- 3271 - MARS ROCKS- meteorites and Martian rocks! - The first rocks reveal a potentially habitable sustained environment. Water was there on the surface for a long time. The first core samples is basaltic in composition and may be the product of lava flows. The presence of crystalline minerals in volcanic rocks is especially helpful in radiometric dating.
------------------- 3271 - MARS ROCKS - meteorites and Martian rocks!
- Also see Review 3267 - “MOON ROCKS - still learning new science?”. When the Apollo spacecraft visited the Moon one of the operations conducted by astronauts was sample-returns, where lunar rocks were picked up and brought back to Earth. These moon rocks revealed a great deal about the composition, structure, and geological history of the Moon. This led to profound discoveries, including the presence of water on the Moon and the fact that both Earth and its only satellite formed together,
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- We are also studying Mars Rocks. Rocks that are still on Mars and also some that have already arrived here on Earth. “Mars Perseverance” rover successfully collected its first pair of rock samples September, 2021.
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- After collecting its first sample, named "Montdenier," on September 6, the team collected a second, "Montagnac," from the same rock on September 8, 2021.
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- Analysis of the rocks from which the Montdenier and Montagnac samples were taken and from the rover's previous sampling attempt may help the science team piece together the timeline of the area's past, which was marked by volcanic activity and periods of persistent water.
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- Mars had a potentially habitable sustained environment. Water was there on the surface for a long time. The first core samples is basaltic in composition and may be the product of lava flows. The presence of crystalline minerals in volcanic rocks is especially helpful in radiometric dating.
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- The volcanic origin of the rock could help scientists accurately date when it formed. Each sample can serve as part of a larger chronological puzzle; put them in the right order, and scientists have a timeline of the most important events in the crater's history.
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- Some of those events include the formation of Jezero Crater, the emergence and disappearance of Jezero's lake, and changes to the planet's climate in the ancient past.
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- Salts have been found within these rocks. These salts may have formed when groundwater flowed through and altered the original minerals in the rock, or more likely when liquid water evaporated, leaving the salts.
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- The salt minerals in these first two rock cores may also have trapped tiny bubbles of ancient Martian water. They could serve as microscopic time capsules, offering clues about the ancient climate and habitability of Mars. Salt minerals are also well-known on Earth for their ability to preserve signs of ancient life.
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- The Perseverance science team already knew a lake once filled the crater; for how long has been more uncertain. The scientists couldn't dismiss the possibility that Jezero's lake was a "flash in the pan": Floodwaters could have rapidly filled the impact crater and dried up in the space of 50 years.
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- But, the level of alteration that scientists see in the rock that provided the core samples ,as well as in the rock the team targeted on their first sample-acquisition attempt , suggests that groundwater was present for a long time.
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- This groundwater could have been related to the lake that was once in Jezero, or it could have traveled through the rocks long after the lake had dried up. Though scientists still can't say whether any of the water that altered these rocks was present for tens of thousands or for millions of years, they feel more certain that it was there for long enough to make the area more welcoming to microscopic life in the past.
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- These samples have high value for future laboratory analysis back on Earth. We may be able to work out the sequence and timing of the environmental conditions that this rock's minerals represent.
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- Perseverance is currently searching the crater floor for more samples that can be brought back to Earth to answer profound questions about Mars' history. Promising samples are sealed in titanium tubes the rover carries in its chassis, where they'll be stored until Perseverance drops them to be retrieved by a future mission.
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- Perseverance will likely create multiple "depots" later in the mission, where it will drop off samples for a future mission to bring to Earth. Having one or more depots increases the likelihood that especially valuable samples will be accessible for retrieval to Earth.
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- Perseverance's next likely sample site is just 656 feet away in "South Séítah," a series of ridges covered by sand dunes, boulders, and rock shards that Farley likens to "broken dinner plates."
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- The rover's recent drill sample represents what is likely one of the youngest rock layers that can be found on Jezero Crater's floor. South Séítah, on the other hand, is likely older, and will provide the science team a better timeline to understand events that shaped the crater floor, including its lake.
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- By October, 2021, all Mars missions will be standing down from commanding their spacecraft for several weeks, a protective measure during a period called “Mars solar conjunction“. Perseverance isn't likely to drill in South Séítah until sometime after that period.
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- A key objective for Perseverance's mission on Mars is “astrobiology“, including the search for signs of ancient microbial life. The rover will characterize the planet's geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith --broken rock and dust.
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- Subsequent missions would send spacecraft to Mars to collect these sealed samples from the surface and bring them to Earth for in-depth analysis.
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- Not all Mars rocks have to be brought here. Some have already arrived as meteors. The largest piece of Mars ever to fall to Earth weighs 32 pounds and measures 10 inches across at its widest point.
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- This meteor was unveiled September 1, 2021 at the Maine Mineral and Gem Museum in Bethel, which also houses over 6,000 extraterrestrial rocks, including the largest piece of moon rock and the oldest igneous rock, formed from volcanic activity, in the solar system.
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- The lump of rock wound up on Earth after a large asteroid or comet blasted it off the Martian surface. The Martian rock is named “Taoudenni 002“, and is by far the largest complete uncut Martian meteorite on Earth.
