- 3648 - METEOR - flyby, or catch it? A "potentially hazardous" asteroid the size of a blue whale is set to zip past Earth on Friday, August 12, 2022. The asteroid, “2015 FF“, has an estimated diameter between 42 and 92 feet, or about the body length of an adult blue whale. It will zoom past the Earth at 20,512 mph.
--------------------- 3648 - METEOR - flyby, or catch it?
- At its closest approach, the asteroid traveling at around than 27 times the speed of sound will come within about 2,670,000 miles of Earth. This is a little more than eight times the average distance between Earth and the moon.
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- NASA flags any space object that comes within 120 million miles of Earth as a "near-Earth object" and any fast-moving object within 4.65 million miles is categorized as "potentially hazardous."
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- Once the objects are flagged, astronomers closely monitor them, looking for any deviation from their predicted trajectories that could put them on a devastating collision course with Earth.
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- NASA knows the location and orbit of roughly 28,000 asteroids. These maps are with the “Asteroid Terrestrial-impact Last Alert System“. ATLAS is an array of four telescopes capable of performing a complete scan of the entire night sky once every 24 hours.
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- Since ATLAS came online in 2017, it has detected more than 700 near-Earth asteroids and 66 comets. Two of the asteroids detected by ATLAS, “2019 MO” and “2018 LA“, actually hit Earth, the former exploding off the southern coast of Puerto Rico and the latter landing near the border of Botswana and South Africa. Fortunately, those asteroids were small and didn’t cause any damage.
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- NASA has estimated the trajectories of all the near-Earth objects beyond the end of the century, and the good news is that Earth faces no known danger from an apocalyptic asteroid collision for at least the next 100 years.
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- In March , 2021, a bowling ball-sized meteor exploded over Vermont with the force of 440 pounds of TNT. The most explosive recent meteor event, which occurred near the central Russian city of Chelyabinsk in 2013.
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- As the Chelyabinsk meteor struck the atmosphere, it generated a blast roughly equal to around 400 to 500 kilotons of TNT, or 26 to 33 times the energy released by the Hiroshima bomb. Fireballs rained down over the city and its environs, damaging buildings, smashing windows and injuring approximately 1,200 people.
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- If astronomers were to ever spy an asteroid careening straight toward our planet, space agencies around the world are already working on possible ways to deflect the object. On November 24, 2021, NASA launched a spacecraft as a part of its “Double Asteroid Redirection Test” (DART) mission, which plans to redirect the non-hazardous asteroid Dimorphos by ramming it off course in autumn 2022.
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- China is also in the early planning stages of an asteroid-redirect mission. By slamming 23 Long March 5 rockets into the asteroid Bennu, the country hopes to divert the space rock from a potentially catastrophic impact with Earth.
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- Three meteorites were found to contain the molecular building blocks of DNA and its cousin RNA. A subset of these building blocks had been detected in meteorites before, but the rest of the collection seemed mysteriously absent from space rocks .
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- This discovery supports the idea that, some four billion years ago, a barrage of meteorites may have delivered the molecular ingredients needed to jump-start the emergence of the earliest life on Earth.
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- One subset of building blocks, compounds known as “pyrimidines“, appeared in "extremely low concentrations" in the meteorites. This finding hints that the world's first genetic molecules emerged not due to an influx of DNA components from space but rather as a result of the geochemical processes unfolding on early Earth.
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- What concentration of DNA building blocks meteorites would have needed to contain to help drive the emergence of life on Earth?
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- Such space rocks have been found to contain nucleobases, the nitrogen-containing compounds that serve as the "letters" in the genetic code of our DNA and RNA. Nucleobases come in five primary flavors — adenine (A), thymine (T), guanine (G), cytosine (C) and uracil (U), but, previously, only A, G and U had ever been identified in meteorites.
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- In lab settings, scientists have recreated the chemical conditions of interstellar space, the space between stars, where immense clouds of gas and dust measure about 10 kelvins (minus 441.67 degrees Fahrenheit, or minus 263.15 degrees Celsius) and the parent asteroids of meteorites can be found. Through these experiments, researchers synthesized thymine, cytosine and the other primary nucleobases, suggesting that all of these compounds could theoretically be detectable in meteorites.
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- Scientists went hunting for these nucleobases in three well-known meteorites. "Murchison, Murray and Tagish Lake meteorites belong to a class of meteorites. Hydrocarbons and the building blocks of proteins (amino acids) had been identified in these three meteorites. They have detected an elusive molecule called “hexamethylenetetramine” (HMT), which is thought to be an important precursor to organic molecules, in the space rocks.
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- The researchers used a technique called “high-performance liquid chromatography“, which involved using pressurized water to separate the meteorite samples into their component parts. In this way, the team extracted the nucleobases from each sample and then analyzed the bases using mass spectrometry, a technique that revealed the chemical makeup of the material in fine detail. This method enabled the detection of nucleobases with very low concentrations, as low as parts per trillions.
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- By comparing the diversity of nucleobases found in the meteorite against that found in the soil, the team concluded that the compounds in the space rock formed in space. And because of this, they expect that the nucleobases contributed to the emergence of genetic properties for the earliest life on Earth.
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- The soil sample analyzed by the researchers contained higher concentrations of cytosine, uracil and thymine than they'd found in the Murchison meteorite, so it's difficult to determine how much is extraterrestrial versus terrestrial in the meteorite. The team didn't identify a specific chemical process that would produce C, U, T and their various isomers; such an analysis could have supported the idea that all of the compounds formed in interstellar space.
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- Even if the detected C, T and U are extraterrestrial, their scant presence in the meteorites casts doubt on the theory that the first life on Earth was seeded by DNA components from space. If these results are representative of typical pyrimidine concentrations in meteorites, then geochemical synthesis on early Earth would likely have been responsible for the emergence of genetic material, rather than inputs from extraterrestrial delivery.
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- Scientists hope to hunt for nucleobases in material collected directly from asteroids, rather than from meteorites on Earth. This could minimize the issue of Earth-born contaminants.
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- The Japanese spacecraft Hayabusa2 recently brought the asteroid Ryugu down to Earth. And, NASA's OSIRIS-REx probe is due to touch down with samples of the near-Earth asteroid Bennu in 2023. We have a lot more to learn. How did we get here?
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August 11, 2022 3648
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