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NASA preparing for long-duration SpaceX commercial crew test flight – SpaceNews

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WASHINGTON — NASA is leaning increasingly towards making SpaceX’s crewed test flight to the International Space Station a long-duration mission, a move that could alleviate concerns about a lack of crew on the station later this year.

NASA’s Johnson Space Center released Feb. 22 images of NASA astronauts Bob Behnken and Doug Hurley training for their upcoming Demo-2 mission to the station on SpaceX’s Crew Dragon spacecraft. That included Behnken in a spacesuit, training for spacewalks in the center’s Neutral Buoyancy Laboratory, while Hurley worked on robotics training.

“The last week NASA Johnson included EVA and robotics training as well as medical testing and training,” said Hurley in a tweet referencing one from JSC. “We also had a day of SpaceX lessons here in Houston. Headed back to California next week. More Crew Dragon training!”

The original plans for the Demo-2, also known as DM-2, mission called for the flight to be a relatively short one, spending no more than a couple weeks at the station. In recent months, though, agency officials have suggested that they might extend the mission for months in order to have more astronauts on the station. The station’s crew will be at just three people, including one NASA astronaut, Chris Cassidy, starting in roughly mid-April.

“We might look at making that first crew be a longer duration crew for the purpose of getting the maximum amount of capability out of the International Space Station,” NASA Administrator Jim Bridenstine said at a Jan. 19 press conference after the successful in-flight abort test of the Crew Dragon spacecraft.

In order to extend it, he said, the crew would need additional training, such as for spacewalks. “It also gives us the opportunities to do extravehicular activities that may not right now be scheduled but may pop up based on things that happen on the ISS,” he said. “It’s always better to have more crew on board to do those activities rather than less.”

Bridenstine added that no decision had been made yet, and that a decision would come in several weeks. The spacewalk training by Behnken — who performed six spacewalks on two space shuttle missions in 2008 and 2010 — is evidence that NASA is, at the very least, continuing to preserve that option, if it has not made a decision.

One former astronaut said he believes NASA has already decided to extend the Demo-2 mission. Garrett Reisman, a former astronaut and SpaceX employee who is now a professor at the University of Southern California and an advisor to SpaceX, said Feb. 23 that Behnken and Hurley “are being trained for a long-duration mission as ISS crewmembers. This is a change from the original plan to do a min. duration test flight, driven by NASA needs to staff the ISS.”

Another factor in any decision to extend Demo-2 is the status of the other commercial crew vehicle, Boeing’s CST-100 Starliner. That vehicle flew an uncrewed test flight in December, but software problems during the flight, including one which shortened the mission and prevented a docking with the ISS, have raised questions about whether a second uncrewed test flight will be needed. An investigation into those problems is expected by the end of this month.

Even if NASA decides a second uncrewed test flight of Starliner is not needed, a review of all of the spacecraft’s one million lines of code, and other reviews, is likely to delay a crewed test flight of the spacecraft. NASA and Boeing had previously agreed to make that test flight a long-duration mission, with NASA astronauts Mike Fincke and Nicole Mann and Boeing astronaut Chris Ferguson performing space station training in addition to that for the Starliner itself.

The additional training needed for a long-duration mission could delay the Demo-2 launch, although it’s not clear by how much. SpaceX Chief Executive Elon Musk said at that January press conference that while the spacecraft should be ready in the first quarter, final reviews and other assessments made it likely the mission would take place in the second quarter of this year. The Crew Dragon spacecraft arrived in Florida earlier this month for final tests and launch integration activities.

“Like all NASA astronauts, we’ll be ready for whatever Space Station needs during our visit,” Behnken tweeted Feb. 23 in response to the JSC training photos. “These photos are just some of the recent training for NASA’s & SpaceX’s DM2 test flight. But for some reason, housekeeping (our top skill!) didn’t make the highlights…”

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NASA astronauts replace faulty space station antenna during spacewalk – Financial Post

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Two NASA astronauts completed a 6-1/2 hour spacewalk on Thursday to replace a faulty antenna on the International Space Station, a mission NASA said carried slightly higher risk posed by orbital debris left from a Russian missile test weeks ago.

Astronauts Thomas Marshburn and Kayla Barron exited an airlock of the orbiting research lab some 250 miles (400 km) above Earth to begin their work at 6:15 a.m. Eastern time (1115 GMT), an hour ahead of schedule.

The “extra-vehicular activity” (EVA) followed a 48-hour delay prompted by a separate orbital debris alert – believed to be the first such postponement in more than two decades of space station history – which NASA later deemed inconsequential.

