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There’s an old joke among astronomy students about a question on the final exam for a cosmology class. It goes like this: “Describe the Universe and give three examples.” Well, a team of researchers in Germany, the U.S., and the UK took a giant leap toward giving at least one accurate example of the Universe.

To do it, they used a set of simulations called “MillenniumTNG”. It traces the buildup of galaxies and cosmic structure across time. It also provides new insight into the standard cosmological model of the Universe. It’s the latest in cosmological simulations, joining such ambitious efforts as the AbacusSummit project of a couple of years ago.

This simulation project takes into account as many aspects of cosmic evolution as possible. It uses simulations of regular (baryonic) matter (which is what we see in the Universe). It also includes dark matter, neutrinos, and the still-mysterious dark energy on the formation mechanisms of the Universe. That’s a tall order.

Simulating the Universe

More than 120,000 computer cores in the SuperMUC-NG in Germany went to work on the data for MillenniumTNG. That tracked the formation of about a hundred million galaxies in an area of space about 2,400 million light-years across. Then the Cosma8 at Durham went to work computing a larger volume of the Universe but filled with a trillion simulated dark matter particles and another 10 billion that tracked the action of massive neutrinos.

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 Projections of gas (top left), dark matter (top right), and stellar light (bottom center) for a slice in the largest hydrodynamical simulation of MillenniumTNG at the present epoch. The slice is about 35 million light-years thick. Courtesy MPA.

The result of this number crunching was a simulated area of the Universe that mirrored the formation and distribution of galaxies. The size was big enough that cosmologists can use it to extrapolate assumptions about the entire Universe and its history. They can also use it to probe for “cracks” in the Standard Cosmological Model of the Universe.

The Cosmological Model and Prediction

Cosmologists have this basic model they propose to explain the evolution of the Universe. It goes like this: The Universe has different types of matter. There’s ordinary baryonic matter, which is what all of us and the stars, planets, and galaxies are made of. It’s just under 5% of the “stuff” of the cosmos. The rest is dark matter and dark energy.

A composite model of matter distribution (with dark matter overlay) in a galaxy formation simulation made by the TNG  Collaboration.
A composite model of matter distribution (with dark matter overlay) in a galaxy formation simulation made by the TNG Collaboration.

The cosmology community calls this strange set of cosmic circumstances the “Lambda Cold Dark Matter” model (LCDM, for short). It actually describes the Universe pretty well. However, there are some discrepancies. Those are what the simulations should help solve. The model is based on data from a huge variety of sources, including cosmic microwave radiation to the “cosmic web”, where galaxies are arranged along an intricate network of dark matter filaments.

What’s still missing is a good understanding of exactly what dark matter is. And, as for dark energy, well, it’s a challenge. And, astrophysicists and cosmologies are looking for a better understanding of LCDM and the existence of the two big unknowns. That requires a lot of sensitive new observations from astronomers. On the other side of the coin, it also needs more detailed predictions for what the LCDM model actually implies. It’s a huge challenge and is what’s driving the big MillenniumTNG simulations. If cosmologists can successfully simulate the Universe then they can use those simulations to help understand what’s happening “in real life.” That
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Déjà vu All Over Again: Backpacking in Glacier National Park

By Michael Lanza

In the second week of September, the cool air in the shade of the forest nips at our cheeks as we leave our first night’s camp beside Glenns Lake in the backcountry of Glacier National Park, starting at a reasonably early hour for a day where we will walk nearly 16 miles and 6,000 feet of combined uphill and downhill. I’m hiking in a fleece hoodie, pants, and gloves and my friends Pam Solon and Jeff Wilhelm are similarly layered up. Once the sun reaches us within an hour, we’ll strip down to shorts and T-shirts.

Where the trail crosses a meadow, the expansive view west across a calm and insistently blue Cosley Lake reveals what looks like a long wall of overlapping stone shields jammed into the earth, each 2,000 or more feet tall and tilting at different angles. At the lake’s outlet—now in warm sunshine—we ford the Belly River, ankle- to calf-deep here with just a few tiny riffles and not very cold. More hiking through quiet forest brings us to the refrigerated, cliff-shaded alcove below Dawn Mist Falls, which spills thunderously over a sheer drop and crashes onto fallen boulders at its base, its force releasing a perpetual mist. Moss wallpapers the alcove’s short cliffs.

