4171 - WEBB TELESCOPE - sees the most distant galaxies?

 

-    4171   -    WEBB  TELESCOPE  -  sees the most distant galaxies?     The power of JWST is finding that things that have been studied for years are now surprising us.

-------------  4171  -  WEBB  TELESCOPE  -  sees the most distant galaxies?   

-  The James Webb Space Telescope (JWST) is bringing us spectacular images of distant galaxies and discoveries of dozens of new black holes. Yet JWST is also rewriting scientists’ understanding of objects on a slightly smaller, more relatable scale: how planets form from swirls of gas and dust around young stars. Such ‘protoplanetary’ disks are what the environs of the Sun would have been like 4.6 billion years ago, with planets coalescing from the whirling material around an infant star.

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-   JWST is revealing how water is delivered to rocky planets taking shape in such disks. It’s providing clues to the exotic chemistry in these planetary nurseries. And it has even found fresh evidence for a cosmic hit-and-run in one of the most famous debris disks, encircling the star Beta Pictoris.

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-    Other telescopes have probed many of these disks before. Astronomers have taken impressive pictures of dark gaps etched like grooves in a bright vinyl record, marking where planets are being born and clearing out gas and dust from the disk.   But JWST’s unprecedented vision allows astronomers to probe these realms in original ways.

-

-    New JWST glasses were use to gaze on the protoplanetary disks of four stars. The scientists could see that two of the disks contained large amounts of cool water, just close enough to the star for the water to be liquid rather than frozen.

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-    That observation supports a theory put forward decades ago, that icy pebbles can drift inwards from the outer part of the disk until they get warm enough to release their water into the inner disk.  This reservoir of water can serve as a raw ingredient for planets forming close to the star.   

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-   The protoplanetary disk surrounding a small star called ”J160532” has a surprisingly large amount of carbon. A planet taking shape in a disk awash in carbon compounds could draw on a wide variety of interesting chemistry as it forms. Small stars such as this one frequently host small rocky planets; if such planets can sweep up diverse ingredients as they form, the results could be planets that are mind-bogglingly different from our Solar System’s rocky planets, such as Venus, Earth and Mars.

-

-   Benzene was found in the disk around J160532 which is the first observation of the molecule in a protoplanetary disk. Benzene is a carbon-containing ‘organic’ molecule, but its detection probably does not signal the presence of the ingredients required for life. It might mean that radiation flooding from the star is destroying dust grains rich in carbon, releasing benzene into the disk. The disk also contains lots of other carbon-containing compounds, such as acetylene, and indeed has more carbon than oxygen overall.

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-   It’s really a chemistry we’ve never seen before in disks.  Even disks that have probably already formed all their planets are giving up their secrets to JWST.   The disk around Beta Pictoris, a star that lies 19 parsecs from Earth in 1984 became the first star known to have a debris disk encircling it.

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-    These images have revealed a filament of dust that astronomers are calling the cat’s tail stretching out of the debris disk at a quizzical upright angle. The cat’s tail of Beta Pictoris is probably a stream of dust and other debris that was kicked out of the star’s disk when large rocky chunks smashed into each other.

-

-    We’re seeing the aftermath of a massive collision in the disk around the bright star Fomalhaut had also shown clouds and belts of dust expanding outwards, suggesting that lots more could be going on in the system than anyone had suspected.

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September 27,  2023             4170

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--------------------- ---  Thursday, September 28, 2023  ---------------------------------

 

 

 

 

 

           

 

 

4170 - NEUTRINOS - seeing instead of using photons?

 

-    4170   -    NEUTRINOS  -  seeing instead of using photons?    We all know that are eyes see by receiving light “photons”.   “Neutrinos” are subatomic particles that have almost no mass, like photons.  What if we could “see” using neutrinos instead of photons?

--------------  4170  -  NEUTRINOS  -  seeing instead of using photons?

-    Scientists have revealed a uniquely different image of our galaxy by determining the galactic origin of thousands of neutrinos.  Neutrinos invisible 'ghost particles' which exist in great quantities but normally pass straight through Earth undetected. The neutrino-based image of the Milky Way is the first of its kind.  It is a galactic portrait made with particles of matter rather than electromagnetic energy, light.

