Astronomy

Is it possible to find what crater the Mars meteorites come from?

Is it possible to find what crater the Mars meteorites come from?

A few dozen meteorites have been determined to come from Mars. These meteorites likely formed from three separate events.

Each one of these events must have created a big enough crater that rocks would escape Mars' gravitational field. This restricts the number of craters to look at.

The composition of the meteorites can also give clues. For instance, the basalts on the floor of Gusev crater are somewhat more mafic than the meteorites, so they don't come from Gusev.

Using crater size, rock composition,… would it be possible to determine which craters the Mars meteorites come from?


Scientists think they have - the Mojave crater. Also see https://science.sciencemag.org/content/343/6177/1343


Hunting for Meteorites

How many times have you wished that you could find a way to make a little money from your 4-wheeling weekend, dirt bike, metal detector, or just walkin' across one of California's desolate dry lakes? Well, if you're observant, persistent and a little bit lucky, there may be some bucks waiting out there in the boondocks, just under your nose. and literally right out of the blue. [See collecting rules from the BLM below.]

Meteor Crater, near Winslow, Arizona, from the southeast the uplift around the rim can be seen. USGS Photo

Meteorites are remnants of other worlds, pieces of comets or asteroids blown apart by collisions with each other or, in some cataclysmic cases, with the earth. These pieces of rock or iron (or both) which survive their fiery plunge through our atmosphere can create huge craters like the one near Winslow, Arizona. This crater, nearly a mile in diameter and 600 deep, was created in 10 seconds, about 50,000 years ago by a 100-foot diameter chunk of iron and nickel traveling about 40,000 mph.

This hyper-rock created an unimaginable explosion, most of it disintegrating upon impact, but throwing small pieces over a 12 mile area. There are more than 15 known impact craters throughout the U.S. from which fragments are still being found by treasure hunters, hikers and off-road vehicle enthusiasts.


The largest fragment discovered from the meteorite that formed Meteor Crater, exhibited at the tourist center in Meteor Crater, Flagstaff, Arizona.
Photo by Mariordo Mario Roberto Duran

In addition to craters, there are locations where meteorites have exploded or fragmented at high altitude and dispersed pieces over a wide area, known as a strewn field. These zones can cover just a couple of square acres (Holbrook, Arizona) or several thousand square miles (Namibia, Africa).


Strewn field / distribution ellipse of the Bassikounou Meteorite Fall, Mauretania 2006
Dr. Svend Buhl, www.niger-meteorite-recon.de, CC BY 3.0, via Wikimedia Commons

Such areas may contain pieces barely distinguishable from surrounding rocks, or they may stand out like a sore thumb, as on a dry lake bed or wide expanse of desert. The fragments may range in size from 1 gram to 1 ton and have high levels of iron or barely a trace. (Magnets will be attracted to 95% of all meteorites, so that is a simple preliminary test you can make in the field.)

Most meteorites that have recently arrived on Earth will have a dark brown or black fusion crust on their surface, the result of a high-speed entry into the atmosphere. Newly identified falls are of great interest to researchers and scientists who can study the sample before it has rusted or become contaminated with terrestrial pollutants.


ALHA1 - Allan Hills 77005 - Martian Meteorite - Found on Earth in 1977. Exterior view of ALHA 77005 showing small patches of fusion crust. https://www2.jpl.nasa.gov/snc/alha.html

One of the most famous, if not the most valuable meteorite to be scrutinized by NASA and the news media, was found in Antarctica (Allan Hills) in 1984. After reexamination with an electron microscope it was found to have possible fossilized materials believed to have come from the planet Mars.

If you happen to be ice-biking, or 4-wheeling or prospecting near glaciers or ice fields, keep in mind that solitary rocky material is seldom found embedded in ice, and if you see one, it could be a rare kind of meteorite. Some museums and universities have paid from $100 to $5,000 per gram for this particular (Allan Hills 840001) specimen, but most iron meteorites are sold or traded by collectors from 10 cents to $1.50 per gram, depending upon their variety, authenticity and size. Like gold nuggets, the price is determined by the market -- sometimes a feeding frenzy develops over a particular stony-iron, or recently acquired one-of-a-kind meteorite.

There are many informative and educational books available to anyone interested in prospecting for meteorites. Two of my personal favorites are "Rocks From Space" by O. Richard Norton, (Mountain Press, Missoula Montana) and "History of Meteorites" by Astronomical Research Network (Maplewood, Minnesota).

