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On this episode of NASA Connect, you'll learn about the science concepts of remote sensing,

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see how it's being used by archaeologists, and apply your math skills with a remote sensing

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activity.

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All on NASA Connect, Landscape Archaeology.

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Hi, I'm Jennifer Pooley, and welcome to NASA Connect, the show that connects you to math,

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science, technology, and NASA.

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Right now, we are at an archaeological dig site in historic Jamestown, Virginia.

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Imagine being a settler in Jamestown in 1607.

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You and your family gave up the comfort of the life you knew in England to set off on

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a perilous transatlantic journey in a small boat.

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Now, you and the others in your party were headed for a place you knew little about and

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would need to find a way to survive.

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What if you had a way to remotely gather information about the region before you began the journey?

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Would this have influenced your decision to go?

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Could the information better prepare you to face the living conditions?

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This is not unlike the journey we envision for human settlement on Mars.

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What can we learn from the past that will help us tomorrow?

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On today's show, you'll learn how researchers observe the Earth from space in ways that

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we can't do here on its surface.

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You'll see how the data they collect from satellites is being used to help us make better

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use of our environment today by looking at how yesterday's civilizations used their precious

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resources.

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During the course of this program, your teacher will stop the tape and ask you several inquiry-based

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questions.

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Now, this is your time to explore and become critical thinkers.

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Just as archaeologists in Jamestown are looking to the past for answers to the future, so

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is a dedicated team of researchers in the rainforest in Guatemala.

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Imagine you and your family are farmers in the northern quarter of Guatemala.

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Your family is using the land in the same way as your ancestors have for thousands of

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years.

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Now imagine that a group of scientists warn you that the type of farming you are practicing

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could jeopardize your family's way of life and the future of the Patan rainforest that

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you live in.

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You could even be changing the Earth's climate for the worse.

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While you have noticed few changes in your immediate surroundings, scientists tell you

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they have been observing this region from space and have evidence you are making the

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same dangerous mistakes in your environment that your ancestors did.

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What would you do?

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You know, this is a real problem facing the people of Guatemala today.

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So, on today's show, we will look at one of the ways NASA is working to preserve our

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environment by learning lessons from the past.

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But first, let's put on our thinking caps.

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Students working in groups take a few minutes to answer the following questions.

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What do you think remote sensing means?

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What are some of the ways that you collect information about the world around you?

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Choose an object in the class and describe it using as many details as possible without

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getting close to it or touching it.

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It's now time to pause the program and answer the questions.

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So, how did you do with the questions?

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Great job, everyone.

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Have you ever heard of the term remote sensing?

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Well, it's a rather simple activity that we do every day of our lives.

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In fact, as you're watching this program right now, you're actively engaged in remote sensing.

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Coming from the screen is energy in the form of visible light.

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The radiated light is detected by sensors in our eyes, which collect data about the

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energy and transmit that information to the brain.

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In the brain, those data are interpreted and meaning is attached to it.

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We experience such sensations as heat.

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We react to chemical signals from food.

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We understand the textures of different surfaces all without coming in direct contact.

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Now, this can be called remote sensing.

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Now, at NASA, remote sensing has a slightly more technical definition.

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So, let's talk to an expert in that field, Dan Irwin at NASA Marshall Space Flight Center.

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Thanks, Jennifer.

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Remote sensing is gathering information about the Earth from a distance.

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Information can be collected about the land using special cameras or instruments

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located just a few feet above the Earth's surface,

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or an airplane flying hundreds to thousands of feet above the ground,

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or even from a satellite orbiting hundreds of miles above the Earth.

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Now that you know what remote sensing means, let's talk about terrestrial remote sensing.

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Terrestrial refers to the Earth.

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So, terrestrial remote sensing means gathering information about the Earth from a distance.

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This involves the detection and measuring of electromagnetic energy

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coming from different objects made of various materials.

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The spectrum of sunlight reflected by the Earth's surface

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contains information about the materials it is made of.

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Since sand, rocks, crops, and dense vegetation each have different temperatures

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and reflect light in different ways,

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sensors can reveal clues about past human activities, such as agriculture,

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that our eyes may not be able to detect.

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Most of the universe is invisible to humans.

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In fact, the only part that we can see with our detectors, or our eyes,

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is part of the electromagnetic spectrum known as visible light.

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If the entire electromagnetic spectrum were scaled to the size of the Earth's circumference,

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the portion of visible light would be as wide as a pencil.

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But scientists have been able to build sensors

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that can see portions of the electromagnetic spectrum that we cannot.

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For example, Norbert is standing next to a hot stove.

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He cannot see the infrared energy coming from it,

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but the sensors in his skin send data to his brain that's interpreted as heat.

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He knows to move away.

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We know to protect our skin from ultraviolet radiation.

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While we cannot see this energy with our eyes, we can see its effects on our skin.

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So what is the electromagnetic spectrum?

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The electromagnetic spectrum is just a name that scientists give

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to a bunch of types of radiation when they want to talk about them as a group.

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Radiation is energy that travels and spreads out as it goes.

