Piepklein, maar niet klein te krijgen. Dat is het beerdiertje in een notendop. Maar er valt nog zoveel meer over te vertellen.

En dat doen we aan de hand van tien interessante feitjes waarmee je op een verjaardag of bij de koffiemachine op het werk moeiteloos de blits kan maken. Want beerdiertjes zijn hartstikke cool!

1. Klein en overal te vinden (ook in Nederland!)
Beerdiertjes – ook wel waterberen genoemd – zijn heel kleine, meercellige organismen. Ze kunnen tot een halve millimeter lang worden en hebben acht pootjes, waarmee ze kunnen lopen én rennen. Hét beerdiertje bestaat niet; er zijn meer dan 1000 soorten beerdiertjes bekend! En die leven in uiteenlopende omgevingen; van bergtoppen tot diepe zeeën en van tropische regenwouden tot op Antarctica. Ook in Nederland komen beerdiertjes voor. Zo zijn ze bijvoorbeeld aangetroffen op de stranden langs de Oosterschelde.

2. Beerdiertjes zijn stokoud
Zo’n 66 miljoen jaar geleden sloeg op aarde een planetoïde in. Het bleek de laatste nagel aan de doodskist van de dinosaurussen en tal van andere soorten te zijn. Het is misschien wel de bekendste massa-extinctie die de aarde trof. En hoe catastrofaal de gevolgen ook waren; het beerdiertje heeft deze massa-extinctie overleefd. Net als de vier(!) grote massa-extincties daarvoor, want wetenschappers denken dat het beerdiertje al zo’n 540 miljoen jaar op aarde voorkomt.

3. Het beerdiertje gaat waarschijnlijk nog wel even mee
Hoewel de beerdiertjes al heel wat jaren meegaan en menig catastrofe het hoofd hebben weten te bieden, denken veel onderzoekers dat er voor de minuscule beestjes nog veel meer in het verschiet zit. Zo suggereerde een studie in 2017 dat eigenlijk alleen het sterven van de zon tot het uitsterven van de taaie beerdiertjes zou kunnen leiden. Het zou betekenen dat beerdiertjes nog zo’n 10 miljard jaar voor de boeg hebben.

4. Kou is geen probleem…
Waar wij bij een paar graden vorst al flink beginnen te klagen, geven beerdiertjes geen krimp. Sterker nog: je kunt ze jaren invriezen en er vervolgens als je ze ontdooit, getuige van zijn hoe ze hun leven moeiteloos weer oppakken! Dat ontdekten onderzoekers een jaar of vijf geleden, toen ze beerdiertjes aantroffen in Antarctisch mos dat 30 jaar eerder voor onderzoeksdoeleinden was ingevroren. Ze ontdooiden twee beerdiertjes en zagen vervolgens hoe één ervan zijn in 1983 stilgelegde leven weer succesvol oppakte en een week of zes na zijn ontdooiing zelfs eitjes legde die ook nog eens bijna allemaal uitkwamen. Ook een eitje dat in het mos werd aangetroffen, kwam na ontdooiing – en dus met zo’n 30 jaar vertraging – uit en het beerdiertje dat daar uit kwam zetten, plantte zich ook weer succesvol voort.

5. …en gevaarlijke UV-straling ook niet
Beerdiertjes hebben in naam der wetenschap al heel wat te verduren gekregen. Zo werden ze vorig jaar bijvoorbeeld nog onder een kiemdodende ultraviolette lamp gelegd. Doel was om te achterhalen hoeveel UV-straling verschillende soorten beerdiertjes konden hebben. De meeste beerdiertjes bleken behoorlijk taai te zijn. Een dosis die voor bacteriën en rondwormen al na vijf minuutjes fataal is – bleek de meeste beerdiertjes pas na 24 uur fataal te worden. En één van de onderzochte soorten gaf helemaal geen krimp, waarop de onderzoekers besloten de dosis ultraviolet licht vier keer te verhogen. En ook deze keer gaven de mysterieuze beerdiertjes zich niet zomaar gewonnen. Ongeveer zestig procent van deze kranige beerdiertjes leefde na toetakeling nog zeker een maand door!

6. Je kunt ze ook afschieten
Alsof dat experiment nog niet heftig genoeg was, gingen wetenschappers – op jacht naar de grenzen van het beerdiertje – eerder dit jaar nog een stap verder. Ze stopten bevroren beerdiertjes in een geladen geweer en schoten ze vervolgens met hoge snelheid af. Het onderzoek wees uit dat beerdiertjes inslagen tot ongeveer 900 meter per seconde kunnen overleven. “Het zijn taaie beestjes,” zo concludeerde onderzoeker Mark Butchell, die middels het experiment wilde vaststellen of beerdiertjes die tijdens een inslag op aarde samen met gesteente naar de maan worden geslingerd, dat kunnen navertellen. De experimenten suggereren dat het onder bepaalde omstandigheden denkbaar is. Of ze vervolgens ook van de maan hun thuis zouden kunnen maken, is trouwens dan weer heel twijfelachtig.

7. Of uit laten drogen
Wanneer wij enkele dagen op rij niet drinken, raken we uitgedroogd. En dat is niet best. Het beerdiertje is een stuk minder afhankelijk van vocht; experimenten wijzen uit dat het diertje tot wel tien jaar zonder water kan! Zodra ze minder dan vijf procent van hun normale hoeveelheid water herbergen, gaan ze in standby-modus en maken en passant eiwitten aan die delen van hun lichaam in een soort glasachtige substantie veranderen en er zo voor zorgen dat hun cellen tegen uitdroging beschermd zijn. En als ze dan toch weer nattigheid voelen? Dan kunnen ze – zelfs als ze jaren op water gewacht hebben – in twintig minuten tijd weer tot leven komen.

8. Ze zijn al in de ruimte geweest
Ruimtevaarder worden: wie droomt daar nu niet van? Voor sommige beerdiertjes is die droom al werkelijkheid geworden. In 2007 schoot ESA een bonte verzameling beerdiertjes de ruimte in. “Onze belangrijkste ontdekking is dat het vacuüm in de ruimte – en daarmee gepaard gaande uitdroging – en kosmische straling geen probleem waren voor beerdiertjes,” zo concludeerde onderzoeker Ingemar Jönsson in 2008. Hetzelfde gold voor de extreme kou waaraan de beerdiertjes in de ruimte werden blootgesteld. In de jaren erna volgden nog meer experimenten in de ruimte en stuk voor stuk bevestigden ze dat het beerdiertje over het algemeen niet erg onder de indruk is van de daar geldende omstandigheden. Wetenschappers kunnen dat nog altijd lastig verklaren en daarom zijn eerder dit jaar beerdiertjes naar het internationale ruimtestation gestuurd. Tijdens experimenten wordt gekeken wat er met de genen van beerdiertjes gebeurt wanneer ze in de ruimte vertoeven. Welke genen worden uitgezet of juist geactiveerd? En wat gebeurt er dan? Onderzoekers hopen zo meer inzicht te krijgen in de overlevingsstrategieën van het beerdiertje en daar kunnen toekomstige astronauten dan misschien weer hun voordeel mee doen. Zo kan het leiden tot nieuwe manieren om biologische materialen – zoals voedsel, maar ook medicijnen – beter te wapenen tegen extreme temperaturen, uitdroging en kosmische straling.

Naar de maan
Dat de piepkleine beestjes naar het ISS zijn afgereisd en daar weleens een grote bijdrage kunnen leveren aan toekomstige ruimtemissies is al heel indrukwekkend. Maar er zijn beerdiertjes die het nog verder geschopt hebben en helemaal naar de maan zijn gevlogen. Deze beerdiertjes liftten in 2019 mee met maanlander Beresheet. De lander crashte helaas op het maanoppervlak, maar de beerdiertjes hebben de crash misschien wel overleefd. Het is echter uitgesloten dat ze de maan as we speak aan het koloniseren zijn; in de lander bevonden zich uitgedroogde beerdiertjes die alleen weer actief kunnen worden als ze aan behoorlijke hoeveelheden water worden blootgesteld en die zijn op de maan niet voorhanden.

9. Ze leggen enorme drollen (relatief gezien dan)
Beerdiertjes mogen dan veel weghebben van superhelden; in bepaalde opzichten zijn ze ook weer net als wij. Zo moeten ze soms ook gewoon poepen. Maar de beerdiertjes zouden geen beerdiertjes zijn als ze ook op dat gebied niet de show zouden stelen. Zo heeft onderzoek uitgewezen dat de piepkleine beestjes enorme drollen fabriceren die soms bijna net zo groot zijn als zijzelf! En jawel, daar zijn beelden van. Klik!