A backpacker hiking the Ptarmigan Tunnel Trail in Glacier National Park.
” data-image-caption=”Pam Solon backpacking the Ptarmigan Tunnel Trail in Glacier National Park.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?fit=900%2C600&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?resize=900%2C600&ssl=1″ alt=”A backpacker hiking the Ptarmigan Tunnel Trail in Glacier National Park.” class=”wp-image-61144″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?resize=1024%2C683&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?resize=300%2C200&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?resize=768%2C512&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?resize=150%2C100&ssl=1 150w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/12/Gla7-35-Pam-Solon-backpacking-the-Ptarmigan-Tunnel-Trail-in-Glacier-National-Park.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Pam Solon backpacking the Ptarmigan Tunnel Trail in Glacier National Park.

After a thoroughly relaxing lunch break on the pebbly beach at Elizabeth Lake—where the perfect combination of solar warmth and soft breeze probably converts in direct value to about a thousand hours of counseling—we start the long climb to the Ptarmigan Tunnel. Reaching the open alpine terrain, I repeatedly stop to spin 180 degrees and take big bites of our view of the valley of Helen and Elizabeth lakes and the peaks on the other side, which shelter what remains of a couple of glaciers in the shade of north-facing cliffs just below the mountaintops.

I’ve backpacked this trail before; this isn’t new to me. But time slowly renders a bit fuzzier the memory of how constantly breathtaking it is—which is, in a funny way, a gift to us: We get to experience that awe anew each time.

Everyone laughed when the legendary Yogi Berra said, “It’s like déjà vu all over again,” but I think I knew what he meant.

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Fly Slowly Through Enceladus’ Plumes to Detect Life

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Enceladus is blasting water into space from the jets at its southern pole. This makes it the ideal place to send a dedicated mission, flying the spacecraft through the plumes with life-detection instruments s. A new study suggests that a spacecraft must proceed carefully through the plumes, keeping its speed below 4.2 km/second (2,236 miles per hour). Using a specialized, custom-built aerosol impact spectrometer at these speeds will allow fragile amino acids to be captured by the spacecraft’s sample collector. Any faster, they’ll shatter, providing inclusive results.

One of the biggest surprises of the 20-year Cassini mission to the Saturn system was the discovery of the active geysers at Enceladus. At only about 500 km (310 miles) in diameter, the ice-covered Enceladus should be too small and too far from the Sun to be active. Instead, this little moon is one of the most geologically dynamic objects in the Solar System.

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Geysers spew from Enceladus in this image from the Cassini spacecraft. Credit: NASA/Cassini mission.

Cassini’s stunning backlit images of this moon show plumes erupting in Yellowstone-like geysers, emanating from tiger-stripe-shaped fractures in the moon’s surface. The discovery of the geysers took on more importance when Cassini later determined the plumes contained water ice and organics. Since life as we know it relies on water and a source of energy, this small but energetic moon has been added to the short list of possible places for life in our Solar System.

During three of Cassini’s passes of Enceladus in 2008 and 2009, the spacecraft’s Cosmic Dust Analyser measured the composition of freshly ejected plume grains. The icy particles hit the detector target at speeds of 6.5–17.5 km/s, and vaporized instantly. While electrical fields inside the instrument were able to separate the various constituents of the resulting impact cloud for analysis, for a future mission, scientists would like to measure the particles in the plumes without completely vaporizing them.

Back in 2012, researchers from the University of California San Diego started working on a custom-built unique aerosol impact spectrometer, designed to study collision dynamics of single aerosols and particles at high velocities. Although it wasn’t built specifically to study ice grain impacts, it turns out this instrument might be exactly what planetary scientists are looking for to use at Enceladus, or even at Jupiter’s moon Europa, where there is growing evidence of active plumes of water vapor erupting from its surface.