There are several individuals and organizations -- with catalogs or websites -- that buy and sell meteorites or can help identify suspected meteorites including:

New England Meteoritical Society (Mendon, MA)
Bethany Sciences (New Haven Connecticut)
Smithsonian Institute (Washington, D.C.)
Center for Meteorite Study (Arizona State Univ., Tempe, Arizona)
Robert Haag (Tucson, AZ)
Mare Meteorites (Oakland, CA)
MMR Inc. (San Jose, CA)
Walter Zeitschel (Hanau, Germany)
Swiss Meteorite Lab (Glarus, Switzerland).

Much information about the formation of our sun and surrounding planets can be derived by scientists, geologists and astronomers studying these visitors from outer space. Astronomic and geophysical theories about how Earth was created (and will perhaps end) have been derived from the chemical and crystalline structures of the three major meteorites categories: iron, stony and stony-iron.

If you think you've found a meteorite, three preliminary tests should be performed:

  1. Is it heavier than a normal rock of the same size?
  2. Does it attract a magnet?
  3. Does it have a dark brown or black crust?

If you can answer "yes" to all three questions, there is a chance that you may have a meteorite. For a nominal fee, most university planetary science departments or a licensed mineral testing laboratory will conduct an accurate final analysis. (Don't buy any meteorite until it has been tested and a written verification has been presented. It's very easy to mistake a meteorite for an ordinary piece of hematite, iron slag or other material. There is a growing "counterfeit" problem among meteorite sales.)

If you see a meteorite fall, it's important to record the exact date and time, geographical location, visible landmarks, approximate angle of descent and impact, color, size and shape of the object and whether or not you heard any sounds or explosions. If you find something on a dry lake bed, sand dune or glacier that looks out of place, or your metal detector indicates iron or nickel in that strange looking rock, it's probably worth further investigation and might make you a little richer.

BLM - Rules for meteorite hunters 10/01/2012 - on BLM land.

Casual Collection: Meteorites may be casually collected (i.e., free and without a permit), pursuant to BLM’s regulations at 43 CFR 8365.1-5. In accordance with those regulations:

Collection of meteorites is limited to certain public lands. Public lands closed to casual collection include: developed recreation sites, certain units of the National Landscape Conservation System, areas excluded from casual collection in a Land Use Plan such as an Area of Critical Environmental Concern (ACEC) or a wilderness area, and areas closed by supplemental regulations

Individuals are limited to collecting what can be easily hand-carried, up to a maximum of ten pounds of meteorites per individual, per year Only surface collection of meteorites using non-motorized and non-mechanical equipment is allowed (metal detectors may be used) and

Casually-collected meteorites are for personal use only, and may not be bartered or sold for commercial purposes.

Scientific and Educational Use:

Individuals or institutions intending to collect meteorites for scientific research or educational use must obtain an Antiquities Act permit through a Bureau of Land Management (BLM) State Office, in accordance with 43 CFR 3.

Applications for an Antiquities Act permit will be reviewed by the authorized officer in the BLM State Office with jurisdiction over the Cultural Resources program.

Collection amounts allowed for scientific or educational use are specified in the permit and are not subject to the limits (ten pounds) established for casual collection.

Meteorites collected under permit must be curated in an approved repository, and must meet the requirements for curation as defined in 36 CFR 79.

Commercial Collection:
Unless otherwise prohibited by laws, regulations, land use plans or closures, meteorites may be commercially collected by individuals possessing a land use permit issued under the authority of the Federal Lands Policy and Management Act (FLPMA). Land use permits are issued by the local BLM office in accordance with the regulations in 43 CFR 2920.

The applicant must pay an application fee, a purchase price based on either a unit price or a percentage of the fair market value of the removed material, and a reclamation fee as appropriate. The permittee must comply with all environmental laws and regulations for surface disturbing activities on public lands.

Collection amounts allowed for commercial use are specified in the permit and are not subject to the limits (ten pounds) established for casual collection.

Treasure Hunting message board - Enter meteorite in the search box on the top right above the logo.


Meteorite

Meteorites are space rocks that fall to Earth's surface.

Earth Science, Astronomy, Geology, Meteorology, Geography, Physical Geography

Photograph by Thomas J. Abercrombie, National Geographic

Meteorite or Meteorwrong?
How can you tell if that rock you found fell from the sky? First of all, meteorites get burned when they enter Earths atmosphere, so they are usually black and crusty on the outside. Also, meteoriteseven stony meteoritescontain iron, so a magnet will stick to them.

