- 3712 - RYUGU - bringing back bits of the asteroid. Samples from asteroid Ryugu contain bits that came from outside the Solar System. Long before our Sun began to form, stars were dying in our part of the galaxy. One of them exploded as a supernova.
--------------------- 3712 - RYUGU - bringing back bits of the asteroid.
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- The supernova explosion created minute grains of dust and the force of the explosion blasted through a nearby cloud of gas and dust. That action seeded the cloud with “alien” materials from the dead star. The shock wave from the supernova also caused the cloud to collapse in on itself to create the Sun. The “leftovers” of the cloud became the planets, moons, rings, comets, and asteroids of our solar system.
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- Asteroid “162173 Ryugu” contains grains of that ancient material from the long-gone star. The Japanese “Hayabusa2” mission explored Ryugu and returned samples of those dust grains for scientists to analyze. They provide hints about that star and what conditions were like before the Sun was born.
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- Through chemical analysis, astronomers can figure out when these dust grains formed as a star aged and died. Most of them are oxygen-rich silicates or oxides or carbon-enriched grains. The silicates are somewhat rare. That’s because chemical weathering or other processes on an asteroid, or on Earth, destroy them. So, if they’re found at all, they’re usually in a sheltered portion of an asteroid.
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- Micro-analytical tests on the Hayabusa2 samples are compared with the results from similar tests done on “carbonaceous chondrites” , that is primitive meteorites, found here on Earth. These samples of “pre-solar grains” in the Ryugu materials were carbonaceous grains. Bits of the samples were fragile silicate material, which provides a clue to their formation and to conditions they experienced on the asteroid.
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- Different types of presolar grains originated from different types of stars and stellar processes, which we can identify from their isotopic signatures. Isotopes are versions of elements with the same number of protons, but a different number of neutrons. Their presence in the dust samples give hints about when they formed and stellar activity occurring at the time.
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- Scientists sort presolar grains into groups that link them to the types of stars that created them. Many grains with oxygen isotopes likely formed in the winds of asymptotic giant branch (AGB) stars with different masses and metallicities.
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- The compositions and abundances of the presolar grains found in the Ryugu samples are similar to what we’ve previously found in carbonaceous chondrites. This gives us a more complete picture of our solar system’s formative processes that can inform models and future experiments on Hayabusa2 samples, as well as other meteorites.
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- Ryugu is a near-Earth asteroid about 1 kilometer in diameter, discovered in 1999. It’s a potentially hazardous asteroid in the Apollo group. Ryugu orbits the Sun once every 16 months and its path intersects Earth’s. At its closest, it can get as close as a quarter of the Moon’s distance from our planet.
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- This asteroid is also a perfect candidate to help scientists understand the pre-solar nebula and the history of asteroids. It’s part of an asteroid family left over from the collision of two larger objects. That event sent shards spinning through space.
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- Its larger parent body had internal heating. Ryugu is round, but with a bulge at its equator, and its surface is covered with boulders. Some have even suggested that it’s a dead comet.
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- Hayabusa 2 went to Ryugu to sample its surface. Scientists now classify Ryugu as an orbiting rubble pile. That means it’s loosely bound together and its volume is at least “half empty”. The surface is quite porous and has 77 impact craters. Ryugu created a new small one when it injected a small copper mass into the ground to study subsurface materials.
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- Other highlights of the mission include the deployment of a small surface rover called MASCOT. There were three other rovers that went to explore different parts of the surface (although one failed).
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- The surface sample retrieval part of the mission ended in February 2019, and later that year Hayabusa2 began its journey back to Earth with its precious eons-old samples for study. Detailed studies of the materials revealed more than the presence of alien dust grains. There are also tantalizing hints of amino acids in the asteroid’s regolith.
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- When Huyabusa2 returned a sample of Ryugu to Earth in December 2020. Scientists have found a particular grain in the sample Huyabusa2 collected that shows how the asteroid formed.
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- An ion mass spectrometer partially vaporizes a sample and then analyzes the different ion types released from those vapors.
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- Ryugu is derived from an earlier, larger asteroid that was formed around the same time as the solar system. Some cataclysmic event eons ago broke off the piece that is today thought of as an asteroid, but some of its constituent parts are still from that primordial soup of the early solar system.
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- The sample surprised scientists, there were anhydrous silicates, a type of rock that contains no water. This contrasts with other types of silicates that were subjected to a prolonged period of exposure to water. The particular grain this was found in only contained about 0.5% of its volume as the anhydrous silicates.
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- This discovery helps place Ryugu more solidly among the different classifications of asteroids and points to a better understanding of the early solar system awaiting more regular visits to other asteroids.
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- As space exploration enters a new commercial phase, and one of the primary commercial ends is utilizing asteroid resources to build the space infrastructure necessary to expand, there are sure to be more missions to asteroids that will collect more samples.
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October 17, 2022 RYUGU - bringing back bits of the asteroid 3712
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