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6 mysterious structures hidden beneath the Greenland ice sheet – Space.com

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Fridtjof Nansen, the leader of the first expedition to cross Greenland, once described what he found in the Arctic as “the great adventure of the ice, deep and pure as infinity.” Nansen, who made his journey in 1888, could not have known of the wonders hidden below the icy landscape beneath his skis. 

Today, thanks to radar and other technologies, the part of Greenland that sits below its 9,800-foot-thick(3,000 meters) ice sheet is coming into focus. These new tools reveal a complex, invisible landscape that holds clues to the past and future of the Arctic.

The world’s longest canyon

3D view of the subglacial canyon, looking northwest from central Greenland. (Image credit: J. Bamber, University Bristol)

The Greenland ice sheet hides the longest canyon in the world. 

Discovered in 2013, the canyon stretches 460 miles (740 kilometers) from the highest point in central Greenland to Petermann Glacier on the northwest coast. That’s significantly longer than China’s 308-mile-long (496 km) Yarlung Tsangpo Grand Canyon, the longest canyon on the planet that you can actually see. 

The canyon plunges up to 2,600 feet (800 m) deep in places and is 6 miles (10 km) wide. For comparison, the Grand Canyon in Arizona averages about 1 mile (1.6 km) deep and 10 miles (16 km) across. 

Parts of the canyon may route meltwater from beneath the ice sheet to the sea. It probably formed before the ice sheet and was once the channel for a mighty river. 

Invisible mountains

As ice in Greenland melts at the surface, water carves fissures and reaches the base, where ice meets land. This sub-glacial ice can lubricate a glacier, causing it to flow to the ocean faster and be depleted more quickly. (Image credit: Ashley Cooper via Getty Images)

The canyon isn’t the only rugged part of Greenland’s under-ice landscape. Decades of mapping the island by ice-penetrating radar (which is usually mounted on airplanes) have revealed rugged mountain ranges and plunging fjords beneath the ice sheet. 

A 2017 map of Greenland stripped of its ice shows a bowl-like depression in the center of the island. A circle of coastal mountain ranges rings this depression. The map revealed the topography underlying Greenland’s flowing glaciers, which can help scientists predict how fast the glaciers will move in warming conditions and how quickly they will calve icebergs into the ocean. 

A primeval lake

Ice seems to go on forever at Humboldt Glacier in northwest Greenland. (Image credit: VWPics/Universal Images Group via Getty Images)

Hundreds of thousands or millions of years ago, before Greenland was covered with ice, it was home to a lake the size of Rhode Island and Delaware combined

Today, the lake is a depression filled with sediment. But it was once filled with water 800 feet (250 m) deep in some places. The lake basin covers 2,700 square miles (7,100 square km) and was fed by at least 18 different streams. 

The lake bed could hold valuable clues to the climate of the Arctic in the distant past, though discovering these secrets would require drilling through the 1.1 miles (1.8 km) of ice that now caps the ancient site.

Hidden gems

The blue rivers and splotches are Greenland’s surface meltwaters. (Image credit: Andrew Sole/University of Sheffield)

Greenland’s ice sheet also hides a landscape of jewel-like lakes filled with crystalline meltwater. There are at least 60 of these small lakes, mostly clustered in northern and eastern Greenland, Stephen Livingstone, a senior lecturer in physical geography at the University of Sheffield in the United Kingdom and co-researcher of a study into the lakes, Live Science previously reported.

The lakes range in size from 656 feet (200 m) across to 3.7 miles (5.9 km) across. The meltwater in these lakes may flow from the surface of the ice sheet, or it may melt because of friction from the movement of ice or geothermal energy from below. 

Evidence of meteor impacts

Crater in Greenland below the ice sheet. (Image credit: NASA’s Goddard Space Flight Center/ Cynthia Starr)

Not all the topography below the ice sheet is of Earthly origin. Scientists have found at least two likely meteor craters buried beneath the ice. Both are in northwest Greenland: One sits below Hiawatha Glacier, while the other is 114 miles (183 km) away from the first. The Hiawatha crater sits under about a half-mile (930 m) of ice, while the second crater is buried under 1.2 miles (2 km) of ice. The second crater is 22 miles (36 km) across, making it the 22nd-largest impact crater ever found on Earth. The first is a bit smaller at 19 miles (31 km) across. 

Perfectly preserved fossil plants

Greenland’s ice sheet may have disappeared far more recently than once thought, enabling plants and trees to thrive. (Image credit: Joshua Brown/UVM)

An ice core dug up during a Cold War-era attempt at building a nuclear weapons base was rediscovered in a freezer in 2017 and found to hold the perfectly preserved fossils of plants dating to a million years ago. 

