geschreven door peter  

James Webb Space Telescope spots the most distant galaxy ever seen (image)

Related: 

• James Webb Space Telescope spots 3 of our universe's earliest galaxies

The announcement of the discoveries, made in Oct. 2023 and Jan. 2024, are the latest developments in the ongoing investigation of cosmic dawn that the $10 billion telescope has facilitated as part of the JWST Advanced Deep Extragalactic Survey (JADES) program. JADES aims to provide vital insights into the ways in which the stars, gas, and black holes were evolving in primordial galaxies when the 13.8 billion-year-old universe was very young. 

"These galaxies join a small but growing population of galaxies from the first half billion years of cosmic history where we can really probe the stellar populations and the distinctive patterns of chemical elements within them," team member and Kavli Institute for Cosmology scientist Francesco D’Eugenio said in a statement.

JADES-GS-z14-0 isn't just remarkable for how distant it is from Earth and how early it existed in the cosmos, though. With a width of around 1,600 light-years across, this "cosmic dawn" galaxy is also remarkable for how big and bright it is.

"The size of the galaxy clearly proves that most of the light is being produced by large numbers of young stars, rather than material falling onto a supermassive black hole in the galaxy's center, which would [make it] appear much smaller, "JADES team leader Daniel Eisenstein from the Harvard & Smithsonian's Center for Astrophysics (CfA) said in a separate statement. 

The extreme brightness of JADES-GS-z14-0 and the fact this luminosity is powered by young stars means this galaxy represents the most striking evidence for the rapid formation of large, massive galaxies in the early universe found thus far.

JADES team member and University of California-Santa Cruz researcher Ben Johnson added that JADES-GS-z14-0 shows that galaxy formation in the early universe was very rapid and intense. 

"The JWST will allow us to find more of these galaxies, perhaps when the universe was even younger," he said. "It is a marvelous opportunity to study how galaxies get started."

The James Webb Space Telescope sees red to spot early galaxies

The JWST is adept at seeing early galaxies thanks to the high infrared sensitivity of its instruments, particularly its primary imager, the Near Infrared Camera (NIRCam). 

Light leaves these cosmic dawn galaxies with a wide range of wavelengths similar to light from galaxies that are closer to the Milky Way. It is the journey of billions of years that transforms this light into low-energy and long-wavelength light in the near-infrared and infrared regions of the electromagnetic spectrum.

The very fabric of space is expanding, and as light passes through it, its wavelength is stretched along with it. This causes the light to "shift" down to the red end of the electromagnetic spectrum, hence the name for this phenomenon, "redshift."

Galaxies that are farther away have to cross more space (which is being stretched as it expands) before their light reaches us, and thus, that light experiences more redshift. Redshift, denoted as z, can, therefore, be used to measure the distance to celestial objects with a known spectrum. And because light takes a finite amount of time to travel, this distance can be used to calculate how long ago these galaxies existed as we see them.

JADES-GS-z14-0 has a redshift of z = 14.32, while the previous most distant galaxy, JADES-GS-z13-0, has a redshift of z = 13.2, which placed it as existing 400 million years after the Big Bang. Clearly, this newly found galaxy has absolutely smashed that record, with the JWST seeing back in time by another 100 million years or so.

"JADES-GS-z14-0 now becomes the archetype of this phenomenon," JADES collaboration team member Stefano Carniani of the Scuola Normale Superiore said. "It is stunning that the universe can make such a galaxy in only 300 million years."

JADES-GS-z14-0 delived some surprises

Not everything about JADES-GS-z14-0 was immediately clear to the JADES team and some elements could confuse our picture of the early cosmos.

When it was first spotted, the primordial galaxy was so close to a closer foreground galaxy that the team suspected they could be celestial neighbors.  This idea was dispelled in October last year when the JADES crew spent five days performing a deep analysis of JADES-GS-z14-0 with NIRCam. The application of filters that are specifically tailored to identify early galaxies confirmed the extreme distance to JADES-GS-z14-0.

"We just couldn’t see any plausible way to explain this galaxy as being merely a neighbor of the more nearby galaxy," JADES team member and University of Arizona researcher Kevin Hainline said.

