National Aeronautics and

Space Administration

Educational Product

Teachers Grades 5-12

Exploring Meteorite Mysteries

Slide Set with Script

Just after riding bikes Brian and Brodie were

standing talking on Brodie's lawn. Suddenly they heard a low-pitched whistling sound and Brian

saw an object spinning through the air past

Brodie.

The object, which looked like a rock, landed with a thud on the ground near them. The boys picked up

the rock and found it slightly warm. They looked around, but couldn't find anyone who might have

thrown it.

A scientist from Purdue University confirmed that

the rock really was a meteorite.

13 year old Brodie Spaulding and 9 year old Brian Kinzie

August 31, 1991Noblesville, Indiana

It is a typical stony meteorite, gray inside and covered It is a typical stony meteorite, gray inside and covered with a dark crustwith a dark crust

About 30,000 small meteorites like Noblesville fall on About 30,000 small meteorites like Noblesville fall on Earth each year, but only a few are foundEarth each year, but only a few are found

BRIANBRIAN

ANDAND

BRODIE’SBRODIE’S

ROCKROCK

NowNowknown known as theas the

NoblesvilNoblesvillele

MeteoritMeteoritee

Large meteorite falls are rare, Large meteorite falls are rare, about one every ten or twenty about one every ten or twenty

years over the whole Earth years over the whole Earth

One of the most spectacular One of the most spectacular occurred in 1947, in the occurred in 1947, in the

Sikhote-Alin mountains of Sikhote-Alin mountains of eastern Russia eastern Russia

February 12, the calm was February 12, the calm was shattered by a bright meteor, shattered by a bright meteor,

visible for more than 300 visible for more than 300 kilometerskilometers

After it streaked over the After it streaked over the horizon, great explosions roared horizon, great explosions roared

and echoed from the hills, so and echoed from the hills, so loud they were heard 100 loud they were heard 100

kilometers awaykilometers away

It must have been larger It must have been larger before it hit the Earth, because before it hit the Earth, because

some of it vaporized in the some of it vaporized in the atmosphere and on impactatmosphere and on impact

Some of the Some of the meteorites were meteorites were

embedded in trees!embedded in trees!

The Sikhote-Alin The Sikhote-Alin meteorite was meteorite was

probably a piece probably a piece broken off an broken off an

asteroidasteroid

Clearings in the Clearings in the thick forest were thick forest were

blasted open by the blasted open by the impactimpact

There were 106 There were 106 craters and holes in craters and holes in the forest where the the forest where the

meteorites had meteorites had landedlanded

This is one This is one fragment of the fragment of the

Sikhote-Alin Sikhote-Alin meteoritemeteorite

It is about 15 cm It is about 15 cm acrossacross

The photograph The photograph shows the original shows the original meteorite surface, meteorite surface, melted into thumb-melted into thumb-print shapes during print shapes during

its flight through its flight through our atmosphereour atmosphere

Larger meteorites Larger meteorites are extremely rare, are extremely rare,

but make but make enormous craters enormous craters when they hit the when they hit the

EarthEarth

It was formed It was formed about 50,000 years about 50,000 years ago when a large ago when a large iron meteorite hit iron meteorite hit

the Earththe Earth

Scientists Scientists estimate that the estimate that the

meteorite weighed meteorite weighed one million tonsone million tons

Meteor Crater in Arizona is Meteor Crater in Arizona is over one kilometer across and over one kilometer across and

150 meters deep150 meters deep

Many meteorites have Many meteorites have been found in deserts, been found in deserts,

where the heat and where the heat and dryness have kept them dryness have kept them

from rusting awayfrom rusting away

When meteorites are When meteorites are discovered, they are discovered, they are

called findscalled finds

Over 2,000 meteorite Over 2,000 meteorite finds have been made finds have been made

around the worldaround the worldSome of these meteorites were Some of these meteorites were on Earth for hundreds of on Earth for hundreds of

thousands of years before being thousands of years before being foundfound

The best collecting The best collecting place in the world is place in the world is

Antarctica, where Antarctica, where meteorites fell on meteorites fell on the ice and were the ice and were preserved in itpreserved in it

Here scientists Here scientists have found a have found a

meteorite, and have meteorite, and have taken pictures to taken pictures to

document their finddocument their find

Each sample is Each sample is photographed, given photographed, given

a number, and a number, and carefully packaged.carefully packaged.

