Selasa, 28 Februari 2023

Should the moon have its own time zone? - DC News Now | Washington, DC

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Should the moon have its own time zone?  DC News Now | Washington, DCView Full Coverage on Google News
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2023-02-28 17:44:06Z
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Jupiter and Venus to make rare approach in night sky on Wednesday, March 1st - PembrokeToday.ca

Jupiter and Venus to make rare approach in night sky on Wednesday, March 1st

The Backyard Astronomer, Gary Boyle

March is set to kick off with a pair of “spooky eyes” in the sky.

Astronomy educator Gary Boyle has passed long a note to myFM that Jupiter and Venus are set to meet in a small area of the sky the width of a full moon on the evening of Wednesday, March 1st.

He says Venus is climbing up into the sky each night while Jupiter is moving towards the horizon, and the two planets will line up into a pair of “spooky eyes” in an event known as “conjunction.”

The orbits of the two planets will appear to approach each other from our line of sight even though they’ll be hundreds of millions of miles apart.

Both planets are visible to the naked eye on a clear night, but Boyle says you can check in with any astronomy app on your cellphone or tablet if you find yourself having trouble tracking the two celestial bodies down on March 1st.

(written by Kasey Egan)

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2023-02-28 11:37:29Z
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Worried about Sea Level Rise? Look for the Lichens. - Hakai Magazine

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The clock is ticking for many low-lying coastal areas. Sea level is rising faster than at any time in recorded history, promising to radically redraw the map. At a broad scale, we know this to be true. But knowing precisely which plots will be inundated and which will remain dry land is a much more daunting task. That effort may have an ally almost no one would have guessed: one of the smallest and least conspicuous forms of life—lichens.

More than 18,000 species of lichens have been described worldwide. Each is a community made up of one or more species of fungus and an alga or cyanobacteria. This combination has enabled lichens to survive in diverse and often hostile conditions, everything from tropical heat to bitter Antarctic cold.

To scratch out its niche, each species has developed to tolerate different levels of temperature, light, air quality, and other factors. Because of this sensitivity, lichens are already used by scientists to gauge environmental disturbance, such as the influence of logging or nitrogen pollution. Lichens also vary in their salt tolerance. It’s this property, says botanist Roger Rosentreter at Idaho’s Boise State University, that makes them so useful in understanding sea level rise.

“Lichens are a good indicator of site history,” says Rosentreter, who has studied lichens and related species for over 40 years. Specifically, the species of lichens that grow on a coastal site may be an effective indicator of low levels of saltwater intrusion and spray, which can be caused by infrequent flooding or storm events. Since sea levels are continuing to rise, any site that has experienced occasional salt water in the past is likely to see more frequent flooding and storm effects in the future.

Recently, Rosentreter and his wife, fellow Boise State botanist Ann DeBolt, studied the lichen communities of two state parks near West Palm Beach, Florida. One park, on a barrier island, is subject to frequent salt spray and storm flooding, while the other is inland just 500 meters away. The scientists found two surprisingly different lichen communities at each site. By comparing the two, they started building a list of lichen species that can be useful indicators of the long-term or historical presence of salt water.

Left: the powdery medallion lichen is very sensitive to salt but is not a good indicator of whether a site has experienced the first effects of sea level rise. Photo by Vitaly Charny. Right: the ruffled blue jellyskin is also sensitive to salt, but its slow growth makes it a better indicator. Photo by David Bird

It takes more than just salt sensitivity to make a lichen a good indicator of whether a site has experienced the first effects of sea level rise. The lichen’s own life history also comes into play.

Species like the powdery medallion lichen (left photo) can be killed if subjected to too much salt water by a storm or flood. But this lichen’s quick reproduction lets it swiftly recolonize after the sea recedes. Larger species with slower growth and reproduction, and also low salt tolerance, like the ruffled blue jellyskin (right photo), can better tell the saltwater history of a site. These salt-intolerant lichens could not have survived and grown if a saltwater event like storm spray or flooding had occurred at any point during their life. Since some lichen species can live for decades or longer, the record they provide can be both hyperlocal in space and extensive in time.

Of the 48 different lichen species Rosentreter and DeBolt found at their two Florida survey sites, 11 are reliable indicators of salt water’s presence. Seven of the species only like to grow in places with very low saltwater impact, while four are salt tolerant, so finding them growing suggests the site has a moderate history of salt and a higher risk of being affected by rising seas.

In general, they found that the species that best indicate if a site will be relatively safe from sea level rise and saltwater inundation are lichens that are larger and leafier and often light green or blue in color. But lichens can be tricky to identify, and some promising indicator species look quite similar to less useful ones. “You’ve got to be at least an intermediate plant person to figure it out,” says Rosentreter.

“The good thing is, these aren’t just in Florida. They’re in the whole southeast coastal plain,” he says. Reports on iNaturalist, for instance, put the ruffled blue jellyskin all along the US East Coast and beyond.

Borja G. Reguero, an expert in conserving natural defenses against sea level rise at the University of California, Santa Cruz, who was not involved in the research, sees parallels between how coastal communities and lichens handle environmental change. “It makes a lot of sense to find those indicator [species] where the frequency of spray or flood events are over a threshold where some species are not able to live anymore,” he says. “You could say the same thing about humans and coastal infrastructure. You get to a tipping point where specific neighborhoods get flooded so regularly that they don’t get insurance.”

Modern science offers an array of tools to study sea level rise, from satellite data to groundwater and soil sampling. Lichens could be another way to see, at smaller site-specific scales, where the sea is coming next, and just as importantly, where it is not.

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2023-02-28 08:02:10Z
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Senin, 27 Februari 2023

SpaceX launch cancelled last minute due to engine issue - CTV News

CAPE CANAVERAL, Fla. -

Last-minute technical trouble forced SpaceX to call off Monday's attempt to launch four astronauts to the International Space Station for NASA.

The countdown was halted with just two minutes remaining until liftoff from Kennedy Space Center. With just a split second to blast off, there was no time to deal with the problem, which involved the engine ignition system.

SpaceX delayed the launch until at least Thursday.

Strapped into the capsule atop the Falcon rocket were two NASA astronauts, one Russian cosmonaut and one astronaut from the United Arab Emirates. They had to wait until all the fuel was drained from the rocket -- an hourlong process -- before getting out.

"We'll be sitting here waiting," commander Stephen Bowen assured everyone. "We're all feeling good."

Bowen and his crew -- including the first astronaut from the United Arab Emirates assigned to a monthslong mission, Sultan al-Neyadi -- will replace four space station residents who have been up there since October.