“The best way to describe them is freeze-dried,” Andrew Christ, lead author of a study into the core and a postdoctoral fellow and lecturer in the Department of Geology at The University of Vermont in Burlington, told Live Science at the time. “When we pulled these out and put a little water on them, they kind of unfurled, so they looked like they died yesterday.”

The core came from northwestern Greenland, and the plants held within may have grown in a boreal forest. Such a forest could only grow in largely ice-free conditions, suggesting that parts of Greenland’s ice sheet may be younger than researchers previously believed.

Originally published on Live Science

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SpaceX launch marks 300th successful booster landing – Phys.org

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Credit: Unsplash/CC0 Public Domain

SpaceX sent up the 30th launch from the Space Coast for the year on the evening of April 23, a mission that also featured the company’s 300th successful booster recovery.

A Falcon 9 rocket carrying 23 of SpaceX’s Starlink internet satellites blasted off at 6:17 p.m. Eastern time from Cape Canaveral Space Force Station’s Space Launch Complex 40.

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The first-stage booster set a milestone of the 300th time a Falcon 9 or Falcon Heavy booster made a successful recovery landing, and the 270th time SpaceX has reflown a booster.

This particular booster made its ninth trip to space, a resume that includes one human spaceflight, Crew-6. It made its latest recovery landing downrange on the droneship Just Read the Instructions in the Atlantic Ocean.

The company’s first successful booster recovery came in December 2015, and it has not had a failed booster landing since February 2021.

The current record holder for flights flew 11 days ago making its 20th trip off the .

SpaceX has been responsible for all but two of the launches this year from either Kennedy Space Center or Cape Canaveral with United Launch Alliance having launched the other two.

SpaceX could knock out more launches before the end of the month, putting the Space Coast on pace to hit more than 90 by the end of the year, but the rate of launches by SpaceX is also set to pick up for the remainder of the year with some turnaround times at the Cape’s SLC-40 coming in less than three days.

That could amp up frequency so the Space Coast could surpass 100 launches before the end of the year, with the majority coming from SpaceX. It hosted 72 launches in 2023.

More launches from ULA are on tap as well, though, including the May 6 launch atop an Atlas V rocket of the Boeing CST-100 Starliner with a pair of NASA astronauts to the International Space Station.

ULA is also preparing for the second launch ever of its new Vulcan Centaur rocket, which recently received its second Blue Origin BE-4 engine and is just waiting on the payload, Sierra Space’s Dream Chaser spacecraft, to make its way to the Space Coast.

Blue Origin has its own it wants to launch this year as well, with New Glenn making its debut as early as September, according to SLD 45’s range manifest.

2024 Orlando Sentinel. Distributed by Tribune Content Agency, LLC.

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SpaceX launch marks 300th successful booster landing (2024, April 24)
retrieved 24 April 2024
from https://phys.org/news/2024-04-spacex-300th-successful-booster.html

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Wildlife Wednesday: loons are suffering as water clarity diminishes – Canadian Geographic

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The common loon, that icon of northern wilderness, is under threat from climate change due to declining water clarity. Published earlier this month in the journal Ecology, a study conducted by biologists from Chapman University and Rensselaer Polytechnic Institute in the U.S. has demonstrated the first clear evidence of an effect of climate change on this species whose distinct call is so tied to the soundscape of Canada’s lakes and wetlands.

Through the course of their research, the scientists found that July rainfall results in reduced July water clarify in loon territories in Northern Wisconsin. In turn, this makes it difficult for adult loons to find and capture their prey — mainly small fish — underwater, meaning they are unable to meet their chicks’ metabolic needs. Undernourished, the chicks face higher mortality rates. The consistent foraging techniques used by loons across their range means this impact is likely echoed wherever they are found — from Alaska to Canada to Iceland.

The researchers used Landsat imagery to find that there has been a 25-year consistent decline in water clarity, and during this period, body weights of adult loon and chicks alike have also declined. With July being the month of most rapid growth in young loons, the study also pinpointed water clarity in July as being the greatest predictor of loon body weight. 

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One explanation for why heavier rainfall leads to reduced water clarity is the rain might carry dissolved organic matter into lakes from adjacent streams and shoreline areas. Lawn fertilizers, pet waste and septic system leaks may also be to blame.

The researchers, led by Chapman University professor Walter Piper, hope to use these insights to further conservation efforts for this bird Piper describes as both “so beloved and so poorly understood.”

Return of the king

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Giant prehistoric salmon had tusk-like teeth for defence, building nests

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The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.

Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.

It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.

But then came discovery of two skulls in 2014.

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Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.

“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.

In that position, the tusk-like teeth could not have been used for biting, he says.

“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.

“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.

Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”

It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.

The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.

It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.

Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.

“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.

Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.

“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.

“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”

Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.

“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”

This report by The Canadian Press was first published April 24, 2024.

Brenna Owen, The Canadian Press

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