Meteorites Meteorites collected by U.S. collected by U.S.

expeditions in expeditions in Antarctica are sent Antarctica are sent to this clean lab at to this clean lab at

NASA's Johnson NASA's Johnson Space Center in Space Center in Houston, TexasHouston, Texas

There they are There they are described, described,

classified, and classified, and distributed to distributed to

researchers around researchers around the world for studythe world for study

Although people have Although people have seen meteorites fall seen meteorites fall

since the earliest since the earliest times, it was only times, it was only about 1800 when about 1800 when scientists finally scientists finally

became convinced that became convinced that rocks really did fall rocks really did fall

from the skyfrom the sky

Since then, we've Since then, we've discovered that most discovered that most meteorites come from meteorites come from the asteroid belt, the the asteroid belt, the

area of the solar area of the solar system between the system between the orbits of Mars and orbits of Mars and

Jupiter where many Jupiter where many asteroids orbit the sunasteroids orbit the sun

Asteroids are small Asteroids are small planets, fragments of planets, fragments of rock and iron left over rock and iron left over

from the formation of the from the formation of the solar system or the solar system or the breakup of larger breakup of larger

fragmentsfragments

Many asteroids Many asteroids probably look like Ida, probably look like Ida,

the asteroid in this the asteroid in this picture taken by the picture taken by the Galileo spacecraft in Galileo spacecraft in

19931993

Ida is about 30 Ida is about 30 kilometers long, is made kilometers long, is made

of rock, and has many of rock, and has many craterscraters

Comets are small bodies Comets are small bodies made of rock, dust and made of rock, dust and

ice, formed in the distant ice, formed in the distant reaches of the solar reaches of the solar

systemsystem

Then solar radiation Then solar radiation heats the comet's surface, heats the comet's surface, causing part of the ice to causing part of the ice to

boil off into space and boil off into space and carry some of the dust carry some of the dust

with itwith it

When this happens the When this happens the comet can develop a "tail" comet can develop a "tail"

millions of kilometers millions of kilometers long, and leave a dust long, and leave a dust

trail behind in solar orbittrail behind in solar orbit

Very few asteroid pieces get the chance to travel that farVery few asteroid pieces get the chance to travel that far

Most asteroids never do, and spend eternity in space, Most asteroids never do, and spend eternity in space, quietly orbiting the Sunquietly orbiting the Sun

Larger Larger meteoritemeteorite

s s don't don't come come from from

comets comets but from but from asteroidsasteroids

It's a It's a long way long way from the from the asteroid asteroid belt to belt to

the Earththe Earth

Every now and again the Every now and again the orbits of asteroids cross and orbits of asteroids cross and

their quiet times endtheir quiet times end

Then the asteroids collide Then the asteroids collide and shatter, and the pieces and shatter, and the pieces

fly into different orbits around fly into different orbits around the sun the sun

Some of these pieces orbit Some of these pieces orbit closer and closer to the suncloser and closer to the sun

Eventually some of their Eventually some of their orbits cross the Earth's orbit, orbits cross the Earth's orbit, and the piece of asteroid can and the piece of asteroid can

hit the Earthhit the Earth

We see this moving We see this moving flame as a meteor flame as a meteor crossing the sky crossing the sky

If the asteroid fragment If the asteroid fragment is big enough, fist-sized is big enough, fist-sized or so, it won't burn up or so, it won't burn up

completely and will fall to completely and will fall to the Earth as a meteorite the Earth as a meteorite

These small meteorites These small meteorites do not explode or make do not explode or make craters when they hit craters when they hit

They just hit like an They just hit like an extra large hailstone or a extra large hailstone or a rock thrown from across rock thrown from across

the streetthe street

Stony meteorites are Stony meteorites are commonly made of commonly made of

familiar minerals like familiar minerals like plagioclase, pyroxene, plagioclase, pyroxene,

and olivineand olivine

Scientists believe that Scientists believe that they were formed in the they were formed in the outer parts of asteroidsouter parts of asteroids

The two main types of The two main types of stony meteorites are stony meteorites are

chondrites and chondrites and achondritesachondrites

Stony meteorites look a Stony meteorites look a lot like Earth rocks, and lot like Earth rocks, and are often not recognized are often not recognized

as meteoritesas meteorites

Iron meteorites Iron meteorites probably formed in the probably formed in the

cores of asteroidscores of asteroids

Inside, many iron Inside, many iron meteorites are made of meteorites are made of

criss-crossing criss-crossing intergrown crystals of intergrown crystals of

two iron-nickel mineralstwo iron-nickel minerals

The sizes and shapes of The sizes and shapes of the crystals suggest that the crystals suggest that

they cooled down so they cooled down so slowly, a few degrees slowly, a few degrees

each million years, that each million years, that they must have been they must have been inside large asteroidsinside large asteroids

