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Webb Telescope Approaches Launch, With an Eye Toward Cosmic Origins – The New York Times

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The biggest space telescope in history aims to answer astronomy’s oldest question: How did we get from the Big Bang to here?

There are only a few times in the history of a species when it gains the know-how, the audacity and the tools to greatly advance the interrogation of its origins. Humanity is at such a moment, astronomers say.

According to the tale that they have been telling themselves (and the rest of us) for the last few decades, the first stars flickered on when the universe was about 100 million years old.

They burned hard and died fast in spectacular supernova explosions, dispelling the gloomy fog of gas left over from the primordial fireworks known as the Big Bang 13.8 billion years ago. From those sparks came all that we care about in the universe — the long, ongoing chain of cosmic evolution that has produced everything from galaxies and planets to microbes and us.

But is that story right?

The tools to address that question and more are at hand. Sitting in a spaceport in French Guiana, wrapped like a butterfly in a chrysalis of technology, ambition, metal and wires, is the biggest, most powerful and, at $10 billion, most expensive telescope ever to be launched into space: the James Webb Space Telescope. Its job is to to look boldly back in time at the first stars and galaxies.

“We’re looking for the first things to come out of the Big Bang,” said John Mather of the Goddard Space Flight Center in Green Belt, Md., the chief scientist for the telescope. Or, as he likes to ask: “How did we get here from the Big Bang?”

If all goes well — always a dubious prospect in the space business — the telescope will be loaded onto an Ariane 5 rocket and, on the morning of Dec. 24, blast off on a million-mile journey to a spot beyond the moon where gravitational forces commingle to create a stable orbit around the sun.

Over the next 29 days on its way up, the chrysalis will unfold into a telescope in a series of movements more complicated than anything ever attempted in space, with 344 “single points of failure,” in NASA lingo, and far from the help of any astronaut or robot should things become snarled. “Six months of high anxiety,” engineers and astronomers call it.

First, antennas will pop out and aim at Earth, enabling communication. Then the scaffolding for a sunscreen the size of a tennis court will open, followed by the sunscreen itself, made of five thin sheets of a plastic called Kapton.

Finally, 18 gold-plated beryllium hexagons will snap into place to form a segmented mirror 6.5 meters, or 21 feet, across. By then, the telescope will have reached its destination, a point called L2, floating on its sun shield and aimed at eternity.

Astronomers will then spend six months tweaking, testing and calibrating their new eye on the cosmos.

The James Webb Space Telescope, named after the NASA administrator who led the agency through the Apollo years, is a collaboration between NASA, the Canadian Space Agency and the European Space Agency. Its official mission is to explore a realm of cosmic history that was inaccessible to Hubble and every telescope before it.

“We are all here because of these stars and galaxies,” said Alan Dressler of the Carnegie Observatories in Pasadena, Calif.

That mission requires the Webb to be tuned to a different kind of light than our eyes or the Hubble can see. Because of the expansion of the cosmos, those earliest stars and galaxies are rushing away from Earth so fast that their light is shifted to longer, redder wavelengths, much as the siren from an ambulance shifts to a lower register as it speeds by.

What began as blue light from an infant galaxy 13 billion years ago has been stretched to invisible infrared wavelengths — heat radiation — by the time it reaches us today.

To detect those faint emanations, the telescope must be very cold — less than 45 degrees Celsius above absolute zero — so that its own heat does not wash out the heat being detected. Hence the sun shield, which will shade the telescope in permanent, frigid darkness.

NASA, ESA and J. Olmsted (STScI)

Even before the Hubble Space Telescope was launched, in 1990, astronomers were arguing about what should come next. Dr. Dressler was the head of a committee proposing a Next Generation Space Telescope powerful enough to see the first stars and galaxies in the universe. It would need to be at least 4 meters in diameter (Hubble’s mirror was only 2.4 meters across) and highly sensitive to infrared radiation, and it would cost $1 billion.

NASA was game, but Dan Goldin, the agency’s administrator, worried that a 4-meter telescope would not be keen-eyed enough to detect those first stars. In 1996, he marched into a meeting of the American Astronomical Society and scolded Dr. Dressler and his committee for being too cautious. The new telescope, he said, would be 8 meters wide, a drastic leap in power, cost and development time.