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-   From visible starlight to radio waves, the Milky Way galaxy has long been observed through the various frequencies of electromagnetic radiation it emits.  The “IceCube Neutrino Observatory” at Amundsen-Scott South Pole Station in Antarctica was used to observe through neutrinos.

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-    This immense observatory detects the subtle signs of high-energy neutrinos from space by using thousands of networked sensors buried deep within a cubic kilometer of clear, pristine ice.

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-    At this point in human history, we're the first ones to see our galaxy in anything other than light.  The capabilities provided by the highly sensitive IceCube detector, coupled with new data analysis tools, have given us an entirely new view of our galaxy.

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-    Unlike the case for light of any wavelength, in neutrinos, the universe outshines the nearby sources in our own galaxy.  The even more ambitious goal is determining where they came from.

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-    When neutrinos happen to interact with the ice beneath IceCube, those rare encounters produce faint patterns of light, which IceCube can detect. Some patterns of light are highly directional and point clearly to a particular area of the sky, allowing researchers to determine the source of the neutrinos. Such interactions were the basis for the discovery of neutrinos that came from another galaxy 47 million light-years away.

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-    Other interactions are far less directional and produce cascading "fuzz balls of light" in the clear ice. Scientists developed a machine-learning algorithm that compared the relative position, size and energy of more than 60,000 such neutrino-generated cascades of light recorded by IceCube over 10 years.

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-    When they fed the real IceCube-provided data to the algorithm, what emerged was a picture showing bright spots corresponding to locations in the Milky Way that were suspected to emit neutrinos. Those locations were in places where observed gamma rays were thought to be the byproducts of collisions between cosmic rays and interstellar gas, which theoretically should also produce neutrinos.

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-   Over many decades, scientists have revealed countless astronomical discoveries by expanding the methods used to observe the universe. Once-revolutionary advances such as radio astronomy and infrared astronomy have been joined by a new class of observational techniques using phenomena such as gravitational waves and now, seeing with neutrinos.

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-    The neutrino-based image of the Milky Way is yet another step in discovery. Neutrino astronomy will be honed like the methods that preceded it, until it too can reveal previously unknown aspects of the universe.

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September 27,  2023        NEUTRINOS  -  seeing instead of using photons?         4170

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--------------------- ---  Thursday, September 28, 2023  ---------------------------------

 

 

 

 

 

           

 

 

4169 - MARS - watery history under study?

 

-    4169   -    MARS  -  watery history under study?   Curiosity Mars rover reaches perilous ridge on Red Planet after 3 failed attempts.  Curiosity captured a 360-degree panorama while parked below “Gediz Vallis Ridge”, a formation that preserves a record of one of the last wet periods seen on this part of Mars.

---------------------  4169  -  MARS  -  watery history under study?

-   Curiosity Mars rover reaches perilous ridge on Red Planet after 3 failed attempts.  Curiosity captured a 360-degree panorama while parked below “Gediz Vallis Ridge”, a formation that preserves a record of one of the last wet periods seen on this part of Mars.

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-    On September 18, 2021, NASA confirmed that, after three failed attempts, its Curiosity Mars rover managed to reach a precarious destination on this Red Planet.

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-    As to why this formation was worth such turmoil for Curiosity? Scientists believe that three billion years ago, when Mars was much wetter than the arid land it is now, powerful debris flows carried mud and boulders down the side of a mountain in the vicinity known as Mount Sharp.  This debris spread into a fan that was later eroded by wind into a towering ridge.

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-   That story means this ridge holds proof of Mars' blue watery past and maybe more excitingly, information about the planet's ancient, dangerous landslides.   Huge rocks were ripped out of the mountain high above, rushed downhill, and spread out into a fan below.

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-    The target was reached on the 3,923rd Martian day (sol), of the mission. After settling in, Curiosity's Mastcam took 136 individual images of the site that were stitched together to form a 360-degree panorama that was later color-enhanced for visual purposes.

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-   To get to the Gediz Vallis Ridge, Curiosity had to get past quite a few hurdles. First, the rover had some trouble accessing this long-sought region on the Red Planet after scaling a spot in 2021 known as the Greenheugh Pediment.