The galaxy also surprised its discoverers because its light is even redder than expected. That is because the light from JADES-GS-z14-0 is being "reddened" by dust within it that will become the building blocks of stars that will help this galaxy grow even larger.

Another surprise was the discovery of oxygen in JADES-GS-z14-0. Elements heavier than hydrogen and helium are forged by stars during their lifetimes and then distributed through galaxies when these stars explode. The observation of oxygen in JADES-GS-z14-0 could indicate that at least one generation of stars has already lived and died in this very early galaxy.

"All of these observations, together, tell us that JADES-GS-z14-0 is not like the types of galaxies that have been predicted by theoretical models and computer simulations to exist in the very early universe,"  JADES researcher Jake Helton of Steward Observatory and the University of Arizona said. "Given the observed brightness of the source, we can forecast how it might grow over cosmic time, and so far, we have not found any suitable analogs from the hundreds of other galaxies we’ve observed at high redshift in our survey."

Helton added that given the relatively small region of the sky that the JWST searched to find JADS-GS-z14-0, its discovery has profound implications for the predicted number of bright galaxies we see in the early universe.

"It is likely that astronomers will find many such luminous galaxies, possibly at even earlier times, over the next decade with the JWST," he concluded. "We're thrilled to see the extraordinary diversity of galaxies that existed at cosmic dawn!”

{ https://www.space.com/ }

31-05-2024 om 23:14 geschreven door peter  

Rare 'exo-Venus' with Earth-like temperature discovered

Gliese 12 b, which orbits a cool, red dwarf star located just 40 light-years away, promises to tell astronomers more about how planets close to their stars retain or lose their atmospheres. In this artist’s concept, Gliese 12 b is shown retaining a thin atmosphere.

Credit NASA/JPL-Caltech/R. Hurt (Caltech-IPAC)

Licence type

Attribution (CC BY 4.0)

Astronomers have made the rare and tantalising discovery of an Earth-like exoplanet 40 light-years away that may be just a little warmer than our own world.

The potentially-habitable planet, named Gliese 12 b, orbits its host star every 12.8 days, is comparable in size to Venus - so slightly smaller than Earth - and has an estimated surface temperature of 42°C (107°F), which is lower than most of the 5,000-odd exoplanets confirmed so far.

That is assuming it has no atmosphere, however, which is the crucial next step to establishing if it is habitable.

It may have an Earth-like atmosphere, one more akin to Venus - which experienced a runaway greenhouse effect that made it a 400°C (752°F) hellhole - no atmosphere, or perhaps a different kind of atmosphere not found in our solar system.

Getting an answer is vital because it would reveal if Gliese 12 b can maintain temperatures suitable for liquid water - and possibly life - to exist on its surface, while also unlocking answers about how and why Earth and Venus evolved so differently.

Gliese 12 b is by no means the first Earth-like exoplanet to have been discovered, but as NASA has said, there are only a handful of worlds like it that warrant a closer look.

It has been billed as "the nearest, transiting, temperate, Earth-size world located to date" and a potential target for further investigation by the US space agency's £7.5billion James Webb Space Telescope.

The closest Earth-like exoplanet to us - and possibly the most famous - is Proxima Centauri b, which is only 4 light-years away. However, because it is not a transiting world we still have a lot to learn about it, including whether it has an atmosphere and the potential to harbour life.

Most exoplanets are discovered using the transit method, where a planet passes in front of its star from our point of view, causing a dip in the host star's brightness.

During a transit, the star's light also passes through an exoplanet's atmosphere and some wavelengths get absorbed. Different gas molecules absorb different colours, so the transit provides a set of chemical fingerprints that can be detected by telescopes like Webb.

Gliese 12 b’s estimated size may be as large as Earth or slightly smaller — comparable to Venus in our solar system. This artist’s concept compares Earth with different possible Gliese 12 b interpretations, from one with no atmosphere to one with a thick Venus-like one.

