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NASA delays tightening James Webb Space Telescope sunshield to study power system – Space.com

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NASA personnel are spending the day studying the power subsystem of the massive James Webb Space Telescope to ensure the observatory is ready to execute a key procedure: tensioning its vast sunshield.

The Webb space telescope, which launched on Dec. 25, is conducting a month-long deployment procedure necessary to prepare the telescope to gather data. But most steps in that procedure are controlled from the ground: While NASA has a tentative schedule for the work, mission leaders can decide to adjust the timeline along the way. So after taking Saturday (Jan. 1) as a rest day, the Webb team is spending Sunday (Jan. 2) studying the observatory’s power subsystem, NASA announced.

“Nothing we can learn from simulations on the ground is as good as analyzing the observatory when it’s up and running,” Bill Ochs, Webb project manager at NASA’s Goddard Space Flight Center (GSFC) in Maryland, said in an agency statement released Sunday (Jan. 2). “Now is the time to take the opportunity to learn everything we can about its baseline operations. Then we will take the next steps.”

Live updates: NASA’s James Webb Space Telescope mission
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In particular, the team is focused on the temperature of a set of motors that will be used during sunshield tensioning, the process that separates and smooths the five delicate layers of the kite-shaped sun deflector. (Webb specializes in infrared observations, which are sensitive to heat, making the sunshield a vital component of the observatory.)

“We’ve spent 20 years on the ground with Webb, designing, developing, and testing,”  Mike Menzel, Webb’s lead systems engineer at GSFC said in the same statement. “We’ve had a week to see how the observatory actually behaves in space. It’s not uncommon to learn certain characteristics of your spacecraft once you’re in flight. That’s what we’re doing right now. So far, the major deployments we’ve executed have gone about as smoothly as we could have hoped for. But we want to take our time and understand everything we can about the observatory before moving forward.”

Tensioning the sunshield is a complex process that NASA expects to take two days. NASA initially intended to start the work on Saturday, but Friday’s operations ran later than expected and the team decided to take New Year’s Day to rest.

And when mission managers decided to take a closer look at the motor temperatures, they didn’t want the team to be working on two aspects of the observatory at once.

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After the sunshield is fully tensioned, the team will move on to deploying the secondary mirror.

Although deployment has paused, the observatory is still making progress. As of just before 3 p.m. EST (2000 GMT), Webb was more than 510,000 miles (825,000 kilometers) away from Earth, or 57% of the way to its final destination of the Earth-sun Lagrange point 2. That point, also known as L2, is located nearly 1 million miles (1.6 million kilometers) from Earth in the direction opposite the sun.

Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook. 

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Massive Iceberg Released Over 150 Billion Tons of Fresh Water Into Ocean As It Scraped Past South Georgia – SciTechDaily

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The A68A iceberg with some smaller parts of ice that have broken off around it (November 21, 2020). Credit: MODIS image from NASA Worldview Snapshots

Scientists monitoring the giant A68A Antarctic iceberg from space reveal that a huge amount of fresh water was released as it melted around the sub-Antarctic island of South Georgia.

152 billion tonnes of fresh water – 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 the megaberg A68A melted over 3 months in 2020/2021, according to a new study. 

In July 2017, the A68A iceberg snapped off the Larsen-C Ice Shelf on the Antarctic Peninsula and began its epic 3.5 year, 4000 km journey across the Southern Ocean. At 5719 square kilometers in extent – 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.

Researchers from the Centre for Polar Observation and Modelling (CPOM) and British Antarctic Survey (BAS) used satellite measurements to chart the A68A iceberg’s area and thickness change throughout its life cycle. The authors show that the berg 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 tonnes of fresh water in close proximity to the island – a disturbance that could have a profound impact on the island’s marine habitat.

A68A Iceberg Approaching the Island of South Georgia

A68A iceberg approaching the island of South Georgia (December 14, 2020). The left-hand part of the image are clouds. Credit: MODIS image from NASA Worldview Snapshots

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 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 in the Scotia Sea 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 iceberg alley and into the Scotia Sea where it then gained speed and approached the island of South Georgia very closely.”

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Thinning and breakage of the A68A iceberg over time. Melt rates increase sharply once the iceberg is drifting in open ocean north of the Antarctic peninsula. Iceberg thickness was derived from satellite altimetry data from Cryosat-2 and ICESat-2. Iceberg shape and size were sourced from Sentinel-1, Sentinel-3 and MODIS satellite data. Credit: Anne Braakmann-Folgmann CPOM

If an iceberg’s keel is too deep it can get stuck 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 afterward, 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 meltwater 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 tonnes of fresh water and nutrients.