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-  Then, last year, 2020,  Curiosity ran into some knife-edged "gator-back" rocks stippled along another possible path to the ridge. The moniker "gator-back" comes from the fact these rocks resemble scales on an alligator's back. They're believed to be made of sandstone, which also made them the hardest type of rock Curiosity had run into on Mars.

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-  And earlier this year, 2021,  Curiosity faced another setback on the way to Gediz Vallis after checking out the Marker Band Valley. Getting out of Marker Band, NASA said at the time, was comparable to partaking in a Martian "slip-and-slide." That whole ordeal left Curiosity in delicate shape.

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-  After three years, we finally found a spot where Mars allowed Curiosity to safely access the steep ridge.  It’s a thrill to be able to reach out and touch rocks that were transported from places high up on Mount Sharp that we’ll never be able to visit with Curiosity.

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-   Curiosity was never meant to make the climb towards Mount Sharp's peak, which means dissecting rocks on the ground that once stood at the formation's apex is a uniquely important opportunity.

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-   The rover has been exploring the 3-mile-tall mountain since 2014, stumbling upon evidence of ancient streams.  Gediz Vallis ridge was a whole new area to investigate and the youngest section of the region.

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-    Curiosity spent 11 days at the ridge after its mid-August arrival. During this time, it photographed dark rocks in the region that "clearly originated elsewhere on the mountain," as well as others lower on the ridgeline, "some as large as cars." These shards are expected to have come from higher places on Mount Sharp.

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-    The rover offered scientists the first-ever up-close views of a geologic creature called a "debris flow fan," which refers to a phenomenon where debris flowing down a slope spreads out into a fan shape.

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-     With Gediz Vallis under its belt at last, Curiosity is headed to find a path above the ridge to learn about the watery history of Mount Sharp.

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September 27,  2023             4169

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--------------------- ---  Wednesday, September 27, 2023  ---------------------------------

 

 

 

 

 

           

 

 

4168 - EARLIEST GALAXIES - make astronomers rethink evolution?

 

-    4168   -   EARLIEST  GALAXIES  -  make astronomers rethink evolution?   Galaxies from the early universe are more like our own Milky Way than previously thought, flipping the entire narrative of how scientists think about structure formation in the universe.

  4168  -  EARLIEST  GALAXIES  -  make astronomers rethink evolution?

-   Astronomers are finding an abundance of Milky Way–like galaxies in the early universe, rewriting cosmic evolution theories

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-   Using the James Webb Space Telescope (JWST), astronomers have discovered that galaxies like our own Milky Way dominate throughout the universe and are surprisingly common. These galaxies go far back in the universe's history with many of these galaxies forming 10 billion years ago or longer.

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-   The Milky Way is a typical disk galaxy, which has a shape similar to a pancake or compact disk, rotating about its center and often containing spiral arms. These galaxies are thought to be the most common in the nearby universe and might be the types of galaxies where life can develop given the nature of their formation history.

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-   However, astronomers previously considered that these types of galaxies were too fragile to exist in the early universe when galaxy mergers were more common, destroying what we thought was their delicate shapes.

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-    The new discovery finds that these disk galaxies are 10 times more common than what astronomers believed.  Using the Hubble Space Telescope they thought that disk galaxies were almost non-existent until the universe was about 6 billion years old, these new JWST results push the time these Milky Way–like galaxies form to almost the beginning of the universe.

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-   The research completely overturns the existing understanding of how scientists think our universe evolves, and the scientists say new ideas need to be considered.

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-    Previously, astronomers using the Hubble Space Telescope believed that galaxies had mostly irregular and peculiar structures that resemble mergers. However, the superior abilities of JWST now allows us to see the true structure of these galaxies for the first time.

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-   This implies that most stars exist and form within these galaxies which is changing our complete understanding of how galaxy formation occurs. These results also suggest important questions about dark matter in the early universe which we know very little about.

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-   Based on our results astronomers must rethink our understanding of the formation of the first galaxies and how galaxy evolution occurred over the past 10 billion years.

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-  September 26,  2023   EARLIEST  GALAXIES  -  rethink evolution?          4168

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---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------

--------------------- ---  Tuesday, September 26, 2023  ---------------------------------

 

 

 

 

 

           

 

 

4167 - DARK MATTER - is it warping our galaxy ?