Officials said the problem involved ground equipment used for loading the engine ignition fluid. The launch team could not be sure there was a full load. A SpaceX engineer likened this critical system to spark plugs for a car.

------

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Science and Educational Media Group. 

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2023-02-27 11:46:52Z
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Jupiter and Venus to 'join' in the evening sky on Wednesday - CBC News

On Wednesday, you can see two of the brightest planets in the night sky come together.

If you're looking toward the west after sunset, you'll be able to see two bright "stars" in the sky: Those are actually Jupiter and Venus, and they've been getting closer and closer every night. 

"It is an apparent close approach from our perspective, as the planets are in fact hundreds of millions of kilometres apart," said Paul Delaney, professor emeritus with York University's department of physics and astronomy.

"Nonetheless, winter sky watchers will have noticed the steady approach of these planets over the last several weeks. It peaks on March 1 — a great photo opportunity."

Venus — often referred to as the "evening star" or "morning star" depending on where it is in the sky — is the brightest of the two and can be found low in the west.

Jupiter, the largest planet in our solar system, can be found just above and to the left of Venus.

How and when to see them

One of the best things about conjunctions is that you don't need binoculars or telescopes to see them. If you do happen to have a pair of binoculars, however, you can get a great closeup view of the pair.

"Venus and Jupiter will be within about half a degree (or the width of the full moon) together in the sky," said Elaina Hyde, director of York University's Allan I Carswell Observatory.

"This means with most binoculars, you will be able to see them together."

What makes it even more interesting is that you can also see four of Jupiter's brightest moons. And if you take a look through a pair of binoculars over several nights, you will be able to see how the moons move night after night. 

On Wednesday, however, three of the moons will be visible to the left of Jupiter, beginning with Io (closest to the planet), followed by Ganymede and then Callisto.

"At magnitude –2.1 and –4, the planets Venus and Jupiter are two of our brightest objects to see in the night sky," Hyde said in an email.

"Venus and Jupiter are somewhat common conjunctions, occurring about once a year, but if you have clear skies it should still be a very fun object to view."

A telescope is silhouetted against an evening sky, with two bright star-like objects that are actually Jupiter and Saturn.
Planetary conjunctions happen relatively often, like this one of Jupiter and Saturn, though they may not always be as close as the one coming up on Wednesday. (Shutterstock/AstroStar)

Delaney recommended people watch the planets a few days before and after the close conjunction on March 1, as it illustrates just how the planets move as they orbit the sun.

If your area doesn't have clear skies on Wednesday, Hyde said the observatory plans to livestream images of the event on its YouTube channel, weather permitting. The Virtual Telescope Project will also be hosting a livestream. You can also check your local astronomy clubs for any observing sessions.

"Any time the brightest planets, as seen from Earth, 'get together,' it is worth the look," said Delaney. "While these planets do enter conjunction reasonably often (every few years), I never tire of watching their dance with respect to the background stars." 

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2023-02-27 11:15:34Z
1773113852

SpaceX aborts launch of four-man crew to space station just before liftoff - CBS News

In a frustrating disappointment, the launch of a SpaceX Crew Dragon capsule carrying a four-man crew bound for the International Space Station was called off with just two minutes to go because of trouble with a system used to ignite the Falcon 9's first stage engines.

Crew-6 commander Stephen Bowen, Warren "Woody" Hoburg, cosmonaut Andrey Fedyaev and Emerati astronaut Sultan Alneyadi, the first Arab assigned to a long-duration station flight, took the scrub in stride and patiently waited inside the spacecraft while the rocket's propellants were drained away.

NASA says the next attempt to launch Crew-6 will be March 2 at 12:34 a.m. EST, assuming the engine ignitor issue can be resolved in time. The team is passing up a possible Tuesday launch try due to expected bad weather.

The fluid is a chemical known as triethylaluminum triethylboron, or "TEA TEB." 

It was the first last-minute launch scrub of a Crew Dragon due to a technical problem since the ferry ships started carrying astronauts to the space station in 2020, ending NASA's sole reliance on Russian Soyuz spacecraft to take astronauts to and from the lab complex.

Along with disappointing the crew, the last-minute scrub also ended a chance for SpaceX to launch three Falcon 9s in just 13 hours, with afternoon launches planned in Florida and California to put two batches of Starlink internet satellites into orbit. It wasn't immediately known if those flights would remain on schedule.

But flight safety is the top priority, and SpaceX will no doubt fix the ignitor issue after engineers have a chance to track down what went wrong. The only question is how long it might take.

Whenever they take off, Bowen and company will be welcomed aboard the station by Crew-5 commander Nicole Mann, Josh Cassada, Japanese astronaut Koichi Wakata and cosmonaut Anna Kikina, the first Russian to launch aboard a Crew Dragon. They arrived at the station last October and plan to return to Earth around March 6 to close out a 151-day mission.

Also welcoming the Crew-6 fliers will be Sergey Prokopyev, Dmitri Petelin and NASA astronaut Frank Rubio. They launched to the lab last September and originally planned to fly home in March.

But their Soyuz MS-22 ferry ship was crippled December 14 when a presumed micrometeoroid ruptured a coolant line. After an analysis, Russian engineers concluded the spacecraft could not safely be used again because of the possibility sensitive systems could overheat.

Instead, a replacement Soyuz -- MS-23 -- was launched last Thursday, carrying equipment and supplies instead of a crew. The spacecraft docked with the station Saturday night, providing Prokopyev and his crewmates with a safe ride home.

But to get the crew rotation schedule back on track, the trio will have to spend an additional six months in space, coming home this fall after a full year in orbit. They'll share the station with Crew 6 for most of that time.

Alneyadi, a father of six, is the second Emerati to fly in space but the first named to a full-duration six-month stay aboard the station. During his expedition, two Saudi fliers will visit the lab complex for about a week as part of a commercial mission managed by Houston-based Axiom Space.

"I think it's going to be really interesting," Alneyadi said after arriving at the Kennedy Space Center last week. "It's for the sake of science, for the sake of spreading the knowledge about how important it is to fly (in space) and to push the boundaries of exploration, not only in the leading countries.

"Our region is also thirsty to learn more. And I think we will be ambassadors in these missions. Hopefully, we can come back with knowledge and share whatever we learn with everybody."

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2023-02-27 08:56:00Z
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Minggu, 26 Februari 2023

The Planet That Shouldn't Exist - Universe Today

As of this writing, almost 5300 exoplanets spanning approximately 4000 planetary systems have been confirmed to exist in our universe. With each new exoplanet discovery, scientists continue to learn more about planetary formation and evolution that has already shaken our understanding of this process down to its very core. One such example is “Hot Jupiters”, which are Jupiter-sized exoplanets, or larger, that orbit closer to their parents stars than Mercury does to our own. This is in stark contrast to our own Solar System, which has rocky planets closer towards our Sun and the gas giant planets much farther out.