NASA/JPL-Caltech/R. Hurt (Caltech-IPAC)

Licence type

Attribution (CC BY 4.0)

Gliese 12 b could also be significant because it may help reveal whether the majority of stars in our Milky Way galaxy - i.e. cool stars - are capable of hosting temperate planets that have atmospheres and are therefore habitable.

The discovery of the 'exo-Venus', by two international teams of astronomers, has been published today in the Monthly Notices of the Royal Astronomical Society.

It orbits a cool red dwarf star called Gliese 12, which is almost 40 light-years away from Earth in the constellation Pisces.

"Gliese 12 b represents one of the best targets to study whether Earth-size planets orbiting cool stars can retain their atmospheres, a crucial step to advance our understanding of habitability on planets across our galaxy," said Shishir Dholakia, a doctoral student at the Centre for Astrophysics at the University of Southern Queensland in Australia.

He co-led a research team with Larissa Palethorpe, a doctoral student at the University of Edinburgh and University College London.

The exoplanet's host star is about 27 per cent of the size of our Sun and has a surface temperature that is around 60 per cent of our own star.

However, the distance separating Gliese 12 and the new planet is just 7 per cent of the distance between Earth and the Sun. Gliese 12 b therefore receives 1.6 times more energy from its star as Earth does from the Sun and about 85 per cent of what Venus experiences.

This difference in solar radiation is important because it means the planet's surface temperature is highly dependent on its atmospheric conditions. As a comparison to Gliese 12 b's estimated surface temperature of 42°C (107°F), Earth has an average surface temperature of 15°C (59°F).

"Atmospheres trap heat and - depending on the type - can change the actual surface temperature substantially," Dholakia explained. "We are quoting the planet's 'equilibrium temperature', which is the temperature the planet would be if it had no atmosphere.

"Much of the scientific value of this planet is to understand what kind of atmosphere it could have. Since Gliese 12 b gets in between the amount of light as Earth and Venus get from the Sun, it will be valuable for bridging the gap between these two planets in our solar system."

Palethorpe added: "It is thought that Earth's and Venus's first atmospheres were stripped away and then replenished by volcanic outgassing and bombardments from residual material in the solar system.

"The Earth is habitable, but Venus is not due to its complete loss of water. Because Gliese 12 b is between Earth and Venus in temperature, its atmosphere could teach us a lot about the habitability pathways planets take as they develop."

The closest Earth-like exoplanet to us - and possibly the most famous - is Proxima Centauri b (pictured in an artist's impression), which is only 4 light-years away. However, because it is not a transiting world we still have a lot to learn about it, including whether it has an atmosphere and the potential to harbour life.

NASA Visualization Technology Applications and Development (VTAD)

Licence type

Attribution (CC BY 4.0)

The researchers, along with another team in Tokyo, used observations by NASA's TESS (Transiting Exoplanet Survey Satellite) to help make their discovery.

"We've found the nearest, transiting, temperate, Earth-size world located to date," said Masayuki Kuzuhara, a project assistant professor at the Astrobiology Center in Tokyo, who co-led a research team with Akihiko Fukui, a project assistant professor at the University of Tokyo.

"Although we don't yet know whether it possesses an atmosphere, we've been thinking of it as an exo-Venus, with similar size and energy received from its star as our planetary neighbour in the solar system."

An important factor in retaining an atmosphere is the storminess of its star. Red dwarfs tend to be magnetically active, resulting in frequent, powerful X-ray flares.

However, analyses by both teams conclude that Gliese 12 shows no signs of such extreme behaviour, raising hopes that Gliese 12 b's atmosphere may still be intact.

"We know of only a handful of temperate planets similar to Earth that are both close enough to us and meet other criteria needed for this kind of study, called transmission spectroscopy, using current facilities," said Michael McElwain, a research astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and a co-author of the Kuzuhara and Fukui paper.

"To better understand the diversity of atmospheres and evolutionary outcomes for these planets, we need more examples like Gliese 12 b."

At 40 light-years from Earth, Gliese 12 b is about the same distance as the TRAPPIST-1 system.

This is made up of seven planets, all roughly in Earth's size range and likely rocky, orbiting a red dwarf star.

