Mystery Event Decimated 90 Per Cent of Shark Diversity 19 Million Years Ago, New Study Finds
A new study has found that a single mysterious event about 19 million years ago wiped nearly the entire population of sharks. Scientists behind the new research say that studying the shark teeth buried in deep-sea sediment, revealed that the current diversity among sharks is only a tiny remnant of a much larger variety that existed back then. They say this unidentified major ocean extinction caused the reduction in the shark diversity by over 70 percent and nearly a complete loss in total abundance. The cause of this event remains a mystery, scientists said.
Researchers say that this single event led to the virtual disappearance of sharks from open-ocean sediments, declining in abundance by almost 90 percent. They added that the abrupt extinction was independent of any known global climate event.
According to the research report published in the journal Science, modern shark forms began to diversify within two to five million years after the near extinction, but they represent only a sliver of what sharks once were.
A report in Life Science quoted Elizabeth Sibert, a postdoctoral fellow at Yale University’s Institute for Biospheric Studies and co-author of the study, as saying, “Sharks have been around for 400 million years; they’ve weathered a lot of mass extinctions.”
The study into the ichthyolites, microscopic fossils of shark scales, found in most types of sediments but are tiny and relatively rare when compared to other microfossils, led to the discovery, Sibert told Live Science.
While scientists in the 1970s and ’80s studied ichthyolites, only a few researchers examined them before Sibert, who investigated them for her doctorate, which she completed in 2016. “A lot of what I’ve done in my early career as a scientist was figuring out how to work with these fossils, what kinds of questions we can ask about them,” Sibert said.
For their new study, Sibert and Leah Rubin, a co-author who was an undergraduate student at the College of the Atlantic in Bar Harbor, Maine at the time of the research, studied sediment cores extracted many years ago by deep-sea drilling projects from two different sites: one in the middle of the North Pacific, and the other in the middle of the South Pacific.
“We picked those sites particularly because they are far away from land and they’re far away from any influences of changing ocean circulation or ocean currents,” Sibert said.
Rubin, who is now going to be a doctoral student at the State University of New York College of Environmental Science and Forestry, said that the extreme nature of this decline in the diversity of sharks was the most surprising aspect of the study to them as well. The million-dollar question, Rubin says, is what caused it?
The paper is just the beginning, Sibert says, and hopes it’s going to be a really interesting next decade to figure out more about what happened at the time that caused the extinction among sharks.
NASA-ISRO Working Together to Make India’s Space Station, Launch NISAR in 2024
Stepping up collaboration, National Aeronautics and Space Administration Administrator Bill Nelson on Tuesday said the US was open to helping India build its own space station.
On a visit to India, Nelson said the US and India were working on plans to send an Indian astronaut to the International Space Station by the end of next year, while the Indian Space Research Organisation (ISRO) will launch the state-of-the-art joint venture satellite with NASA — NISAR — in the first quarter of 2024.
Nelson met Science and Technology Minister Jitendra Singh here and discussed strengthening cooperation between the two countries in the space sector.
“ISRO is also exploring the feasibility of utilising NASA’s Hypervelocity Impact Test (HVIT) facility for testing Gaganyaan module Micrometeoroid and orbital debris (MMOD) protection shields,” an official statement from the science and technology ministry said.
During the meeting, the two leaders also discussed US President Joe Biden’s offer to send an Indian astronaut to the International Space Station in 2024.
“The selection of astronaut is determined by ISRO. NASA will not make the selection,” Nelson said in an interaction with reporters here.
Nelson urged Singh to expedite the programme related to India’s first astronaut aboard a NASA rocket to the International Space Station.
NASA is identifying an opportunity in the private astronaut mission for Indian astronauts in 2024.
In response to a question, he said the US would be ready to collaborate with India in building the space station if it so desires.
“We expect by that time to have a commercial space station. I think India wants to have a commercial space station by 2040. If India wants us to collaborate with them, of course, we will be available. But that’s up to India,” Nelson said.
Prime Minister Narendra Modi has asked ISRO to aim to build an Indian space station by 2035 and land astronauts on the moon by 2040.
Built at a cost of $1.5 billion (nearly Rs. 12,500 crore), NISAR (NASA-ISRO Synthetic Aperture Radar) is targeted for launch onboard India’s GSLV rocket.
Data from NISAR will be highly suitable for studying the land ecosystems, deformation of solid earth, mountain and polar cryosphere, sea ice, and coastal oceans on a regional to global scale.
ISRO has developed the S-band SAR which was integrated with NASA’s L-band SAR at JPL/NASA. The integrated L & S band SAR is currently undergoing testing with the satellite at the U R Rao Satellite Centre (URSC), Bengaluru with the participation of NASA/JPL officials.
An official statement said ISRO and NASA have formed a Joint Working Group (JWG) on Human spaceflight cooperation and are exploring cooperation in radiation impact studies, micrometeorite and orbital debris shield studies; space health, and medicine aspects.
ISRO is also in discussion with prominent US industries (like Boeing, Blue Origin, and Voyager) on specific items of cooperation and also to explore joint collaborations with Indian commercial entities.
A concept paper on the Implementing Arrangement is under consideration between ISRO and NASA. After a few iterations, both sides arrived at a mutually agreed draft and the same is processed for intra-governmental approvals, the official statement said.
Amazon Claims Prototype Satellites for Kuiper Network Operating Successfully
Amazon.com said on Thursday its two prototype satellites for its planned Kuiper internet network have been operating successfully in orbit, with the project on track to start launching operational satellites by mid-2024. The Kuiper internet network is set to compete against billionaire Elon Musk‘s Starlink, the world’s largest satellite operator, to offer broadband internet service globally to consumers, companies and governments. Amazon said it had achieved a 100 percent success rate within the first 30 days of the launch of the prototype satellites from Florida aboard an United Launch Alliance Atlas 5 rocket.