Therefore, it is only right that a recent discovery published in The Astrophysical Journal continues to push our understanding of the cosmos. In this study, an international team of researchers led by the Carnegie Institution for Science confirm the existence of a new Jupiter-sized exoplanet, TOI-5205b, orbiting a young, low-mass, main-sequence red dwarf (M dwarf) star, TOI-5205, located approximately 87 parsecs (284 light-years) from Earth.

What makes this discovery unique is the mass of TOI-5205b is rather large for orbiting such a young and small red dwarf star, thus challenging previous understandings of planetary formation and evolution. This is because gas giant exoplanets have traditionally been observed orbiting older and larger M dwarf stars.

“The host star, TOI-5205, is just about four times the size of Jupiter, yet it has somehow managed to form a Jupiter-sized planet, which is quite surprising!” exclaimed Dr. Shubham Kanodia, who is a postdoctoral fellow in the Carnegie Earth & Planets Lab and an expert in red dwarf stars, and lead author of the study. Dr. Shubham recently discussed the discovery in an in-depth blog post, as well. Using food as an analogy, Jupiter orbiting our Sun is equivalent to a pea orbiting a grapefruit, whereas TOI-5205b orbiting its parent star would be equivalent to a pea orbiting a lemon.

Artist illustration demonstrating size comparisons of TOI-5205b orbiting its parent star (left) compared to Jupiter orbiting our Sun (right). (Artwork Credit: Katherine Cain/Carnegie Institution for Science)

The general theory of planetary formation begins with a massive, rotating disk of gas and dust encircling young stars, with gas planets initially being formed from rocky material comprising approximately 10 Earth masses. Over time, this material forms the core of the giant planet which then accumulates large amounts of gas from the disk to produce the massive gas giants we observe today. As it turns out, the confirmation of TOI-5205b could throw this theory into disarray.

Artist illustration of TOI-5205b orbiting its parent star. (Artwork Credit: Katherine Cain/Carnegie Institution for Science)

“TOI-5205b’s existence stretches what we know about the disks in which these planets are born,” explained Dr. Kanodia. “In the beginning, if there isn’t enough rocky material in the disk to form the initial core, then one cannot form a gas giant planet.  And at the end, if the disk evaporates away before the massive core is formed, then one cannot form a gas giant planet.  And yet TOI-5205b formed despite these guardrails. Based on our nominal current understanding of planet formation, TOI-5205b should not exist; it is a ‘forbidden’ planet.”

The discovery was initially made using data from NASA’s Transiting Exoplanet Survey Satellite (TESS), which uses the transit detection method for locating exoplanets, and the data indicated that TOI-5205b blocks approximately 7% of its parent star’s light, making TOI-5205b one of the largest transits ever recorded for a confirmed exoplanet in orbit around a main-sequence star.

Learn more about NASA’s TESS mission!

To confirm the TESS data, follow-up observations were made from an international collaboration of instruments and observatories. These include the Habitable-zone Planet Finder, the ARCTIC camera on the 3.5-m Apache Point Observatory, the NN-Explore Exoplanet Stellar Speckle Imager, the 0.6-m Red Buttes Observatory, and the Three-hundred MilliMeter Telescope.

Given the very large transit that TOI-5205b produced, the researchers demonstrated that this could make this exoplanet an ideal candidate for future atmospheric observations using NASA’s James Webb Space Telescope (JWST), which could help scientists better understand the secrets behind its formation and evolution, as well. This is because JWST has already been successful in observing exoplanet atmospheres in incredible detail, as it recently demonstrated with exoplanet, WASP-39b.

Learn about the recent JWST atmospheric observation of WASP-39b, and a similar study could also be conducted on TOI-5205b!

What fascinating new discoveries will scientists make about exoplanets in the coming years and decades, and how much will these discoveries continue to push our knowledge of planetary formation and evolution? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

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2023-02-26 15:19:23Z
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Russian ship docks with ISS to replace damaged capsule - Phys.org

space
Credit: Pixabay/CC0 Public Domain

An uncrewed Russian Soyuz capsule docked early Sunday with the International Space Station and will eventually bring home three astronauts whose initial return vehicle was damaged by a tiny meteoroid.

The MS-23 ship autonomously latched to the orbiting research lab, from ISS-partner NASA showed, completing the Soyuz's two-day journey after launching off from Kazakhstan.

It is expected to bring home US astronaut Frank Rubio and Russian cosmonauts Dmitry Petelin and Sergei Prokopyev in September.

The three arrived at the ISS last September aboard MS-22, and were originally only supposed to stay about six months, until the end of March.

But their capsule began leaking coolant in mid-December after being hit by what US and Russian officials believe was a tiny space rock.

Roscosmos, the Russian space agency, decided to send MS-23 to replace the damaged vessel, but without its own three planned .

With no one to replace them, Rubio, Petelin and Prokopyev will now spend almost a year in space.

The damaged MS-22 is expected to depart the without passengers and return to Earth in late March.

There are four others currently on board the ISS, who arrived on a SpaceX Dragon capsule last October as part of the Crew-5 mission.

They are scheduled to be joined next week by members of the Crew-6 mission—two Americans, an Emirati and a Russian—who will also arrive aboard a SpaceX capsule expected to launch Monday from Florida.

After a few days of overlap, Crew-5 will then return to Earth.

© 2023 AFP

Citation: Russian ship docks with ISS to replace damaged capsule (2023, February 26) retrieved 26 February 2023 from https://phys.org/news/2023-02-russian-ship-docks-iss-capsule.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

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2023-02-26 11:43:19Z
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Soyuz Capsule Docks With Space Station In Unusual 'Lifeboat' Mission - Radio Free Europe / Radio Liberty

Ukrainian President Volodymyr Zelenskiy says the pressure on Moscow must increase and called for "decisive steps" against Russia's nuclear industry in addition to more pressure through sanctions on the Russian military and banking sectors.

Zelenskiy noted on Twitter on February 25 that the European Union the day before approved a 10th package of sanctions against Russian industry that is supporting the military and against propaganda, but he called for more.

Live Briefing: Russia's Invasion Of Ukraine

RFE/RL's Live Briefing gives you all of the latest developments on Russia's ongoing invasion, Kyiv's counteroffensive, Western military aid, global reaction, and the plight of civilians. For all of RFE/RL's coverage of the war, click here.