“The crowd went wild,” Dr. Dressler recalled recently. “But many of us knew from that day on that this was big trouble. Webb became the perfect storm: The more expensive it got, the more critical it was that it not fail, and that made it even more expensive.”

Doubled in size, the telescope could no longer fit aboard any existing rocket. That meant the telescope’s mirror would have to be foldable and would have to assemble itself in space. NASA eventually settled on a mirror 6.5 meters wide — almost three times the size of Hubble’s and with seven times the light-gathering power. But all the challenges of developing and building it remained.

If the foldable mirror operates as planned, the mission could augur a new way to launch giant telescopes too big to fit on rockets. Only last month, a National Academy of Sciences panel recommended that NASA develop a giant space telescope 8 meters or more across to look for habitable planets. But if Webb’s origami fails, NASA and the astronomical community will have to take a long walk back to the drawing board.

“NASA committed too early to a particular design,” Dr. Dressler said. “I think this discouraged creative solutions that might have delayed the start of construction but made the telescope better and more affordable and, in the end, faster to launch.”

M.Pedoussaut/ESA
Chris Gunn/NASA, via EPA, via Shutterstock

The setbacks mounted. At one point, the telescope was projected to cost about $5 billion and be ready in 2011; in the end, it took almost $10 billion and 25 years. Cost overruns and mistakes threatened to suck money from other projects in NASA’s science budget. The journal Nature called it “the telescope that ate astronomy.” Ten years ago, Congress considered canceling it outright.

Naming the telescope was its own challenge. In 2002, Sean O’Keefe, the NASA administrator at the time, announced that the instrument would be named for Mr. Webb, who had been a champion of space science and the agency’s leader during the crucial days of the Apollo program. Some astronomers were disappointed that it did not honor a scientist, like the Hubble Telescope or the Einstein X-ray Observatory do. Some of them were critical of Mr. Webb, questioning his role in a purge of gay men and lesbians from the State Department during the Truman administration.

Others in the astronomy community joked that the telescope’s initials stood for the “Just Wait Space Telescope.” The delays were par for the course, Dr. Mather said: “We had to invent 10 new technologies to build this telescope, and that’s always harder than people think it will be.”

Designing the foldable mirror and the sunscreen was particularly difficult. In early 2018, the sunscreen was torn during a rehearsal of the unfolding process, and the project was set back again.

Finally, last October, the telescope arrived by ship in French Guiana, where it would be launched aboard an Ariane 5 rocket. But the telescope’s troubles were not over. As technicians prepared to attach it to the spacecraft, a clamp let loose unexpectedly and the whole instrument quivered.

The launch date was pushed back four days, from Dec. 18 to Dec. 22, while NASA confirmed that the telescope had not been damaged. A few days later, a broken data cable set the adventure back another couple of days.

Chris Gunn/NASA

Almost 14 billion years ago, when the universe was less than one-trillionth of a second old, quantum fluctuations in the density of matter and energy gave rise to lumps that would become the first stars.

These stars were different from those we now see in the night sky, scientists believe, because they were composed of only hydrogen and helium created in the thermonuclear furnace of the Big Bang. Such stars might have quickly grown to be hundreds of times more massive than the sun and then just as quickly exploded as supernovas. They do not exist in the present-day universe, it seems.

For all their brilliance, these early stars might still be too faint to be seen individually with the Webb, Dr. Mather said. But, he added, “they come in herds,” clumps that might be the seeds for the earliest protogalaxies, and they explode: “We can see them when they explode.”

Those supernova explosions are surmised to have began the process, continuing today, of seeding the galaxy with heavier and more diverse elements like oxygen and iron, the things necessary for planets and life.

A top item on the agenda will be to hunt for those first galaxies, Marcia Rieke of the University of Arizona said. Dr. Rieke has spent the last 20 years leading the development of a special camera, the Near Infrared Red Camera, or NIRcam, one of four instruments that take the light gathered by the telescope mirror and convert it into a meaningful image or a spectrum.