 

-    4167   -  DARK  MATTER  -  is it warping our galaxy ?     Our entire Milky Way galaxy is warping, and a gigantic blob of dark matter could be to blame.  An invisible halo of misaligned dark matter could explain the warps at the Milky Way's edges.

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--------------------  4167 -  DARK  MATTER  -  is it warping our galaxy ?

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-  The Milky Way galasxy isn't flat; it's warped. A new study suggests an invisible halo of dark matter could explain why.   Scientists initially believed that the Milky Way was a flat disk dominated by two spiral arms trailing stars from a central bar, but measurements taken since the mid-20th century reveal that it's bent inexplicably out of shape.

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-    The warping occurs mostly at our galaxy's borders, where some regions bend downward while others flare upward. Now, computer simulations may have revealed the cause: a mysterious event that knocked our galaxy's invisible halo of dark matter out of alignment.

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-   Dark matter is a mysterious and somewhat contradictory type of matter. It makes up 85% of the universe's matter; but because it doesn't directly interact with light, it is completely invisible.

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-    However, scientists can observe its gravitational effects on its surroundings. Dark matter makes its presence known by accelerating stars to otherwise inexplicable speeds as they orbit galactic centers; warping distant starlight; and by giving shape to the Milky Way's galactic halo.

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-  The galactic halo rests just beyond the spiral arms of the Milky Way. In a 2022 study, astronomers investigated this region using the European Space Agency's Gaia spacecraft, which maps the positions and movements of the Milky Way's roughly 2 billion stars.   They discovered that the stars suspended in the galactic halo were strangely off-kilter.

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-   To see what an unbalanced stellar halo might mean for the dark matter halo it is suspended in, the researchers used a computer model to recreate a young Milky Way-like galaxy with a dark matter halo tilted 25 degrees with respect to its disk. After simulating the galaxy over 5 billion years, the researchers found that they had created a very similar galaxy to our own.

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-    What caused the dark matter around our galaxy to fall out of tilt isn't clear, but the researchers' simulations suggest it is likely to have been a gigantic collision, likely from another galaxy flying into our own. This collision could have caused the dark matter halo to tilt up by as much as 50 degrees before slowly swinging down to its current 20-degree angle elevation.

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September 26,  2023     DARK  MATTER  -  is it warping our galaxy ?        4167

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--------------------- ---  Tuesday, September 26, 2023  ---------------------------------

 

 

 

 

 

           

 

 

-- 4166 - HUBBLE EXPANSON RATE ?

 

-    4166   -   HUBBLE  EXPANSON  RATE  ?     According to most models, the Hubble constant should equal something around 68 kilometers per second per megaparsec (km/s/Mpc). One megaparsec is 1,000,000 parsecs, or about 3,260,000 light-years. But after scanning stars and galaxies across our universe, some experts calculate the constant to be 69.8 km/s/Mpc, while others find it to be as high as 74 km/s/Mpc, depending on the method of measurement.

--------------------------------  4166  -  HUBBLE  EXPANSON  RATE  ?  

-   One of the biggest and most heated cosmic debates of our time surrounds a peculiar dilemma the “Hubble tension”.   This phrase describes the fact that, even though scientists are aware the cosmos is constantly ballooning outward in every direction.   We can clearly see stars and galaxies drifting farther and farther away from us over time.  The rate is accelerating, a startling discovery astronomers made in the late 1990s that could be due in part to the existence of dark energy.

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-    The James Webb Space Telescope (JWST) has weighed in on the situation for the first time, but it did not solve the mystery. In fact, JWST actually thickened it.

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-    The problem with calculating the rate is that it depends on resolving the true value of the Hubble constant, which is a crucial number in calculating the universe's expansion rate. Yet, for whatever reason, our theoretical predictions of the constant do not appear to match up with reality.

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-    According to most models, the Hubble constant should equal something around 68 kilometers per second per megaparsec (km/s/Mpc). One megaparsec is 1,000,000 parsecs, or about 3,260,000 light-years. But after scanning stars and galaxies across our universe, some experts calculate the constant to be 69.8 km/s/Mpc, while others find it to be as high as 74 km/s/Mpc, depending on the method of measurement.

