Whether Saturn’s Rings are Young or Old, its Moons are as Ancient as the Planet Itself
Saturn is best known for two things: its iconic ring structures and its large system of natural satellites. Currently, 146 moons and moonlets have been discovered orbiting the ringed giant, 24 of which are regular satellites. These include the seven largest moons, Titan, Rhea, Iapetus, Dione, Tethys, Enceladus, and Mimas, which are icy bodies believed to have interior oceans. In addition, there are unresolved questions about the age of these satellites, with some suspecting that they formed more recently (like Saturn’s rings, which are a few hundred million years old).
To address these questions, an international team of astronomers created a series of high-resolution simulations coupled with improved estimates of Trans-Neptunian Object (TNO) populations. This allowed them to construct a chronology of impacts for Saturn’s most heavily cratered regular satellites – Mimas, Enceladus, Tethys, Dione, and Rhea. This established age limits of 4.1 and 4.4 billion years for all five, with the two innermost moons appearing more youthful than the outer three. These results could have significant implications for our understanding of the formation and tidal evolution of moons in the outer Solar System.
The research was led by Emily Wai Wong, a researcher with the Earth-Life Science Institute (ELSI) at the Tokyo Institute of Technology. She was joined by Ramon Brasser, an associate professor at the ELSI and the Origins Research Institute at the Research Centre for Astronomy and Earth Sciences (ORI-RCAES), Stephanie C. Werner, the deputy director of the Center for Planetary Habitability (PHAB) at the University of Oslo, and lead research scientist Michelle R. Kirchoff of the Southwest Research Institute (SwRI). Their paper, “Saturn’s ancient regular satellites,” recently appeared in the journal Icarus.
Saturn’s largest moons. Credit: NASA/JPL-Caltech/Emily Lakdawalla, Ted Stryk, Gordan Ugarkovic, & Jason Perry
Since sample-return missions have not yet been sent to the Saturn system, obtaining accurate ages for its satellites is very difficult. In lieu of radiometric dating samples, Wong and her team turned to establishing a crater chronology of these satellites. By dating impact craters on the surface, some general constraints can be established for how long these moons have been around. The first step in this process was to model cratering rates in the outer Solar System, where the migration of the giant planets led to periods of bombardment by displaced TNOs and other objects.
In a previous study, Wong and her colleagues conducted a timeline simulation of the outer Solar System starting from the onset of giant planet migration, which they set at 4.5 billion years ago. They then used predictive Monte Carlo simulations to determine the expected crater densities, assuming two different size-frequency distributions of TNOs encountering the giant planets and their satellites. These were combined to derive surface ages for the most heavily cratered satellites of Jupiter, Saturn, and Uranus, ranging from 3.8 to 4.4. billion years.
Unfortunately, these and other previous simulations suffered from poor resolutions for the last 3.5 billion years because of a limited number of planetesimals in their simulations. This prevented them from obtaining accurate ages of satellites with low crater densities (like Enceladus), and the ages derived showed significant variation based on the two different sizes of TNOs. As they note in their paper:
“In this work, we obtained a more accurate crater chronology onto the icy regular satellites that can be applied to the whole history of the Solar System. We computed model surface ages for said satellites for various crater diameters from age isochrons similar to those that exist for the Moon and Mars in the inner Solar System. We applied this new chronology to the inner Saturnian satellites to compute more accurate model surface ages of their most densely cratered surfaces.”
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Iran Sent a Capsule Capable of Holding Animals into Orbit.
Despite popular opinion, the first animals in space were not dogs or chimps, they were fruit flies launched by the United States in February 1947. The Soviet Union launched Laika, the first dog into space in November 1957 and now, it seems Iran is getting in on the act. A 500kg capsule known as the “indigenous bio-capsule” with life support capability was recently launched atop the Iranian “Salman” rocket. It has been reported by some agencies that there were animals on board but no official statement has been released.
The Iranian Space Agency (ISA) are gearing up to getting humans into space before 2029 but is testing its launch capability with animal passengers. The capsule was launched on December 6 2023 and attained an orbital altitude of 130 kilometres. According to their Telecommunications Minister Isa Zarepour, it is aimed at sending Iranian astronauts to space by 2029.
The “Salaman” solid-fuelled rocket was designed by the aerospace division of the Ministry of Science, Research and Technology and built and launched by the Ministry of Defence and Armed Forces Logistics. It has already been used to launch a data collecting satellite and in 2013 successfully sent and returned monkeys into space.
Ham, a chimpanzee, became the first great ape in space during his January 31, 1961, suborbital flight aboard Mercury-Redstone 2 (Credit : NASA)
To date, only three counties have human spaceflight capability; USA, Russia and China. India are attempting to become the fourth as they work on their Gaganyaan program. Will Iran become the fifth!? Iran plans further tests with further launches bearing animal occupants before attempting to send humans up.
According to the Iranian Space Agency, its satellite program is purely for scientific research and other civilian applications. There is however, international suspicion because there are suspicions that the Salamn rockets could very easily be converted to long range missiles.
Source : Iran says it sent a capsule capable of carrying animals into orbit as it prepares for human missions
The post Iran Sent a Capsule Capable of Holding Animals into Orbit. appeared first on Universe Today.
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What Could a Next Generation Event Horizon Telescope Do?
Telescopes have come a long way in a little over four hundred years! It was 1608 that Dutch spectacle maker Hans Lippershey who was said to be working with a case of myopia and, in working with lenses discovered the magnifying powers if arranged in certain configurations. Now, centuries on and we have many different telescope designs and even telescopes in orbit but none are more incredible than the Event Horizon Telescope (EHT). Images las year revealed the supermassive black hole at the centre of our Galaxy and around M87 but now a team of astronomers have explored the potential of an even more powerful system the Next Generation EHT (ngEHT).
There is no doubt that our understanding of the processes within our Universe have come on leaps and bounds since the invention of the telescope. The resolution of these space piercing instruments is dictated by the telescope’s aperture. The technique known as interferometry hooks individual telescopes together and combines their signal so they act as one BIG telescope, boosting the resolution.
Telescopes like the EHT have been using interferometry to great advantage to study black holes. These enigmatic and mysterious stellar corpses defy our probing; we do not fully understand their origins and processes and indeed our laws of physics break down if you get too close to the point source in the centre, the singularity. Due to their interaction with space and time, understanding the full nature of black holes will – hopefully – unlock our understanding of the Universe.
Previously, observations have only revealed the movement of stars around galactic centre suggesting an object was lurking there weighing in at around 4 million times the mass of the Sun. Data from the EHT collected during 2022, finally revealed an image of the object at the centre – SgrA* – a super massive black hole and the matter in the immediate vicinity of the event horizon. Whilst this image did not reveal the black hole itself – another article required to explain that – it certainly revealed the telltale signs.
Sag A* compared to M87* and the orbit of Mercury. Credit: EHT collaboration
A recently published paper explores the possibilities of the ngEHT and how they might be able to unpick some of the physics around black holes. The ngEHT will increase the geographical footprint of EHT by 10 further instruments that span across the Earth. Making use of the significant improvement in resolution, the ngEHT will also improve image dynamics range, provide a multi-wavelength capability and facilitate long term monitoring.
The team conclude that future enhancements in measurement sensitivity and data analysis techniques in ngEHT will substantially advance our understanding of black holes and the immediate environments surrounding them with particular focus on the photon ring, mass and spin analysis, binary supermassive black holes and more besides.
Source : Fundamental Physics Opportunities with the Next-Generation Event Horizon Telescope
The post What Could a Next Generation Event Horizon Telescope Do? appeared first on Universe Today.
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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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