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Visible light that comes from a lamp in your house

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or radio waves that come from a radio station

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are two types of electromagnetic radiation.

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Other examples of electromagnetic radiation are microwaves,

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infrared and ultraviolet light, X-rays and gamma rays.

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Hotter, more energetic objects create higher energy radiation than cooler objects.

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Visible satellite images are similar to pictures a photographer might record

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in that they relay and display reflected light just as our eyes would see the scene.

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As long as light is available, land features like mountains, river courses, lakes,

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silt runoff from rivers into the sea, and coastlines are clearly visible.

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But what about the energy that we cannot see?

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Infrared images display gradients of temperature differences.

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Infrared sensors pick up data both day and night.

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They show the pattern of heat released from the earth.

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Heat-producing areas such as warm water currents or cities

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with heat-absorbing concrete and asphalt,

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and heat-producing cars, people and factories

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are bright spots on the infrared images.

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Archaeologists use data collected by sensors located on satellites

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to reveal clues about the past temperature and chemical composition

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to find potential agricultural and other areas of human occupation.

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For example, let's take a look at a satellite image of the Sahara Desert in Africa.

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Right now you're looking at an image in visible light

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as if you were in an airplane or a spacecraft looking out the window.

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A 50-kilometer-wide path from the Shuttle Imaging Radar mission over the Sahara

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is now shown superimposed on the previous image.

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The radar penetrated a few meters beneath the desert sand

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to reveal a prehistoric river system.

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Archaeologists have found artifacts in animal remains

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showing that this was once a moist and densely vegetated area.

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While each of these instruments creates a different image,

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imagine if they could be combined to give scientists and researchers

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new information about a particular area.

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That's what GIS does.

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GIS stands for Geographic Information System.

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GIS is a system of computer software, computer hardware, data,

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and humans that help manipulate, analyze, and present information

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about a specific geographic location.

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The human part of the system is the thinking explorer,

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who is key to the power of GIS.

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Simply put, GIS combines layers of information about a place

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to give you a better understanding of that place.

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What layers of information you combine depends on what you want to know.

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If you want to find the best location for a new sporting goods store,

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you might want to know the traffic pattern and population density.

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You might also want to know if there are any potential customers living nearby.

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Hi, everybody, and welcome back to Jamestown Settlement.

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Now, so far, we've seen some of the science involved

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in investigating these ancient mysteries.

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But now, let's take a look at the math concepts used,

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and I bet you'll know a few of them.

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Now, you know that a number line is a series of numbers

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that begin at the origin, 0, and move away from that origin

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in both a positive direction and a negative direction toward infinity.

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Each division of a number line always represents the same increment.

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We use number lines to compare data.

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Sometimes, when scientists compare data, they use number lines.

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Now, on a number line, the number to the left

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is always less in value than the number to the right.

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You can graph integers on a number line by drawing a dot.

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For example, let's graph 5 on the number line.

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Now, start at the origin and move 5 spaces to the right.

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Okay, now let's graph negative 3 on the number line.

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Start again at the origin and move 3 spaces to the left.

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Let's take a couple of minutes and try the following example.

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Draw a number line from negative 10 to 10.

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Graph the integers 9 and negative 7.

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Graph the numbers you think might be their opposite integers.

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Teachers, this might be a good time to pause the tape

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so that students can give this a try.

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Welcome back, guys. Well, let's see how you did.

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The number line you made should have looked like this

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with the origin, or 0, in the middle.

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Each integer on the number line has an opposite integer

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that is equally distanced from the origin.

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For example, let's look at the number 9.

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It is 9 spaces from the origin to the right.

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Its opposite integer is negative 9.

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Both numbers are an equal distance on the number line from the origin.

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You should have also plotted negative 7 and 7 using the same method.

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Now, don't worry if you didn't get it right the first time.

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You can try again later, now that you know how.

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Now that you understand number lines, let's continue.

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Depending on the data that scientists are analyzing,

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they may need to use what we call the rectangular coordinate system.

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Now, this system consists of not one, but two number lines.

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These number lines cross at their origins and are perpendicular to each other.

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The area they create is called a plane.

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A plane is a two-dimensional object.

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The central point where the two lines cross is called the origin.

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Each number line now has a special name.

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The horizontal number line is called the x-axis.

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The vertical number line is called the y-axis.

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Now, the x- and y-axes divide the plane into four sections called quadrants.

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These quadrants are labeled counterclockwise as the first, second, third, and fourth.

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Now, remember where the two axes cross is called the origin.

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Points to the right and above the origin are labeled with positive numbers,

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1, 2, 3, etc.

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Points to the left and below the origin are labeled with negative numbers,

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1, 2, 3, etc.

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When plotting numbers in the rectangular coordinate system, we use coordinates.

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Now, these coordinates are the addresses of those points and are called ordered pairs.

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The first coordinate, then, is called the x-coordinate.

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The second is called the y-coordinate.

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Now, we always write these coordinates as pairs,

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with the first number representing the x-axis position

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and the second number representing the y-axis position.

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So, what do you think the ordered pair is for the origin?

