Tag Archives: meters

The latest technology enables scanning of faces in 3D from hundreds of meters away

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The new imaging device can capture 3D scans of human faces hundreds of meters away

Aon McCarthy of Heriot Watt University

After 325 meters apart, your eyes can probably distinguish a person’s head from the body. However, new laser-based devices can create three-dimensional models of faces.

Aongus McCarthy The University of Heriot Watt in Scotland and his colleagues have built a device that can create detailed three-dimensional images containing 1 millimeter ridges and indents a few hundred meters apart. An imaging technique called Lidar is used to emit pulses of laser light, collide with the object and is reflected on the device. Based on how long it takes each pulse to return, Lidar can determine the shape of the object.

To reach this level of detail, the team had to carefully tune and align many different components, McCarthy said, including small parts that direct the laser pulse into the device. To enable discrimination between single light particles, the researchers used photodetectors based on extremely thin superconducting wires, a component not common in LIDAR. Exclude sunlight that could enter the detector and break down the image was another challenge.

Researchers tested the rider system on a roof near the lab by taking detailed three-dimensional images of the team members’ heads from 45 meters and 325 meters apart. On a small scale, they captured LEGO figurines from a distance of 32 meters.

The imaging system can scan LEGO characters from 32 meters away

Aon McCarthy of Heriot Watt University

Another test imaged a segment of a communications tower one kilometre away. “It was a very difficult test. I couldn’t control what the scene could do due to the bright background. [that we were imaging]McCarthy says.

Feihu Xu At the University of Science and Technology in China, the team previously used LIDAR for imaging From 200km awayMcCarthy and his colleagues say they achieved “amazing results” in terms of the device’s depth resolution. “It’s the best so far,” he says.

Lidar says that modern technology is only becoming more relevant Vivek Goyal at Boston University, Massachusetts. He says that being able to create detailed 3D maps of the surroundings is also important for self-driving cars and some robots, but before using them for this purpose, new devices need to be made smaller and more compact. There is.

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Source: www.newscientist.com

The Hills of Sicily were Submerged 40 Meters Below Water During the Great Flood.

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A ridge in southeastern Sicily eroded by the Great Flood

Kevin Sciberras and Neil Petroni

The jumbled deposits of rocks found on a hilltop in southeastern Sicily are left behind by the Great Flood, the largest known flood in Earth's history, which refilled the Mediterranean Sea five million years ago.

Rock deposits and eroded hills in this part of the Italian island of Sicily are the first evidence found on land of a mega-flood, scientists say. pole curling at the University of Southampton, UK. “You can actually walk around and look at it,” Carling said.

About 6 million years ago, during the so-called Messinian salinity crisis, the Mediterranean Sea separated from the Atlantic Ocean and began to dry up. Vast salt deposits were formed during this period, and sea levels may have fallen by more than a kilometer.

About 5.3 million years ago, water once again began to flow through the Strait of Gibraltar into the Mediterranean Sea. Researchers initially thought the giant waterfall near Gibraltar had been reclaimed over tens of thousands of years.

But in 2009, a massively eroded channel was discovered at the bottom of the strait, suggesting more sudden deluges could occur. Since then, this evidence has continued to grow.

Carling said the flood first filled the western basin of the Mediterranean Sea. The eroded topography of the ocean floor suggests that it then spilled into the eastern basin over an underwater ridge known as the Sicilian Sill.

team members Giovanni Barreca The professor at the University of Catania in Italy, who grew up in southeastern Sicily, suspected that the land there was also formed by the Great Flood. So he and his fellow researchers took a closer look at the rock samples and analyzed them.

Sure enough, we found that the intricate deposits near the tops of some hills contained rocks that had been eroded from deeper layers and somehow transported to the top of the hills. “You can tell by their nature that they come from a lower level,” Carling says. “And they were carried over this hill.”

Many of the hills themselves have a streamlined shape, resembling the hills of Montana carved out by the great floods caused by the bursting of ice dams at the end of the last ice age. “They're very distinctive,” Carling says. “And only a very large, massive flood could streamline a feature of this magnitude.”

Detail of a Sicilian ridge formed by a huge flood

Daniel Garcia Castellanos

The researchers estimated that at the peak of the flood, water was flowing at about 115 kilometers per hour, covering the top of the hill, which is about 100 meters above modern sea level, with about 40 meters of water.