Robert Continetti’s one-of-a-kind aerosol impact spectrometer was used in this experiment. Ice grains impact the microchannel plate detector (far right) at hypervelocity speeds, which can then be characterized in-situ.

Continetti and several colleague have now tested the device in a laboratory, showing that amino acids transported in ice plumes — like at Enceladus — can survive impact speeds of up to 4.2 km/s. Their research is published in The Proceedings of the National Academy of Sciences (PNAS).

“This apparatus is the only one of its kind in the world that can select single particles and accelerate or decelerate them to chosen final velocities,” said Robert Continetti, a professor from UC San Diego, in a press release. “From several micron diameters down to hundreds of nanometers, in a variety of materials, we’re able to examine particle behavior, such as how they scatter or how their structures change upon impact.”

From Cassini’s measurements, scientists estimate the ice plumes at Enceladus blast out at approximately .4 km/s (800 miles per hour). A spacecraft would have to fly at the right speeds to make sure the particles could be captured intact.

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This composite image shows suspected plumes of water vapour erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The plumes, photographed by Hubble’s Imaging
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The International Space Station Celebrates 25 Years in Space

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NASA recently celebrated the 25th anniversary of the International Space Station (ISS) with a space-to-Earth call between the 7-person Expedition 70 crew and outgoing NASA Associate Administrator, Bob Cabana, and ISS Program Manager, Joel Montalbano. On December 6, 1998, the U.S.-built Unity module and the Russian-built Zarya module were mated in the Space Shuttle Endeavour cargo bay, as Endeavour was responsible for launching Unity into orbit that same day, with Zarya having waited in orbit after being launched on November 20 from Kazakhstan.

“I cannot believe it was 25 years ago today that we grappled Zarya and joined it with the Unity node,” said Cabana during the call from NASA Headquarters in Washington, D.C. “Absolutely amazing.”

While this milestone marks 25 years since the first two ISS modules were attached, it would be another two years until the ISS had a crew, Expedition 1, which arrived at the ISS in November 2000 and stayed until March 2001, beginning an uninterrupted human presence on the ISS that continues today. During the two-year period between the first mating and Expedition 1, the Russian-built Zvedza module was attached to the Unity and Zarya modules on July 26, 2000, after launching from Kazakhstan two weeks earlier. Assembly of the large modules of the ISS would continue until 2021 when the Roscosmos-funded Nauka module was attached in July 2021.

Now in its final configuration, the ISS is approximately the size of an American gridiron football field consisting of 8 solar arrays that provide the station’s power while maintaining an average altitude of 400 kilometers (250 miles). Its massive size consists of a pressurized module length along the major axis of 67 meters (218 feet), a truss (primary body) length of 94 meters (310 feet), a solar array length (measured along the truss) of 73 meters (239 feet), and a total mass of 419,725 kilograms (925,335 pounds).

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Artist rendition of the ISS compared to an American gridiron football field. (Credit: NASA)
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Image of the ISS taken by SpaceX Crew-2 mission on November 8, 2021 after it successfully undocked from the ISS Harmony module. (Credit: NASA)

Ever since the 3-person Expedition 1 crew first took command of the ISS, a total of 273 individuals from 21 countries have visited the orbiting laboratory and have been comprised of trained astronauts and private visitors. From most visitors to least, the following visitor countries include the United States, Russia, Japan, Canada, Italy, France, Germany, Saudi Arabia, United Arab Emirates, Belgium, Brazil, Denmark, Great Britain, Israel, Kazakhstan, Malaysia, Netherlands, South Africa, South Korea, Spain, and Sweden.

“One of my favorite aspects of the International Space Station is the international part of it,” said NASA Astronaut and Expedition 70 Flight Engineer, Jasmin Moghbeli, during the call. “We each bring our unique perspectives, not just from our different nationalities, but also our different backgrounds. I think we’re definitely strengthened by the international partnership. It’s just like gaining redundancy when you have multiple partners working together. It’s stronger and more resilient to any sort of problems or obstacles that come our way and so it definitely makes us stronger. And I think that’s why we have had the International Space Station up here for 25 years now.”

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