10. Liften is wel gevaarlijk
Het beerdiertje lijkt onverwoestbaar, maar toch vonden wetenschappers vorig jaar iets wat in sommige gevallen zelfs voor het beerdiertje een slecht idee is: liften. Beerdiertjes leggen namelijk enorme afstanden af door mee te liften met slakken. Dit gebeurt trouwens ongevraagd. Als een slak over een beerdiertje glijdt, dan wordt een beerdiertje meegenomen en deze blijft dan aan de slak plakken. En dat is niet zonder gevolgen. Slechts 34 procent van de beerdiertjes wist het contact met het slakkenslijm te overleven.

Bronmateriaal

• Afbeelding bovenaan dit artikel: Frank Fox (via Wikimedia Commons)

{ https://scientias.nl/ }

06-02-2024 om 00:27 geschreven door peter  

Repeated signals from the center of the Milky Way could be aliens saying hello, new study claims

A hypothetical alien craft transmits radio signals into space. Scientists are on the hunt for signals like these. 

(Image credit: Breakthrough Listen / Danielle Futselaar)

Could intelligent aliens be lurking at the heart of the Milky Way? 

A new search for extraterrestrial life aims to find out by listening for radio pulses from the center of our galaxy. Narrow-frequency pulses are naturally emitted by stars called pulsars, but they're also used deliberately by humans in technology such as radar. Because these pulses stand out against the background radio noise of space, they're an effective way of communicating across long distances — and an appealing target to listen for when searching for alien civilizations. 

• https://youtu.be/8UgLGFIia4w

Scientists described the alien-hunting strategy in a new study, published May 30 in The Astronomical Journal. Researchers led by Cornell University graduate student Akshay Suresh developed software to detect these repetitive frequency patterns and tested it on known pulsars to be sure it could pick up the narrow frequencies. These frequency ranges are very small, at about a tenth of the width of frequencies used by a typical FM radio station. The researchers then searched data from the Green Bank Telescope in West Virginia using the method. 

Related: 

• Are aliens real?

"Until now, radio SETI has primarily dedicated its efforts to the search for continuous signals," study coauthor Vishal Gajjar of the SETI Institute, a nonprofit organization dedicated to the search for intelligent life in the universe, said in a statement. "Our study sheds light on the remarkable energy efficiency of a train of pulses as a means of interstellar communication across vast distances. Notably, this study marks the first-ever comprehensive endeavor to conduct in-depth searches for these signals."

{ https://www.space.com/ }

05-02-2024 om 23:49 geschreven door peter  

BY KIONA SMITH

Gene Roddenberry’s ashes are set to burn up in Earth’s atmosphere later this week, along with those of half the main cast of his original Star Trek series, as well as a lunar rover, a small flock of robots, and millions of dollars in scientific instruments, all of which were originally supposed to land on the Moon.

Astrobotic’s Peregrine One lander was originally scheduled to be in lunar orbit early next week, preparing for a landing on the Moon’s near side in late February. Instead, the spacecraft is now headed back to Earth, where it will disintegrate in Earth’s upper atmosphere – so at least it’s going out in a blaze of glory. Here’s everything you need to know about the doomed mission and what went wrong.

• https://youtu.be/s1TiGJ3ETnM

WHAT HAPPENS NOW?

As of this morning, January 16, the Peregrine Mission One spacecraft is on its way back to Earth after a 238,000-mile flight out to cross the path of the Moon’s orbit. The ill-fated spacecraft is scheduled to re-enter Earth’s atmosphere and disintegrate dozens of miles above the ground. Astrobotic says both the company and NASA are tracking the spacecraft’s path, and its re-entry won’t pose any safety risk to anyone on the ground.

The return to Earth is based on recommendations from NASA, other U.S. government agencies, and other members of “the space community” to prevent Peregrine from turning to a potentially hazardous piece of space debris orbiting the Moon or Earth, says Astrobotic in a recent update on its website.

“Ultimately, we must balance our own desire to extend Peregrine's life, operate payloads, and learn more about the spacecraft, with the risk that our damaged spacecraft could cause a problem in cislunar space,” the company says.

WHAT WENT WRONG?

Shortly after the mission’s launch from Cape Canaveral on January 8, things began to go wrong. It looks like a valve between the spacecraft’s oxidizer tank and a tank of high-pressure helium got stuck in the open position, according to Astrobotic. Here’s what that actually means:

It actually takes several ingredients to fuel a spacecraft. The stuff that actually burns, producing hot gas that gets pushed out the back end of the spaceship to create thrust, is called the propellant, and it’s usually something like liquid hydrogen, hydrazine, or even kerosene. But nothing burns without oxygen, so rocket engines need a second ingredient, called the oxidizer, to mix with the propellant so it can actually ignite.

Most of the time, the propellant and the oxidizer are stored in separate tanks, so they only combine when and where engineers want them to (most variations on that are catastrophically bad). Some spaceships – like Peregrine One – use pressurized helium to push the oxidizer and the propellant into the combustion chamber. Helium is a good choice because it won’t react with the oxidizer or the propellant.

But when the valve that’s supposed to push a small amount of helium into the oxidizer tank gets stuck, you end up with way too much helium in the tank – and like an overinflated balloon, the tank pops. Oxidizer goes everywhere except where the spaceship actually needs it to go, and suddenly, there’s not enough oxidizer to mix with the propellant to steer the spaceship to a safe landing on the Moon.

“While this is a working theory, a full analysis report will be produced by a formal review board made up of industry experts after the mission is complete,” says Astrobotic. “All available data is being downloaded from the lander to support this assessment.”

By January 14, the leak had started slowing down, and by January 15, Astrobotic reported, “The propellant leak caused by the anomaly has practically stopped.”

But by then, it was too late.

“Due to the anomaly, the fuel to oxidizer ratio is well outside of the normal operating range of the main engines, making long controlled burns impossible,” the company wrote in an update on its website.

MOON LANDINGS ARE HARD

If it had succeeded, Peregrine would have been the first U.S.-based lander to reach the Moon since Apollo 17 visited in 1972, and the first private mission ever to pull it off.

The most recent successful Moon landing was India’s Chandrayaan-3, which touched down near the lunar south pole in August 2023. Just a few days earlier, Russia’s Luna-25 lander “ceased to exist as a result of a collision with the surface of the Moon” in the same region. Like the Peregrine lander for the U.S., Luna-25 would have been Russia’s first Moon landing in more than 50 years (or technically ever: the last Russian spacecraft to land on the Moon was actually built by the Soviet Union, not the modern Russian Federation).

India is now the fourth country ever to make a “soft landing” — as opposed to a crash, either accidental or on purpose — on the Moon, following the Soviet Union (but not post-Soviet Russia), the United States, and China. But nobody’s track record for Moon landings is perfect; India lost its Chandrayaan-2 lander in 2019 thanks to a software glitch.

An Israeli spacecraft also crashed on the Moon in 2019, spilling a payload of tardigrades and DNA onto the lunar surface. Oops.

WHAT’S BEING LOST?

Peregrine Mission One was originally meant to orbit the Moon for several weeks before landing on February 23. Its controversial payload of human remains and DNA made headlines, but the spacecraft is also carrying a payload of several instruments for NASA, a quintet of tiny robots for the National Autonomous University of Mexico (UNAM) and the Mexican space agency (AEM), a lunar rover from Carnegie Mellon University, and several other privately-funded instruments and experiments.

Several of those instruments managed to switch on and collect some data during the flight to lunar distance (meaning the distance at which the Moon orbits Earth, as opposed to “lunar orbit,” which would mean orbit around the Moon). Two NASA instruments successfully measured cosmic rays from deeper in our galaxy and space weather driven by our Sun’s activity.

“This data helps characterize the interplanetary radiation environment for humans and electronics,” says NASA in a statement.”

And although the five tiny robots from UNAM and AEM, called Colmena, didn’t get to trundle adorably around the lunar surface, they did get to power up and collect some data during the flight — making them the first Mexican instrument to operate in cislunar space.

Meanwhile, the doomed lander also carries the cremated remains of Star Trek creator Gene Roddenberry (mingled with those of his wife and son), Star Trek actors Nichelle Nichols, DeForest Kelley, and James Doohan, science fiction author Arthur C. Clarke, and others, along with DNA samples from several former U.S. presidents. Some of the ashes — a payload from “memorial spaceflight” company Celestis — were intended for interment on the lunar surface, while others were planned to carry on into deep space, but they will now return to Earth and burn up on re-entry later this week.