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The origin of the newly detected debris was left unclear by NASA. A spokesperson said there was no indication it came from fragments of the defunct satellite that Russia blew to pieces https://www.reuters.com/world/us-military-reports-debris-generating-event-outer-space-2021-11-15 with a missile test last month.

Thursday’s outing was the fifth spacewalk for Marshburn, 61, a medical doctor and former flight surgeon with two previous trips to orbit, and a first for Barron, 34, a U.S. Navy submarine officer and nuclear engineer on her debut spaceflight for NASA.

“It was awesome,” Barron told Marshburn afterward.

During the spacewalk, they removed a defective S-band radio communications antenna assembly, now more than 20 years old, and replaced it with a spare stowed outside the space station.

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The space station is equipped with other antennae that can perform the same functions, but installing a replacement system ensures an ideal level of communications redundancy, NASA said.

Marshburn worked with Barron while positioned at the end of a robotic arm maneuvered from inside by German astronaut Matthias Maurer of the European Space Agency, with help from NASA crewmate Raja Chari.

The four arrived at the space station Nov. 11 in a SpaceX Crew Dragon capsule launched from the Kennedy Space Center in Florida, joining two Russian cosmonauts and a NASA astronaut, Mark Vande Hei, already aboard the orbiting outpost.

Four days later, an anti-satellite missile test conducted without warning by Russia generated a debris field in low-Earth orbit, forcing the seven ISS crew members to take shelter in their docked spaceships to allow for a quick getaway until the immediate danger passed, NASA said.

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The residual cloud of debris from the blasted satellite has dispersed since then, according to Dana Weigel, NASA deputy manager of the ISS program.

NASA has calculated that remaining fragments continue to pose a “slightly elevated” background risk to the space station as a whole, and a 7% higher risk of puncturing spacewalkers’ suits, as compared to before Russia’s missile test, Weigel told reporters on Monday.

NASA determined those risk levels fall within an acceptable range and moved ahead with preparations for a spacewalk on Tuesday as originally planned, only for mission control to delay the EVA mission hours before it was to start.

The operation was postponed after NASA received notice from U.S. military space trackers warning of a newly detected debris-collision threat. NASA concluded later there was no risk to spacewalkers or the station after all, and the antenna replacement was rescheduled for Thursday morning.

Thursday’s exercise marked the 245th spacewalk in support of assembly and upkeep of the space station, and the first on record delayed due to a debris alert, NASA spokesperson Gary Jordan said. (Reporting by Steve Gorman in Los Angeles and Brendan O’Brien in Chicago; Editing by Angus MacSwan and Rosalba O’Brien)

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Global extinction event led to evolution of weapon-like teeth in marine reptiles – India Today

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The discovery of a new fossil from central Colombia could shed light on the evolution of marine reptiles. The well preserved metre-long skull discovered by researchers from Canada, Colombia, and Germany is one of the last surviving ichthyosaurs — ancient animals that look like living swordfish.

The marine animal has been named Kyhytysuka, which translates to “the one that cuts with something sharp” in an indigenous language from the region in central Colombia where the fossil was found.

The animal shows the evolution of a unique arsenal of teeth to devour its prey against other ichthyosaurs that had small, equally sized teeth for feeding on small prey. The study of the marine fossil published in the Journal of Systematic Palaeontology states that the discovery has helped in a better understanding of the anatomy of the marine reptile.

Hans Larsson, Director of the Redpath Museum at McGill University and a lead author of the study said that the animal evolved a unique dentition that allowed it to eat large prey. “Whereas other ichthyosaurs had small, equally sized teeth for feeding on small prey, this new species modified its tooth sizes and spacing to build an arsenal of teeth for dispatching large prey, like big fishes and other marine reptiles,” he added.

Skeleton of Kyhytysuka compared to a human for scale. Known bones are shown in white. Credit: (Photo: Dirley Cortés)

Researchers said that they decided to name it Kyhytysuka, to honour the ancient Muisca culture that existed in the region where the fossil was found.

In a bid to clarify the evolution of the unique animal, researchers compared it with other Jurassic and Cretaceous ichthyosaurs and defined a new type of ichthyosaur. They concluded that the species comes from an important transitional time during the Early Cretaceous period when the Earth was coming out of a relatively cool period, had rising sea levels, and the supercontinent Pangea was splitting into northern and southern landmasses.

In a release by McGill University, researchers said that there was also a global extinction event at the end of the Jurassic that changed marine and terrestrial ecosystems.