Rocky Cookie
The best place to hunt for meteorites is in Antarctica. Because most of Antarctica is covered in ice and snow, rocky meteorites stand out like chocolate chips in a cookie.

removal of material from the surface of an object, including melting, evaporation, or erosion.

oral or written description of events.

type of stony meteorite containing no hardened droplets (chondrules).

nutrient containing carbon, hydrogen, oxygen, and nitrogen that is critical for all life.

generally or near an exact figure.

irregularly shaped planetary body, ranging from 6 meters (20 feet) to 933 kilometers (580 miles) in diameter, orbiting the sun between Mars and Jupiter.

person who studies space and the universe beyond Earth's atmosphere.

layers of gases surrounding a planet or other celestial body.

line separating geographical areas.

type of stony meteorite containing hardened droplets, called chondrules, of silicate minerals.

small droplet of silicate mineral found in stony meteorites.

type of sedimentary rock that is able to be shaped when wet.

arrangement of the parts of a work or structure in relation to each other and to the whole.

the extremely hot center of Earth, another planet, or a star.

rocky outermost layer of Earth or other planet.

type of mineral that is clear and, when viewed under a microscope, has a repeating pattern of atoms and molecules.

remains of something broken or destroyed waste, or garbage.

type of crystal that is pure carbon and the hardest known natural substance.

very large, extinct reptile chiefly from the Mesozoic Era, 251 million to 65 million years ago.

to learn or understand something for the first time.

to fall apart and disappear.

microscopic particles of rocks or minerals drifting in space. Also called cosmic dust or space dust.

chemical that cannot be separated into simpler substances.

to attach firmly to a surrounding substance.

on the outside or outdoors.

process of complete disappearance of a species from Earth.

force produced by rubbing one thing against another.

state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.

circular surface depression made by the impact of a meteorite.

rock, made of iron and nickel, that has crashed to Earth from outside the atmosphere.

molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface.

having to do with Earth's moon or the moons of other planets.

middle layer of the Earth, made of mostly solid rock.

fourth planet from the sun, between Earth and Jupiter.

category of elements that are usually solid and shiny at room temperature.

rocky debris from space that enters Earth's atmosphere. Also called a shooting star or falling star.

type of rock that has crashed into Earth from outside the atmosphere.

small, rocky body traveling around the sun.

dust-size particle of space debris that burns up as it enters Earth's atmosphere.

instrument used to view very small objects by making them appear larger.

inorganic material that has a characteristic chemical composition and specific crystal structure.

natural satellite of a planet.

Earth's only natural satellite.

chemical element with the symbol Ni.

to move in a circular pattern around a more massive object.

chemical substance that contains the element carbon.

type of stony-iron meteorite containing olivine or peridot crystals embedded in an iron-nickel webbing.

large, spherical celestial body that regularly rotates around a star.

memento or surviving object of the past.

natural substance composed of solid mineral matter.

vehicle that remotely explores a region, such as the surface of a moon, planet, or other celestial body.

solid material transported and deposited by water, ice, and wind.

most common group of minerals, all of which include the elements silicon (Si) and oxygen (O).

the sun and the planets, asteroids, comets, and other bodies that orbit around it.

vehicle designed for travel outside Earth's atmosphere.

individual organism that is a typical example of its classification.

rock, made of nearly equal parts metal and silicate minerals, that has crashed to Earth from outside the atmosphere.

rock, made of silicate minerals, that has crashed to Earth from outside the atmosphere.

star at the center of our solar system.

sudden, violent explosion of a massive star.

physical or tactile characteristics of a substance.

having to do with heat or temperature.

to cause or begin a chain of events.

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Caryl-Sue, National Geographic Society

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Related Resources

Solar System

A solar system is a group of planets, meteors, or other objects that orbit a large star. Our solar system includes everything that is gravitationally drawn into the sun's orbit. While there are at least 200 billion other stars in our galaxy, the sun is the center of Earth's solar system. Astronomers have discovered there are many other large stars within our galaxy, the Milky Way. Use these resources to teach students about the objects and relationships within our solar system.

Space

For thousands of years, people have looked up at the night sky with questions. As technologies have advanced so to has our ability to investigate those questions. First, with telescopes, then with satellites, then space rovers, and ultimately with manned spacecraft. Humans have set foot on the moon, successfully landed rovers on Mars, and even photographed other galaxies. Take your classroom into the great beyond with these out-of-this-world resources.

Martian Meteorites

Fewer than 100 meteorites have been traced to the planet Mars, one of our closest neighbors in the solar system. Learn more about them here.

Meteoroid

Meteoroids are lumps of rock or iron that orbit the sun, just as planets, asteroids, and comets do. Meteoroids, especially the tiny particles called micrometeoroids, are extremely common throughout the solar system. They orbit the sun among the rocky inner planets, as well as the gas giants that make up the outer planets.

Related Resources

Solar System

A solar system is a group of planets, meteors, or other objects that orbit a large star. Our solar system includes everything that is gravitationally drawn into the sun's orbit. While there are at least 200 billion other stars in our galaxy, the sun is the center of Earth's solar system. Astronomers have discovered there are many other large stars within our galaxy, the Milky Way. Use these resources to teach students about the objects and relationships within our solar system.