For Roddenberry, at least, Peregrine wasn’t his only memorial spaceflight. Other portions of the late screenwriter’s ashes traveled into space aboard the Space Shuttle Columbia in 1992 among the personal possessions of astronaut Jim Wetherbee, and aboard a Celestis orbital mission, which burned up during re-entry in 2002 (on purpose that time). Counting the Peregrine mission, Roddenberry’s remains have flown to space more times than many living astronauts.

{ https://www.inverse.com/ }

05-02-2024 om 23:31 geschreven door peter  

RESEARCHERS HAVE LONG SUSPECTED DEEP SEDIMENTARY LAYERS LIE BENEATH JEZERO

Over the last few decades, images captured by satellites orbiting Mars have long hinted at the idea of eroded subsurface layers in the region. However, researchers knew that up close analysis by Perseverance’s ground penetrating radar was the only way to confirm those suspicions.

“From orbit, we can see a bunch of different deposits, but we can’t tell for sure if what we’re seeing is their original state or if we’re seeing the conclusion of a long geological story,” said David Paige, a UCLA professor of Earth, planetary and space sciences and first author of the paper detailing the findings. “To tell how these things formed, we need to see below the surface.”

Fortunately, Perseverance’s mission planners included the Radar Imager for Mars’ Subsurface Experiment, or RIMFAX, as one of the seven instruments on board the rover. Like ground penetrating radar used on Earth, the RIFMAX fires radar waves directly into the Mars surface, then reads their reflections as they bounce off different sedimentary layers.

Mars Perseverance Rover RIMFAX ground penetrating radar measurements of the Hawksbill Gap region of the Jezero Crater Western Delta, Mars. Hawksbill Gap.

CREDIT: Svein-Erik Hamran, Tor Berger, David Paige, University of Oslo, UCLA, California Institute of Technology Jet Propulsion Laboratory, NASA

“The periods of deposition and erosion took place over eons of environmental changes, the radar indicates, confirming that inferences about the Jezero crater’s geologic history based on Mars images obtained from space are accurate,” the UCLA and the University of Oslo researchers explain,

FINDINGS INCREASE ODDS FOR SIGNS OF ANCIENT LIFE IN JEZERO SOIL SAMPLES

Although Perseverance has completed numerous missions and made countless significant findings about the red planet since its landing in February of 2021, few tasks undertaken by the SUV-sized rover have tantalized researchers and the public as much as the soil samples it collected and stored away for an eventual return to Earth. Not only did the original mission planners choose to study Jezero in hopes that there had been an ancient lake at the site, but the exact areas the vehicle has studied within the 30-mile wide crater were selected as the likeliest places to find signs of ancient life.

“The changes we see preserved in the rock record are driven by large-scale changes in the Martian environment,” Paige said of the timescale revealed by the findings. “It’s cool that we can see so much evidence of change in such a small geographic area, which allows us [to] extend our findings to the scale of the entire crater.”

Ultimately, the sooner those samples can be returned to Earth, the sooner researchers can use the most advanced tools and techniques to analyze them. Given these latest findings, researchers may end up finding signs of ancient extraterrestrial life in the exact place they hoped to discover them.

“If life ever existed on Mars, the Perseverance rover’s verification of lake sediments at the base of the Jezero crater reinforces the hope that traces might be found in the crater,” the researchers explain.

• Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.

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

05-02-2024 om 22:52 geschreven door peter  

Hele Marsmannetjes moet je niet verwachten, maar de hoop om sporen van leven te vinden op de rode planeet is wel weer opgelaaid. Nieuw onderzoek heeft namelijk aangetoond dat de krater waarin Marsrover Perseverance momenteel rondrijdt ooit gevuld was met water.

Toen het meer in deze Jezero-krater kromp, bleven er sedimenten achter op de bodem, maar ook in de rivieren die het water aanvoerden. Langzaam kwam de hele krater en het gebied eromheen droog te staan en ontstond een delta met de specifieke kenmerken die nu nog zichtbaar zijn.

Eindelijk bevestigd
De periodes waarin sedimentatie werd afgewisseld met erosie vonden plaats gedurende vele eeuwen waarin de omgeving steeds veranderde, zo blijkt uit radargegevens. Het maakt duidelijk dat de aannames, die op basis van beelden uit de ruimte zijn gedaan over de geschiedenis van de Jezero-krater, dus echt kloppen.

“Vanuit een baan om de aarde kunnen we een heleboel verschillende afzettingen zien, maar we kunnen niet met zekerheid zeggen of wat we bekijken de oorspronkelijke staat is, of dat we het slot zien van een lang geologisch verhaal”, zegt UCLA-professor David Paige. “Om echt te weten hoe deze dingen zijn ontstaan, moeten we onder het oppervlak kijken.”

Stukje volharding
Marsrover Perseverance doet zijn naam eer aan. Al sinds 2021 onderzoekt het ding, zo groot als een auto, minutieus de kraterbodem van 48 kilometer breed. Met maar liefst zeven wetenschappelijke instrumenten aan boord bestudeert hij de samenstelling van de grond, kijkt naar de atmosfeer en verzamelt monsters. De monsters moeten door een toekomstige expeditie terug naar de Aarde worden gebracht om ze te onderzoeken op sporen van leven.

Eerder al trad de Perseverance buiten de gebaande paden van de kraterbodem en bezocht de delta eromheen. Dit is een enorm uitgestrekt gebied met 3 miljard jaar oude sedimenten, die vanaf de ruimte lijken op de rivierdelta’s op Aarde. Een van de instrumenten van de Marsrover stuurde iedere 10 centimeter radargolven naar de bodem om zo tot 20 meter onder het oppervlak te kunnen kijken.

RIMFAX
Om met de radar echt iets te kunnen zeggen over de structuur en de samenstelling van de ondergrondse lagen is eerst op Aarde jarenlang onderzoek gedaan met het zogenoemde RIMFAX-instrument (afkorting van Radar Imager for Mars’ Subsurface Experiment). Het resultaat is indrukwekkend: de ondergrondse beelden tonen gesteentelagen die zich laten lezen als de dwarsdoorsnee van een snelweg. “Sommige geologen vinden dat het vermogen van de radar om onder het oppervlak te kijken een beetje op bedrog lijkt”, zegt onderzoeker Paige.

Mooi inkijkje
Maar wat kan het schelen als het zo’n mooi inkijkje oplevert in de Marsbodem. De radar wist twee periodes van sedimentafzettingen te onderscheiden, met daar tussenin twee periodes van erosie. Omdat de bodem onder de delta niet perfect vlak is, heeft er waarschijnlijk een periode van erosie plaatsgevonden voor de afzetting van de sedimenten. Die zijn overigens heel regelmatig en horizontaal van vorm, net als de sedimenten in meren op Aarde. In eerdere studies werd al gesuggereerd dat er sedimenten in het meer zouden zijn, maar dat is door dit onderzoek pas bevestigd.

Een tweede periode van afzettingen ontstond toen schommelingen in het waterpeil ervoor zorgden dat de rivier een veel bredere delta vormde. Ooit strekte die zich uit tot ver in het meer, maar door erosie is hij veel kleiner geworden. “De veranderingen die in het gesteente terug te vinden zijn, duiden op enorme wijzigingen in de omgeving op Mars”, zegt Paige. “Het is mooi dat we zoveel bewijs zien van veranderingen in zo’n klein gebied, waardoor we onze bevindingen kunnen uitbreiden naar de hele krater.

Bronmateriaal

• "Ground penetrating radar observations of the contact between the western delta and the crater floor of Jezero Crater, Mars" - Science
  
• Afbeelding bovenaan dit artikel: Helen Field / Getty (via Canva.com)

{ https://scientias.nl/ }

05-02-2024 om 22:40 geschreven door peter  

The discovery was initially made during the rover’s one-year mission, which lasted from May 2021 to May 2022, in the Utopia Planitia region. Described by researchers from the Institute of Geology and Geophysics under the Chinese Academy of Sciences as the largest impact crater in the entire solar system, the researchers behind this mysterious find say that Utopia Planitia “has both experienced and recorded variations of the Martian palaeoclimate.”

By using the rover’s ground penetrating radar, researchers scoured a 1.2-kilometer-wide area for various geological features. As a result, 16 mysterious polygons were spotted below a depth of 35 meters, meaning they were likely formed billions of years in the planet’s past.

A mysterious string was spotted on the Martian surface.

Image credit: NASA

Rover operators have also spotted an unusual “flower” on Mars, a feature described as a “door,” and a number of pieces of debris left behind my previous missions. Just last October, rover operators even recorded a Martian whirlwind racing across the planet’s surface.