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Anne Braakmann-Folgmann, a researcher at CPOM and PhD candidate at the University of Leeds’ School of Earth and Environment, is lead author of the study. She said:

“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.”

The journey of A68A has been charted using observations from 5 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, said:

“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.”

Reference: “Observing the disintegration of the A68A iceberg from space” by A. Braakmann-Folgmann, A. Shepherd, L. Gerrish, J. Izzard and A. Ridout, 10 January 2022, Remote Sensing of Environment.
DOI: 10.1016/j.rse.2021.112855

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Shattered 'alphabet soup' iceberg flushed a lot of fresh water into the ocean – Space.com

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A rogue iceberg that drifted dangerously close to an Antarctic penguin population in 2020 and 2021 released billions of tons of fresh water into the ocean during its breakup.

A new study, based on satellite data, tracks the aftermath of the once-mighty iceberg A-68a, which held the title of world’s largest iceberg for more than three years before shattering into a dozen pieces. (NASA’s Earth Observatory once dubbed the various mini-bergs “alphabet soup.”)

For a while, there were worries the iceberg might threaten a penguin-filled island called South Georgia, located about 940 miles (1,500 kilometers) northeast of the Antarctic Peninsula. Happily, that never came to pass, but the new research shows that the iceberg flooded the region with fresh water, potentially affecting the local ecosystem and providing yet another example of the effects of global warming on the oceans.

Related: Watch this giant iceberg break off from Antarctica

The research consulted data gathered by missions including Sentinel-1 (operated by European Space Agency, or ESA), Sentinel-3 (ESA), CryoSat-2 (ESA) and ICESat-2 (NASA), as well as the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument that flies aboard two NASA satellites, Aqua and Terra.

The satellite data shows that during the iceberg’s three-month melting period in late 2020 and early 2021, the former A-68a flushed into the ocean about 162 billion tons (152 billion metric tonnes) of fresh water — equivalent to 61 million Olympic-sized swimming pools, according to a press release from United Kingdom study participant University of Leeds.

“The berg had melted enough as it drifted to avoid damaging the sea floor around South Georgia by running aground,” the university stated. “However, a side effect of the melting was the release of a colossal 152 billion tonnes of fresh water in close proximity to the island — a disturbance that could have a profound impact on the island’s marine habitat.”

Fresh meltwater and nutrients tend to flow from melting icebergs. The freshwater flooding alters ocean circulation and the ocean ecosystem nearby the glacier fragment, the university noted.

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“The next thing we want to learn is whether it had a positive or negative impact on the ecosystem around South Georgia,” Leeds lead author and Ph.D. candidate Anne Braakmann-Folgmann said in the same statement. 

She noted the iceberg moved across a common ocean “highway” known as the Drake Passage, so the fate of A68-A may help understand how icebergs in that zone influence the ocean in general.

A study based on the research was published in the forthcoming March 1 issue of Remote Sensing of Environment.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook

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Robot dog that can hike peaks in the Swiss Alps unaided could be used on other planets – Euronews

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This robot dog hiked over a steep mountain in Switzerland – and it didn’t need the help of its humans to overcome the many obstacles of the rough terrain.

The skilled dog bot could be used to reach areas that are too dangerous or inaccessible to humans, including other planets, according to its creators.

The research by ETH Zurich effectively allows ANYmal, a four-legged robot dog, to move quickly over rough terrain while still taking care – a new trait for robots.

The robot dog is able to work out how to walk over any terrain by combining what its sensors can “see” with what it knows about its surroundings, just like people or animals.

“Until now when a robot used perception mostly they were just assuming that the map is always correct,” said Takahiro Miki, a PhD student at the Robotics Systems Lab at ETH Zurich.

“But often when we go outdoors this doesn’t happen, like when you go into the tall grass”.

The team used landscapes with visual obstacles like deep snow and tall grass as an example of when a robot’s camera systems produce a map of the landscape that doesn’t work when the robot puts its foot down.

ANYmal’s control system allows it to prioritise its sense of touch over its visual perception.

The team put the ability to the test on a hiking route up Mount Etzel in the Swiss Alps which stands 1,098 metres above sea level.

“The slope was quite steep, like it was even hard sometimes for us. It was quite exhausting but the robot could go over all of these obstacles and we didn’t need to help the robot,” Miki said.

The scientists hope the new skill could allow ANYmal to be deployed anywhere on Earth and on space missions to other planets.

Hundreds of four-legged robots, many of them made by Hyundai-owned Boston Dynamics, are already in use, some in hostile industrial environments, including one performing survey work in Chernobyl and another working on a BP oil rig in the Gulf of Mexico.

For more on this story, watch the video in the media player above.

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