Space

For thousands of years, people have looked up at the night sky with questions. As technologies have advanced so to has our ability to investigate those questions. First, with telescopes, then with satellites, then space rovers, and ultimately with manned spacecraft. Humans have set foot on the moon, successfully landed rovers on Mars, and even photographed other galaxies. Take your classroom into the great beyond with these out-of-this-world resources.

Martian Meteorites

Fewer than 100 meteorites have been traced to the planet Mars, one of our closest neighbors in the solar system. Learn more about them here.

Meteoroid

Meteoroids are lumps of rock or iron that orbit the sun, just as planets, asteroids, and comets do. Meteoroids, especially the tiny particles called micrometeoroids, are extremely common throughout the solar system. They orbit the sun among the rocky inner planets, as well as the gas giants that make up the outer planets.


See also

Video talks

I have started a series of short talks on contamination issues in my youtube channel on Mars and space colonization. Recently did some talks about whether we should return a sample from mars. The second one is about this topic of transfer of microbes on meteorites.

I've also done some video presentations with slides, on Reasons not to live on Mars, great to explore

I'm Robert Walker, inventor & programmer. I have had a long term special interest in astronomy, and space science since the 1970s, and most of.


NWA 6694 Eucrite-pmict Meteorite 3.0g

NWA 6694 Eucrite-pmict Meteorites For Sale

NWA 6694 is a Polymict Eucrite which has large clasts of white, gray and black that are made of very fine grain material. Many of the pieces offered here have at least one edge with interesting brown eucrite fusion crust. This is a very visually interesting meteorite with its large clasts breccia structure.


  • Researchers say the crater is 8 miles wide, 11 miles long and over 300ft thick
  • It has been found in the lava fields on the Bolaven Plateau in southern Laos
  • The meteor was known about for more than a century but not where it landed
  • Experts used searched for differences in rock density to find the crater location

Published: 12:44 BST, 9 January 2020 | Updated: 15:35 BST, 9 January 2020

A crater left by a giant meteor that crashed into the Earth 800,000 years ago - spreading rocky debris across the planet - is finally found by scientists.

The meteor impact has been known about for more than a century but the location has been a mystery, the team from Singapore said.

Researchers from Nanyang Technical University in Singapore claim it was buried under volcanic lava on the Bolaven Plateau in southern Laos.

The team created a 'gravity map' of the area and discovered an 'elongated crater' under the rock that was about 300ft thick, 8 miles wide and 11 miles long.

A crater left by a giant meteor that crashed into the Earth 800,000 years ago - spreading rocky debris across the planet - is finally found by scientists

Researchers investigated several volcanic lava fields as part of the study. The one in southern Laos was the best match in terms of age and that is where they found the possible crater

Discovering the location of the crater could help to predict what we might expect if a similarly large asteroid were to hit again, says Kerry Sieh, study author.

The team haven't physically seen the crater - which was likely buried tens of thousands of years ago - but say there is strong evidence that this is the correct location.

Scientists were aware of the impact thanks to millions of tiny glassy blobs of melted rock from the same period that have been found all over the world.

These lumps of rocky debris called 'tektites' have been found from China to eastern Antarctica and from the Indian to Pacific ocean and would have been thrown up by a massive meteor impact somewhere - likely in Indochina.

The research team say experts have known about this crash for more than a century and have been trying to identify the impact site for as long.

Researchers from Nanyang Technical University in Singapore claim it was buried under volcanic lava on the Bolaven Plateau in southern Laos


Is it a Meteorite?

/>Now for about a hundred dollars you can find out. A company out of Colorado named Geo Labs is making it easy to get your stone analyzed using their meteorite identification service. They offer XRF services specifically designed for meteorite identification. They require that all samples be submitted with a sample submission form and that samples adhere to their strict submission guidelines. They use a state of the art X-Ray Fluorescence technology to determine the bulk elemental composition of a sample, and can usually give you a quick yes or no answer within about a week to that burning question, is it a meteorite?


LPI | Education

Players assume the roles of meteorites and play a board game to learn about meteors, meteoroids, and meteorites. They compete to get to Antarctica, where they have the chance to be found and studied by scientists! The game can be played as a whole group activity, in teams, or by individuals.

Ages: 3rd grade and up
Duration: 15 – 45 minutes

What's the Point?

Participants will:

  • Learn about meteorites and how we discover them.
  • Discover that the odds of a meteorite landing on Earth and being discovered are low, and yet hundreds to thousands are found each year!
  • Have fun!