As for the recently discovered mysterious polygons hidden beneath the Martian surface, the researchers say they were potentially formed sometime between 3.7 and 2.9 billion years ago. While the exact process is unknown, the researchers say that their creation almost certainly involved large amounts of water, perhaps from water trapped underground that was pulled to the surface or even from ancient snowfall on the red planet.

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

05-02-2024 om 20:42 geschreven door peter  

It’s a long way to the nearest star, which means conventional rockets won’t get us there. The fuel requirements would make our ship prohibitively heavy. So an alternative is to travel light. Literally. Rather than carrying your fuel with you, simply attach your tiny starship to a large reflective sail, and shine a powerful laser at it. The impulse of photons would push the starship to a fraction of light speed. Riding a beam of light, a lightsail mission could reach Proxima Centauri in a couple of decades. But while the idea is simple, the engineering challenges are significant, because, across decades and light-years, even the smallest problem can be difficult to solve.

One example of this can be seen in a recent arXiv paper. It looks at the problem of how to balance a lightsail on a laser beam. Although the laser could be aimed directly toward a star, or where it will be in a couple of decades, the lightsail would only follow the beam if it is perfectly balanced. If a sail is slightly tilted relative to the beam, the reflected laser light would give the lightsail a slight transverse push. No matter how small this deviation is, it would grow over time, causing its path to drift ever away from its target. We will never align a lightsail perfectly, so we need some way to correct small deviations.

For traditional rockets, this can be done with internal gyroscopes to stabilize the rocket, and engines that can dynamically adjust their thrust to restore balance. But a gyro system would be too heavy for an interstellar lightsail, and adjustments of the beam would take months or years to reach the lightsail, making quick changes impossible. So the authors suggest using a radiative trick known as the Poynting–Robertson effect.

That little forward component of light can slow down the asteroid ever so slightly. This effect causes dust to drift toward the inner solar system over time.

In this paper, the authors consider a two-dimensional model to see how the Poynting–Robertson effect might be used to keep our lightsail probe on course. To keep things simple, they assumed the light beam to be a simple monochromatic plane wave. Real lasers are more complex, but the assumption is reasonable for a proof of concept. They then showed how a simple two-sail system can use the effects of relative motion to keep the craft in balance. As the sails tilt off course slightly, a restorative force from the beam counters it. Thus proving the concept could work.

However, the authors noticed that over time the effects of relativity come into play. Earlier studies have taken the Doppler effect of relative motion into effect, but this study shows the relativistic version of chromatic aberration would also come into play. The full relativistic effects would need to be accounted for in a realistic design, which would require sophisticated modeling and optics.

So a lightsail still seems like a possible way to reach the stars. We just have to be careful not to make light of the engineering challenges.

Reference: 

• Mackintosh, Rhys, et al. “Poynting-Robertson damping of laser beam driven lightsails.” arXiv preprint arXiv:2401.16924 (2024).

• https://www.youtube.com/watch?v=xfgqqBA1DGI

{ https://www.universetoday.com/ }

05-02-2024 om 16:48 geschreven door peter  

Major 'magnetic anomaly' discovered deep below New Zealand's Lake Rotorua

Researchers at GNS Science, a research institute in New Zealand, have now mapped Lake Rotorua's floor in never-before-seen detail, revealing eruption craters, an ancient river and a large magnetic anomaly in the southern part of the lake. These new maps prove for the first time that Rotorua's mainland hydrothermal systems extend into the lake's hidden depths.

Cornel de Ronde, a principal scientist at GNS Science, told Live Science that seeing the maps was like wearing glasses for the first time when you didn't realize you needed them. "You finally put those glasses on, and you can see the fine print," he said. 

Related: 

• Over half of the world's largest lakes and reservoirs are losing water

The maps cover 21 square miles (55 square kilometers), which is around 68% of the lake's floor, according to a statement released by GNS Science. The Royal New Zealand Navy collected some of the data, mapping the lake floor's physical features using a multibeam echo sounder — a type of sonar. They also carried out magnetic surveys, which revealed the magnetic anomaly. 

"Normally with volcanic rocks, when you run a magnetometer over the top of them, you get very positive anomalies, but in this case we're getting negative anomalies, likely due to very low magnetic susceptibilities," de Ronde said. 

Volcanic rocks typically contain the highly magnetic mineral magnetite, but in Lake Rotorua, researchers believe hydrothermal fluids have passed through the rock and transformed the magnetite into pyrite, or fool's gold, which has almost no magnetic signal. This hydrothermal process would severely diminish the magnetic signal and explain the negative anomaly.

The researchers also found other evidence of hydrothermal activity in the same general area as the magnetic anomaly. A heat flow map shows heat, which is probably hot water, rising up to the lake floor from beneath. Craters are also visible in this same region, which de Ronde noted are likely hydrothermal eruption craters. 

Despite all of this activity, water temperatures near the bottom of the lake are usually around a cool 57 degrees Fahrenheit (14 degrees Celsius), according to de Ronde. That's because the lake is so large that there's enough cool water to counteract heat coming up from below, and the temperature only fluctuates by around 1.8 degrees F (1 degree C) over a month.

"Nobody swimming in the lake would notice it, but with instrumentation, we do," de Ronde said. 

Editor's note: Updated at 5:46 p.m. EST to note that the hydrothermal process would severely diminish the magnetic signal, not flip it, as had been previously stated.

{ https://www.space.com/ }

04-02-2024 om 23:56 geschreven door peter  

SpaceX's Dragon reentry and splashdown with Ax-2 astronauts looks amazing in these nighttime photos and videos

04-02-2024 om 18:38 geschreven door peter  

Marsrover vindt overblijfselen van een groot meer – is er misschien leven?

Geavanceerde ruimtetechnologie groef diep onder het oppervlak van Mars, en het gevonden materiaal heeft de vermoedens van veel wetenschappers bevestigd.

Dat is een belangrijke ontdekking, en het bevestigt de vermoedens dat hier ooit water stroomde.

‘De radarbeelden laten zien dat de sedimenten regelmatig en horizontaal zijn – net als sedimenten in meren op aarde,’ zei David Paige, professor aard-, planeet- en ruimtewetenschappen aan de UCLA en hoofdauteur van de studie, in een persbericht.

De resultaten ondersteunen de theorie die NASA-wetenschappers al lang aanhangen: dat het koude, droge, levenloze Mars ooit warm, nat – en misschien bewoonbaar – was.

Perseverance verzamelt nu zo snel als de technologie het toelaat monsters uit de Jezerokrater.

De bodem- en gesteentemonsters zullen uiteindelijk naar de aarde worden gestuurd, en de wetenschappers achter dit onderzoek hopen er sporen van leven in te vinden.

{ https://wibnet.nl/heelal }

04-02-2024 om 16:55 geschreven door peter  

The habitable zone is a rather crude way to identify planets that may have liquid water. Its boundaries are unclear and even contradictory since stellar spectral type, planetary albedo, mass, and even how cloudy its atmosphere is can determine if a planet has liquid water.

The idea of a conservative habitable zone (CHZ) is more helpful. It comes from a 2014 paper by Kopparapu et al. It’s a region around a star where a rocky planet receives between 0.42 and 0.842 as much solar insolation as Earth does. Any rocky planet receiving that much energy is in the CHZ, regardless of distance.

Discovering a Super-Earth in a star’s CHZ is always exciting. It fuels our sense of wonder about other planets and the possibility that some may harbour other life. For that reason, they’re more intriguing than planets like Hot Jupiters for instance, which have zero possibility of hosting liquid water or life. Not even the hardiest extremophiles can survive a Hot Jupiter’s wicked environment.

But this discovery is also exciting for a couple of other reasons.

Now that we’ve discovered thousands of exoplanets, astronomers are seeing trends in the population. One of the things they noticed is a gap in the small planet population between 1.5 and 2 Earth radii. It’s known as the small planet radius gap or the sub-Neptune radius gap (also called the Fulton gap and the photoevaporation valley.) At 1.55 Earth radii, TOI-715b is inside the gap.

It’s extremely unlikely that no planets form in this radius gap. Planets must start out larger and lose mass to end up in the gap. So, the Fulton Gap tells us something about how some planets lose mass. Astronomers think that planets in the gap start out larger, but their stars strip away some of their mass by photoevaporation, shrinking them. That’s why it’s sometimes called the photoevaporation valley. There’s a lot of uncertainty around the valley and photoevaporation, and astronomers want to study planets in the valley to see what they can learn.

“The importance of the radius valley lies in its potential to teach us about planetary formation and post-formation evolution, and hence, planets inside this gap are crucial in furthering our understanding of the factors that sculpt it,” the authors explain.

