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NASA’s mission to deflect asteroid is a step towards preparing the world for a potential future asteroid strike like the one which killed the dinosaurs some 66 million years ago, the chances of which are very slim in our lifetime, Indian scientists said.

In a first-of-its-kind mission, the Double Asteroid Redirection Test (DART) spacecraft successfully crashed into an asteroid on Tuesday to test whether space rocks that might threaten Earth in the future could be nudged safely out of the way.

DART – the world’s first planetary defence technology demonstration — targeted the asteroid moonlet Dimorphos, a small body just 160 metres in diameter.

“We are surrounded by several asteroids and comets that orbit our Sun. Very few of them are potentially hazardous to Earth. Hence, It is better to prepare our defenses to avoid such asteroids on a collision course with Earth in the future,” said Chrisphin Karthick, a scientist at the Indian Institute of Astrophysics (IIA), Bengaluru.

Karthick, who is involved in the DART project, noted that the mission “certainly is a step towards” preparing the world for a potential future event like the one which is believed to have led to the extinction of dinosaurs some 66 million years ago.

“This successful DART mission is an example of that. We now know to precisely aim the spacecraft for such a small body. We can also prepare ourselves for the larger body from the post-impact observations of this DART mission,” Karthick told PTI.

Dimorphos orbits a larger 780-metre asteroid called Didymos. Neither asteroid poses a threat to Earth. By comparison, the dinosaur-killing asteroid that hit Earth was about 10 kilometers in diameter.

The DART mission’s one-way trip, confirmed NASA, can successfully navigate a spacecraft to intentionally collide with an asteroid to deflect it, a technique known as kinetic impact.

Goutam Chattopadhyay, a senior scientist at NASA’s Jet Propulsion Laboratory (JPL) in the US also noted that the mission will help to prepare for a future-threatening asteroid.

“DART is an experimental mission to try out a concept of deflecting an asteroid. The idea is, if we can encounter these asteroids whose trajectory is towards us and we do that at a sufficient distance from the Earth, then a minor deflection will be enough to change the path of the asteroid,” he added.

However, scientists noted that most of the asteroids, which are somewhat significant in size and can cause damage on impact with the Earth, have a minuscule chance of hitting the planet.

“However, the probability of that is non-zero and we must always be vigilant. There is always a possibility that a big one might be headed towards us and the question becomes, what would be our approach and how we could mitigate that. That’s why these programs are important,” Chattopadhyay told PTI.

“At least for the next century, there is no such threat from the known asteroids that can cause mass casualties,” said Karthick, adding that this risk assessment is, however, based on the asteroids known to science so far.

Small asteroids are always hitting the Earth all the time but they burn due to the heat generated in the atmosphere. However, for sufficiently large asteroids, that is not the case as the outer core will burn but there will be sufficient mass left to create damage.

The team will now observe Dimorphos using ground-based telescopes to confirm that DART’s impact altered the asteroid’s orbit around Didymos.

Researchers expect the impact to shorten Dimorphos’ orbit by about 1 per cent, or roughly 10 minutes; precisely measuring how much the asteroid was deflected is one of the primary purposes of the full-scale test.

“Post impact, the team will observe Dimorphos using ground-based telescopes to confirm that DART’s impact altered the asteroid’s orbit around Didymos,” Karthick said.

“The expected output of the impact is to shorten Dimorphos’ orbit by about 1 per cent, or roughly 10 minutes. One of the primary goals is to measure the deflection of the asteroid’s orbit,” he added.

However, Chattopadhyay said whether the mission has been able to deflect the orbit of the asteroid will be known only once all the data has been collected.

“I would emphasise that our calculations and small-scale lab experiments show that it might work well,”. he added NASA has a multi prong approach to monitor Near Earth Asteroids (NEAs). The space agency initiated observations program in 1998. Most discoveries are supported by ground-based telescopic surveys, “We primarily use radars and lidars for this. Mostly they are ground-based systems. However, our existing satellites in space are also used to image and track these objects,” the scientist added.

Lidar is a method for determining distance by targeting an object or a surface with a laser and measuring the time for the reflected light.

“The DART mission is humanity’s first attempt to alter the trajectory of an asteroid by crashing a human made object into it. Today’s successful impact is a big step forward in that direction.

“However, to know the eventual success of this concept, we have to wait a few more years by when any significant change in the trajectory would be clearly apparent,” said Dibyendu Nandi, space scientist at Indian Institutes of Science Education and Research, Kolkata.


Buying an affordable 5G smartphone today usually means you will end up paying a “5G tax”. What does that mean for those looking to get access to 5G networks as soon as they launch? Find out on this week’s episode. Orbital is available on Spotify, Gaana, JioSaavn, Google Podcasts, Apple Podcasts, Amazon Music and wherever you get your podcasts.
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Hubble finds missing globular cluster in Milky Way’s crowded stellar halo

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Hubble finds missing globular cluster in Milky Way’s crowded stellar halo

A striking new image captured by NASA’s Hubble Space Telescope has shed light on an underexplored gatekeeper of our galactic neighbours’ achievements and tragedies. Adorned with multi-hued stars, the spherical cluster glitters amid the expanse of stars in our Milky Way galaxy. This type of globular cluster is a very dense grouping of stars — about the same mass as 100,000 suns — that orbit all around the centre of their galaxy. Stars in a cluster are typically roughly the same age, as they formed from the same collapsing gas cloud. In this new view, stars show up in temperatures indicated in red and blue colours: red for colder and blue for hotter stars.