The two types of crystals in The two types of crystals in this sample are several this sample are several

centimeters widecentimeters wide

Some meteorites are Some meteorites are mixtures of iron and mixtures of iron and

fragments of rockfragments of rock

They are called stony-They are called stony-iron meteoritesiron meteorites

This sample, like the This sample, like the one in the Meteorite one in the Meteorite

Sample Disk, formed at Sample Disk, formed at the boundary between the boundary between the metal core and the the metal core and the

rocky mantle of an rocky mantle of an asteroidasteroid

The story of meteorites The story of meteorites begins 4.6 billion years begins 4.6 billion years

agoago

The solar system began The solar system began as a spinning cloud of gas as a spinning cloud of gas and dust, called the solar and dust, called the solar nebula, which collapsed nebula, which collapsed under its own weight to under its own weight to form a new star, our Sunform a new star, our Sun

As the solar nebula spun As the solar nebula spun and churned, dust grains and churned, dust grains stuck together to form stuck together to form

dustballs, and huge bolts dustballs, and huge bolts of lightning melted them of lightning melted them

into small spheresinto small spheres

These solidified into rocky These solidified into rocky balls called chondrulesballs called chondrules

This diagram shows an This diagram shows an undifferentiated stony asteroid which undifferentiated stony asteroid which was heated enough for the inside to was heated enough for the inside to

meltmelt

In an asteroid the densest material is In an asteroid the densest material is iron metal, shown as black dots, which iron metal, shown as black dots, which

sinks toward the centersinks toward the center

The lightest minerals, silicates called The lightest minerals, silicates called feldspar, float toward the surface feldspar, float toward the surface

The remaining material solidifies to The remaining material solidifies to form the minerals olivine and form the minerals olivine and

pyroxene, which stay in the middlepyroxene, which stay in the middle

The Earth and Moon differentiated The Earth and Moon differentiated just this wayjust this way

Early in the solar Early in the solar system's history, about system's history, about

4.4 billion years ago, the 4.4 billion years ago, the Earth's surface was a Earth's surface was a violent, lifeless placeviolent, lifeless place

Primitive meteorites, Primitive meteorites, called carbonaceous called carbonaceous chondrites, may have chondrites, may have

brought water and brought water and carbon into this carbon into this

inhospitable world, and inhospitable world, and so helped set the stage so helped set the stage

for lifefor life

It was covered with active It was covered with active volcanoes and hot lava flows, volcanoes and hot lava flows,

as in this photoas in this photo

The dinosaurs were The dinosaurs were killed 65 million years killed 65 million years

ago after a huge ago after a huge meteorite hit the Earthmeteorite hit the Earth

The explosion caused The explosion caused great storms and great storms and

waves, and the sky was waves, and the sky was dark for months with dark for months with

dust and ashdust and ash

The dinosaurs, along The dinosaurs, along with many other with many other

animals and plants, animals and plants, were probably killed by were probably killed by

the climate changes the climate changes that followed the that followed the

explosionexplosion

Meteorites have also had Meteorites have also had devastating effects on life...devastating effects on life...

In 1993 a comet was In 1993 a comet was discovered heading for discovered heading for

JupiterJupiter

That planet's immense That planet's immense gravity had torn the gravity had torn the

comet into more than 20 comet into more than 20 fragments, which were fragments, which were

lined up and heading for lined up and heading for Jupiter at over 60 Jupiter at over 60

km/secondkm/second

In the summer of 1994 In the summer of 1994 one fragment after one fragment after

another smashed into another smashed into the planet, producing the planet, producing

huge explosionshuge explosions

We saw, from a safe We saw, from a safe distance, the kind of distance, the kind of

massive impacts that have massive impacts that have scarred all of the planets, scarred all of the planets,

including Earthincluding Earth

Today, we look to Today, we look to the future, toward the future, toward space missions to space missions to the asteroids, and the asteroids, and

eventually to eventually to human travel to human travel to

other planetsother planets

Guided by the Guided by the meteorites that fall meteorites that fall to Earth, we might to Earth, we might mine the asteroids mine the asteroids for oxygen, water for oxygen, water

or metalor metal

We might also search them for We might also search them for more clues to our origins, as we more clues to our origins, as we

continue to explore the solar continue to explore the solar systemsystem

One day humans One day humans will explore the will explore the

surface of Mars and surface of Mars and other worlds other worlds

farther still from farther still from EarthEarth

In order to stay In order to stay for long periods, we for long periods, we will have to learn to will have to learn to "live off the land," "live off the land,"

just like the just like the pioneers of oldpioneers of old

Resources from Resources from the planets and the planets and asteroids may asteroids may

provide the key to provide the key to humanity's humanity's

exploration across exploration across the solar systemthe solar system

The Moon is covered The Moon is covered

with craters in a wide with craters in a wide

range of sizesrange of sizes

You can see a few of You can see a few of

the largest with your the largest with your

naked eyes, and many naked eyes, and many

more with binocularsmore with binoculars

The planet Mercury, The planet Mercury, as seen by the as seen by the

Mariner 10 spacecraft, Mariner 10 spacecraft, is also covered with is also covered with

craterscraters

Mercury has Mercury has essentially no essentially no

atmosphere, and its atmosphere, and its cratered surface looks cratered surface looks much like that of the much like that of the