There’s some uncertainty if this radius gap exists around M-dwarfs or not. It’s possible that M-dwarfs have a density gap rather than a radius gap. “A recent study by Luque & Pallé (2022), however, indicates that M-dwarf planets may have a density gap rather than a radius gap separating two populations of small planets (rocky and water worlds),” the authors write.

Whether it’s a radius gap or a density gap, TOI-715b should have something to tell us about exoplanets, photoevaporation, and the nature of exoplanet distribution around red dwarfs. But to discover what it has to tell us requires further, detailed observations. That’s the second reason why this Super-Earth is so intriguing.

Ever since we started finding exoplanets, scientists have looked forward to the day when the James Webb Space Telescope is operational. “At long last, the era of JWST has arrived, and with it, the age of detailed exoplanetary atmospheric characterization,” the authors write in their paper. The JWST has the ability to observe the spectra of exoplanet atmospheres and determine their constituents. But even though the JWST is enormously powerful, some targets present better opportunities for transmission spectroscopy than others.

TOI-715b is a prime target because it’s close to its star. Since TOI-715 is a small red dwarf, and the planet orbits it every 19 days, the exoplanet’s transits in front of its star are deeper and more frequent. That means the JWST doesn’t need much time to observe the planet’s atmosphere, making it an efficient use of the space telescope’s time. “In the context of atmospheric characterization by transmission spectroscopy, bright, nearby M dwarfs are ideal planetary hosts as small temperate planets will transit frequently, enabling high signal-to-noise detections of atmospheric features with fewer hours of telescope time,” the authors explain.

Can this Super-Earth be habitable? Lacking the JWST’s spectroscopy, we’re reduced to speculating. It’s in the conservative habitable zone, but that doesn’t get us very far. Still, there are some hopeful signs.

TOI-715 is a little older than our Sun at about 6.6 billion years old. The star shows a “low degree of magnetic activity,” according to the authors. That’s probably why the star shows an absence of flaring in the TESS light curves compared to younger M-dwarfs. Red dwarfs are known to exhibit extremely powerful flaring that can sterilize planets. They can also strip away atmospheres, which could be responsible for the exoplanet photoevaporation valley.

Another planet may be orbiting TOI-715. It’s currently only a candidate named TIC 271971130.02, but if confirmed, it will be the smallest habitable zone planet TESS has ever found. But follow-up observations are needed to confirm it.

The TOI-715 system is a compelling target for further study. TOI-715b is waiting its turn, but eventually, the JWST will examine its atmosphere. If those results support habitability, astronomers’ excitement will only grow. At the same time, we may learn more about the radius or density gap, an obstacle to a more thorough understanding of exoplanets.

Add in the fact that the star may host another habitable zone planet, the smallest one found yet by TESS, and the TOI-715 system becomes even more importan

{ https://www.universetoday.com/ }

03-02-2024 om 23:07 geschreven door peter  

About eROSITA

eROSITA is a soft x-ray imaging telescope aboard the Spectrum-RG satellite. Its first all-sky survey, called eRASS1, took place over 7 months beginning on December 12, 2019. At its most sensitive setting, the telescope detected 170 million X-ray photons. That allowed the cameras to measure their energies and arrival times.

The astronomy team, led by principal investigator Andrea Merloni, put together a first-release catalog of data. They also published more than 50 new science papers based on their findings. After finishing this first survey, the instrument carried out three more scans of the entire sky between June 2020 and February 2022. That huge treasuring of x-ray data will be released shortly. The video below explains more about the mission.

eROSITA’s Treasury of X-ray Sources

X-ray astronomy focuses on hot and energetic objects and events in the Universe. Those would be the cores of galaxies (where supermassive black holes lurk), supernova explosions, newborn stars, and other places where matter gets heated to high temperatures.

This preliminary data eRASS1 data set pinpoints about 710,000 supermassive black holes, 180,000 x-ray emitting stars in the Milky Way, and 12,000 clusters of galaxies. It also covers a small number of other exotic sources like X-ray-emitting binary stars, supernova remnants, pulsars, and other objects.

“These are mind-blowing numbers for X-ray astronomy,” says Andrea Merloni, eROSITA principal investigator and first author of the eROSITA catalog paper. “We’ve detected more sources in 6 months than the big flagship missions XMM-Newton and Chandra have done in nearly 25 years of operation.”

The eROSITA first data release is a rich, “multi-layered” look at the sky at several X-ray energies. Each energy level tells astronomers something about the objects and events emitting the X-rays. And, for each set of images and data, the consortium provides more information. There are lists of source classes, sky positions, energies, and precise arrival times of the photons to the instrument. “We’ve made a huge effort to release high-quality data and software,” added Miriam Ramos-Ceja, who leads the eROSITA Operations team. “We hope this will broaden the base of scientists worldwide working with high-energy data and help push the frontiers of X-ray astronomy.”

Zeroing in on Specific X-ray Objects

eROSITA’s science objectives are to use X-rays as a way to detect the hot intergalactic medium of 50 to 100,000 galaxy clusters and groups. It also looks at hot gas in filaments between them. Those filaments glow in X-rays. The instrument is also tasked with detecting accreting black holes hidden in galaxies. Finally, it studied the physics of galactic X-ray sources (which include pre-main-sequence stars, supernova remnants, and X-ray binaries).

At least one of the papers released with the new survey data uses x-ray data to constrain cosmological models using clusters of galaxies. In one release image, we see a newly discovered filament of material. It stretches between one portion of the galaxy cluster Abell 3667 and the nearby cluster Abell 3651. This may help astronomers determine how much matter exists in the so-called “warm-hot intergalactic medium”. It gives insight into the formation of large-scale structures (like galaxy clusters) in the Universe.

The nearby Virgo Cluster of galaxies also shows up in the eRASS1 survey and provides a way to study large-scale filamentary structures. In particular, astronomers want to understand the physical effects operating in the outskirts of these massive galaxy clusters. Using the new survey data, plus other all-sky images, a science team explored the structure of the cluster’s outskirts. That included high-energy emissions around galaxies and groups within the cluster. They also studied a so-called 320-kiloparsec-long “x-ray extension” near the galaxy M49.

eROSITA’s Past Work and Future

eROSITA has enabled a huge leap forward in X-ray astronomy since its launch in June 2019. It began operations in October of that year, providing high-resolution X-ray vision of the cosmos. As it scanned the sky, it glimpsed changes in a distant quasar called SMSS J114447.77-430859.3. Those changes give some clues to the growth of the black hole at the heart of the quasar. It observed changes in the brightness variations at the heart of the quasar, indicating that the black hole swallows some of the material that strays into its event horizon. Other material escapes in the form of powerful winds.

The instrument has also detected a newly forming black hole in the early Universe and traced the existence of hot gas all around our own Milky Way Galaxy. The instrument had its first light on October 22, 2019. Currently, it’s in safe mode and technicians are assessing its health and status.

For More Information

• eROSITA
• eROSITA Science Papers
• The X-ray Sky Opens to the World
• Discovery of a >13 Mpc long X-ray filament between two galaxy clusters beyond three times their virial radii
• The SRG/eROSITA All-Sky Survey: View of the Virgo Cluster

{ https://www.universetoday.com/ }

03-02-2024 om 22:54 geschreven door peter  

5 GIGANTISCHE ASTEROÏDEN ZO GROOT ALS EEN VOETBALSTADION NADEREN DE AARDE

By thalena

Maak je je zorgen over wat deze week gaat brengen? Nou, hou je vast: er zijn 5 gigantische asteroïden onderweg naar de aarde! Maar voordat je in doemdagmodus schiet, geen paniek. Volgens NASA zullen deze ruimterotsen, waaronder eentje zo groot als een voetbalstadion, onze mooie blauwe planeet niet raken. Laten we hopen dat ze geen rekenfoutje hebben gemaakt en eens duiken in de details van deze kosmische voorbijgangers en ontdekken waarom we toch rustig kunnen slapen.

Niet Zomaar Een Steen

NASA houdt deze week 5 gigantische asteroïden in het vizier die onze richting uit komen. Onder hen bevindt zich een ware reus met een diameter van ongeveer 280 meter, vergelijkbaar met de omvang van een flink voetbalstadion! Hoewel de gedachte aan zo’n gigantische ruimterots misschien angstaanjagend is, is er gelukkig geen enkel gevaar voor een botsing met onze planeet. Deze asteroïden zullen ons op veilige afstand passeren, waardoor de aarde gespaard blijft van een potentieel catastrofale impact. Deze kosmische voorbijgangers bieden een unieke kans voor wetenschappers om meer te leren over de samenstelling en het gedrag van dergelijke ruimteobjecten.