Hubble Maps Forgotten Star Cluster ESO 591-12 to Uncover Milky Way’s Ancient Stellar Secrets

As per a report from NASA’s Hubble team, ESO 591-12 was imaged during the Hubble Missing Globular Clusters Survey—an initiative targeting 34 Milky Way globular clusters that had never been observed by the space telescope. The aim is to construct a comprehensive database of the ages, distances, and stellar populations of all the galaxy’s known globular clusters and star formations. However, it has always been tough for telescopes on Earth to pick out individual stars in these densely populated regions, so Hubble’s high resolution has done much to finally be able to track the movements of stars to unlock their histories and formation.

The ESO 591-12 data are part of an ongoing study to improve knowledge of the formation and evolution of globular clusters in the galaxy’s bulge and halo. These star clusters are cosmic fossils that have preserved cosmic conditions from the primordial universe. Their work helps build a fuller narrative of the evolution of the Milky Way and how it has changed over billions of years.

This new image is a further example of how advanced space-based observing facilities are helping astronomers to excavate the contents of the dark and dusty skeleton cloaking the Milky Way and sculpt a better understanding of not only the universe’s evolution but also that of our cosmic home.
Each one tells part of the astronomical story, and Hubble is digging out new chapters to enrich the tale, such as probing data for clusters as much as ESO 591-12, which have been mostly neglected until now. This finding adds to our knowledge of the early universe by shining a spotlight on something that was in plain sight.

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Very Massive Stars Blow Away Outer Layers in Powerful Winds Before Black Hole Collapse

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Massive stars shed extreme mass before collapsing into black holes

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Massive stars shed extreme mass before collapsing into black holes

New research indicates that the most monstrously huge stars — those more than 100 times as massive as the sun — shed at least 20 times more matter before they collapse than previously thought to do so as they cool off to become black holes. These stars blow off a significant portion of their outer layers in quite powerful stellar winds over the brief but intense course of their lives, leaving behind low masses at the end. One benefit of this extreme mass loss is that it can account for observed strangeness in stars such as those in the Tarantula Nebula, providing new information on stellar evolution, black hole formation, and sources of gravitational waves.

Hurricane-like Stellar Winds Explain Extreme Mass Loss in Universe’s Most Massive Stars

As per a report from Space.com, researchers used sophisticated models and observations to learn that very massive stars give off winds so powerful they act more like hurricanes than gentle solar breezes. Their results agree very well with observations of WNh-type Wolf-Rayet stars in the Tarantula Nebula, which are hotter and more compact than would be expected by standard models. The improved models explain the very high temperatures at the surface and the stability of hydrogen, which address previous challenges.

One key subject in this study is R136a1 — the most massive known star — with a mass up to 230 times that of the sun. The researchers suggested that it either formed as a single star of around 200 solar masses or as a binary star system where the two stars had a combined mass of about 200 solar masses. In both such cases, the star must have lost a huge amount of mass early in its life, so the findings would call into question how it is that massive stars can live long enough to leave such a wreckage in the Large Magellanic Cloud.

The implications extend to black hole formation as well. More massive stellar winds erode more mass, resulting in the production of smaller black holes and decreasing the chances of creating elusive intermediate-mass black holes. This revision also enhances the matches of the model with the observed gravitational wave signal of a coalescing black hole binary.

Although the models are restricted to stars in the Tarantula Nebula, the researchers stress that in order for their findings to be considered universal, it is important to understand stars in different chemical environments as well. The results not only reshape predictions of black hole populations but may also adjust our understanding of how the most massive stars in the universe live — and die.

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New Interstellar Comet 3I/ATLAS Speeds Through Solar System

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Astronomers Capture First-Ever Image of a Dead Star That Exploded Twice in Rare Supernova Event

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Astronomers Capture First-Ever Image of a Dead Star That Exploded Twice in Rare Supernova Event

For the first time, a team of astronomers has captured a clear image of a white dwarf star that exploded not just once, but twice, as a Type Ia supernova — a “double-detonation” that scientists hadn’t thought possible until now. The extraordinary observation could revise our long-held notions of how stars die, suggesting that some stars can explode as supernovas without ever crossing the Chandrasekhar limit, the minimum mass normally thought necessary for such an explosion. The astronomers employed the Very Large Telescope’s MUSE instrument to zoom in on the four-century-old supernova remnant SNR 0509-67.5, which sits 60,000 light-years away in the constellation Dorado, revealing evidence of two separate blasting catastrophes in its construction.

First Visual Proof Shows White Dwarfs Can Explode Twice Without Reaching Chandrasekhar Limit

As the researchers report on July 2 in Nature Astronomy, the team found a distinctive “fingerprint” in the debris of SNR 0509-67.5 in the Large Magellanic Cloud that the models predicted. White dwarfs—which are the dead stage of sun-like stars—usually blow up into Type Ia supernovas after they hit the Chandrasekhar limit by stealing matter from a neighbouring star.

However, this finding shows that the detonation can be launched at an earlier time. The explosion is likely to have a two-step origin, the team argues, with the initial blast being generated when an unstable layer of helium that the star had acquired exploded on its surface; the resulting shock wave then drove a second and main detonation.

“This physical proof of a double-detonation not only helps solve a long-standing mystery of what causes these explosions, but it represents the most visually compelling evidence for this origin.” Priyam Das, University of New South Wales, team leader and author.

Something is happening to Type Ia supernovas, the “standard candles” used to measure cosmic distances, because their brightness doesn’t fluctuate. But they have long mystified scientists with how they explode. Until this discovery, an explosion white dwarf that didn’t surpass the Chandrasekhar limit was only considered in theory.

This fresh visual evidence for the double detonation model further informs our knowledge of stellar evolution and also informs how we should interpret light from distant supernovas. More than its scientific implications, its discovery adds a colourful new page to the story of dying stars — stars that, as it now appears, will not go gently into that night but will light up the sky twice over in fantastic fireworks before vanishing from the cosmos.

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