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Speaker 1: Welcome to Astronomy Daily.

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Speaker 2: I'm excited to bring you another fascinating day of space

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and astronomy news. There's quite a bit to cover today,

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from orbital drama to seasonal changes on the Red planet.

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We'll start with a concerning development in Earth orbit, where

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a retired military weather satellite has broken up into dozens

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of pieces, adding to a pattern of similar incidents with

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these particular spacecraft. Then we'll look ahead to SpaceX's upcoming

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Bandwagon two mission, which will carry an impressive array of

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thirty different payloads into orbit, including an advanced.

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Speaker 1: Radar satellite for South Korea.

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Speaker 2: We'll also take a journey to Mars, where NASA's Mars

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Reconnaissance Orbiter has been capturing some incredible seasonal phenomena. Unlike

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Earth's gentle seasonal transitions, Mars experiences some remarkably explosive changes

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during its spring thaw, and I can't wait to tell

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you all about them. Plus, we've got to look at

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a new theory about that mysterious dark energy, and we'll

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revisit an age old debate with some new research.

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Speaker 1: So let's get started.

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Speaker 2: In a concerning development, the US Space Force has reported

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that a defunct military weather satellite experienced what they're calling

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a low velocity fragmentation event on December eighteenth. The incident

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occurred at an altitude of about eight hundred and forty kilometers,

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creating more than fifty pieces of trackable debris, according to

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radar observations from commercial space monitoring company Leo Labs. The

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satellite in question, known as DMSP five D two F fourteen,

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was launched back in nineteen ninety seven as part of

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the Defense Meteorological Satellite Program. After serving its purpose for

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over two decades, it was retired in twenty twenty, but

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remained in its Sun synchronous orbit. Weighing about seven hundred

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and fifty kilograms, this spacecraft is now the latest in

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a series of similar satellites to meet this unfortunate fate.

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What's particularly concerning is that this isn't an isolated incident.

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Several other satellites from the same family have experienced similar

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breaks make ups over the years. In October twenty sixteen,

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the F twelve satellite broke apart, following the fragmentation of

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F thirteen. In February twenty fifteen, going back even further,

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the F eleven spacecraft created fifty six pieces of tracked

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debris when it broke up in two thousand four. The

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root cause appears to be a known design flaw in

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these satellites battery assemblies that makes them vulnerable to explosion.

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This issue isn't limited to military satellites either. Similar civilian

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weather satellites operated by Noah have suffered the same fate,

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with Noah sixteen breaking up in twenty fifteen and Noah

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seventeen following suit in twenty twenty one. Most troubling is

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that these breakups occurred despite attempts to prevent them through

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a process called passivation, where satellites are prepared for decommissioning

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by draining their batteries and venting fuel tanks.

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Speaker 1: Industry experts note.

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Speaker 2: That this process may not be fully effective on older

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satellites that were designed before modern orbital debris mitigation practices

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were established. Next up, SpaceX is gearing up for an

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exciting ride share mission from Vandenberg Space for Space in California.

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The Bandwagon two mission, scheduled for a three thirty four

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am Pacific launch on December twenty first, will carry an

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impressive array of thirty different payloads to orbit the Star

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of this mission is a sophisticated radar satellite for South Korea,

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capable of seeing through clouds and darkness to capture detailed

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images of Earth. This spacecraft is part of South Korea's

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four hundred and twenty five project, a constellation of military

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Earth observation satellites that combines both optical and radar imaging capabilities.

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Among the other fascinating payloads are two satellites from Ice

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that will join their radar imaging constellation, and a trio

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of satellites from Hawkeye three hundred and sixty that will

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work together to pinpoint radio frequency transmissions from orbit. Two

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compact weather satellites from tomorrow dot Io will collect valuable

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atmospheric data, while LIZZISATI will test out new imaging and

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computing technologies in space. The mission will use Falcon nine

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booster B one THY seventy one, making its twenty first flight.

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After sending its passengers on their way, the booster will

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return to land at landing Zone four, right next to

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its launch pad. The second stage will perform a carefully

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choreographed series of burns to deploy the satellites at two

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different altitudes, most at five hundred and ten kilometers and

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the South Korean satellite at five hundred and seventy kilometers.

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This launch represents SpaceX's one hundred thirty first Falcon mission

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of the year, marking an incredibly busy period for the company.

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It's also their second dedicated ride share mission to a

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mid inclination orbit, specifically chosen to keep these satellites positioned

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over more populated areas of our planet rather than following

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the polar orbits typically used for Earth observation missions. After deployment,

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these satellites will begin their diverse missions from Earth imaging

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and weather monitoring, to testing new space technologies and providing

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communications serve vises. Together, they represent a remarkable snapshot of

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the increasing variety and capability of small satellites being launched today.

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Ever thought about the concept of seasons on other planets.

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While we're celebrating the approaching new year here on Earth,

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Mars has already completed its journey around the Sun, marking

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the end of its six hundred and eighty seven Earth

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Day year this past November. But unlike Earth's northern winter

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wonderland or southern hemispheres summer, Mars is experiencing a spectacular

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spring awakening that's far more dramatic than anything we see

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here at home. Instead of gentle snow melt and trickling streams,

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Mars puts on an explosive show. The red planet's thin

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atmosphere means ice doesn't gradually melt into liquid. It transforms

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directly into gas in a process called sublimation. This creates

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some truly remarkable phenomena that NASA's Mars Reconnaissance orbiter has

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been tracking for nearly two decades. One of the most

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dramatic events are the frost avalanche. Imagine witnessing a massive

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chunk of carbon dioxide frost wider than a house, breaking

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free and tumbling down Martian cliffs. The orbiter's high resolution

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cameras actually captured one of these spectacular events, showing a

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sixty six foot wide block of dry ice in freefall.