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- There are around 300 pieces of Martian rock on Earth, totaling around 500 pounds. However, collectors often break them apart to sell them separately, so the actual number of known Martian meteorites on Earth is between 100 and 150.
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- After powerful impacts eject the rocks from Mars, they drift through space and eventually end up on an Earth-crossing orbit around the Sun. A local meteor hunter discovered Taoudenni 002 near a desert salt mine in Mali. The meteorite fall was not witnessed, but it was likely recent, perhaps in the last few 100 years, due to its well preserved condition.
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- Martian meteorites have specific chemical signatures, and the minerals and elements in Taoudenni 002 perfectly matched the known Martian minerals. It is a “shergottite“, which is the main type of Martian meteorite. It contains the minerals olivine, pyroxene and shock-transformed feldspar, which formed from the Mars impact that ejected it.
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- The meteorites' composition also hinted at how the rock was created. It most likely was formed in a volcanic episode on Mars more than 100 million years ago. Even larger Martian rocks may be hidden on Earth, potentially buried under a sand dune in the Sahara, or deep in the ice in Antarctica, or perhaps at the bottom of the ocean.
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- At any moment, a rock traveling at 20,000 miles per hour could fall out of the blue sky above, crash onto our planet.
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- Here's a few of modern-era meteorites that have hit people, made them sick, or simply wrecked their cars:
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- On October 9, 1992, a giant fireball came crashing through the evening sky and up the East Coast. First visible in West Virginia, the shards traveled northeast as they fell and eventually impacted the ground in Peekskill, NY, giving the meteorite its name. One fragment wrecked a car.
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- Because of the shallow angle at which it fell relative to the Earth it burned through the atmosphere, at a slant, for a full 40 seconds the Peekskill meteorite was seen by thousands of people, and captured on video from at least 16 different perspectives. The footage has been used by scientists to study the trajectories of meteors in the atmosphere.
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- On September 15, 2007, a meteorite impacted Earth near the village of Carancas, Peru, creating a 50-foot-wide crater . When local officials went to investigate, they saw boiling water bubbling at the bottom of the hole. Sickeningly foul-smelling, noxious gases rose out of it, striking the investigators ill on the spot.
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- In the days after the impact, about 200 villagers came down with a mysterious illness, suffering nausea, headaches and vomiting. Later, tests of the impact site by scientists showed that the locals had likely suffered mild arsenic poisoning. The meteorite unleashed gaseous arsenic when its hot surface met an underground water supply tainted with the poisonous element, the scientists said.
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- On November 30, 1954, a fireball streaked through the Alabama sky. It produced a sonic boom that nearly knocked a boy off his bicycle in Montgomery, and created television interference in homes up to 70 miles away from where it landed. The space rock broke up into three main pieces as it ripped through the atmosphere.
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- Ann Elizabeth Hodges was snoozing on the couch in the living room of her home in Oak Grove near Sylacauga, Alabama when the largest of those pieces, a grapefruit-sized rock, suddenly came crashing down through her roof. It ricocheted off her console radio and struck her on the hip. Badly bruised but still able to walk, Hodges became the only person on record ever to be injured by an extraterrestrial object.
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- The United States Air Force immediately sent a helicopter to Oak Grove to claim the meteorite. Analysis showed it was an H4 chondrite, a ferrous type of rock.
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- In 1947, about 200,000 pounds of almost pure iron fell from the sky in Eastern Siberia. The Sikhote-Alin meteorite, named for the mountains upon which it landed, entered the atmosphere at an astonishing speed of 8.7 miles per second, or over 31,000 mph. It appeared brighter than the sun as it streaked downwards, and was visible from up to 190 miles away.
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- A residual smoke trail could be seen for several hours after the impact, and for years, fragments of iron were found driven into trees.
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- On June 24, 1938 a meteoroid exploded as it entered the atmosphere above Chicora, Pennsylvania. Based on the size of the explosion, scientists estimated the rock's initial mass before it broke up to have been more than 450 tons.
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- However, only scant pieces of the meteorite were ever found located miles away from where the main mass, missing to this day, is thought to have landed.
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- The biggest and most mysterious impact event in recorded history took place above the Podkamennaya Tunguska River in Russia on the morning of June 30, 1908. The Tunguska explosion, which was 1,000 times more powerful than the atomic bomb dropped by the United States on Hiroshima during World War II, is believed to have been caused by the collision of a large meteoroid or comet with the atmosphere, 3 to 6 miles above the Earth's surface.
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- The shockwave from the explosion knocked over an estimated 80 million trees covering 830 square miles of land below it, and knocked people off their feet hundreds of miles away.
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- For several months following the Tunguska event, the Smithsonian Astrophysical Observatory in the United States observed a decrease in atmospheric transparency because of suspended dust from the explosion.
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- The scale of the Tunguska event sparked many people's imaginations. Some have hypothesized that it was caused by the crash of an alien spaceship. Others say it happened when a blackhole passed through Earth, and yet others say it resulted from the annihilation of a chunk of antimatter from outer space when it hit the matter in the atmosphere.
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- None of those theories account for the mineral debris left over from the explosion, however. It was a meteorite sure as I’m sitting here. Be ready to duck!
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- September 11, 2021 MARS ROCKS - meteorites and Martian rocks! 3271
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