Amazon said it used the prototype satellites for brief two-way video calls, streaming a high-definition movie on Prime Video and ordering items off Amazon’s website. “We still have a lot of hard work ahead, and scaling for mass production won’t be easy,” said Rajeev Badyal, vice president of technology for Project Kuiper. The US Federal Communications Commission has required Amazon to deploy half of its more than 3,000-planned satellite constellation by 2026.
On the heels of the successful prototype tests, Amazon expects to start building production-ready satellites next month for a launch in the second quarter of 2024, Badyal told Reuters. Badyal declined to say how many satellites Amazon would launch per rocket.
Badyal said he expects the network will be capable of providing broadband coverage in some parts of the world by late 2024, for an early beta phase targeted to begin in early 2025.
Early partners like Vodafone and Verizon are set to become the first telecom firms to beta test the service.
Amazon last year announced a bulk launch deal for 83 launches — the largest commercial rocket procurement ever — from various rocket companies, including Jeff Bezos’ Blue Origin, ULA and Europe’s Arianespace.
The Boeing-Lockheed joint venture United Launch Alliance is set to loft the first several batches of Kuiper satellites aboard its Atlas 5 and the company’s upcoming Vulcan rocket.
© Thomson Reuters 2023
NASA Astronomers Predict Near-Earth Asteroid’s 2029 Close Encounter
About 5 and a 1/2 years from now, astronomers predict, an asteroid about as wide as the Empire State Building is tall will streak through space within 20,000 miles (32,200 kms) of Earth, the closest any celestial object of that size will have come to our planet in modern history.
When it does, a spacecraft launched by NASA in 2016 is expected to be in position to provide a detailed examination of this rare close encounter.
The mission, directed by University of Arizona scientists, is expected to yield insights into planetary formation and knowledge that could inform efforts to build a defense system against possible doomsday asteroid collisions with Earth.
At the time of its 2004 discovery, the asteroid Apophis, named for a demon serpent embodying evil and chaos in ancient Egyptian mythology, appeared to pose a dire impact threat to Earth, with scientists forecasting a potential collision in 2029. Refined observations have since ruled out any impact risk for at least another century.
Still, its next approach in 2029 will bring the asteroid within a cosmic cat’s whisker of Earth — less than one-tenth the moon‘s distance from us and well within the orbits of some geosynchronous Earth satellites.
The spacecraft now headed for a rendezvous with Apophis is OSIRIS-REx, which made headlines plucking a soil sample from a different asteroid three years ago and sending it back to Earth in a capsule that made a parachute landing in Utah in September.
Spacecraft’s second act
Rather than retire the spacecraft, NASA has rebranded it as OSIRIS-APEX — short for APophis EXplorer — and fired its thrusters to put it on course for its next target.
The Apophis expedition was detailed in a mission overview published in the Planetary Science Journal.
Apophis, oblong and somewhat peanut-shaped, is a stony asteroid believed to consist mostly of silicate materials along with iron and nickel. Measuring about 1,110 feet (340 meters) across, it is due to pass within about 19,800 miles (31,860 kms) of Earth’s surface on April 13, 2029, becoming visible to the naked eye for a few hours, said Michael Nolan, deputy principal investigator for the mission at the University of Arizona.
“It’s not going to be this glorious show,” Nolan said, but it will appear as a point of reflected sunlight in the night sky over Africa and Europe.
An asteroid that large passing so near to Earth is estimated to occur roughly once every 7,500 years. The Apophis flyby is the first such encounter predicted in advance.
The tidal pull of Earth’s gravity likely will cause measurable disturbances to the asteroid’s surface and motion, changing its orbital path and rotational spin. Tidal forces could trigger landslides on Apophis and dislodge rocks and dust particles to create a comet-like tail.
The spacecraft is set to observe the asteroid’s Earth flyby as it nears and ultimately catches up with Apophis. These images and data would be combined with ground-based telescope measurements to detect and quantify how Apophis was altered as it passed by Earth.
OSIRIS-APEX is scheduled to remain near Apophis for 18 months – orbiting, maneuvering around it and even hovering just over its surface, using rocket thrusters to kick up loose material and reveal what lies beneath.
Planetary science and defense
Like other asteroids, Apophis is a relic of the early solar system. Its mineralogy and chemistry are largely unchanged in more than 4.5 billion years, offering clues to the origin and development of rocky planets like Earth.
Close examination of Apophis could give planetary defense experts valuable information about the structure and other properties of asteroids. The more scientists know about the composition, density and orbital behavior of such celestial “rubble piles,” the greater the chances of devising effective asteroid-deflection strategies to mitigate impact threats.
NASA deliberately crashed a spacecraft into a small asteroid last year in a planetary-defense test that nudged the rocky object from its normal path, marking the first time humankind altered the natural motion of a celestial body.
Apophis is substantially larger than that asteroid but tiny compared with the one that struck Earth 66 million years ago, wiping out the dinosaurs.
While not big enough to pose an existential threat to life on Earth, an Apophis-sized asteroid striking the planet at hypersonic speed still could devastate a major city or region, Nolan said, with ocean impact unleashing tsunamis.
“It wouldn’t be globally catastrophic in the sense of mass extinctions,” but an impact “would definitely come under the category of bad,” Nolan said.
“This thing is coming in at many miles per second if it hits. And at that speed, it kind of doesn’t whether if it’s made of gravel or ice or rocks or whatever. It’s just a big, heavy thing moving fast,” Nolan added.
© Thomson Reuters 2023
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