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Ten months after launch, NASA’s asteroid-deflecting DART spacecraft neared a planned impact with its target on Monday in a test of the world’s first planetary defense system, designed to prevent a doomsday collision with Earth.

The cube-shaped “impactor” vehicle, roughly the size of a vending machine with two rectangular solar arrays, was on course to fly into the asteroid Dimorphos, about as large as a football stadium, and self-destruct around 7pm EDT (4:30 IST) some 6.8 million miles (11 million km) from Earth.

The mission’s finale will test the ability of a spacecraft to alter an asteroid’s trajectory with sheer kinetic force, plowing into the object at high speed to nudge it astray just enough to keep our planet out of harm’s way.

It marks the world’s first attempt to change the motion of an asteroid, or any celestial body.

DART, launched by a SpaceX rocket in November 2021, has made most of its voyage under the guidance of NASA’s flight directors, with control to be handed over to an autonomous on-board navigation system in the final hours of the journey.

Monday evening’s planned impact is to be monitored in real time from the mission operations center at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.

DART’s celestial target is an asteroid “moonlet” about 560 feet (170 metres) in diameter that orbits a parent asteroid five times larger called Didymos as part of a binary pair with the same name, the Greek word for twin.

Neither object presents any actual threat to Earth, and NASA scientists said their DART test cannot create a new existential hazard by mistake.

Dimorphos and Didymos are both tiny compared with the cataclysmic Chicxulub asteroid that struck Earth some 66 million years ago, wiping out about three-quarters of the world’s plant and animal species including the dinosaurs.

Smaller asteroids are far more common and pose a greater theoretical concern in the near term, making the Didymos pair suitable test subjects for their size, according to NASA scientists and planetary defense experts.

Also, their relative proximity to Earth and dual-asteroid configuration make them ideal for the first proof-of-concept mission of DART, short for Double Asteroid Redirection Test.

Robotic mission suicide

The mission represents a rare instance in which a NASA spacecraft must ultimately crash to succeed.

The plan is for DART to fly directly into Dimorphos at 15,000 miles per hour (24,000 kph), bumping it hard enough to shift its orbital track closer to its larger companion asteroid.

Cameras on the impactor and on a briefcase-sized mini-spacecraft released from DART days in advance are designed to record the collision and send images back to Earth.

DART’s own camera is expected to return pictures at the rate of one image per second during its final approach, with those images streaming live on NASA TV starting an hour before impact, according to APL.

The DART team said it expects to shorten the orbital track of Dimorphos by 10 minutes but would consider at least 73 seconds a success, proving the exercise as a viable technique to deflect an asteroid on a collision course with Earth – if one were ever discovered. A small nudge to an asteroid millions of miles away could be sufficient to safely reroute it away from the planet.

The test’s outcome will not be known until a new round of ground-based telescope observations of the two asteroids in October. Earlier calculations of the starting location and orbital period of Dimorphos were confirmed during a six-day observation period in July.

DART is the latest of several NASA missions in recent years to explore and interact with asteroids, primordial rocky remnants from the solar system’s formation more than 4.5 billion years ago.

Last year, NASA launched a probe on a voyage to the Trojan asteroid clusters orbiting near Jupiter, while the grab-and-go spacecraft OSIRIS-REx is on its way back to Earth with a sample collected in October 2020 from the asteroid Bennu.

The Dimorphos moonlet is one of the smallest astronomical objects to receive a permanent name and is one of 27,500 known near-Earth asteroids of all sizes tracked by NASA. Although none are known to pose a foreseeable hazard to humankind, NASA estimates that many more asteroids remain undetected in the near-Earth vicinity.

NASA has put the entire cost of the DART project at $330 million (roughly Rs. 2,700 crore), well below that of many of the space agency’s most ambitious science missions.

© Thomson Reuters 2022


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Did Domesticated Cats Originate in Tunisia? New Study Sheds Light

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Did Domesticated Cats Originate in Tunisia? New Study Sheds Light

The origin of domestic cats has been a prominent topic amongst researchers. Their emergence has been linked to the Neolithic period, where they accompanied the farmers while spreading across Europe, along with the agricultural adaptation. However, further investigations have been conducted wherein the significance puzzled the archaeologists. Recently, two large-scale investigations were conducted by the University of Rome Tor Vergata and 42 institutions, and another by the University of Exeter and contributors from 37 institutions, pointing out that Tunisia could be the place of the origin of the domestic cat.

The Tor Vergata Study on Cats

The expert team of researchers from the University of Rome Tor Vergata conducted paleo-genomic analyses, where they analyzed the specimens of cats from 97 archaeological sites across Europe and Anatolia. Likewise, they also took samples from North Africa, Bulgaria, and Italy.

According to the study published on bioRxiv titled “The dispersal of domestic cats from Northern Africa and their introduction to Europe over the last two millennia”, the researchers analysed a total of 70 low-coverage ancient genomes, 37 radiocarbon-dated cat remains, and 17 modern and museum genomes.

The Tor Vergata Study Results

The Tor Vergata Team, as a result of the nuclear DNA analyses, identified felines embedded by domestic ancestry that appeared from the first century CE onwards in Europe. The team also identified two introductory waves — one from the second century BCE, where wildcats were brought from Northwest Africa to Sardinia, raising the current island population, whereas the other wave belonged to the Roman Imperial period, where the cats genetically sounded similar to domestic cats in Europe. Here, Tunisia was observed as the base for early domestication.