University of Arizona

So far, the earliest and most distant known galaxy, discovered by the Hubble, dates to a time only 400 million years after the Big Bang. The Webb telescope will be able to see back farther, to a mere 100 million years after the Big Bang.

In that foggy realm, Dr. Rieke expects to find dozens more infant galaxies, she said. Astronomers believe these were the building blocks for the clusters of galaxies visible today, agglomerations of trillions of stars.

Along the way, these galaxies somehow acquire supermassive black holes at their centers, with masses millions or billions larger than the sun. But how and when does this happen, and which comes first: the galaxy or its black hole?

Priyamvada Natarajan, an astrophysicist at Yale, and her colleagues are among those hoping to use Webb to find an answer to the origins of these black holes.

Did they come from the collapses of those first stars? Or were the black holes already there, legacies of the Big Bang?

“A lot is on the line, intellectually in terms of our understanding of black-hole growth, and practically in terms of careers for the younger members of our team and that of others working on this important open question,” Dr. Natarajan said. “Assuming, of course, that all goes well, and JWST takes data as expected.”

ESO/Digitized Sky Survey 2

In the years that Webb has been in development, the hunt for and study of exoplanets — worlds that orbit other stars — has become the fastest-growing area of astronomy. Scientists now know that there are as many planets in the galaxy as there are stars.

“Everything we have learned about exoplanets has been a surprise,” Dr. Mather said.

Seeking such a surprise, he said, the telescope will look at Alpha Centauri, a star only 4.5 light-years from Earth: “We don’t expect planets there, but who knows?”

As it turns out, infrared emissions are also ideal for studying exoplanets. As an exoplanet passes in front of its star, its atmosphere is backlit, enabling scientists on Earth to study the spectroscopic signatures of elements and molecules. Ozone is one such molecule of interest, as is water, said Sara Seager, a planetary expert at the Massachusetts Institute of Technology.

The astronomers with viewing time on the Webb telescope have made a list of about 65 exoplanets to observe; all are relatively nearby, circling small stars known as red dwarfs. None is a true analog to our planet, an Earth 2.0 orbiting a sunlike star, Dr. Mather said. Finding one of those will require a bigger, next-generation space telescope. But they could be habitable nonetheless.

Paul E. Alers/NASA

As a result, some of the most anticipated early observations with the Webb will be of the planets in the Trappist-1 system, just 40 light-years away. There, seven planets circle a dim red-dwarf star. Three are Earth-size rocks orbiting in the habitable zone, where water could exist on the surface.

Dr. Seager is part of a team that has first dibs on observing one of the most promising of these exoplanets, Trappist-1e. The researchers will begin by trying to determine whether the world has an atmosphere.

“Nothing is scheduled yet,” she said, and recounted the many steps needed before the telescope is operational. “I liken it to waking someone up from a coma. You don’t ask them to run a marathon right away. It’s step-by-step testing.”

Dr. Mather, when asked what he was looking forward to studying, mentioned primordial galaxies, dark energy and black holes. “What I really hope for is something we don’t expect,” he said.

NASA, ESA

Wendy Freedman could be excused for thinking she is living through a déjà vu moment.

Thirty years ago, before the Hubble Space Telescope was launched, eminent astronomers were arguing bitterly about how fast the universe was expanding. At issue was the correct value of the Hubble constant, which has been called the most important number in the universe. It measures the cosmic expansion rate, but astronomical measurements disagreed by a factor of two on its value. This meant astronomers could not reliably compute the age or fate of the cosmos or the distance to other galaxies.

The Hubble Telescope was to resolve this impasse, and Dr. Freedman, now at the University of Chicago, wound up running a “key project” that settled on an answer. But recent measurements have revealed a new disagreement about the cosmic expansion rate. And Dr. Freedman finds herself again in the middle, using a new space telescope to remeasure the Hubble constant.

“Today we have a chance to learn something about the early universe,” she said in an email. “As we have gotten increasingly higher accuracy, the issue has changed — we can now ask if there are cracks in our current standard cosmological model. Is there some new missing fundamental physics?”

“So yes, it is exciting,” she said. “Once again, a new fantastic space telescope that will allow us to resolve a controversy!”