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-   Perhaps the models that presently thread our understanding of the universe are missing something?   The JWST's results have crossed one more item off that list. In a nutshell, it showed that the so-called crisis is probably not due to technical issues with measurements made by the Hubble Space Telescope. Back in the 1920s, the American astronomer Edwin Hubble discovered that the universe is expanding.

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-    The most common features that scientists use to decode the Hubble constant are from Cepheid stars.   Webb measurements provide the strongest evidence yet that systematic errors in Hubble’s Cepheid photometry do not play a significant role in the present Hubble tension.

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-    Comparison of Cepheid period-luminosity relations are used to measure distances. Hubble is a key device used in resolving Hubble tension because it's able to measure stellar brightnesses with incredible precision.  It sits above Earth's blurring atmosphere, unlike ground-based observatories hampered by our planet's hazy shield.

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-  Such brightnesses can tell us how far away those stars are and, because we know the immutable speed of light, for how long that light has been traveling to reach us. After some calculations, scientists reason that this kind of information taken from lots and lots of stars should help us figure out the Hubble constant.

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-    Prior to Hubble’s 1990 launch the expansion rate of the universe was so uncertain astronomers weren’t sure if the universe has been expanding for 10 billion or 20 billion years.  There is one star in particular that scientists like to focus on with Hubble to tease out the universe's expansion rate: Cepheids. These are supergiant stars with something like 100,000 times the luminosity of our sun.

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-   Cepheids pulsate, expand and contract in size, which indicates their relative luminosities. The longer the period the intrinsically brighter they are,  and this provides baseline brightnesses and ultimately more accurate measurements.

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-    The  Hubble telescope perched above our atmosphere can identify individual Cepheids in galaxies more than a hundred million light-years away, thus measuring the time interval over which these galaxies change their brightness.

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-   The combined power of the Hubble and Webb space telescopes nails down precise distances to a special class of variable star that is used in calibrating the expansion rate of the universe. These Cepheid variable stars are seen in crowded star fields. Light contamination from surrounding stars may make the measurement of the brightness of a Cepheid less precise. Webb’s sharper infrared vision allows for a Cepheid target to be more clearly isolated from surrounding stars.

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-     The Webb data confirms the accuracy of 30 years of Hubble observations of Cepheids that were critical in establishing the bottom rung of the cosmic distance ladder for measuring the universe’s expansion rate.

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-   It's not quite sensitive enough to infrared light wavelengths, which are found beyond the red end of the electromagnetic spectrum and remain invisible to human eyes. Hubble’s red-light vision is not as sharp as its blue, so the Cepheid starlight we see there is blended with other stars in its field of view.

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-    Infrared vision is important when peering at faraway objects because light coming from distant sources gets stretched out on the way to our vantage point on Earth. Once-tight bluish wavelengths turn into longer, reddish ones. That's actually where the term "redshifted galaxies" comes from, referring to realms falling deeper toward that end of the spectrum from our ground-based perspective.

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-  Only infrared light has the ability to pass through dust unscathed, meaning if a Cepheid is stuck behind a shroud of interstellar matter, it'd appear fainter to us. That runs the risk of its light blending in with light from another Cepheid in the vicinity, for instance, or making it seem like a star is farther away than it truly is.

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-   The James Webb Space Telescope is a $10 billion observatory, sitting nearly 1 million miles away from Earth, is built to unveil the infrared universe to us.

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-   The first step involved observing Cepheids in a galaxy with a known geometric distance for calibration purposes. That galaxy was NGC 4258. The second step was to observe Cepheids in the host galaxies of recent Type Ia supernovas, which are bright star explosions, to basically double check whether Hubble's observations were right.

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September 25,  2023      HUBBLE  EXPANSON  RATE  ?        4166

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--------------------- ---  Tuesday, September 26, 2023  ---------------------------------

 

 

 

 

 

           

 

 

4165 - ASTREROID SAMPLE RETURN

 

-    4165   -   ASTEROID  SAMPLE  RETURN  -   Largest asteroid sample ever collected is coming down to Earth.  Chunks of asteroid that could tell us about the earliest days of the 4.5 billion-year-old solar system and the possible origins of water on our planet are set to land in the Utah desert in 2023

--------------  4165  -   ASTEROID  SAMPLE  RETURN

-    This sample return is more than a decade in the making for a NASA mission called “OSIRIS-REx”. Its goal was to scoop up a large sample of rocks and dust from a near-Earth asteroid named Bennu and bring it to our planet to study.