The University of Exeter Study

According to a reprint titled, “Redefining the timing and circumstances of cat domestication, their dispersal trajectories, and the extirpation of European Wildcats,” the collaborative study by the University of Exeter shed light on a distinct timeline. They analysed 2,416 archeological field bones around 206 sites and cross-referenced morphological data, accompanied by genetic findings.

The key findings of this collaborative study defined that domestic cats first appeared in the early first millennium BCE in Europe. Their existence occurred before Roman expansion.

The Egyptian Connection

According to mythological theories, the emergence of domestication of cats was related to religious and cultural dimensions. In Egypt, the cats were considered holy. Also, in Greek culture, these creatures became religious symbols of Artemis and Diana — a multifaceted divinity.

Although the two studies offer different understandings, the results indicate that cats appeared in Europe after moving from North Africa as a result of cultural practices, religious reverence, and trade networks.

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Ocean of Magma Might Be Flowing Underneath the Earth’s Surface

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Ocean of Magma Might Be Flowing Underneath the Earth’s Surface

A new study published on March 26 in the Nature journal revealed that the magma ocean formation near Earth’s core started around 4.4 billion years ago. It might be impacting the Earth today as odd mantle anomalies. Discoveries suggest that Earth inevitably sheltered a deep basal magma believed to have existed at the boundary between the mantle and core. This helped the scientists explain the baffling structure of the mantle, such as the Large Low-Velocity (LLVPS) discovered with the help of seismic imaging. This event has played a crucial role in Earth’s shape with thermal and tectonic evolution.

Discovery and Implications

Assistant Professor Charles-Édouard Boukaré of York University, Toronto, who led this study, told Live Science that these magma oceans could affect thermal communication between the mantle and core, further affecting the tectonic plates’ location.

A new model proposed by his team combines geochemical and seismic data to help researchers explore how early crystallisation could lead to the persistent molten layer formed deep inside the planet. Boukaré, James Badro, and Henri Samuel are affiliated with the French Research Institutions and played a major role in the study published in the Nature journal.

Formation of Basal Magma Ocean

The team discovered that the magma ocean formation is inevitable, irrespective of the direction of Earth’s mantle solidification, either from core to surface or vice versa. In each case, the new Earth model proposes that dense iron oxide-rich solids sank near the Earth’s core and remelted (iron has a low melting point) due to the high temperature and pressure conditions, causing a permanent ocean of magma. Boukaré emphasised that a basal melt would be formed despite the least conducive scenarios.

Lasting Effects and Geological Memory

This study shows that the deep magma ocean left a lasting imprint on the interior of Earth around a few hundred million years ago. In a statement given to the publication, Boukaré said that there is a memory, explaining that Earth’s internal structure was shaped very early in the past and still plays a significant role in bringing geological processes such as tectonic movement and mantle convection. Dating back around 4.4 billion years, LLVPS may be the remnants of this ancient primordial layer.

Looking to Other Planets

Boukaré is seeking to expand the model with further trace elements and practice it on other planets made of rocks. He said that maybe this basal magma ocean event is not so unique to the Earth. This research could open new doors into comprehending the planetary formation across the solar system.

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Exoplanet Found Orbiting Binary Stars on a Sideways Path

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Exoplanet Found Orbiting Binary Stars on a Sideways Path

Researchers have found an odd Milky Way planet orbiting over and under the poles of two failing stars. Star systems arise from flattened, spinning disks of gas and dust, with materials gathering along the plane of the disk, forming planets, moons, and asteroids around a newborn star. Only sixteen exoplanets had ever been verified to circle a binary pair; all of those planets orbit in the plane of the stars’ orbits of one another, not over the poles. The elusiveness of these planets makes this find very fascinating.

Researchers knew of the two objects this odd planet orbits before they came upon it. They originally identified the do-si-doing pair using the SPECULOOS Southern Observatory in Chile in 2018, only to find they were brown dwarfs, failed stars insufficient in mass to ignite. The system began to look stranger once they zoomed in on the binary pair with the Very Large Telescope at the Paranal Observatory in Chile.

Scientists Find First Polar Planet in Bizarre Double-Brown-Dwarf System

According to the report, scientists have found the strangest planetary system yet observed, featuring the first-ever “polar planet” and a planet that orbits two stars. Better known as “failed stars,” brown dwarfs—stellar bodies that fail to gather enough materials to attain the mass required to start the fusion of hydrogen to helium in their cores—are the parent stellar bodies of exoplanet 2M1510 (AB). This discovery is the first solid evidence of such a fully formed system.

Exoplanet 2 M1510 (AB) b is a stellar body known as a “failed star” because it fails to gather enough matter to reach the mass needed to start the fusion of hydrogen to helium in its core. The chance of stellar bodies having a binary partner increases with mass, making a double-brown-dwarf star system pretty surprising.

Rare Eclipsing Brown Dwarf Pair Hosts First Known Polar-Orbit Planet

This is only the second pair of eclipsing brown dwarfs ever discovered, meaning one of the brown dwarfs eclipses the other, as seen from Earth’s vantage point. Team member Amaury Triaud of the University of Birmingham said that “a planet orbiting not just a binary, but a binary brown dwarf, as well as being on a polar orbit, is rather incredible and exciting.”

The discovery was incidental, since the observations were not aimed at such a planet or orbital arrangement. This realization usually helps one to understand what is sensible on the interesting planet we live on.

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