Three of these are in the habitable zone but at least two - and probably all of them - have no atmosphere and are likely barren, dismissing hopes when they were first discovered eight years ago that they could be water worlds hosting life.

• The new paper "Gliese 12 b, A Temperate Earth-sized Planet at 12 Parsecs Discovered with TESS and CHEOPS", Shishir Dholakia and Larissa Palethorpe et al., has been published in the Monthly Notices of the Royal Astronomical Society.

{ https://ras.ac.uk/ }

31-05-2024 om 20:54 geschreven door peter  

De planeet heeft een geschatte oppervlaktetemperatuur van slechts 42 graden Celsius en bevindt zich op ongeveer dezelfde afstand als het bekende TRAPPIST-1 systeem.

Al jaren speuren astronomen het universum af naar planeten die mogelijk leven kunnen ondersteunen of op zijn minst bewoonbaar zijn, in de hoop werelden te vinden die op de aarde lijken. En een nieuwe ontdekking heeft nu voor grote opwinding gezorgd. Op zo’n 40 lichtjaar afstand zijn onderzoekers namelijk op de veelbelovende planeet Gliese 12 b gestuit. Zou dit de planeet kunnen zijn waar we al zo lang naar op zoek zijn?

Gliese 12 b
De mogelijk bewoonbare planeet Gliese 12 b draait elke 12,8 dagen om zijn moederster. Qua grootte is de exoplaneet vergelijkbaar met Venus, wat betekent dat hij slechts iets kleiner is dan de aarde. Daarnaast heeft deze aardachtige planeet ook nog eens een aardachtige temperatuur. Zo wordt de oppervlaktetemperatuur geschat op 42 graden Celsius. Hiermee is hij iets warmer dan de aarde, maar opvallend koeler dan de meeste van de ongeveer 5.000 tot nu toe ontdekte exoplaneten. De ontdekking van deze ‘exo-Venus’, is vandaag gepubliceerd in de Monthly Notices of the Royal Astronomical Society.

Exo-Venus
Onderzoekers kwamen de veelbelovende planeet op het spoor met behulp van planetenjager TESS, die al heel wat exoplaneten aan het licht heeft gebracht. En onderzoekers zijn enthousiast. “We hebben de dichtstbijzijnde, gematigde wereld ter grootte van de aarde tot nu toe ontdekt,” benadrukt onderzoeker Masayuki Kuzuhara. “Hoewel we nog niet weten of Gliese 12 b een atmosfeer heeft, beschouwen we ‘m als een ‘exo-Venus’. Het heeft een vergelijkbare grootte en ontvangt een vergelijkbare hoeveelheid energie van zijn ster als onze buurplaneet in ons eigen zonnestelsel.”

Atmosfeer
Om er echter zeker van te zijn dat de planeet leefbaar is, is het van cruciaal belang om te bepalen of er wel of geen atmosfeer aanwezig is. Het is mogelijk dat de planeet een atmosfeer heeft die vergelijkbaar is met die van de aarde. Deze kan echter ook meer lijken op die van Venus, waar een omvangrijk broeikaseffect ervoor zorgde dat het oppervlak een verzengende 400 graden Celsius bereikte. Een andere mogelijkheid is dat de planeet geen atmosfeer heeft. Of misschien heeft ie wel een soort atmosfeer die we nog niet in ons eigen zonnestelsel hebben gezien. Het is erg belangrijk om hierop een antwoord te krijgen omdat het ons zal vertellen of Gliese 12 b temperaturen kan handhaven die geschikt zijn voor vloeibaar water – en mogelijk leven – op het oppervlak.

Moederster
Om dit te achterhalen, is ook de moederster relevant. De moederster van Gliese 12 b is een koele rode dwergster genaamd Gliese 12, die zich zoals gezegd op bijna 40 lichtjaar afstand van de aarde bevindt, in het sterrenbeeld Vissen. De ster is ongeveer 27 procent zo groot als onze zon en heeft een oppervlaktetemperatuur van ongeveer 60 procent van die van onze zon. Over rode dwergsterren is echter bekend dat het ‘opvliegende’ sterren zijn, die vaak magnetisch actief zijn. Dit resulteert in frequente, krachtige uitbarstingen, waardoor een mogelijk rondom cirkelende planeet van zijn atmosfeer wordt ontdaan. Toch lijkt Gliese 12 b er beter vanaf te komen. Analyses hebben namelijk aangetoond dat Gliese 12 geen tekenen vertoont van dergelijk extreem gedrag. Dit verhoogt de hoop dat de potentiële atmosfeer van Gliese 12 b nog steeds intact is.