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-   The sample returned will help scientists get a snapshot of what materials were present when our solar system first formed. Researchers believe asteroids like Bennu haven't changed much since the birth of our cosmic neighborhood. They plan to study the recovered rocks and use the mission to inform future exploration.

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-   Asteroids could have been the source material not just for building up the rocky parts of our planet, but also for delivering the water that makes up our hydrologic system.

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-   Scientists don't know exactly how much sample is in the container, but suspect it's the most ever collected from an asteroid, weighing roughly 250 grams. That will give them more rocks to analyze than ever before.

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-   The spacecraft left Bennu with this sample in 2021, and has been en route to Earth ever since. First, the probe will release the sample container, roughly the size of a tire, into space.

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-    If that goes well, from there it will make its way down to the planet, taking roughly four hours to reach Earth's atmosphere. During that time, there's no way to control the capsule.  Once we release it, it's really just a ballistic object.

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-   The container will come into the atmosphere at about 27,000 miles per hour and heat up to around 5,000 degrees Fahrenheit. It has a heat shield, a critical piece of hardware meant to prevent the sample from burning up.

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-    As it descends, the capsule will release a drogue parachute to keep it steady, followed by another parachute to slow it down. If all goes to plan, the capsule will gently touch down in Utah at 10 to 11 miles per hour.

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-  From there, a helicopter will tow it via cable to a clean room, where a nitrogen purge will rid it of possible contaminants. Then it will head to NASA's Johnson Space Center in Houston.

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-  No other country has fetched pieces of asteroids, preserved time capsules from the dawn of our solar system that can help explain how Earth—and life—came to be.  The landing concludes a 4 billion-mile journey highlighted by the rendezvous with the carbon-rich Bennu, a unique pogo stick-style touchdown and sample grab, a jammed lid that sent some of the stash spilling into space, and now the return of NASA's first asteroid samples.

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-    THE LONG JOURNEY  -  Asteroid chaser Osiris-Rex blasted off on the $1 billion mission in 2016. It arrived at Bennu in 2018 and spent the next two years flying around the small spinning space rock and scouting out the best place to grab samples. Three years ago, the spacecraft swooped in and reached out with its 11-foot (3-meter) stick vacuum, momentarily touching the asteroid's surface and sucking up dust and pebbles.

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-    ASTEROID BENNU  -  Discovered in 1999, Bennu is believed to be a remnant of a much larger asteroid that collided with another space rock. It's barely one-third of a mile wide, roughly the height of the Empire State Building, and its black rugged surface is packed with boulders. Roundish in shape like a spinning top,

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-    Bennu orbits the sun every 14 months, while rotating every four hours. Scientists believe Bennu holds leftovers from the solar system's formation 4.5 billion years ago. It may come dangerously close and strike Earth on Sept.ember 24, 2182—exactly 159 years after the asteroid's first pieces arrive.

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-    Osiris-Rex's up-close study can help humanity figure out how to deflect Bennu if needed.

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 -   Osiris-Rex will release the sample capsule from 63,000 miles out, four hours before it's due to touch down at the Defense Department's Utah Test and Training Range on Sunday morning. The release command will come from spacecraft builder Lockheed Martin's control center in Colorado.

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-    Soon afterward, the mothership will steer away and take off to explore another asteroid. The capsule, 3 feet wide and 1.6 feet tall, will hit the atmosphere at 27,650 mph for the final 13 minutes of descent remaining. The main parachute will slow the last mile, allowing for a mild 11 mph touchdown.

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-    Once everything is deemed safe, the capsule will be hustled by helicopter to a makeshift clean lab at the range. The next morning, a plane will carry the sealed container full of rubble to Houston, home to NASA's Johnson Space Center. NASA is livestreaming the touchdown.

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-    CLEANER THAN CLEAN  -   A new lab at Johnson will be limited to the Bennu rubble to avoid cross-contamination with other collections.  Building 31 already holds the moon rocks brought back by the Apollo astronauts from 1969 through 1972, as well as comet dust and specks of solar wind collected during two previous missions and Mars meteorites found in Antarctica. The asteroid samples will be handled inside nitrogen-purging gloveboxes by staff in head-to-toe clean room suits.