And that, doubtless, will create new ones. As Klaus Pontoppidan, an astronomer with the Space Telescope Science Institute, said at a recent news conference: “The telescope was built to answer questions we didn’t know we had.”

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The drifting giant A68 iceberg released billions of tons of fresh water in South Georgia ecosystem – MercoPress

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Saturday, January 22nd 2022 – 10:56 UTC

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Satellite images shows A68a heading towards the sub-Antarctic island of South Georgia. Credit: MODIS from NASA Worldview Snapshots

Scientists monitoring the giant A68a iceberg from space reveal that a huge amount of freshwater was released as it melted around the sub-Antarctic island of South Georgia. An estimated 152 billion tons of freshwater – equivalent to 20 x Loch Ness or 61 million Olympic sized swimming pools, entered the seas around the sub-Antarctic island of South Georgia when A68a melted over three months in 2020/2021, according to a new study published this month by the British Antarctic Survey.

In July 2017, A68a calved off the Larsen-C Ice Shelf on the Antarctic Peninsula and began its epic three-and-a-half year, 4.000 km journey across the Southern Ocean. At 5719 square kilometers – about a quarter the size of Wales – it was the biggest iceberg on Earth when it formed and the sixth largest on record. Around Christmas 2020, the berg received widespread attention as it drifted worryingly close to South Georgia, raising concerns it could harm the island’s fragile ecosystem.

A team from Center for Polar Observation and Modeling and BAS used satellite measurements to chart the iceberg’s area and thickness change throughout its life cycle. The authors show that the iceberg had melted enough as it drifted to avoid damaging the sea floor around South Georgia by running aground. However, a side effect of the melting was the release of a colossal 152 billion tons of fresh water in close proximity to the island – a disturbance that could have a profound impact on the island’s marine habitat.

For the first two years of its life, A68a stayed close to Antarctica in the cold waters of the Weddell Sea and experienced little in the way of melting. However, once it began its northwards journey across the Drake Passage it traveled through increasingly warm waters and began to melt. Altogether, the iceberg thinned by 67 meters from its initial 235 m thickness, with the rate of melting rising sharply as the berg drifted around South Georgia.

Laura Gerrish, GIS and mapping specialist at BAS and co-author of the study said, “A68 was an absolutely fascinating iceberg to track all the way from its creation to its end. Frequent measurements allowed us to follow every move and break-up of the berg as it moved slowly northwards through an area called ‘iceberg alley’, a route in the ocean which icebergs often follow, and into the Scotia Sea where it then gained speed and approached the island of South Georgia very closely.”

If an iceberg’s keel is too deep it can become grounded on the sea floor. This can be disruptive in several different ways; the scour marks can destroy fauna, and the berg itself can block ocean currents and predator foraging routes. All of these potential outcomes were feared when A68a approached South Georgia. However, this new study reveals that it collided only briefly with the sea floor and broke apart shortly afterwards, making it less of a risk in terms of blockage. By the time it reached the shallow waters around South Georgia, the iceberg’s keel had reduced to 141 meters below the ocean surface, shallow enough to avoid the seabed which is around 150 meters deep.

Nevertheless, the ecosystem and wildlife around South Georgia will certainly have felt the impact of the colossal iceberg’s visit. When icebergs detach from ice shelves, they drift with the ocean currents and wind while releasing cold fresh melt-water and nutrients as they melt. This process influences the local ocean circulation and fosters biological production around the iceberg. At its peak, the iceberg was melting at a rate of 7 meters per month, and in total it released a staggering 152 billion tons of fresh water and nutrients.

“This is a huge amount of melt water, and the next thing we want to learn is whether it had a positive or negative impact on the ecosystem around South Georgia. Because A68a took a common route across the Drake Passage, we hope to learn more about icebergs taking a similar trajectory, and how they influence the polar oceans,” said Anne Braakmann-Folgmann, a researcher at CPOM and PhD candidate at the University of Leeds’ School of Earth and Environment, and lead author of the study.