Materials

    (one per each group of players)
  • Game Pieces (use pebbles or game pieces from other games) (or powerpoint questions in English or Español, computer, and projector)
  • Information about Space Rocks for facilitator (below)
  • Dice
  • Optional Supporting Videos:
    • History Channel – The Secrets of Meteorites. http://www.history.com/shows/how-the-earth-was-made/videos/the-secrets-of-meteorites
    • PBS NOVA – Hunting for Meteorites. http://www.pbs.org/wgbh/nova/space/matson-meteorite.html
    • NASA’s Solar System Exploration – Meteors and Meteorites. https://solarsystem.nasa.gov/asteroids-comets-and-meteors
    • Killer Asteroids. http://www.killerasteroids.org
    • NASA Goddard Scientific Visualization Studio – Asteroids. http://svs.gsfc.nasa.gov/search/Keyword/Asteroid.html

    Preparation

    • Print the Space Rocks game board if possible, laminate or glue to poster board
    • Determine whether you will project the questions from a computer or use physical cards. If using cards, print and cut apart the Space Rocks! Game Cards. (Laminating the cards will increase their durability)

    Activity

    1. Welcome and introduce the topic. Ask participants what they know about meteorites. After participants have shared and compared their thoughts, share some background:
      • Impacts cause explosions that blast meteoroids off of the surface of their parent body and eventually land on the surface of another moon or planet.
      • Most meteorites come from asteroids, such as the large asteroid Vesta.
      • While they are moving through space, these rocks are known as meteoroids.
      • While they pass through the Earth’s atmosphere, they create a streak of light called a meteor.
      • Most meteoroids are small and burn up in Earth’s atmosphere.
      • Many meteorites land in the ocean or other locations where they are never discovered.
      • On Earth, we have found meteorites from the Moon, Mars, and asteroids.
      Describe the game: they will be playing individually or in teams to move their rock from a parent body (the Moon, Mars, Vesta, or Bennu) to Earth their goal is to land their rock on Antarctica where it has a larger chance of being discovered.
    2. Set up the game. Place the game board in the center of each group of players and place the cards (question-side down) nearby. If more than 4 participants are playing, either conduct multiple games or invite them to play as teams. Invite each player or team to select their “meteoroid” game piece to move about the game board, starting from one of the four corners (parent bodies): Moon, Mars, Vesta, or Bennu.
    3. Rules of the game. Make sure that everyone understands the game and their role in it before proceeding to play. Reassure them that they can ask for your help in the process, if needed, as the game is played.
      • The players or teams will move from their parent body (Moon, Mars, Vesta, or Bennu) in toward the Earth. The first player or team to land in Antarctica and correctly answer a final question wins.
      • Whether they can move forward depends on both what they roll on the dice and whether they can answer a card question correctly. If they don’t roll the correct number or answer the question correctly, they need to stay in the same spot until it’s their turn again.
      • If a group is playing together as a single team, then all can help to answer the questions.
      • More information about the correct answers is available on a cheat sheet that the facilitator can use to explain the answers, or that the players can review after the game.
    4. Game Instructions.
      • Roll a die to determine which player or team will go first. The player or team with the highest number will begin the game. Play always passes to the player on the left. The rules for their play depends on which zone their piece is in.
      Leaving the Parent Body (Moon, Mars, Vesta, or Bennu)
      • The first player or team rolls a die. If they roll an odd number, their turn ends. If the player rolls an even number, then an impact has occurred, which may blow your rock into space to become a meteoroid. Another player picks a card and reads the question aloud for the active player to answer. If they answer correctly, they can move forward to the Meteoroid Zone before their turn ends.
      • The die passes to the player or team on the left again, they need to roll an even number and then answer a card question correctly to move forward to the next zone. If player answers the question incorrectly, they will remain in their current position and pass the die.
      • Continue passing the die to the left.
      The Meteoroid Zone: Once in the meteoroid zone, a player needs to roll a 5 or a 6 to approach Earth. If they roll 1 -4, their turn ends. If the player rolls a 5 or a 6, then their space rock is approaching Earth. Another player picks a card and reads the question aloud for the active player to answer. If they answer correctly, they can move forward to the Meteor Zone before their turn ends. The Meteor Zone: Once in the meteor zone, a player needs to roll an odd number to land on Earth. If they roll an even number, their turn ends. If the player rolls an odd number, and answers a question correctly, they can move forward to the Meteorite Zone before their turn ends. The Meteorite Zone: Once in the meteorite zone, a player needs to roll a 1 to determine whether they landed in Antarctica, where they are more likely to be discovered by scientists. If they roll 2-6, their turn ends. If the player rolls a 1, and answers a question correctly, they land in Antarctica and win.