Researchers also investigated the ocean floor around Sicily and found further evidence of the deluge, including eroded ridges and channels. Their modeling suggested that the entire Mediterranean Sea was backfilled between two and 16 years, but the main flooding event in Sicily probably lasted only a few days, Carling said.

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Source: www.newscientist.com

Webb finds 138 main belt asteroids measuring 10 meters in diameter

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These asteroids are as small as 10 meters in diameter, making them the smallest asteroids ever observed in the major asteroid belt.

Artist Webb's illustration reveals clusters of main-belt decameter asteroids in infrared light. Image credit: Ella Mall/Julian de Wit.

The discovery of asteroids is essential to planetary defense efforts aimed at preventing collisions with Earth, such as the frequent megaton explosions caused by decameter impactors.

Large asteroids (=>100 km) remain in the main belt since their formation, while smaller asteroids are typically transported into the near-Earth object (NEO) population.

“We were able to detect NEOs very close to Earth, up to 10 meters in size,” said MIT researcher Dr. Artem Brudanov.

“We now have a way to discover these small asteroids when they are far away, so we can do more precise trajectory tracking, which is important for planetary defense.”

For this study, astronomers used data from the NASA/ESA/CSA James Webb Space Telescope to search for small asteroids.

Coincidentally, asteroids orbiting the main asteroid belt are much brighter in infrared wavelengths than in visible wavelengths, making them much easier to detect with Webb's infrared capabilities.

Researchers were able to discover eight known asteroids in the main asteroid belt.

Further investigation subsequently discovered 138 new asteroids around the belt, all within a few tens of meters in diameter, making them the smallest main-belt asteroids ever detected. .

They think several asteroids may be on their way to becoming NEOs, and one of them is probably the Trojans, or Jupiter-tracking asteroids.

“We thought we would only detect a few new objects, but we detected far more objects than we expected, especially small ones,” said Professor Julian de Witt of the Massachusetts Institute of Technology.

“This is an indication that we are exploring a new population regime, where many more small objects are formed by a chain of collisions that very efficiently disintegrates asteroids smaller than about 100 meters. It will be done.”

“This is a completely new and unexplored territory that we are entering, thanks to modern technology,” said Dr. Brudanov.

“This is a great example of what we can do as a field when we look at data from a different perspective. Sometimes the benefits can be huge, and this is one of them.”

“The statistics of these very small main-belt asteroids are very important for modeling asteroid populations,” said Dr. Miroslav Broz, a researcher at Charles University in Prague.

In fact, these are debris ejected during the impact of larger, kilometer-sized asteroids, which are observable and often exhibit similar orbits around the sun, placing them in a “family” of asteroids. Can be grouped. ”

“We never expected that we could use state-of-the-art exoplanet observations to achieve such impactful solar system bonus science,” said Dr. Michael Guillon, a researcher at the University of Liège.

ESA researcher Dr Marco Micheli said: “Thanks to the web, we can now discover these small asteroids even when they are located far from Earth, allowing us to make more accurate orbit determinations. “This is extremely important for planetary defense.” Near Earth Object Coordination Center.

of the team paper Published in today's magazine nature.

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AY Brudanov others. JWST sighting of a 10-meter main belt asteroid and views on the meteorite source. naturepublished online on December 9, 2024. doi: 10.1038/s41586-024-08480-z

Source: www.sci.news

Building the moon base 3 meters underground to prevent radiation exposure.

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A base below the surface of the moon may be needed to protect moon residents from radiation.

Shutterstock/Shiva Shankara

To protect astronauts on the Moon from harmful radiation, a long-term lunar base would need to be protected by 2-3 metres of regolith – the layer of rock and dust on the Moon’s surface.

Guo Jingnan and Mikhail Dbinde Researchers at the Hefei University of Science and Technology in China analyzed how the thickness of shielding for a lunar base would affect radiation doses for people living on the Moon. Their study included using lunar soil as shielding as well as additional artificial shielding.

According to Guo, there are two main types of radiation that are dangerous to astronauts: the ubiquitous background levels of galactic cosmic rays, which pose a long-term cancer risk, and solar energetic particles (SEPs) from sporadic solar activity. These SEPs can cause more serious symptoms of radiation exposure, such as skin damage and damage to bone marrow and lymphatic tissue, which are involved in the production of blood cells and platelets. In severe cases, exposure to SEPs can lead to death.