Beeld: wikipedia

5 gigantische asteroïden

Deze asteroïden variëren in grootte, van zo groot als een vliegtuig tot een voetbalstadion, en hun afstanden tot de aarde zijn zowel indrukwekkend als veilig. De dichtstbijzijnde zal ons missen met 1,7 miljoen mijl, terwijl de anderen zelfs nog verder verwijderd zijn, wat ons een comfortabele veiligheidsmarge biedt en de kans geeft om deze fascinerende ruimterotsen van een afstand te observeren en te bestuderen.

Beeld: wikipedia

Hoe Dichtbij Is Dichtbij?

Voor wat perspectief: de gemiddelde afstand tussen de aarde en de maan is ongeveer 239.000 mijl. Deze asteroïden zullen dus aanzienlijk verder weg zijn, ruim buiten de baan van de maan. Dit betekent dat we, ondanks hun indrukwekkende grootte, geen Hollywood-achtige doemscenario’s hoeven te verwachten. Hun passage is een kans voor wetenschappers om meer te leren, terwijl wij veilig op aarde blijven.

Geen risico

Dus, daar heb je het: een hemelse parade van 5 gigantische asteroïden, met een als headliner die de grootte heeft van een voetbalstadion. Hoewel het een fascinerend kosmisch spektakel is, benadrukt NASA dat er geen risico is op een botsing met onze planeet. Deze week hoeven we dus niet te vrezen voor een doemdag-scenario. In plaats daarvan kunnen we genieten van de wonderen van ons zonnestelsel, veilig en wel vanaf onze eigen blauwe marmer.

Check ook:

• Asteroïde ‘Bennu’ mogelijk op ramkoers met aarde: ‘Kracht van 22 atoombommen’

{ https://sgxl.nl/ }

03-02-2024 om 17:44 geschreven door peter  

Countless robotic pioneers have explored the surface and atmosphere of Mars in incredible detail and continue to teach us whether Mars once had—or currently has—life. However, humans could provide an extra level of exploration since they won’t be hindered by waiting for instructions from Earth ground controllers, which can take anywhere from 5 to 20 minutes one way. If something goes wrong, human explorers can make on-the-spot decisions to find solutions, whereas robot explorers are faced with waiting for engineers back on Earth to find solutions, followed by sending instructions, and more waiting. Regarding technological advancements, a human mission will undoubtedly teach us how to live and work on Mars, and this includes testing shelters, food, bathroom facilities, and even combating the mental fatigue from being so far from Earth for a prolonged period. All things considered, what are the pros and cons of sending humans to Mars?

Dr. Bretzfelder tells Universe Today, “Pros are as above, and many examples of the benefits of humans in the field can be found in the history of the Apollo missions; instances where certain scientifically valuable rocks were collected due to the quick thinking and judgement of the astronauts. Cons include the difficulties involved in keeping astronauts alive and safe on a distant and environmentally complicated planetary surface. Additionally, the possibility of accidentally introducing terrestrial microbes to Mars is a potential risk.”

Whether it’s a robotic or human mission, NASA’s Office of Planetary Protection is responsible for ensuring that microbes don’t hitch a ride and contaminate extraterrestrial environments that we wish to explore, but especially to protect us from any microbes that could potentially be brought back to Earth.

Regarding the ongoing robotic exploration of Mars, there are presently seven active Mars orbiters from several nations teaching us more and more about the Red Planet and unlocking its secrets. On the surface, there are currently three active missions: NASA’s Curiosity and Perseverance rovers, and China’s Zhurong rover. Past successful surface missions include NASA’s Viking 1 and Viking 2 landers, Mars Pathfinder, Spirit and Opportunity rovers, Phoenix lander, and InSight lander. From marsquakes to finding evidence for past surface liquid water, each of these missions spent years unlocking the secrets of Mars, both above and below the surface. But what additional science could be conducted by a human mission compared to a robotic mission?

“As above, humans (within limits based on their suits and other equipment) have the ability to navigate terrain that may not be suitable for a rover or helicopter,” Dr. Bretzfelder tells Universe Today. “They also can make real time decisions in the field about sampling etc., meaning there is less delay in waiting for signals from mission control to guide the rovers. Humans are also very adaptable to changing conditions and can respond quickly to address any issues or unexpected situations during a mission.”

In terms of an actual human habitat on Mars, countless images, videos, movies, and television shows have depicted a human habitat on the Martian surface, with very little depiction of a human habitat below the surface. While this depiction might be for aesthetics, a habitat on the surface would provide ideal surveying and sampling conditions, along with far better communications with Earth. However, a habitat on the surface would also expose the crew to dangerous amounts of solar radiation since Mars does not possess either an ozone layer or magnetic field like the Earth, both of which protect us from solar storms and other cosmic rays.

In contrast, another type of human habitat could be below the surface, with past studies identifying the use of lava tubes for human settlements to shield them from the harmful solar radiation. However, any surface ventures could become tedious, along with communications with Earth becoming more complicated, even if a communications array was above-ground. Therefore, if humans were to travel to Mars, should it be above the surface or below?

Dr. Bretzfelder tells Universe Today, “An above surface mission, similar to the Apollo and upcoming Artemis missions would be the most feasible given the technology available and would limit impact to the Martian surface by simply operating above ground rather than excavating below ground. Samples or cores taken from depth may be scientifically valuable though.”

This discussion comes as NASA prepares to send humans back to the Moon as part of its Moon to Mars Architecture while SpaceX develops its Starship with the goal of sending humans to Mars, someday. China announced plans in 2021 to send their own astronauts to the Red Planet in 2033, with follow-up launches occurring every two years afterwards. Additionally, NASA has the goal of sending humans to Mars sometime in the 2030s.

“It is an exciting time to be able to seriously consider this type of exploration, and as we return to the Moon, we will likely learn valuable lessons to enable human exploration of Mars,” Dr. Bretzfelder tells Universe Today.

Will we ever send humans to Mars? Will such a mission achieve greater scientific objectives than the myriad of robotic missions sent to the Red Planet, and what could a human mission to Mars teach us about living and working so far from Earth? Only time will tell, and this is why we science!

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

{ https://www.universetoday.com/ }

02-02-2024 om 22:39 geschreven door peter  

Like the Moon and other airless bodies, Ryugu has no protective atmosphere and does not experience weathering or erosion. This ensures that craters caused by past impacts on its surface (which is directly exposed to space) are carefully preserved despite the passage of eons. These impacts generate intense heat that leaves behind melted patches of glass (aka. “melt splashes”), which quickly solidify in the vacuum of space. These impacts cause changes to the composition of the asteroid’s surface materials, revealing information about the history of impacts.

After analyzing the Ryugu samples, Matsumoto and her colleagues found melt splashes ranging in size from 5 to 20 micrometers. Their composition suggests they came from cometary sources that impacted Ryugu while it was in a near-Earth orbit. “Our 3D CT imaging and chemical analyses showed that the melt splashes consist mainly of silicate glasses with voids and small inclusions of spherical iron sulfides,” said Matsumoto in a recent Tohoku University news release. “The chemical compositions of the melt splashes suggest that Ryugu’s hydrous silicates mixed with cometary dust.”

Their analysis revealed small carbonaceous materials with a spongy texture indicative of nano-pores, small voids caused by the release of water vapor from hydrous silicates. This vapor was subsequently captured in the melt splashes, which also contained silicate glasses rich in magnesium and iron (Mg-Fe) and iron-nickel sulfides. The carbonaceous materials are similar in texture to primitive organic matter observed in cometary dust but differ in composition – lacking nitrogen and oxygen. Said Matsumoto:

“We propose that the carbonaceous materials formed from cometary organic matter via the evaporation of volatiles, such as nitrogen and oxygen, during the impact-induced heating. This suggests that cometary matter was transported to the near-Earth region from the outer solar system. This organic matter might be the small seeds of life once delivered from space to Earth.”

Looking ahead, the team hopes to examine more Ryugu samples that will provide further insights into how primitive organic materials were delivered to Earth billions of years ago. Similarly, scientists at NASA’s Johnson Space Center recently completed the careful process of removing the samples collected by the OSIRIS-REx mission from their sample container. Analysis of these samples will reveal the composition and history of asteroid Bennu, another NEA that will provide vital information on how our Solar System evolved.

Further Reading: 

• Tohoku University, 
• Science Advances

{ https://www.universetoday.com/ }

02-02-2024 om 22:30 geschreven door peter  

Swedish astronaut Marcus Wandt took control of a series of robots in Germany while on board the International Space Station, zipping around the Earth at 28,000 kilometers per hour (17,500 mph.) Researchers want to understand how time delays can affect the remote control of robots from an orbiting platform. Future astronauts could control rovers on the Moon’s or Mars’s surface from a spacecraft in orbit. Until now, only wheeled rovers have been part of the tests, but now they have added a dog-like robot called Bert.