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-    This fall is what NASA is calling Asteroid Autumn, with three asteroid missions marking major milestones. The Osiris-Rex touchdown will be followed by the launch of another asteroid hunter on October 5, 2021. Both the NASA spacecraft and its target—a metal asteroid—are named “Psyche”.

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-    Then a month later, NASA's Lucy spacecraft will encounter its first asteroid since soaring from Cape Canaveral, Florida, in 2021. Lucy will swoop past Dinkinesh in the main asteroid belt between Mars and Jupiter on Nov. 1. It's a warmup for Lucy's unprecedented tour of the so-called Trojans, swarms of asteroids that shadow Jupiter around the sun. Neither Psyche nor Lucy will collect souvenirs, nor will Osiris-Rex on its next assignment, to explore the asteroid Apophis in 2029.

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-    OTHER SAMPLE RETURNS  -  This is NASA's third sample return from deep space, not counting the hundreds of pounds of moon rocks gathered by the Apollo astronauts. The agency's first robotic sample grab ended with a bang in 2004. The capsule bearing solar wind particles slammed into the Utah desert and shattered, compromising the samples.

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-   Two years later, a U.S. capsule with comet dust landed intact. Japan's first asteroid sample mission returned microscopic grains from asteroid Itokawa in 2010. It's second trip yielded about 5 grams from the asteroid Ryugu in 2020. The Soviet Union transported moon samples to Earth during the 1970s, and China returned lunar material in 2020.

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September 23,  2023        ASTEROID  SAMPLE  RETURN              4165

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--------------------- ---  Sunday, September 24, 2023  ---------------------------------

 

 

 

 

 

           

 

 

4164 - OLDEST METEORITE - how do we know?

 

-    4164  -   OLDEST METEORITE  -   how do we know?   A 4.6 billion-year-old meteorite could reveal how Earth formed different layers.  The meteorite “Erg Chech 002” found in the Sahara desert in 2020 is one of the oldest known space rocks.

--------------  4164  -   OLDEST METEORITE  -   how do we know? 

-   The rock analysis could reveal secrets about the solar system in its infancy during the birth of the planets and also help scientists better determine the ages of the oldest meteorites that fall to Earth.

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-  The meteorite is encrusted with green crystals.  Meteorites like this are believed to have formed from material in a disk of gas and dust around the infant sun. Cold, dense patches of this "solar nebula" collapsed to birth the planets, but leftover material formed comets and asteroids from which meteors break away, often finding their way to the surface of Earth in the form of meteorites.

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-   Erg Chech 002 contained the radioactive isotope Aluminum-26 when it formed, which is significant because this unstable form of Aluminum is believed to have been important in a later stage of Earth's evolution, so-called "planetary melting”.

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-   “Planetary melting” is believed to be the process by which rocky planets like ours "differentiated" or formed different compositions at different layers. This is because the melting allows denser material to sink to the core of planets. So, for Earth, an example of this differentiation would be the formation of a dense metal core and, above it, a less dense rocky mantle.

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-    Understanding how Aluminum-26 was distributed as the planets were forming around 4.6 billion years ago is thus important to building a picture of how the rocky inner planets of the solar system evolved.   Because Aluminum-26 decays to Magnesium-26, a stable form of Magnesium, it can be used as a dating system for space rocks.

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-    To determine the age they measured the amounts of lead isotopes within it.  Aluminum-26 decays over time within the first four or five million years of the solar system's life. The half-life of Aluminum-26 is around 717,000 years, meaning it is too short-lived to be directly found in large quantities in the 4.6-million-year-old space rock. But, when it decays, this radioactive isotope of Aluminum leaves behind Magnesium-26, a stable non-radioactive isotope of Magnesium.

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-   That means Magnesium-26 can be used to determine the starting amount of Aluminum-26 in a space rock like Erg Chech 002, and this could be used as a dating system (also known as a “chronometer”) for space rocks.

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-    The Aluminum-26 – Magnesium-26 decay system also serves as a high-resolution relative chronometer.  Developing a generalized approach for isotopic dating with Aluminum-26 – Magnesium-26 and other extinct isotope chronometers that accounts for heterogeneous distribution of the parent radionuclide would allow us to produce more accurate and reliable age data for meteorites and asteroidal and planetary materials to advance a better understanding for the formation of our solar system.