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But that's just the beginning. As spring temperatures rise, pressurized

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carbon dioxide gas builds up beneath the surface ice until

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it literally explodes upward, creating powerful geysers that blast dark

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fans of sand and dust into the Martian sky. These

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explosive jets leave behind distinctive patterns in the soil that

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when viewed from orbit, look remarkably like giant spider legs

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etched into the surface. Perhaps most impressive is the planet's

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northern ice cap, a structure as large as Texas that

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features enormous spiral troughs carved by powerful seasonal winds. Some

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of these troughs stretch as long as California, dwarfing similar

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features found in Antarctica. As the spring thaw begins, these

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channels become super highways for warm wind gusts that gain

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speed and heat as they race downhill. These same winds

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are constantly reshaping Mars's landscape, particularly its sand dunes. During winter,

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carbon dioxide frost locks these dunes in place, but once

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spring arrives and the frost sublimates, they begin their slow

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migration across the Martian surface. It's a seasonal dance that's

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been ongoing for eons, sculpting and reshaping the face of

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our neighboring planet. What makes this even more fascinating is

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that each Martian spring is unique, with subtle variations in

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temperature and timing creating different patterns of sublimation and surface activity.

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It's a reminder that Mars, despite its apparent desolation, is

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a dynamically changing world with its own distinctive seasonal rhythm. Now,

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let's dive into a topic that's been puzzling scientists for

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decades dark energy. For years, the term dark energy has

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been used to describe the mysterious force believed to drive

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the accelerated expansion of our universe. It's thought to make

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up about two thirds of the universe's total mass energy content. However,

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recent research from the University of Canterbury in christ Church,

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New Zealand challenges this long standing concept. Led by Professor

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David Wiltshire, the team analyzed supernova light curves with enhanced precision.

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Their findings suggest that the universe's expansion isn't uniform, but

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rather lumpy, varying in different regions. This challenges the conventional

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lambda cold dark matter model, which relies on dark energy

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to explain the universe's accelerating expansion. The researchers propose an alternative,

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the timescape model. This model considers that gravity affects time,

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causing clocks and regions with different gravitational strengths to tick

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at varying rates. For instance, a clock in the emptiness

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of space would run faster than one within a galaxy.

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These time differences could lead to the perception of an

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accelerating universe without invoking dark energy. Professor Wiltshire explains our

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findings show that we do not need dark energy to

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explain why the universe appears to expand at an accelerating rate.

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He suggests that what we've been interpreting as dark energy

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might actually be variations in the kinetic energy of expansion

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influenced by the universe's lumpy structure. This perspective also offers

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insights into the Hubble tension, the discrepancy between the current

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expansion rate of the universe and predictions based on early

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universe observations. By accounting for regional variations and expansion, the

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Timescape model could bridge this gap. While these findings are compelling,

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they don't entirely dismiss the existence of dark energy. Instead,

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they encourage a reevaluation of our cosmological models and highlight

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the importance of considering the universe's complex structure in our calculations.

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As we continue to explore these cosmic mysteries, each discovery

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brings us closer to understanding the true nature of our universe.

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It's a thrilling reminder of how much there is yet

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to learn. Finally, today, let's revisit a classic debate, what

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really caused the extinction of the dinosaurs. For decades, scientists

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have pondered whether massive volcanic eruptions or a catastrophic meteorite

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impact led to the dinosaur's demise. Recent research from utrect

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University and the University of Manchester sheds new light on

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this mystery. The study focuses on the Deccan Traps in India,

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where colossal volcanic eruptions occurred around sixty six million years ago.

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These eruptions released vast amounts of sulfur and carbon dioxide,

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potentially altering the global climate. By analyzing fossil molecules from

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ancient peats in the United States, scientists reconstructed air temperatures

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during this period. They discovered that a significant volcanic eruption

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about thirty thousand years before the meteorite impact caused a

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global cooling of approximately five degrees celsius. However, temperatures rebounded

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twenty thousand years before the impact, likely due to volcanic

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CO two emissions. This timeline suggests that while these volcanic

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events had drastic consequences, for life on Earth. Their climatic

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effects had dissipated thousands of years before the chi Salub

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meteorite struck. Therefore, the meteorite impact remains the primary culprit

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behind the mass extinction event that wiped out the dinosaurs.

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Lauren O'Connor of Utrecht University notes these volcanic eruptions and

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associated CO two and sulfur releases would have had drastic

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consequences for life on Earth, but these events occurred millennia

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before the meteorite impact and probably played only a small

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part in the extinction of dinosaurs. This research underscores the

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catastrophic impact of the Chisalub meteorite, which unleashed wildfires, earthquakes, tsunamis,

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and an impact winter that blocked sunlight and devastated ecosystems.

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Understanding these events helps us piece together Earth's complex history

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and the factors that have shaped life on our planet.

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It's a fascinating reminder of the dynamic forces at play

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over geological timescales, and that wraps up today's fascinating journey

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through space, from Earth orbiting satellite breakups to SpaceX's ambitious

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ride share mission and the dramatic spring spectacle unfolding on Mars.

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I'm Anna and I hope you've enjoyed this episode of

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Astronomy Daily. If you're hungry for more space content, I've

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got great news for you. Head over to Astronomy Daily

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While you're there, you can also catch up on all

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Speaker 1: And TikTok.

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Speaker 2: We'd love to hear your thoughts on today's stories and

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engage with you about all things space. Thank you for

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spending time with us today exploring the wonders of space.

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Until next time, keep looking up and stay curious about

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our cosmic neighborhood.

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Speaker 1: Sunny Day Star is so.

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Speaker 2: Star is Star