This robot research session, called ‘Surface Avatar’ follows initial experiments carried out in July 2023. Wandt operated the robots from a control station in the space station’s Columbus module, commanding three different robots at the German Space Agency’s (DLR) Robotics and Mechatronics Center in Oberpfaffenhofen, Germany. The goal is to develop innovative technologies that will allow humans to control several robots with precision, and have them act semi- or fully autonomously and even have different robots perform a task together.

“Future stations on the Moon and Mars, including astronaut habitats, will be built and maintained by robots operating under the guidance of astronauts,” said Alin Albu-Schäffer, Director of the DLR Institute of Robotics and Mechatronics, in a DLR article. “Our latest control and AI algorithms enable a single astronaut to command an entire team of different robots. Our DLR-ESA team is a world leader when it comes to this technology.”

The remote operation of the dog-like robot Bert was marked the first time a non-wheel-driven robot was controlled remotely from space by astronauts. Previously, DLR’s humanoid service robot Rollin’ Justin and ESA’s Interact Rover have been teleoperated from space.

During the session, Wandt, who is part of the private Axiom Mission 3 (Ax-3), was able to command Bert to utilize several types of gaits and, because of his leg-based locomotion, Bert was able to explore rough terrain, including small caves — areas that the rolling robots cannot reach. At one point, Wandt allowed Bert to explore the lab’s surroundings independently and monitor the terrain with his camera eyes. Meanwhile, Wandt operated Rollin’ Justin and the Interact Rover.

The time delay between the ISS and Earth is usually less than one second.

“That’s because my radio call comes from ISS first to White Sands in the USA,” explained German Space Agency astronaut Matthias Maurer, in a video from DLR. “From there it goes to Houston at NASA. From there it will be forwarded to Munich where our control center is in Oberpfaffenhofen.”

Maurer added that the delay experienced is like what sometimes happens on a Skype call, which occasionally has delays in communications. And of course, the round-trip delay time might be close to 2 seconds, which is deficiently noticeable, especially during conversations.

DLR said that future operations of robots and humans working together must be well planned out in order for them to work as a team. When building a habitat, for example, combining the different skills of several robots is very helpful.

Wandt also tested out this concept and for the first time two robots worked together to accomplish a task: Rollin’ Justin and the Interact Rover jointly installed a short pipe representing a scientific measuring device. Under the command of Wandt, Rollin’ Justin used his dexterous hands to safely grasp the pipe and carefully guide it to the measuring point. Wandt then used the Interact rover’s remote control to install the pipe held in position by Justin.

Robots have also been used in space on board the ISS. Robonaut is a joint DARPA–NASA project that created a humanoid torso robot to test out robotics in space. Additionally, three free-flying robots on the space station, known as Astrobees, support multiple demonstrations of technology for various types of robotic assistance on space exploration missions and on Earth.

{ https://www.universetoday.com/ }

02-02-2024 om 22:20 geschreven door peter  

The habitable zone is a rather crude way to identify planets that may have liquid water. Its boundaries are unclear and even contradictory since stellar spectral type, planetary albedo, mass, and even how cloudy its atmosphere is can determine if a planet has liquid water.

The idea of a conservative habitable zone (CHZ) is more helpful. It comes from a 2014 paper by Kopparapu et al. It’s a region around a star where a rocky planet receives between 0.42 and 0.842 as much solar insolation as Earth does. Any rocky planet receiving that much energy is in the CHZ, regardless of distance.

Discovering a Super-Earth in a star’s CHZ is always exciting. It fuels our sense of wonder about other planets and the possibility that some may harbour other life. For that reason, they’re more intriguing than planets like Hot Jupiters for instance, which have zero possibility of hosting liquid water or life. Not even the hardiest extremophiles can survive a Hot Jupiter’s wicked environment.

But this discovery is also exciting for a couple of other reasons.

Now that we’ve discovered thousands of exoplanets, astronomers are seeing trends in the population. One of the things they noticed is a gap in the small planet population between 1.5 and 2 Earth radii. It’s known as the small planet radius gap or the sub-Neptune radius gap (also called the Fulton gap and the photoevaporation valley.) At 1.55 Earth radii, TOI-715b is inside the gap.

It’s extremely unlikely that no planets form in this radius gap. Planets must start out larger and lose mass to end up in the gap. So, the Fulton Gap tells us something about how some planets lose mass. Astronomers think that planets in the gap start out larger, but their stars strip away some of their mass by photoevaporation, shrinking them. That’s why it’s sometimes called the photoevaporation valley. There’s a lot of uncertainty around the valley and photoevaporation, and astronomers want to study planets in the valley to see what they can learn.

“The importance of the radius valley lies in its potential to teach us about planetary formation and post-formation evolution, and hence, planets inside this gap are crucial in furthering our understanding of the factors that sculpt it,” the authors explain.

There’s some uncertainty if this radius gap exists around M-dwarfs or not. It’s possible that M-dwarfs have a density gap rather than a radius gap. “A recent study by Luque & Pallé (2022), however, indicates that M-dwarf planets may have a density gap rather than a radius gap separating two populations of small planets (rocky and water worlds),” the authors write.

Whether it’s a radius gap or a density gap, TOI-715b should have something to tell us about exoplanets, photoevaporation, and the nature of exoplanet distribution around red dwarfs. But to discover what it has to tell us requires further, detailed observations. That’s the second reason wh

Ever since we started finding exoplanets, scientists have looked forward to the day when the James Webb Space Telescope is operational. “At long last, the era of JWST has arrived, and with it, the age of detailed exoplanetary atmospheric characterization,” the authors write in their paper. The JWST has the ability to observe the spectra of exoplanet atmospheres and determine their constituents. But even though the JWST is enormously powerful, some targets present better opportunities for transmission spectroscopy than others.

TOI-715b is a prime target because it’s close to its star. Since TOI-715 is a small red dwarf, and the planet orbits it every 19 days, the exoplanet’s transits in front of its star are deeper and more frequent. That means the JWST doesn’t need much time to observe the planet’s atmosphere, making it an efficient use of the space telescope’s time. “In the context of atmospheric characterization by transmission spectroscopy, bright, nearby M dwarfs are ideal planetary hosts as small temperate planets will transit frequently, enabling high signal-to-noise detections of atmospheric features with fewer hours of telescope time,” the authors explain.

Can this Super-Earth be habitable? Lacking the JWST’s spectroscopy, we’re reduced to speculating. It’s in the conservative habitable zone, but that doesn’t get us very far. Still, there are some hopeful signs.

TOI-715 is a little older than our Sun at about 6.6 billion years old. The star shows a “low degree of magnetic activity,” according to the authors. That’s probably why the star shows an absence of flaring in the TESS light curves compared to younger M-dwarfs. Red dwarfs are known to exhibit extremely powerful flaring that can sterilize planets. They can also strip away atmospheres, which could be responsible for the exoplanet photoevaporation valley.

Another planet may be orbiting TOI-715. It’s currently only a candidate named TIC 271971130.02, but if confirmed, it will be the smallest habitable zone planet TESS has ever found. But follow-up observations are needed to confirm it.

The TOI-715 system is a compelling target for further study. TOI-715b is waiting its turn, but eventually, the JWST will examine its atmosphere. If those results support habitability, astronomers’ excitement will only grow. At the same time, we may learn more about the radius or density gap, an obstacle to a more thorough understanding of exoplanets.

Add in the fact that the star may host another habitable zone planet, the smallest one found yet by TESS, and the TOI-715 system becomes even more important.

{ https://www.universetoday.com/ }

02-02-2024 om 22:10 geschreven door peter  

Ieder mens is anders en dat geldt ook voor spiraalstelsels. De James Webb-ruimtetelescoop richtte zijn blik op negentien spiraalstelsels en trof verschillende structuren aan.

Op de foto’s zie je waar sterren, gas en stof zich bevinden in deze sterrenstelsels. De infraroodbeelden helpen wetenschappers om meer te weten te komen over spiraalstelsels. Zo kunnen computersimulaties verbeterd worden om zo meer inzicht te krijgen in de vorming en de evolutie van spiraalstelsels. En dat is handig, want ook ons eigen moederstelsel – de Melkweg – is namelijk een spiraalstelsel met een centrale balk.