    Conclusion

    Discuss how unlikely it is for a rock to be blown off another object and land somewhere on Earth where it can be found and studied. And yet hundreds or thousands are found each year!

    Background Information

    Additional details and background information about the questions for the game facilitator: this information is geared toward teens and young adults who can facilitate discussion of the questions and answers. It is not necessary for younger game players to review this information.

    What is a meteor/ what is a meteorite / What is a shooting star/ What is a meteoroid?
    Meteoroids are often small particles, usually no bigger than a grain of sand. When meteoroids enter Earth’s atmosphere, they produce brilliant streaks of light that can be seen in our sky. These brief streaks of light (often called ‘shooting stars’) are meteors. Meteorites are meteoroids that have landed on Earth’s or another planet’s surface.

    Why does a meteor glow? Which object does not have meteors?
    A meteor is the streak of light we see in the sky as a meteoroid passes through our atmosphere however, most of the meteoroids are very small—the size of a grain of sand. We don’t actually see the meteoroid. Instead, we are seeing the air itself glowing as it is ionized from the heat of the meteoroid speeding through it.

    Since meteors are the glowing gases as a meteoroid passes through an atmosphere, objects without an atmosphere (like the Moon) do not have meteors. However, meteors may have occurred on Moon about 3.5 billion years ago, when it was surrounded by a temporary atmosphere.

    How fast does a meteoroid move in our atmosphere?
    Meteoroids are moving incredibly fast (around 50 thousand miles per hour) as they orbit the Sun our Earth runs into them.

    What are the different types of meteorites? What do most meteorites look like?
    Most meteorites found on Earth are pebble to fist size, but some are larger than a building. Meteorites may look very much like Earth rocks, but some have the appearance of a burned exterior called a fusion crust. They may also have thumbprint-like depressions. This crust forms when the exterior of the meteoroid is melted by friction as it passes through the atmosphere.

    Scientists classify meteorites into three groups: stony meteorites, iron meteorites, and stony iron meteorites. Stony meteorites make up about 95% of the meteorites reaching Earth. Iron meteorites make up about 5% of the meteorites found on Earth these come from the cores of shattered planetary bodies (often from a shattered asteroid). These have high amounts of iron and nickel. Scientists thought they knew the origins of the stony and stony iron meteorites, but new evidence has caused them to reconsider. Stony-iron meteorites are in between the other two types of meteorites. These are rare — only about 1% of the meteorite finds on Earth are stony iron meteorites.

    What causes meteor showers/ Which is a meteor shower?
    Meteor showers occur when Earth passes through the trail of dust left by a comet along its highly elliptical orbit. The particles enter Earth's atmosphere and most burn up. Some meteor showers, such as the Perseids in August and the Geminids in December, occur annually when Earth's orbit takes it through the debris path left along the comet's orbit. Comet Halley's trails are responsible for the Orionids meteor shower.

    What is an asteroid? Which is not an asteroid? Asteroid features.
    Asteroids are rocky bodies ranging from 620 miles (1000 km) wide down to dozens of meters, which orbit our Sun or another asteroid. Ceres is the largest of the asteroids, and Vesta is the second largest. Bennu is an asteroid that the OSIRIS-REx mission is studying.

    Most asteroids are irregularly shaped and all have craters from impacts with other asteroids. However, the largest asteroid, Ceres, has sufficient gravity to become nearly spherical, so it is also classified as a dwarf planet! Vesta, another large asteroid, has evidence of ancient lava flows on its surface. Some asteroids, such as Ceres, have large amounts of ice. Asteroids are too small to have an atmosphere, so they cannot have storms.

    What are the types of asteroids?
    Asteroids are classified by their composition. Most of the known asteroids (over 75%) are C-type (carbon-rich) asteroids, located in the outer region of the main asteroid belt. These asteroids are composed of silicate rocks along with some organic compounds and hydrated minerals like clays. Stony or silicate-rich (S-type) asteroids dominate the inner part of the asteroid belt, closest to the Sun. These asteroids are composed of rocky materials and small amounts of metallic iron. M-type (metallic) asteroids are predominantly metallic iron and nickel.

    Where do most meteorites come from?
    Meteorites are ejected from a rocky body by an impact by an asteroid or comet. More than 50,000 meteorites have been found on Earth. Most come from asteroids in particular, several different types of meteorites appear to be from the asteroid Vesta. A few meteorites originate from the Moon and Mars. Meteorites also fall on other solar system bodies. The Mars Exploration Rover, Opportunity, has discovered six meteorites during its travels on Mars.

    What makes an impact crater?
    Craters are roughly circular, excavated holes made by impact events. When an asteroid or comet strikes the solid surface of a planet or another asteroid, a shock wave spreads out from the impact, creating a crater much bigger than the asteroid or comet. The asteroid or comet is shattered into small pieces and may melt or vaporize.