"The pressure on the Russian aggressor must increase: We expect decisive steps against [Russia's state-owned nuclear energy firm] Rosatom & Russian nuclear industry, more pressure on military & banking," he said.

Ukraine's diplomats are working to extend global and European sanctions on the Russian nuclear industry and on all entities involved in the missile program and Russia's "nuclear blackmail," Zelenskiy said later in his evening address.

The United States and Britain already are taking corresponding steps, he said, adding that Ukraine expects "appropriate steps from the European Union as well."

The EU sanctions package, announced on the one-year anniversary of the launch of Russia's full-scale invasion of Ukraine, aims to make it more difficult for Russia to obtain parts for aircraft engines, antennae, and other electronics. The United States also announced new sanctions on dozens of Russian banks, companies, and individuals on the first anniversary of the invasion.

Zelenskiy said earlier that he plans to meet Chinese President Xi Jinping to discuss the country’s cease-fire proposal aimed at ending the war in Ukraine, saying such a meeting would be "important for world security."

China's 12-point paper calling for a "political settlement" does not call on Russia to leave Ukraine. The proposal has been met with skepticism from Ukraine’s allies.

Zelenskiy told journalists on February 24 that China talking about Ukraine "is not bad. But the question is what follows the words. The question is in the steps and where they will lead to.”

There was no immediate reaction from Chinse authorities.

Speaking on February 25, French President Emmanuel Macron called on Beijing to "help us pressure Russia" to end the war in Ukraine.

Macron who said he would visit China in early April, added that peace was only possible if "the Russian aggression was halted, troops withdrawn and territorial sovereignty of Ukraine and its people was respected."

Separately, U.S. President Joe Biden said in an interview that the idea that China would play the role of peacemaker in Ukraine is not “rational.”

“[Russian President Vladimir] Putin's applauding it, so how could it be any good?" Biden told ABC News on February 24. "I've seen nothing in the plan that would indicate that there is something that would be beneficial to anyone other than Russia, if the Chinese plan were followed,” he added.

Biden also ruled out delivering F-16 jet fighters to Ukraine for now, saying Zelenskiy did not need them.

The General Staff of the Ukrainian military said in its evening report on February 25 that Russian forces made several unsuccessful attempts on Ukrainian forces in the Bahkmut direction.

Yevgeny Prigozhin, co-founder and owner of the Wagner mercenary group, claimed that his fighters had taken over the village of Yahidne on the northern outskirts of Bakhmut, a city in the Donetsk region that has been the focus of fighting in recent months.

The Ukrainian military said Russian forces continued attempts to break through Ukrainian defenses, encircle, and seize the city.

The Ukrainian General Staff said earlier on February 25 that the military had to repel 70 attacks by the Russian Army in the direction of the cities of Kupyansk, Lyman, Bakhmut, and Avdiyivka in the east.

Oleksandr Prokudin, the governor of the southern Kherson region, reported 83 Russian shelling attacks, according to AP.

The regional capital, also called Kherson, was hit nine times, and residential buildings, a preschool, and a medical institution were struck, he said.

The head of Ukraine's presidential office reported three civilian wounded in the region.

With reporting by Reuters, dpa, AP, ABC News, and AFP

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2023-02-26 10:48:45Z
1796104167

Sabtu, 25 Februari 2023

Astronomers Discover Bizarre “Forbidden” Planet That Should Not Exist - SciTechDaily

Large Gas Giant Planet Orbiting Small Red Dwarf Star

Artist’s conception of a large gas giant planet orbiting a small red dwarf star called TOI-5205. Credit: Image by Katherine Cain, courtesy of the Carnegie Institution for Science

“Forbidden” Planet Orbiting Small Star Challenges Gas Giant Formation Theories

Based on our current understanding of planet formation, TOI-5205b should not exist; it is a “forbidden” planet.

A team of astronomers has discovered an unusual planetary system in which a large gas giant planet orbits a small red dwarf star called TOI-5205. Their findings challenge long-held ideas about planet formation. Led by Shubham Kanodia from the Carnegie Institution for Science, the researchers published their findings in The Astronomical Journal.

Smaller and cooler than our Sun, M dwarfs are the most common stars in our Milky Way galaxy. Due to their small size, these stars tend to be about half as hot as the Sun and much redder. They have very low luminosities, but extremely long lifespans. Although red dwarfs host more planets, on average, than other, more massive types of stars, their formation histories make them unlikely candidates to host gas giants.

TOI-5205 Hosts Gas Giant Planet

Artist’s conception of a large gas giant planet orbiting a small red dwarf star called TOI-5205. Until now no gas giant has been found in a planetary system around a low-mass M dwarf like TOI-5205. Credit: Image by Katherine Cain, courtesy of the Carnegie Institution for Science

The newly discovered planet—TOI 5205b—was first identified as a potential candidate by NASA’s Transiting Exoplanet Survey Satellite (TESS). Kanodia’s team, which included Carnegie’s Anjali Piette, Alan Boss, Johanna Teske, and John Chambers, then confirmed its planetary nature and characterized it using a variety of ground-based instruments and facilities.

“The host star, TOI-5205, is just about four times the size of Jupiter, yet it has somehow managed to form a Jupiter-sized planet, which is quite surprising!” exclaimed Kanodia, who specializes in studying these stars, which comprise nearly three-quarters of our galaxy yet can’t be seen with the naked eye. He also wrote a blog post about the discovery.

A small number of gas giants have been discovered orbiting older M dwarf stars. But until now no gas giant has been found in a planetary system around a low-mass M dwarf like TOI-5205. To grasp the size comparison here, a Jupiter-like planet orbiting a Sun-like star could be compared to a pea going around a grapefruit; for TOI-5205b, because the host star is so much smaller, it is more like a pea going around a lemon. In fact, when the Jupiter-mass TOI 5205b crosses in front of its host, it blocks about seven percent of its light—one of the largest known exoplanet transits.

TOI-5205 Size Comparison

A Jupiter-like planet orbiting a Sun-like star could be compared to a pea going around a grapefruit; for TOI-5205b, because the host star is so much smaller, it is more like a pea going around a lemon, said lead author Shubham Kanodia. Credit: Artwork by Katherine Cain is courtesy of the Carnegie Institution for Science

Planets are born in the rotating disk of gas and dust that surrounds young stars. The most commonly used theory of gas planet formation requires about 10 Earth masses of this rocky material to accumulate and form a massive rocky core, after which it rapidly sweeps up large amounts of gas from the neighboring regions of the disk to form the giant planet we see today.

The time frame in which this happens is crucial.