“The amount of radiation on the lunar surface is not constant,” Guo said. “For a short lunar stay that does not encounter a strong SEP, the radiation impact should be small.”

But if a solar explosion were to occur, the danger could be enormous. For example, at the end of the Apollo program, Apollo 16 landed astronauts on the Moon for a few days in April 1972. It was followed by Apollo 17 in December of the same year. During that time, there was a massive radiation storm.

“A very large SEP event could have occurred during September, potentially killing any unprotected astronauts on the lunar surface,” Guo said.

The study also found that too little regolith shielding could be worse than no shielding at all, because lunar soil scatters radiation and produces various types of secondary particles, including neutrons. This secondary radiation peaks about 50 centimetres deep on the lunar surface but drops off rapidly beyond that.

“Neutrons have a large biological impact because they interact efficiently with the human body and induce radiation effects in internal organs,” Guo said. “With about 50 centimeters of shielding, neutrons can account for more than 90 percent of the total effective radiation dose.”

The study found that a three-metre deep base could safely house the same crew for more than 20 years without exceeding lifetime and annual radiation limits set by the space agency.

NASA and the Russian Space Agency impose different occupational radiation dose limits for astronauts, at 600 millisieverts and 1000 mSv, respectively. Both agencies also impose annual radiation exposure limits. The annual natural radiation exposure on Earth is approximately 2.4 mSv..

Guo says two metres of shielding would be enough for a single crew member to stay on the moon for no more than a few months, and that crew members could return to Earth frequently enough to avoid exceeding lifetime and annual radiation health limits, she says.

The most practical way to reduce radiation exposure would be to give the base natural shielding, by building it in an existing cave or lava tube, or by constructing habitats below the surface, Guo said.

Better prediction of solar storms is also important to keep astronauts safe when they leave base and conduct surface activities, she said.

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  • Space Exploration

Source: www.newscientist.com

Ancient geese reached the height of three meters and weighed as much as a cow

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Artistic reconstruction of Genyornis newtoni, an ancient relative of the goose

Illustration by Jacob C. Blokland

Australia's prehistoric ptarmigan, once thought to be an ancestor of the emu, was actually the largest goose that ever lived.

This group was reclassified based on analysis going back 45,000 years. Genyornis neutoni The skull was found in the fossil deposits of Lake Carabonna in the South Australian desert.

The newly discovered skull is the first of the extinct species to be discovered since 1913, and the only one well-preserved enough to allow detailed anatomical study. G. Newton He weighed approximately 230 kilograms and was over 2.5 metres tall.

However, its close relativesDromornis stiltoniAt well over three metres tall and weighing up to 600 kilograms, it is not only a contender for the largest bird in history, but also the largest goose ever.

When Thunderbird fossils were first discovered in the 19th century, they were thought to be ancestors of ratites, which include emus, cassowaries and ostriches. Later, some argued that the group, officially called Dromornithiidae, with eight known species, should be classified with land birds, which also include chickens and pheasants.

now, Phoebe McInerney Researchers from Flinders University in Adelaide, Australia, concluded that the Thunderbird is a large waterbird and should be classified as part of the Anseriformes, the same group as geese.

The team was primarily convinced by the anatomy of the beak and skull, including the arrangement of muscles and the deformation of the bones to which they were attached. Genyornis The structure is nearly identical to that of South American screamers, an ancient lineage of waterbirds, and is so complex that it's unlikely it evolved independently, McInerney said.

Artistic reconstruction of the skull of Geniornis newtoni based on fossil data

Illustration by Jacob C. Blokland

All of the ptarmigans were herbivores, she says, but they were probably fierce creatures. “They would have been very tough animals,” McInerney says. “They could defend themselves and they would have been quite formidable beasts. They would have had a very low, loud cry.”

Adam Yates Yates, of the Northern Territory Museum and Art Gallery in Australia, said the study supports the claims of his predecessor, Peter Murray, who proposed in the early 1990s that the Thunderbird was a waterbird. “So it's not a shock to me,” Yates said. “But Genyornis It took so long to find the skull, so we're very happy that it has finally been found.”

Many Thunderbird species became extinct before humans arrived in Australia around 65,000 years ago, which is thought to have been due to climate change.G. Newtoni Humans had inhabited the continent for tens of thousands of years, and some researchers speculate that hunting may have also played a role in their extinction.

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Source: www.newscientist.com