    How long have asteroids been hitting the planets? Do large or small asteroids hit the Earth more frequently?
    Early in the formation of the solar system (4.5 billion years ago), frequent and large impacts were common for all of the planets and moons. Impacts still occur across our solar system, but at a reduced rate. Scientists estimate that Earth and the other terrestrial planets are struck by, on average, five asteroids less than 2 kilometers (a little over 1 mile) across every million years. Larger impacts also still occur, but are more rare.

    Which is hit by the smallest particles from asteroids and comets?
    The Moon does not have an atmosphere to shield the surface from small particles Earth, Venus, and Mars have atmospheres that burn up the smallest particles from asteroids and comets.

    Between the Earth, Moon, and Mars, which does an asteroid hit the fastest?
    Asteroids orbit the Sun at high speeds. When asteroids approach a massive planet, the gravity of that planet pulls them faster. Asteroids hit Earth at a faster speed because the Earth’s gravity is greater than the Moon’s or Mars’.

    Where did an impact cause a mass extinction?
    An asteroid or comet caused a mass extinction on Earth about 66 million years ago, extinguishing dinosaurs and most other life. None of the other planets are known to have any life.

    Which hits the Earth most frequently: asteroids or comets?
    Asteroids hit Earth more frequently. Most asteroids follow orbits between the planets Mars and Jupiter, in planes close to Earth’s (the ecliptic). Comets follow highly elongated orbits around the Sun, which carry them high above and below Earth’s orbit, making them less likely to impact Earth.

    Which asteroid is the OSIRIS REx mission orbiting?
    In 2020, this mission continues to orbit the small asteroid Bennu it will collect a sample of the asteroid to return to Earth for study.

    On Earth, where and when do meteorites fall?
    Meteorites fall everywhere on Earth, all the time. They are easier to find in areas with less vegetation like deserts. Scientists travel to Antarctica annually to collect meteorites from bases of mountain ranges where glaciers deposit them.

    Names of meteorites:
    Meteorites can be named after the places where they are found. For instance, the largest carbonaceous chondrite ever found on Earth, Allende is named after a village in northern Mexico called Pueblito de Allende, where it fell in 1969. Meteorites found in Northwest Africa start with NWA in their names followed by a specific number for each meteorite. Shergotty is a meteorite that was found in Shergotty, India. Later this was identified as a type of Mars meteorite, and the related group of meteorites were named Shergottites.

    Mars meteorites:
    Are ejected from the surface during an impact on Mars, if they are thrown faster than 3 miles per second. They have gases embedded in the meteorites that match the composition of the Martian atmosphere. By 2019, scientists had identified 224 meteorites from Mars. The oldest Mars meteorites were formed on the surface of Mars over 4 billion years ago, but spend much less time in space before landing on Earth for instance, Dhofar 019 spent 20 million years in space.

    Lunar meteorites:
    Meteorites from the Moon can also be called Lunaites. These are ejected from the surface during an impact on the Moon (on all sides of the Moon), if they are thrown faster than 1.5 miles per second. Scientists first identified a meteorite as from the Moon in 1981 by 2019, scientists had identified about 400 meteorites from the Moon that had landed on Earth. None of the lunar meteorites was seen falling as a meteor, and none have been found in North America.


    Where are the samples coming from?

    Perseverance landed at the edge of the Jezero Crater , a landscape that has long intrigued scientists but had previously been deemed too risky to land on . The crater is believed to have once contained a massive lake, billions of years ago when Mars had liquid water on its surface.

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    "Scientists will be looking for rocks that may have formed in water, possibly preserving evidence of the chemical building blocks of life," Lori Glaze, the director of the NASA Planetary Science Division, said in a news briefing last month.

    Jezero has a well-preserved river delta, which formed when a river deposited a large amount of sediment as it emptied into a larger body of water. Life flourishes in river deltas on Earth &mdash scientists are hoping the same was true on ancient Mars.

    "Jezero would have been a place that was habitable," Farley said. "Life as we know it could have lived in that lake, and the mud of a delta is really good at preserving the biosignatures of life."

    "It's not just about the sample, it's about the geologic context of that sample that will also be explored," Thomas Zurbuchen, NASA's director of science operations, said in a news conference Wednesday.