“TOI-5205b’s existence stretches what we know about the disks in which these planets are born,” Kanodia explained. “In the beginning, if there isn’t enough rocky material in the disk to form the initial core, then one cannot form a gas giant planet. And at the end, if the disk evaporates away before the massive core is formed, then one cannot form a gas giant planet. And yet TOI-5205b formed despite these guardrails. Based on our nominal current understanding of planet formation, TOI-5205b should not exist; it is a “forbidden” planet.”

The team demonstrated that the planet’s very large transit depth makes it extremely conducive for future observations with the recently launched JWST, which could shed some light on its atmosphere and offer some additional clues about the mystery of its formation.

Reference: “TOI-5205b: A Short-period Jovian Planet Transiting a Mid-M Dwarf” by Shubham Kanodia, Suvrath Mahadevan, Jessica Libby-Roberts, Gudmundur Stefansson, Caleb I. Cañas, Anjali A. A. Piette, Alan Boss, Johanna Teske, John Chambers, Greg Zeimann, Andrew Monson, Paul Robertson, Joe P. Ninan, Andrea S. J. Lin, Chad F. Bender, William D. Cochran, Scott A. Diddams, Arvind F. Gupta, Samuel Halverson, Suzanne Hawley, Henry A. Kobulnicky, Andrew J. Metcalf, Brock A. Parker, Luke Powers, Lawrence W. Ramsey, Arpita Roy, Christian Schwab, Tera N. Swaby, Ryan C. Terrien and John Wisniewski, 21 February 2023, The Astronomical Journal.
DOI: 10.3847/1538-3881/acabce

The TESS follow-up research was conducted using the Habitable-zone Planet Finder (HPF; Texas, US) and Low Resolution Spectrograph (LRS2; Texas, US) on the 10-m Hobby Eberly Telescope, the ARCTIC camera on the 3.5-m Apache Point Observatory (APO; New Mexico, US), the NN-Explore Exoplanet Stellar Speckle Imager (NESSI, Arizona, US) at the 3.5-m WIYN telescope, the 0.6-m Red Buttes Observatory (RBO, Wyoming, US), and the 0.3 m Three Hundred Millimeter Telescope (TMMT, Chile).

Other members of the research team were: Penn State University’s Suvrath Mahadevan, Jessica Libby-Roberts, Caleb Cañas (also of NASA Goddard Space Flight Center), Andrea Lin, Arvind Gupta, Luke Powers, and Lawrence Ramsey; Princeton University’s Gudmundur Stefansson; University of Texas Austin’s Greg Zeimann and William Cochran; University of Arizona’s Andrew Monson and Chad Bender; UC Irvine’s Paul Robertson; the Tata Institute of Fundamental Research’s Joe Ninan; University of Colorado Boulder’s Scott Diddams; the Jet Propulsion Laboratory’s Samuel Halverson; University of Washington’s Suzanne Hawley; University of Wyoming’s Henry Kobulnicky, Brock Parker, and Tera Swaby; the Air Force Research Laboratory’s Andrew Metcalf; the Space Telescope Science Institute’s Arpita Roy (also of Johns Hopkins University); Macquarie University’s Christian Schwab; Carleton College’s Ryan Terrien; and George Mason University’s John Wisniewski.

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2023-02-25 12:25:31Z
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Webb telescope just found massive objects that shouldn't exist in deep space - Mashable

Scientists expected the James Webb Space Telescope to reveal unknowns in the deepest realms of space.

But they certainly didn't anticipate this.

While scanning a region of the cosmos near the Big Dipper, a group of astronomers identified six faint objects as they appeared well over 13 billion years ago. They suspect the objects are ancient galaxies. Scientists expect such early collections of stars and swirling matter to be relatively small. After all, such galaxies hadn't had much time to form or grow. But these galaxies are giants, the researchers report.

"It’s bananas," Erica Nelson, an astrophysicist at CU Boulder who worked on the new research, said in a statement(Opens in a new tab).

It's bananas because the objects, which are "red and bright" in the Webb observations, might host billions of stars (and many more planets), similar to our Milky Way galaxy. These galaxies formed some 500 to 700 million years after the universe was created during the Big Bang(Opens in a new tab), and at such a time there simply shouldn't have been enough matter around to create fantastic bursts of stars and solar systems, Nelson explained.

The extremely distant galaxies are the fuzzy red objects shown below. They're red because the universe is expanding, and the light traveling through it becomes stretched out, ultimately shifting to longer, redder wavelengths. Importantly, the research about these galaxies is just beginning. There is potential, for example, that some of these bright red masses are a different kind of primordial object, like a quasar (intensely hot, energetic matter spinning around a black hole and emitting tremendous amounts of light into space).

distant galaxies viewed by the James Webb Space Telescope
The six "candidate galaxies" astronomers discovered near the Big Dipper. Credit: NASA / ESA / CSA / I. Labbe (Swinburne University of Technology). Image processing: G. Brammer (Niels Bohr Institute’s Cosmic Dawn Center at the University of Copenhagen)

Astronomers using the Webb telescope have spotted even earlier galaxies, too, including some that formed just 350 million years after the Big Bang. But these galaxies are much smaller. They make more sense than the recently spotted behemoths.

"If even one of these galaxies is real, it will push against the limits of our understanding of cosmology,” Nelson noted. Cosmology is the study of our universe's origins and evolution. Where'd we come from? And how did we get here?

The Webb telescope's powerful abilities

The Webb telescope, a scientific collaboration between NASA, the ESA, and the Canadian Space Agency, orbits the sun 1 million miles from Earth. It's designed to peer into the deepest cosmos and reveal unprecedented insights about the early universe.

Want more science and tech news delivered straight to your inbox? Sign up for Mashable's Top Stories newsletter today.

Here's how Webb is achieving unparalleled things, and likely will for decades:

  • Giant mirror: Webb's mirror, which captures light, is over 21 feet across. That's over two and a half times larger than the Hubble Space Telescope's mirror. Capturing more light allows Webb to see more distant, ancient objects. As described above, the telescope is peering at stars and galaxies that formed over 13 billion years ago, just a few hundred million years after the Big Bang.

    "We're going to see the very first stars and galaxies that ever formed," Jean Creighton, an astronomer and the director of the Manfred Olson Planetarium at the University of Wisconsin–Milwaukee, told Mashable in 2021.

  • Infrared view: Unlike Hubble, which largely views light that's visible to us, Webb is primarily an infrared telescope, meaning it views light in the infrared spectrum. This allows us to see far more of the universe. Infrared has longer wavelengths(Opens in a new tab) than visible light, so the light waves more efficiently slip through cosmic clouds; the light doesn't as often collide with and get scattered by these densely-packed particles. Ultimately, Webb's infrared eyesight can penetrate places Hubble can't.