The journey of A68a has been charted using observations from five different satellites. The iceberg’s area change was recorded using a combination of Sentinel-1, Sentinel-3, and MODIS imagery. Meanwhile, the iceberg’s thickness change was measured using CryoSat-2 and ICESat-2 altimetry. By combining these measurements, the iceberg’s area, thickness, and volume change were determined.

Tommaso Parrinello, CryoSat Mission Manager at the European Space Agency pointed out that “Our ability to study every move of the iceberg in such detail is thanks to advances in satellite techniques and the use of a variety of measurements. Imaging satellites record the location and shape of the iceberg and data from altimetry missions add a third dimension as they measure the height of surfaces underneath the satellites and can therefore observe how an iceberg melts.”

“Observing the Disintegration of the A68A Iceberg from Space” is published in the journal Remote Sensing of Environment at https://doi.org/10.1016/j.rse.2021.112855.

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Are the northern lights caused by 'particles from the Sun'? Not exactly – Phys.org

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Credit: PhotoVisions/Shutterstock

What a spectacle a big aurora is, its shimmering curtains and colorful rays of light illuminating a dark sky. Many people refer to aurora as the northern lights (the aurora borealis), but there are southern lights too (the aurora australis). Either way, if you’re lucky enough to catch a glimpse of this phenomenon, it’s something you won’t soon forget.

The is often explained simply as “particles from the Sun” hitting our atmosphere. But that’s not technically accurate except in a few limited cases. So what does happen to create this natural marvel?

We see the aurora when energetic charged particles—electrons and sometimes ions—collide with atoms in the upper atmosphere. While the aurora often follows explosive events on the Sun, it’s not quite true to say these energetic particles that cause the aurora come from the Sun.

Earth’s magnetism, the force that directs the compass needle, dominates the motions of electrically charged particles in space around Earth. The magnetic field near the surface of Earth is normally steady, but its strength and direction fluctuate when there are displays of the aurora. These fluctuations are caused by what’s called a magnetic substorm—a rapid disturbance in the in near-Earth space.

To understand what happens to trigger a substorm, we first need to learn about . Plasma is a gas in which a significant number of the atoms have been broken into ions and electrons. The gas of the uppermost regions of Earth’s atmosphere is in the , as is the gas that makes up the Sun and other stars. A gas of plasma flows away continuously from the Sun: this is called the solar wind.

Plasma behaves differently from those gases we meet in everyday life. Wave a magnet around in your kitchen and nothing much happens. The air of the kitchen consists overwhelmingly of electrically neutral atoms, so it’s quite undisturbed by the moving magnet. In a plasma, however, with its electrically charged particles, things are different. So if your house was filled with plasma, waving a magnet around would make the air move.

When solar wind plasma arrives at the earth it interacts with the planet’s magnetic field (as illustrated below—the magnetic field is represented by the lines that look a bit like a spider). Most of the time, plasma travels easily along the lines of the magnetic field, but not across them. This means that solar wind arriving at Earth is diverted around the planet and kept away from the Earth’s atmosphere. In turn, the solar wind drags the field lines out into the elongated form seen on the night side, called the magnetotail.

Sometimes moving plasma brings magnetic fields from different regions together, causing a local breakdown in the pattern of magnetic field lines. This phenomenon, called magnetic reconnection, heralds a new magnetic configuration, and, importantly, unleashes a huge amount of energy.

These events happen fairly often in the Sun’s outer atmosphere, causing an explosive energy release and pushing clouds of magnetized gas, called coronal mass ejections, away from the Sun (as seen in the image above).

If a arrives at Earth it can in turn trigger reconnection in the magnetotail, releasing energy that drives electrical currents in near-Earth space: the substorm. Strong electric fields that develop in this process accelerate electrons to high energies. Some of these electrons may have come from the , allowed into near-Earth space by reconnection, but their acceleration in the substorm is essential to their role in the aurora.

These particles are then funneled by the magnetic towards the atmosphere high above the polar regions. There they collide with the oxygen and nitrogen atoms, exciting them to glow as the aurora.

Now you know exactly what causes the northern lights, how do you optimize your chances of seeing it? Seek out dark skies far from cities and towns. The further north you can go the better but you don’t need to be in the Arctic Circle. We see them from time to time in Scotland, and they’ve even been spotted in the north of England—although they’re still better seen at higher latitudes.