    NASA's Mars 2020 rover will store rock and soil samples in sealed tubes on the planet's surface for future missions to retrieve, as seen in this illustration. NASA/JPL-Caltech


    Meteor Crater History

    In 1902 Daniel Moreau Barringer is told the story of a great deposit of iron by Samuel Holsinger. Barringer is initially skeptical but sends Holsinger to stake claims on the crater in 1903. On March 15, 1903 Barringer forms the Standard Iron Company in Philadelphia with the intent of locating and mining the buried deposit of nickel-iron. By May the development work on the claims is complete and on December 24 Barringer’s friend Theodore Roosevelt signs the patents on the claims. Barringer has never been to the crater. He has waited and avoided notice for fear that others would jump the claims because he is well known in the Arizona mining industry.

    In March of 1904 Barringer and his partner in Standard Iron Company, Benjamin C. Tilghman arrive at the crater for the first time. During that visit they collect many specimens of rock that support an impact origin and they find no volcanic rocks of any type. They collect iron meteorites and find during the digging of trenches masses of weathered iron meteorite that they name Shaleball Meteorites. Barringer is convinced that because the crater has a generally circular shape that the asteroid must have fallen from nearly straight down. Barringer was sure the millions of tons of nickel-iron would be found under the crater floor. Standard Iron Company begins their exploration with a hand dug shaft sunk into the crater center in April of 1904. The material of the floor of Meteor Crater was easy to dig and very soon the shaft reaches 181 feet (55 m) in depth. It was at this point that the men hit quicksand and the shaft was abandoned.

    Barringer and Tilghman would turn to drilling holes into the crater floor. By July of 1908 a total of 28 holes had been drilled in the interior of Meteor Crater. During 1905-1906 while the drilling was going on a second attempt to dig a shaft was conducted. The boiler and wench that were used are still at the center of Meteor Crater today. But despite all their efforts this shaft failed also to reach very far beyond the level of the water and quicksand.

    In 1911 while Barringer is traveling in Europe the largest specimen of Canyon Diablo meteorite was discovered by Samuel Holsinger. Meteor Crater was not officially named that until 1948. Meteorites are named for the nearest geographical feature. In the earliest years that was Canyon Diablo just to the west of Meteor Crater. When Holsinger died a few months later in August of 1911 Barringer named the 1409 lbs (639 kgs) iron he had found The Holsinger Meteorite. Meteor Crater has often been referred to as Barringer Crater by scientists.

    Over the remainder of Daniel Moreau Barringer’s life there would be constant attempts to find something of value he could sell from the crater. Fine silica flour created by the cosmic hammer blow occurs in vast quantities around Meteor Crater. The largest deposit on the south slope was mined for a period after Barringer’s death. But despite many samples being sent to manufacturers during his lifetime none ever lead to a commercial product.

    Barringer expended great effort trying to find investors to fund his search for the buried iron. In 1920 he arranged a lease with United States Smelting Refining and Mining Company of Boston. They agreed to spend $75,000 drilling up to ten holes into the rim of Meteor Crater to locate the nickel-iron deposit. Crater Mining Company was formed as a subsidiary of US Smelting in the Spring of 1920. After months of preparation work drilling started with a 10 inch churn drill bit on November 1, 1920. Progress in the drilling was fantastic at first, with the drill reaching 97 feet (29.5 m) in just three days. But soon the creviced and shattered rocks of Meteor Crater would turn the drilling program into a costly nightmare which lasted for two years. Instead of spending $75,000 on up to ten holes the single drill hole cost nearly $200,000.

    Little evidence of meteoric material was discovered during the drilling on the south rim. Two objects that were nearly as hard as the drill bit were ground through with great difficulty. They were each just a few feet thick and may have been iron meteorite fragments. In the last few feet before the drill became stuck for the last time they had reached an area where weathered meteoritic material was being brought to the surface. But no great mass of millions of tons was ever found. Barringer took the small amount of evidence that the drill had revealed and began an even more costly and futile effort. He started tunneling to the area the drill had found. From a location about 1100 feet (335 m) south of the drill hole out on the slope he began the final shaft. He proposed to dig down to the depth where the drill had encountered the meteoric material. This was over 1300 feet (396 m) and then tunnel horizontally over to the mass. He had long believed that the water which had plagued the previous shafts was confined to the crater. He was to discover that it was not. At around 600 feet (182 m) they hit water again. Larger and larger pumps were obtained and millions of gallons of water were removed. They cemented the walls of the shafts as they descended. The miners struggled down to 700 feet (213 m) with enormous effort. After weeks of more effort they had gained just a few more feet when the pump broke down and the shaft flooded. At a final depth of about 713 feet (217 m) this shaft was also abandoned. It would be the last major attempt to find the buried asteroid.

    While the last shaft is being dug science and mathematics are revealing that the asteroid was small and vaporized on impact. The mathematical report of Forest Ray Moulton would be released just days before Barringer’s death on November 30, 1929. Many feel that the shock and distress of that report contributed to his heart attack.


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