    "It lifts the veil," said Creighton.

  • Peering into distant exoplanets: The Webb telescope carries specialized equipment, called spectrometers(Opens in a new tab), that will revolutionize our understanding of these far-off worlds. The instruments can decipher what molecules (such as water, carbon dioxide, and methane) exist in the atmospheres of distant exoplanets — be it gas giants or smaller rocky worlds. Webb will look at exoplanets in the Milky Way galaxy. Who knows what we'll find.

    "We might learn things we never thought about," Mercedes López-Morales, an exoplanet researcher and astrophysicist at the Center for Astrophysics-Harvard & Smithsonian(Opens in a new tab), told Mashable in 2021.

    Already, astronomers successfully found intriguing chemical reactions on a planet 700 light-years away.

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2023-02-25 10:00:00Z
1776452464

Replacement Soyuz launched on fight to space station – Spaceflight Now - Spaceflight Now

STORY WRITTEN FOR CBS NEWS & USED WITH PERMISSION

A Soyuz-2.1a rocket lifts off from the Baikonur Cosmodrome in Kazakhstan with the Soyuz MS-23 spacecraft. Credit: Roscosmos

A Russian Soyuz crew ferry ship blasted off from Kazakhstan Thursday, kicking off an unpiloted but critical flight to the International Space Station to replace a damaged Soyuz and provide an eventual ride home for three of the lab’s crew members.

Lighting up the pre-dawn sky, the Soyuz 2.1a booster carrying the Soyuz MS-23/69S crew ship shot away from the sprawling Baikonur Cosmodrome at 7:24 p.m. EST (5:24 a.m. local time Friday), kicking off a 9-minute climb to space.

If all goes well, the Soyuz, loaded with equipment and supplies in place of a crew, will carry out an automated rendezvous with the space station, docking at the Russian Poisk module at 8:01 a.m. Saturday.

The spacecraft originally was scheduled for launch next month to ferry two cosmonauts and a NASA astronaut to the lab complex to replace another Soyuz that was expected to carry three other station fliers — Sergey Prokopyev, Dmitri Petelin and NASA astronaut Frank Rubio — back to Earth to wrap up a six-month mission.

But on December 14, their Soyuz was hit by a presumed micrometeoroid that ruptured a coolant line. Russian engineers called off the planned return to Earth after concluding the lost coolant could lead to higher-than-normal, possibly unsafe internal temperatures.

Instead, managers ordered engineers to speed up processing for the Soyuz MS-23 vehicle and, after a delay caused by additional problems with a Progress cargo ship, moved launch to Thursday.

The original MS-23 crew — Oleg Kononenko, Nikolai Chub and NASA astronaut Laral O’Hara — now plan to fly in September aboard the next Soyuz in the sequence, replacing Prokopyev, Petelin and Rubio.

Prokopyev and company originally planned to spend six months in space as part of a normal crew rotation. But the damage to their ship and the decision to replace it means they’ll now have to stay in space for a full year.

In any case, the Soyuz MS-23 launching Thursday was critical to providing the trio with a safe ride home at the end of their extended mission as well as serving as the crew’s lifeboat in case of an emergency that might require an immediate evacuation of the space station.

Since the MS-22 vehicle was damaged in December, NASA and the Russian space agency Roscosmos have been forced to rely on a less-than optimal “plan B.”

In case of an emergency before the replacement Soyuz arrives, Rubio would squeeze into a SpaceX Crew Dragon capsule and join that ship’s four crew members for a quick descent to Earth.

Prokopyev and Petelin would attempt re-entry in the damaged Soyuz MS-22 spacecraft. With just two crew members aboard, not as much cooling would be required and Russian engineers are confident the ship could carry out a safe re-entry.

But assuming Thursday’s launch and rendezvous go well, the station will again have two healthy crew lifeboats for use as needed.

Against that backdrop, NASA and SpaceX are gearing up to launch a Crew Dragon spacecraft to the station early Monday carrying Crew-6 astronauts Stephen Bowen and Woody Hoburg, along with cosmonaut Andrey Fedyaev and Emerati astronaut Sultan Alneyadi.

Crew-6 will replace four other station crew members — Nicole Mann, Josh Cassada, Japanese astronaut Koichi Wakata and cosmonaut Anna Kikina — who plan to return to Earth around March 6 aboard their Crew-5 Dragon.

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2023-02-25 04:49:41Z
1796104167

Surprising 'forbidden planet' discovered outside our solar system - CNN Philippines

(CNN)— Astronomers have found an unusually large planet orbiting a small star, located about 280 light-years from Earth.

The unexpected size of the newly discovered world, called TOI 5205b, has led researchers to call it the "forbidden planet."

About the size of Jupiter, it was spotted by researchers using NASA's Transiting Exoplanet Survey Satellite, or TESS. Jupiter is the largest planet in our solar system.

The planet-hunting mission, launched in 2018, surveys the light of the nearest and brightest stars to spot dips in starlight, which suggests those stars have planets orbiting them. The TESS mission has found thousands of potential planets.

The exoplanet orbits a red dwarf star called TOI-5205, which is about 40% the size and mass of our sun, and about 5,660 degrees Fahrenheit (3,127 degrees Celsius) in temperature compared with the sun's blazing average of 9,980 F (5,527 C).

An M dwarf star is smaller, cooler and redder than our sun. These dim stars are some of the most common in the universe, and in recent years, astronomers have discovered that M dwarf stars are more likely to have planets orbiting them.

But astronomers weren't expecting such small stars to host giant planets — and that's exactly what they found when they took a closer look at the TOI-5205 planetary system.

A study detailing the findings was published Tuesday in The Astronomical Journal.

"The host star, TOI-5205, is just about four times the size of Jupiter, yet it has somehow managed to form a Jupiter-sized planet, which is quite surprising," said study author Shubham Kanodia, a postdoctoral fellow at the Carnegie Institution for Science in Washington, DC, in a statement.

Astronomers have found a few gas giant planets orbiting older M dwarf stars, but TOI 5205b is the first gas giant to be found around a low-mass M dwarf star.

The researchers compared the planet to a pea going around a lemon. In our solar system, Jupiter could be compared to a pea orbiting a grapefruit (standing in for our sun).

When TOI 5205b crosses in front of its star during orbit, the planet blocks 7% of its light.

The discovery of the planetary system challenges theories on planet formation.

Stars form from massive clouds of gas and dust in space. The leftover material from star formation swirls around the star and creates a rotating disk where planets are born.