Oppervlaktetemperatuur

Daarnaast is de afstand tussen Gliese 12 en de nieuw ontdekte planeet slechts 7 procent van de afstand tussen de aarde en de zon. Hierdoor ontvangt Gliese 12 b 1,6 keer meer energie van zijn ster dan de aarde van de zon, en ongeveer 85 procent van de hoeveelheid die Venus ontvangt. Dit verschil in de hoeveelheid zonnestraling die de planeet ontvangt, is van groot belang omdat het aangeeft dat de oppervlaktetemperatuur sterk wordt beïnvloed door de atmosferische omstandigheden. Voor je beeldvorming: de geschatte oppervlaktetemperatuur van Gliese 12 b is 42 graden Celsius, terwijl de gemiddelde oppervlaktetemperatuur van de aarde 15 graden Celsius bedraagt. “Atmosferen houden warmte vast en kunnen, afhankelijk van hun samenstelling, de werkelijke oppervlaktetemperatuur aanzienlijk beïnvloeden,” legt onderzoeker Shishir Dholakia uit.

Aarde en Venus
Het onderzoek naar Gliese 12 b heeft overigens niet alleen betrekking op de leefbaarheid van deze planeet. Het helpt ons ook om meer te weten te komen over waarom de aarde en Venus, die in veel opzichten erg op elkaar lijken, toch zo’n andere weg zijn ingeslagen. “Omdat Gliese 12 b een vergelijkbare hoeveelheid licht ontvangt als de aarde en Venus van de zon, kan het ons ook helpen om het verschil tussen deze twee planeten in ons eigen zonnestelsel te verklaren en te begrijpen,” aldus Dholakia. Dit kan waardevolle inzichten bieden in de atmosferische processen die de leefbaarheid van planeten beïnvloeden. Terwijl de aarde bewoonbaar is, is Venus dat niet, voornamelijk vanwege het volledige verlies van water. “Gliese 12 b, met een temperatuur tussen die van de aarde en Venus in, kan ons helpen begrijpen hoe planeten bewoonbaar worden, vooral door te kijken naar welke atmosfeer het heeft,” vertelt mede-auteur Larissa Palethorpe.

Onderzoek naar de veelbelovende exo-Venus gaat onverminderd door. Want het idee dat deze planeet mogelijk leefbaar is, prikkelt de verbeelding van menig astronoom. Gliese 12 b is zeker niet de eerste aardachtige exoplaneet die is ontdekt, maar volgens NASA zijn er maar een paar van zulke werelden die de moeite van nader onderzoek waard zijn. De volgende stap is om de krachtige ruimtetelescoop James Webb op Gliese 12 b te richten. Uiteindelijk hopen onderzoekers te achterhalen of deze planeet al dan geen atmosfeer herbergt. “Gliese 12 b vertegenwoordigt een van de beste doelen om te bestuderen of aardachtige planeten die om koele sterren draaien hun atmosferen kunnen behouden,” zegt Dholakia. “Dit is een cruciale stap om ons begrip van de bewoonbaarheid van planeten in ons sterrenstelsel te bevorderen.”

Bronmateriaal

• "Rare 'exo-Venus' with Earth-like temperature discovered" - Royal Astronomical Society.
  
• Afbeelding bovenaan dit artikel: NASA/JPL-Caltech/R. Hurt (Caltech-IPAC)

{ https://scientias.nl/ }

31-05-2024 om 20:41 geschreven door peter  

Nanoplastics nu ook op onverwachte plek in hart van foetus teruggevonden. En de kans is groot dat dat schadelijk is

Jeannette Kras

 

{ https://scientias.nl/ }

31-05-2024 om 20:22 geschreven door peter