Dirley Cortés working with the skull of Kyhytysuka. (Photo: Dirley Cortés)

“We are discovering many new species in the rocks this new ichthyosaur comes from. We are testing the idea that this region and time in Colombia was an ancient biodiversity hotspot and are using the fossils to better understand the evolution of marine ecosystems during this transitional time,” Dirley Cortés, a graduate student under the supervision of Hans Larsson and Carlos Jaramillo of the Smithsonian Tropical Research Institute said.

Researchers concluded that the new discovery shakes up the evolutionary tree of ichthyosaurs and “lets us test new ideas of how they evolved.”

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Why increased rainfall in the Arctic is bad news for the whole world? – The Tribune

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Loughborough (UK), Dec 2

Before the end of this century, most of the Arctic will for the first time receive more rain than snow across a whole year. That’s one of the key findings of a new study on precipitation in the Arctic which has major implications – not just for the polar region, but for the whole world.

While a reduction in frozen ocean surface is one of the most widely recognised impacts of Arctic warming, it has also long been anticipated that a warmer Arctic will be a wetter one too, with more intense cycling of water between land, atmosphere and ocean.

The shift from a frozen region towards a warmer, wetter Arctic is driven by the capacity of a warmer atmosphere to hold more moisture, by increased rates of evaporation from ice-free oceans, and by the jet stream relaxing.

The Arctic water cycle is expected to shift from a snow-dominated one towards a rain-dominated one during the 21st century, although the timing of this is uncertain. Now, a team of scientists have published a study in the journal Nature Communications which suggests that this shift will occur earlier than previously projected.

The effect will be particularly strong in autumn, with most of the Arctic Ocean, Siberia and the Canadian Archipelago becoming rain-dominated by the 2070s instead of the 2090s.

Warmer and wetter isn’t necessarily better

Such a profound change to the Arctic water cycle will inevitably affect ecosystems on land and in the ocean. You might intuitively expect that a warmer and wetter Arctic would be very favourable for ecosystems – rainforests have many more species than tundra, after all. But the plants and animals of the Arctic have evolved for cold conditions over millions of years, and their relatively simple food web is vulnerable to disturbance.

For example, warmer temperatures can cause larval insects to emerge earlier, before the fish species that feed upon them have hatched. More rainfall means more nutrients washed into rivers, which should benefit the microscopic plants at the base of the food chain.

However, this also makes rivers and coastal waters more murky, blocking light needed for photosynthesis and potentially clogging filter-feeding animals, including some whales or sharks. Brackish water typically supports fewer species than either freshwater or seawater, so increasing flows of freshwater offshore may well reduce the range of animals and plants along Arctic coasts.

Further into the Arctic Ocean, there are more reasons to doubt the potential benefits of warmer temperatures and greater freshwater circulation. The dissolved constituents of rainfall, river water and melting snow and ice reduce the alkalinity of Arctic surface waters, which makes it harder for marine organisms to build shells and skeletons, and limits chemical neutralisation of the acidifying effects of CO2 absorbed in seawater.

At the same time, rivers flowing through degrading permafrost will wash organic material into the sea that bacteria can convert to CO2, making the ocean more acidic. Fresh water also essentially floats on denser seawater.

This causes the ocean to become stratified, impeding exchanges of nutrients and organisms between the deep sea and the surface, and restricting biological activity. Therefore the likely impacts of a warmer, wetter Arctic on food webs, biodiversity and food security are uncertain, but are unlikely to be uniformly positive.

Arctic change is decades ahead of global averages

Temperature increases in the Arctic have raced ahead of the global average. This will only be reinforced as snowfall is reduced and rainfall increases, since snow reflects the sun’s energy back into space. As the land becomes less snowy and less reflective, bare ground will absorb more solar energy, and thus will warm up.

The Arctic is set to continue warming faster than elsewhere, further diminishing the difference in temperature between the warmest and coldest parts of the planet, with complex implications for the oceans and atmosphere.

The recent COP26 climate summit in Glasgow focused on efforts to “keep 1.5°C alive”. It is worth remembering that the 1.5°C figure is a global average, and that the Arctic will warm by at least twice as much as this, even for modest projections.

The new study underscores the importance of the global 1.5°C target for the Arctic. For instance, at that level of warming Greenland is expected to transition to a rainfall-dominated climate for most of the year. While at 3°C warming, which is close to the current pathway based on existing policies rather than pledges, most regions of the Arctic will transition to a rainfall-dominated climate before the end of the 21st-century.

It’s research that adds further weight to calls for improved monitoring of Arctic hydrological systems and to the growing awareness of the considerable impacts of even small increments of atmospheric warming. (The Conversation) 

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