"TOI-5205b's existence stretches what we know about the disks in which these planets are born," Kanodia said.

"In the beginning, if there isn't enough rocky material in the disk to form the initial core, then one cannot form a gas giant planet. And at the end, if the disk evaporates away before the massive core is formed, then one cannot form a gas giant planet. And yet TOI-5205b formed despite these guardrails. Based on our nominal current understanding of planet formation, TOI-5205b should not exist; it is a 'forbidden' planet."

Researchers want to observe the planet in the future using the James Webb Space Telescope, which could detect if TOI-5205b has an atmosphere and unlock more of the secrets about how it formed.

Data collected from the Habitable Zone Planet Finder on the 10-meter Hobby-Eberly Telescope at the University of Texas at Austin's McDonald Observatory is showing the potential for future discoveries, according to the research team.

Observations "are already hinting at the presence of more such planets, which suggests that TOI-5205 b — while definitely an outlier — isn't the only one," Kanodia wrote in a blog post.

This story was first published on CNN.com, "Surprising ‘forbidden planet’ discovered outside our solar system."

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2023-02-25 03:03:47Z
1795799905

Jumat, 24 Februari 2023

Asteroid Ryugu is organic-rich, sample reveals - The Siasat Daily

Washington: Asteroid Ryugu has a rich complement of organic molecules, according to a NASA and international team’s initial analysis of a sample from the asteroid’s surface delivered to Earth by Japan’s Hayabusa2 spacecraft.

The discovery adds support to the idea that organic material from space contributed to the inventory of chemical components necessary for life.

Organic molecules are the building blocks of all known forms of terrestrial life and consist of a wide variety of compounds made of carbon combined with hydrogen, oxygen, nitrogen, sulphur, and other elements.

However, organic molecules can also be made by chemical reactions that don’t involve life, supporting the hypothesis that chemical reactions in asteroids can make some of life’s ingredients.

The science of prebiotic chemistry attempts to discover the compounds and reactions that could have given rise to life, and among the prebiotic organics found in the sample were several kinds of amino acids. Certain amino acids are widely used by terrestrial life as a component to build proteins.

Further, the sample from Ryugu also contained many types of organics that form in the presence of liquid water, including aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-containing heterocyclic compounds.

“The presence of prebiotic molecules on the asteroid surface despite its harsh environment caused by solar heating and ultraviolet irradiation, as well as cosmic-ray irradiation under high-vacuum conditions, suggests that the uppermost surface grains of Ryugu have the potential to protect organic molecules,” said lead author Hiroshi Naraoka of Kyushu University, Fukuoka, Japan, in a statement.

The amino acid results from Ryugu are mostly consistent with what has been seen in certain types of carbon-rich (carbonaceous) meteorites exposed to the most water in space, but sugars and nucleobases (components of DNA and RNA) discovered in some carbon-rich meteorites, have not yet been identified in samples returned from Ryugu, added Daniel Glavin of NASA Goddard, in the paper published online in the journal Science.

The Hayabusa2 spacecraft collected the samples on February 22, 2019, and delivered them to Earth December 6, 2020. They were extracted in Japan in July 2021.

The researchers aim to “do a direct comparison of the samples from Ryugu and the sample from asteroid Bennu when NASA’s OSIRIS-REx mission returns it to Earth in 2023”.

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2023-02-24 14:03:00Z
1794806857

New galaxies discovered by James Webb telescope - UNTV News and Rescue

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2023-02-24 06:25:16Z
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Rabu, 22 Februari 2023

Study uses 560-kilometer-deep earthquake to make elusive measurements of the Earth's layers - Phys.org

earth mantle
Credit: Pixabay/CC0 Public Domain

A new study from a University of Chicago scientist suggests there may be a layer of surprisingly fluid rock ringing the Earth, at the very bottom of the upper mantle.

The finding was made by measuring the lingering movement registered by GPS sensors on islands in the wake of a deep earthquake in the Pacific Ocean near Fiji. Published Feb. 22 in Nature, the study demonstrates a new method to measure the fluidity of the Earth's .

"Even though the mantle makes up the largest part of Earth, there's still a lot we don't know about it," said Sunyoung Park, a geophysicist with the University of Chicago and the lead author on the study. "We think there's a lot more we can learn by using these deep earthquakes as a way to probe these questions."

Mantle mysteries

We still know surprisingly little about the Earth beneath our feet. The furthest anyone has managed to dig down is about seven and a half miles before the increasing heat literally melts the drill. Thus scientists have had to use clues like how seismic waves move to infer the different layers that make up the planet, including the crust, mantle, and core.

One thing that has stymied scientists is a precise measurement of how viscous the mantle layer is. The mantle is the layer below the crust. It's made of rock, but at the intense temperature and pressures at that depth, the rock actually becomes viscous—flowing very slowly like honey or tar.

"We want to know exactly how fast the mantle flows, because that influences the evolution of the entire Earth—it affects how much heat the planet retains for how long, and how the Earth's materials are cycled over time," explained Park. "But our current understanding is very limited and includes a lot of assumptions."

Park thought there might be a unique way to get a measurement of the mantle's properties by studying the aftermath of very deep earthquakes.

Most of the earthquakes we hear about on the news are relatively shallow, originating in the top crust of the Earth. But occasionally, there are earthquakes that originate deep within the Earth—down to 450 miles below the surface. These earthquakes are not as well-studied as shallower ones, because they're not as destructive to human settlements. But because they reach down into the mantle, Park thought they might offer a way to understand the behavior of the mantle.

Park and her colleagues looked at one particular such earthquake, which occurred off the coast of Fiji in 2018. The quake was magnitude 8.2, but it was so deep—350 miles (560 kilometers) down—that it did not cause any major damage or deaths.

However, when the scientists carefully analyzed the data from GPS sensors on several nearby islands, they found the Earth kept moving—after the was over.

The data revealed that in the months following the quake, the Earth was still moving, settling in the wake of the disturbance. Even years later, Tonga is still moving slowly down at a rate of about 1 centimeter per year.

"You can think of it like a jar of honey that slowly comes back to level after you dip a spoon in it—except this takes years instead of minutes," said Park.

This is the first solid observation of the deformation following deep quakes; the phenomenon had been observed before for , but experts thought the effect would be too small to be observable for deep earthquakes.

Park and her colleagues used this observation to infer the viscosity of the mantle.

By examining how the Earth deformed over time, they found evidence of a layer about 50-miles thick that is less viscous (that is, "runnier") than the rest of the mantle, sitting at the bottom of the upper mantle layer. They think this layer may extend around the entire globe.