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-    It’s sometimes hard to remember that meteorites have been hitting our planets for millions of years. And some of them are made of valuable materials such as titanium or iron.   Our bronze and iron age ancestors could have utilized these ready-made metallic rocks without having to dig underground to access them, like they would with regular tin or iron veins.

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-     A new study of an arrowhead made out of a meteorite points out just how valuable iron age society thought these meteorites were and hints at a trade network that reached farther than archeologists initially thought.

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-   They only had two sites in Poland that turned up objects made by meteorites.  Now, there is a third. An arrowhead found in a dwelling near Lake Mörigen in Switzerland in the late 19th century was confirmed to be made from a meteorite. It was dated back to the Bronze Age, somewhere between 900-800 BCE. But several key features about it make it particularly interesting to archeologists.

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-   They were looking for objects of possible meteoritic origin in that part of Switzerland because there had been a known meteorite strike known as the “Twannberg iron meteorite” that fell nearby.   When the Twannberg meteorite fell, it broke into pieces. So far, 2,000 individual pieces have been found with a total weight of over 150 kg.

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-   That’s a lot of easily recoverable metal sitting only a few kilometers from the site at Lake Mörigen, where the arrowhead was found. But strangely, the study found that the arrowhead was conclusively not made of the meteor that fell near Twannberg.

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-    Instead, they believe it was created using pieces from a different meteorite that fell in “Estonia” in 1500 BCE.  Known as the “Kaalijarv meteorite”, it is the best fitting of the three other meteorites with the same chemical signature as the arrowhead. However, its landing site was over 1,600 km away. That is quite the distance for an arrowhead to travel in the Bronze Age.

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-  Some metal meteorites have a tiny magnetic field. But how?  One of the striking things about iron meteorites is that they are often magnetic. The magnetism isn’t strong, but it holds information about their origin. This is why astronomers discourage meteorite hunters from using magnets to distinguish meteorites from the surrounding rock, since hand magnets can erase the magnetic history of a meteorite, which is an important scientific record.

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-   Magnetic meteorites occur because they form in the presence of a magnetic field. The iron grains within the meteorite are aligned along the external magnetic field, which gives the meteorite its own magnetism. For example, the Martian meteorite known as Black Beauty gained its magnetism from the strong magnetic field of young Mars.

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-  Some meteorites are magnetic but shouldn’t have formed in a strong magnetic field. Iron meteorites are typically categorized by chemical composition, such as their ratio of nickel to iron. One type, known as “IVAz', is known to be fragments of smaller asteroids. Small asteroids don’t have strong magnetic fields, so IVA meteorites shouldn’t be magnetic, but many of them are. There’s a new study showing how that’s possible.

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-   Small asteroids form through what is known as the rubble pile method. Small chunks of iron-rich rock aggregate over time, building up to become an asteroid. For a body to generate a strong magnetic field, there needs to be liquid iron to create a dynamo effect, and since small asteroids don’t experience this, they can’t have magnetic fields. Or can they?

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-  Asteroids are also subject to collisions over time. It’s these collisions which break off fragments that become the meteorites we find on Earth.   Impacts can create a magnetic dynamo within an asteroid. If a colliding body is not big enough to shatter the asteroid, but large enough to melt a layer of material near the surface, then a chain of events can occur.

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-    When a cold rubble core is surrounded by a molten layer, the core is heated up. Lighter elements evaporate out of the core and migrate toward the surface, which churns the layers to generate convection. The convection of iron generates a magnetic field, which imprints itself on parts of the asteroid. Later collision then creates magnetic fragments, some of which reach Earth.

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-   So the magnetism of IVA meteorites comes not from the original formation of their parent asteroid, but rather from later collisions that stirred up their core. Knowing this, researchers can gain a better understanding of the history of our solar system, and how things such as planetary drift might have triggered more frequent asteroid collisions.

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-   Yet another reason not to look for meteorites with hand magnets. The very act of finding a meteorite could also erase the history of its collisions.

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September 18,  2023     OLDEST METEORITE  -   how do we know?         4164

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