Dankzij de NIRCam zijn miljoenen sterren gefotografeerd in deze negentien spiraalstelsels. Je kunt deze sterren herkennen als blauwe stipjes. Zie je heldere verdikkingen? Dit zijn sterrengroepen. Het MIRI-instrument van James Webb is gebruikt om het gloeiende stof tussen sterren in kaart te brengen. Dit instrument kan ook protosterren zien. Dit zijn sterren die nog niet volledig zijn gevormd en zich schuilhouden in cocons van stof. Verder zien astronomen grote, ronde schillen van gas. Deze zijn mogelijk ontstaan door geëxplodeerde sterren, oftewel door supernova’s.

Astronomen denken dat sterrenstelsels van binnenuit groeien. De eerste sterren ontstaan nabij het centrum en daarna spreidt stervorming naar buiten. Des te verder een ster is verwijderd van het centrum, des te groter is de kans dat het een jonge ster is. Op de foto’s zie je veel blauwe stippen nabij de centra van de sterrenstelsels, maar dit zijn oude sterren.

Hierboven waren al vier sterrenstelsels zichtbaar. Hieronder volgen de overige vijftien foto’s. Klik op de foto’s om een grotere versie te downloaden, bijvoorbeeld als achtergrond op je telefoon.

{ https://scientias.nl/ }

02-02-2024 om 20:16 geschreven door peter  

Ieder mens is anders en dat geldt ook voor spiraalstelsels. De James Webb-ruimtetelescoop richtte zijn blik op negentien spiraalstelsels en trof verschillende structuren aan.

Op de foto’s zie je waar sterren, gas en stof zich bevinden in deze sterrenstelsels. De infraroodbeelden helpen wetenschappers om meer te weten te komen over spiraalstelsels. Zo kunnen computersimulaties verbeterd worden om zo meer inzicht te krijgen in de vorming en de evolutie van spiraalstelsels. En dat is handig, want ook ons eigen moederstelsel – de Melkweg – is namelijk een spiraalstelsel met een centrale balk.

  NGC 1672 op 60 miljoen lichtjaar van de aarde.

Bronmateriaal

• "Webb depicts staggering structure in 19 nearby spiral galaxies" - ESA
  
• Afbeelding bovenaan dit artikel: ESA

{ https://scientias.nl/ }

02-02-2024 om 20:11 geschreven door peter  

Here, The Debrief looks at three of the past most promising warp drive models, along with one brand new physics concept called the “Tri-Space Model,” which may hold the key to making faster-than-light travel possible.

THE ORIGINAL: ALCUBIERRE/WHITE WARP DRIVE

While Alcubierre’s warp drive concept showed that traveling faster than light was mathematically possible, it was widely criticized for its massive power requirements and use of purely theoretical “exotic matter.” Still, many scientists and engineers were intrigued by his work, including former NASA engineer and physicist Dr. Harold G. “Sonny” White.

Hoping to move Alcubierre’s metric from theory into a published, canonical form, White first looked at the idea more closely in 2003.

“I started working in the (NASA) space program in 2000,” White told The Debrief in an interview. “While I was working in the space program, I was thinking about this Advanced Power propulsion. I was thinking about this Alcubierre Warp metric. You know, it was not published in its canonical form. And so, in 2003, I published a paper in the journal General Relativity and Gravitation.”

White immediately noted how Alcubierre’s math worked but also spotted areas he thought his own background in engineering and physics could improve the concept.

“Some things didn’t quite make sense to me, but by putting it into canonical form, helped me figure out ‘how does this concept really work?’, White told The Debrief. “From the process of not being at warp to being at warp… what would that look like when you look at the mathematics? And the only way I could see to answer the question is to put it in the canonical form in 2003, so that’s what I talked about in that paper.”

Theoretical Warp Bubble Structure

(Image Credit LSI)

Years later, White was asked by NASA to present his updated warp concept, leading to his 2011 paper and the warp drive concept now known as the “Acubierre/White Warp Drive.”

“I got asked to give a talk [about the warp drive] to DARPA and NASA at the DARPA 100-year Starship Symposium in 2011,” he told The Debrief. “I did a sensitivity study on the metric. I looked at what happens when you change the parameters and the mathematics.”

Specifically, White looked at the geometry of the classic warp drive model and found something that dramatically reduced the amount of energy required by Alcubierre.

“It basically comes down to how thick you make the toroidal ring and negative vacuum energy density,” he explained. “How thick or thin to make it, topologically? What does that do to the overall energy required? And so, during that work, I had no ‘objective’ objectives, per se, other than just to explore. In the process of doing that, I discovered that by making that ring a little thicker, instead of being like a wedding band wrapped around your finger, it’s a little bit more like a lifesaver, was key.”

In fact, White’s geometric adjustment to the classic model dramatically reduced the amount of exotic matter required to a much more manageable concept.

“By using that optimization technique, I was able to reduce the amount of exotic matter from a Jupiter-sized amount down to something about the size of the Voyager spacecraft,” said White. “So about two metric tons or just under two metric tons.”

As White notes, even a few tons of a theoretical substance like exotic matter is still unachievable by today’s scientists and engineers, but his changes definitely improved the ultimate viability of Alcubierre’s idea.

“Instead of just being mathematically possible in our work, we potentially move it into the category of maybe it’s plausible,” he noted with a lighthearted shrug. “There are now two metric tons of this stuff we’re not quite sure exactly how to make.”

White’s views about the feasibility of warp drives and their related effects have garnered a fair amount of attention from critics over the years. Among them is astrophysicist Ethan Siegel who, while remaining skeptical of White’s claims, has noted that the warp drive concept “remains an interesting possibility and one worthy of continued scientific investigation, but one that you should remain tremendously skeptical about given the current state of affairs.”

THE LENTZ DRIVE

A decade after White updated the original warp drive concept, reducing the need for exotic matter down from a Jupiter-sized amount to a few tons, another scientist named Dr. Eric W. Lentz decided to take a stab at his own warp drive concept. Published in 2021, his paper “Breaking the warp barrier: hyper-fast solitons in Einstein–Maxwell-plasma theory” lays out a whole new warp drive concept. And unlike Alcubierre and White, Lentz believed that his faster-than-light warp drive model could be accomplished in a completely new and different way.

“The Alcubierre solution provided an intuitive picture of what a warp drive would do: contract the space immediately in front of the central region containing the ship or transport, and expand the space immediately behind,” Dr. Lentz explained in an email to The Debrief. “This gives us the picture of the warp drive as a wave of curvature on which a ship will ride to its destination.”

However, Lentz explains, “this picture is not an essential feature of a warp drive.” Instead, he says, a solution proposed by physicist Jose Natario back in 2002 showed that the expansion and contraction weren’t necessary to transport the ship forward. That work, says Lentz, was critical to forming his own theory, one where a warp field could be created using only traditional matter and not exotic matter.

“[Natario] showed that the expansion could be trivial (zero) everywhere and still perform the same task of transporting a ship,” Lentz told The Debrief. This is a significant breakthrough, he says, because it means that exotic matter that warps the space in front of the theoretical passenger, as well as behind them (as depicted in nearly all theoretical warp drive solutions), is no longer needed to achieve faster-than-light travel.

Could dark matter allow physicists a path toward overcoming the challenges of faster-than-light travel?

(Credit: ESO)

“In the Alcubierre solution, the energy density and curvatures are maximally separated, with the energy being restricted to a small torus between the regions of high contraction and expansion,” Lentz told The Debrief, once again evoking the classic image of the Alcubierre Warp model. “The curvatures and sources in my proposal are instead highly correlated, with the regions of high energy density and high expansion and contraction overlapping almost exactly.”

As his published paper explains, “This is the first example of hyper-fast solitons resulting from known and familiar sources, reopening the discussion of superluminal mechanisms rooted in conventional physics.”

Lentz does freely admit that his theory is somewhat novel, even in this highly theoretical arena. “The expansion factor in my proposal is stranger still [than in Natario or Alcubierre], having regions of large expansion and contraction of space surrounding the central region containing a ship.”

Still, the issue of power requirements is not totally solved by Lentz, although he told The Debrief there is some hope in this area.

“There are a number of very effective energy-saving mechanisms for the Alcubierre drive described in the literature,” he explained. “The challenge would be to either modify these mechanisms to operate using only conventional sources, [like his proposed theory which does not require exotic matter] or to innovate novel energy saving techniques.”

In other words, if these proposed energy reduction techniques don’t work on his drive concept due to the lack of exotic matter, a legitimate concern, then an entirely new solution, the likes of which has not yet been proposed, would need to be found. Fortunately, Lentz says, his drive already accomplishes some of that goal since “not all the energy needs to come directly from the reactor, as we expect much of the energy sourcing the bubble to come from the particles’ rest masses.”

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

01-02-2024 om 23:25 geschreven door peter