MoonMoon

Venus Venus has a thick has a thick atmospheratmospher

e which e which destroys destroys

many many impacting impacting

bodies bodies before before

they reach they reach the surfacethe surface

The colors in this picture were made by a computer, to The colors in this picture were made by a computer, to make it easier to pick out the craters and other featuresmake it easier to pick out the craters and other features

We We cannot cannot see the see the

surface of surface of Venus Venus

directly, directly, since the since the atmospheatmosphere is filled re is filled with thick with thick

cloudsclouds

The surface of Venus has craters tooThe surface of Venus has craters too

Impact craters Impact craters are also visible are also visible on the planet on the planet

MarsMars

The thin The thin martian martian

atmosphere does atmosphere does not do much to not do much to

slow an slow an impacting body impacting body

from spacefrom space

This photo, taken This photo, taken by the Viking by the Viking

spacecraft, shows a spacecraft, shows a relatively fresh relatively fresh crater on the crater on the

martian northern martian northern plainsplains

If craters are so If craters are so common in the solar common in the solar

system, why are system, why are they so rare on they so rare on

Earth?Earth?

The The Earth’s Earth’s

surface is surface is constantly constantly

being being changed changed

by erosionby erosion

Water, Water, ice, wind, ice, wind, and plate and plate tectonics tectonics

have have destroyed destroyed

most of the most of the craters craters

that Earth that Earth once hadonce had

Only relatively young or quite large craters Only relatively young or quite large craters exist on Earth todayexist on Earth today

The craters of some The craters of some impacts can still be impacts can still be seen, often as round seen, often as round lakes like the twin lakes like the twin

Clearwater Lakes in Clearwater Lakes in CanadaCanada

These two craters, 32 These two craters, 32 and 22 km across, are and 22 km across, are both 290 million years both 290 million years

oldold

Manicouagan Manicouagan crater in Canada is crater in Canada is a ring-shaped lake a ring-shaped lake

nearly 70 km nearly 70 km acrossacross

In the 212 million In the 212 million years since it was years since it was formed, the crater formed, the crater has been deeply has been deeply

erodederoded

Some craters have Some craters have been almost been almost

completely eroded completely eroded awayaway

Spider Crater in Spider Crater in Australia, 13 km Australia, 13 km

across, is over 600 across, is over 600 million years oldmillion years old

It is barely It is barely recognizable as an recognizable as an impact structureimpact structure

Chondrules are the Chondrules are the primitive building primitive building blocks of the solar blocks of the solar

systemsystem

The largest The largest chondrule in this chondrule in this

picture is less than 1 picture is less than 1 cm acrosscm across

Most chondrules Most chondrules are so small that it is are so small that it is

difficult to learn difficult to learn much about them much about them

without a microscopewithout a microscope

In the early solar nebula In the early solar nebula chondrules came together chondrules came together to form larger and larger to form larger and larger masses, this process is masses, this process is

called accretion called accretion

In most meteorites, In most meteorites, though, the chondrules though, the chondrules have been partially or have been partially or totally destroyed by totally destroyed by

metamorphism metamorphism

To destroy chondrules To destroy chondrules takes a lot of pressure and takes a lot of pressure and cooking time, so much that cooking time, so much that these meteorites could not these meteorites could not have been formed as small have been formed as small rocks floating in the solar rocks floating in the solar

nebulanebula

In some chondrites the In some chondrites the chondrules are chondrules are

separated by patches of separated by patches of iron metal iron metal

Different types of Different types of chondrite meteorites chondrite meteorites

have different amounts have different amounts of metal and have been of metal and have been

heated to varying heated to varying degreesdegrees

Chondrites are called Chondrites are called primitive because they primitive because they formed early in solar formed early in solar system history and system history and

haven't changed since haven't changed since thenthen

Carbonaceous Carbonaceous chondrite chondrite

meteorites are meteorites are black because they black because they contain carbon, like contain carbon, like soot or pencil leadsoot or pencil lead