Websites such as AuroraWatch UK can tell you when it’s worth heading outside. And remember that while events on the Sun can give us a few days warning, these are indicative, not foolproof. Perhaps part of the magic lies in the fact that you need a little bit of luck to see the aurora in all its glory.


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North Pole solar eclipse excited auroras on the other side of the world


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Hubble telescope spots a black hole fostering baby stars in a dwarf galaxy – Space.com

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Black holes can not only rip stars apart, but they can also trigger star formation, as scientists have now seen in a nearby dwarf galaxy.

At the centers of most, if not all, large galaxies are supermassive black holes with masses that are millions to billions of times that of Earth’s sun. For instance, at the heart of our Milky Way galaxy lies Sagittarius A*, which is about 4.5 million solar masses in size. 

Astronomers have previously seen giant black holes shred apart stars. However, researchers have also detected supermassive black holes generating powerful outflows that can feed the dense clouds from which stars are born.

Video: Dwarf galaxy’s black hole triggers star formation
Related:
The strangest black holes in the universe

A Hubble Space Telescope image of the dwarf starburst galaxy Henize 2-10, shown in visible light. (Image credit: NASA/ESA/Zachary Schutte (XGI)/Amy Reines (XGI)/Alyssa Pagan (STScI))

Black hole-driven star formation was previously seen in large galaxies, but the evidence for such activity in dwarf galaxies was scarce. Dwarf galaxies are roughly analogous to what newborn galaxies may have looked like soon after the dawn of the universe, so investigating how supermassive black holes in dwarf galaxies can spark the birth of stars may in turn offer “a glimpse of how young galaxies in the early universe formed a portion of their stars,” study lead author Zachary Schutte, an astrophysicist at Montana State University in Bozeman, told Space.com.

In a new study, the scientists investigated the dwarf galaxy Henize 2-10, located about 34 million light-years from Earth in the southern constellation Pyxis. Recent estimates suggest the dwarf galaxy has a mass about 10 billion times that of the sun. (In contrast, the Milky Way has a mass of about 1.5 trillion solar masses.)

A decade ago, study senior author Amy Reines at Montana State University discovered radio and X-ray emissions from Henize 2-10 that suggested the dwarf galaxy’s core hosted a black hole about 3 million solar masses in size. However, other astronomers suggested this radiation may instead have come from the remnant of a star explosion known as a supernova.

In the new study, the researchers focused on a tendril of gas from the heart of Henize 2-10 about 490 light-years long, in which electrically charged ionized gas is flowing as fast as 1.1 million mph (1.8 million kph). This outflow was connected like an umbilical cord to a bright stellar nursery about 230 light-years from Henize 2-10’s core.

This outflow slammed into the dense gas of the stellar nursery like a garden hose spewing onto a pile of dirt, leading water to spread outward. The researchers found newborn star clusters about 4 million years old and upwards of 100,000 times the mass of the sun dotted the path of the outflow’s spread, Schutte said.

A closer view of the central region of the dwarf galaxy Henize 2-10 shows the supermassive black hole and the outflow of hot gas. (Image credit: NASA/ESA/Zachary Schutte (XGI)/Amy Reines (XGI)/Alyssa Pagan (STScI))

With the help of high-resolution images from the Hubble Space Telescope, the scientists detected a corkscrew-like pattern in the speed of the gas in the outflow. Their computer models suggested this was likely due to the precessing, or wobbling, of a black hole. Since a supernova remnant would not cause such a pattern, this suggests that Henize 2-10’s core does indeed host a black hole.

Related stories:

“Before our work, supermassive black hole-enhanced star formation had only been seen in much larger galaxies,” Schutte said.

In the future, the researchers would like to investigate more dwarf galaxies with similar black hole-triggered star formation. However, this is difficult for many reasons — “systems like Henize 2-10 are not common; obtaining high quality observations is difficult; and so on,” Schutte said. However, when the James Webb Space Telescope hopefully comes online in the near future, “we will have new tools to search for these systems,” he noted.

Schutte and Reines detailed their findings in the Jan. 19 issue of the journal Nature.

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