This low-viscosity layer could explain some other observations by seismologists that suggested there are "stagnant" slabs of rock that don't move very much, located around the same depth at the bottom of the upper mantle. "It has been hard to reproduce those features with models, but the weak layer found in this study makes it easier to do so," Park said.

It also has implications for how Earth transports heat, cycles and mixes materials between the crust, core, and mantle over time.

"We're really excited," Park said. "There's a lot more to find out with this technique."

The other co-authors on the paper were Jean-Philippe Avouac and Zhongwen Zhan of California Institute of Technology and Adriano Gualandi of Italy's National Institute of Geophysics and Volcanology.

More information: Sunyoung Park, Weak upper-mantle base revealed by postseismic deformation of a deep earthquake, Nature (2023). DOI: 10.1038/s41586-022-05689-8. www.nature.com/articles/s41586-022-05689-8

Citation: Study uses 560-kilometer-deep earthquake to make elusive measurements of the Earth's layers (2023, February 22) retrieved 22 February 2023 from https://phys.org/news/2023-02-kilometer-deep-earthquake-elusive-earth-layers.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

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2023-02-22 16:00:06Z
CBMiUWh0dHBzOi8vcGh5cy5vcmcvbmV3cy8yMDIzLTAyLWtpbG9tZXRlci1kZWVwLWVhcnRocXVha2UtZWx1c2l2ZS1lYXJ0aC1sYXllcnMuaHRtbNIBUGh0dHBzOi8vcGh5cy5vcmcvbmV3cy8yMDIzLTAyLWtpbG9tZXRlci1kZWVwLWVhcnRocXVha2UtZWx1c2l2ZS1lYXJ0aC1sYXllcnMuYW1w

Inmarsat I-6 F2 Mission Successfully Launches from Cape Canaveral - The Maritime Executive

Inmarsat
Inmarsat Launches at Cape Canaveral

Published Feb 22, 2023 10:02 AM by The Maritime Executive

By Brett Keil

Promptly at 10:59 PM on Friday, February 17, 2023, Inmarsat’s newest satellite, the I-6 F2  launched via the SpaceX Falcon 9. It left the planet from Space Launch Complex 40 (SLC 40) at Cape Canaveral, Florida. This was SpaceX’s 211th launch and its second of the day, with the earlier launch from Vandenberg Space Force Base, California.

The similarities between the maritime and space industries are increasing daily. Commercialization of rocket launches has made launching more affordable, safer, and timelier. SpaceX’s spacecraft, boosters and even the payload fairings are reusable. This has changed the way rockets are built and launched. Thanks to these and other innovations, efficiency has improved greatly while costs have decreased significantly. Modern rockets like the Falcon Heavy deliver cargo to the International Space Station (ISS) like liner services here on Earth.

The parallels between deploying Inmarsat’s 1-6 F2 satellite are analogous to the offshore exploration sector. Just as deepwater exploration companies deploy UUVs in our oceans, SpaceX and Inmarsat are doing this in our solar system, as are their competitors.

The Inmarsat I-6 F2 satellite is the second in its series. Its sister, the I-6 F1, was launched back in 2021. These satellites are used by the maritime and aviation industries, militaries and even in fighting wildfires. These satellites will improve Global Xpress to protect mariners all over the world. They will also support ELERA IoT, designed to enhance the internet of things (IoT) framework. 

The previously launched F1 provides coverage over the Indian Ocean, while the recently launched F2 will cover the Atlantic Ocean once it is successfully in orbit seven months from the launch date. It takes seven months for the solar-powered rocket to push the F2 to its geostationary orbit slowly.

What is most impressive at any SpaceX launch is the return of the first stage (booster) back to Earth, 500 km from the launchpad. In this case, one booster safely and promptly landed back on SpaceX’s drone ship named Just Read the Instructions. The booster rocket lands back on the drone ship completely autonomously and can do it in up to 10’ seas. This is a tremendous milestone for autonomous air and sea vessels.

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2023-02-22 15:02:38Z
1778271592

Shear ultrasound shaking found to lower friction between solids - Phys.org

Shear ultrasound shaking found to lower friction between solids
Graphical abstract. Credit: The European Physical Journal E (2022). DOI: 10.1140/epje/s10189-022-00256-5

When high-frequency shaking occurs at an interface between two solids, recent experiments have revealed that the frictional forces between the objects can be weakened. Through a simple new experiment detailed in The European Physical Journal E, Julien Léopoldès at Université Gustave Eiffel, Marne la Vallée (formerly at ESPCI Paris) has discovered that mechanical vibrations also enhance structural aging in these systems, and can sometimes trigger sudden, jerking motions.

The results could lead to a better understanding of how buildings are weakened by ambient vibrations, and may also help geologists to draw new insights into the mechanisms responsible for triggering earthquakes and landslides.

Elastic waves due to and earthquakes can be found ambiently in the environment and are known to induce fracture. To learn more about their influence, Léopoldès constructed an experiment involving a plastic slider with a roughened surface. Using a spring, the slider was driven over a smooth glass slide at a carefully controlled velocity—ranging between 1 nanometer and 1 centimeter per second. The glass slide was itself attached to an ultrasound transducer—which produced shear vibrations, parallel to its with the slider.

In his experiment, Léopoldès measured the frictional forces experienced by the plastic slider as he varied the velocities applied by the spring. As he predicted, the high frequency shaking lowered the friction experienced by the slider—but at lower sliding velocities, he also found that the vibrations were enough to destabilize the entire system. In these jerky "stick-slip" motions, the slider remained static at first, but then moved suddenly as its stored energy was all released at once.

These discoveries could deepen our understanding of how the interfaces at the contact between solids are affected by traveling waves, and may also have important applications in fields including geology and .

More information: J. Léopoldès, Sliding friction perturbed by shear ultrasound vibrations: dynamic lubrication and overaging, The European Physical Journal E (2022). DOI: 10.1140/epje/s10189-022-00256-5

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Citation: Shear ultrasound shaking found to lower friction between solids (2023, February 22) retrieved 22 February 2023 from https://phys.org/news/2023-02-ultrasound-friction-solids.html

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2023-02-22 14:22:51Z
CBMiPWh0dHBzOi8vcGh5cy5vcmcvbmV3cy8yMDIzLTAyLXVsdHJhc291bmQtZnJpY3Rpb24tc29saWRzLmh0bWzSATxodHRwczovL3BoeXMub3JnL25ld3MvMjAyMy0wMi11bHRyYXNvdW5kLWZyaWN0aW9uLXNvbGlkcy5hbXA