They also contain They also contain water, complex water, complex

carbon compounds carbon compounds and mineral grains and mineral grains even older than the even older than the

solar system - solar system - pieces of dust that pieces of dust that formed long ago formed long ago

around far distant around far distant starsstars

Action on an Action on an asteroid may not end asteroid may not end with differentiationwith differentiation

The lava hardens to The lava hardens to a rock called basalta rock called basalt

Some basalts from Some basalts from asteroids fall to Earth asteroids fall to Earth

as meteoritesas meteorites

Some asteroids got so hot Some asteroids got so hot that they melted inside and that they melted inside and

spewed lava onto their spewed lava onto their surfaces, just like this lava surfaces, just like this lava

flow on Earthflow on Earth

Achondrites are a Achondrites are a class of stony class of stony

meteorites, so named meteorites, so named because they do not because they do not contain chondrulescontain chondrules

They look like They look like igneous (lava) rocks igneous (lava) rocks

on Earthon Earth

These achondrites These achondrites formed during formed during

volcanic eruptions on volcanic eruptions on planets or asteroidsplanets or asteroids

This is a meteorite This is a meteorite which was found a few which was found a few years ago in Antarcticayears ago in Antarctica

Scientific studies have Scientific studies have proven that this proven that this

meteorite and a few meteorite and a few others like it are from the others like it are from the Moon, not from asteroidsMoon, not from asteroids

They were blasted off They were blasted off the Moon by other the Moon by other

meteorite impacts there, meteorite impacts there, and quickly traveled the and quickly traveled the short distance from the short distance from the

Moon to the EarthMoon to the Earth

This meteorite, found This meteorite, found in Antarctica, contains in Antarctica, contains

traces of Martian traces of Martian atmosphereatmosphere

The Martian The Martian atmosphere gas is in atmosphere gas is in

black veins and black veins and pockets of glass, which pockets of glass, which you can see on this cut you can see on this cut

surfacesurface

The glass probably The glass probably formed when another formed when another

meteorite hit Mars and meteorite hit Mars and partly melted these partly melted these

rocksrocks

The frozen continent of The frozen continent of Antarctica has proven to Antarctica has proven to

be the best place on Earth be the best place on Earth to find meteoritesto find meteorites

The meteorites fall onto The meteorites fall onto glacial ice and are carried glacial ice and are carried

along until the glacier along until the glacier encounters a mountain encounters a mountain range or other barrierrange or other barrier

The ice then stops and The ice then stops and eventually evaporates, eventually evaporates, leaving the meteorites leaving the meteorites

behindbehind

Meteorite collecting Meteorite collecting trips to Antarctica trips to Antarctica

are not easyare not easy

Teams live in polar Teams live in polar tents far from their tents far from their

permanent bases for permanent bases for months at a timemonths at a time

In bad weather In bad weather team members may team members may be confined to their be confined to their

tents for days, but on tents for days, but on good days they are good days they are

out finding out finding meteoritesmeteorites

They travel by They travel by helicopter and helicopter and

snowmobilesnowmobile

Meteorites Meteorites collected in collected in

Antarctica by U.S. Antarctica by U.S. expeditions are expeditions are brought to this brought to this

special clean lab at special clean lab at the NASA Johnson the NASA Johnson Space Center in Space Center in

Houston, Texas for Houston, Texas for initial studyinitial study

Experienced Experienced curators describe curators describe and classify themand classify them

The meteorites are kept in The meteorites are kept in glove boxes filled with nitrogen glove boxes filled with nitrogen gas to keep them from rusting gas to keep them from rusting

or otherwise changingor otherwise changing

The curators The curators are responsible are responsible for distributing for distributing

meteorite meteorite samples to samples to scientists scientists

around the around the worldworld

Here a piece Here a piece of a small of a small

meteorite is meteorite is being chipped being chipped

off for scientific off for scientific studystudy

The meteorites are The meteorites are examined with many examined with many sophisticated toolssophisticated tools

One of them is the One of them is the scanning electron scanning electron

microscopemicroscope

This microscope can This microscope can take pictures with take pictures with

magnifications of over magnifications of over 100,000 times and 100,000 times and

determine the chemical determine the chemical compositions of bits of compositions of bits of material too small to be material too small to be

seen with the naked seen with the naked eyeeye

Computers are used Computers are used everywhere in everywhere in

scientific laboratoriesscientific laboratories

Some are used to Some are used to control instruments control instruments and some to collect and some to collect

datadata

Scientists also use Scientists also use computers to create computers to create

the diagrams and the diagrams and write the reports that write the reports that

tell others of their tell others of their resultsresults