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Well, if you guessed 0, 0, you are absolutely right.

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Let's take a closer look.

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We use ordered pairs of numbers to describe positions of points on the rectangular plane.

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The ordered pair 2, 3 means over positive 2 and up positive 3.

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However, the ordered pair 3, 2 means over positive 3 and up positive 2.

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Where do you suppose the point negative 3, negative 2 is located?

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Well, in this case, the x-coordinate is a negative number.

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You would move three places to the left of the origin.

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And, since the y-coordinate is a negative number, you would move two spaces down.

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Working in groups, let's see if you can graph the following coordinate pairs.

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2 equals negative 4, 1.

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Teachers, this would be a good time to pause while students give this a try.

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Okay, guys, let's see how you did.

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Here is what your coordinate points should look like.

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Don't be discouraged if yours doesn't come out perfect the first time.

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Later on, you can go back and try it again.

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You know, many times, scientists have to go back and recheck their work to correct their mistakes.

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Now that you know how to plot points using the rectangular coordinate system,

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can you think of when you might have already used this system?

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Norbert and Zot are using it right now.

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We use the rectangular coordinate system all the time.

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In fact, knowing how to locate points on a coordinate grid can actually help you locate points on a map.

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Let's take a look at Norbert and Zot.

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Can you describe their position?

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Can you describe their position now?

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By using a coordinate system, it is much easier to describe the position of objects in the real world.

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A coordinate is a point on a line.

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Two lines perpendicular to each other create a plane.

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Positions in this plane are labeled using two coordinates called an ordered pair.

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Now, in the science world,

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maps are an example of how we use the rectangular coordinate system to describe the location of items on the Earth's surface.

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This special type of map is called a topographical map.

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Sometimes, scientists need to plot data that is three-dimensional.

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To describe three-dimensional images,

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we can just simply add another axis to our rectangular coordinate system and plot points in three dimensions.

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Let's visit with the students in Pasadena, Texas,

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who used the rectangular coordinate system to complete a math and science activity.

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Hello, and welcome to Sophomore Intermediate School.

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We want to show you a cool activity that you can try in your own classroom.

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You can view and download this detailed description of how to do this lesson in your classroom from the NASA Connect website.

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Working in groups, we built imaginary environments instead of shoeboxes.

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We had to keep it top secret from all the other groups.

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Some of us included cool features like ponds, mountains, and trees.

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Next, we covered our environments with foil that had a grid marked on it.

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Then came the fun part.

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We created our shoebox environments with another group.

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We got to act like investigators trying to figure out what the environment in the box was without actually seeing it.

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We took turns using a screw to probe what might be in the box.

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Each person measured the depth of their probe.

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On our data sheets, we were careful to match our measurements for each probe to the correct coordinates of the foil grid.

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We were only allowed to choose 50 different probes.

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This made me realize just how accurate scientists would have to be when they map an area of land.

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Some groups used their data to create topographical maps of what they thought was in the shoeboxes.

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Other groups used a graphing program to create their topographical maps.

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The best part was when we got to look inside the shoeboxes and compare our drawings to what was really there.

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I'll bet that's how explorers will feel when they finally visit someplace like Mars.

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We hope you try this activity with your class.

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That looks like so much fun. I wish I could have been there with you.

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Now let's take a look at how NASA's only archaeologist, Tom Seaver, and other researchers are using the Rectangular Coordinate System,

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remote sensing, and GIS to answer questions about an ancient culture.

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When you think of an archaeologist, what do you picture?

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Someone just digging spearheads or maybe pottery or writing down the words of some primitive tribe?

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My name is Tom Seaver, and I'm a NASA archaeologist.

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And what I do is try to understand why human cultures succeed and why they fail.

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I also excavate artifacts in an attempt to understand the ancient past.

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These artifacts consist of ceramic bowls, of bone material, and of spearheads, lithics, stone material.

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More importantly, what I do is examine the soil structures to try to understand and reconstruct prehistoric environments and ancient climate patterns.

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Where the Patan Rainforest of Guatemala now stands, a great civilization once flourished, the Maya.

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The Maya built vast cities, ornate temples, and towering pyramids.

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At its height around 850 A.D., the population numbered 500 people per square mile in rural areas

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and more than 2,000 people per square mile in the cities, comparable to modern-day Los Angeles County.

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The Maya initially depended on a type of farming known as slash and burn, which means exactly what it sounds like.

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In order to grow crops such as corn, they would completely cut away or slash the dense jungle vegetation, exposing soil for planting crops.

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They would burn the debris that had been cleared.

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Initially, ash from the burned debris gives the soil its fertility, but within three to five years, the soil becomes exhausted, forcing the farmer to move on and cut down a new section.

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Eventually, slash and burn would not support the large population of the Maya, so they developed new agricultural techniques.

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We are trying to determine exactly what these techniques were.

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Without trees, erosion worsened, carrying away fertile topsoil.

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Topsoil is the fertile layer of soil with enough nutrients to support healthy plant growth.

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In the rainforest, this layer of soil is very thin.

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Slash and burn agriculture is being practiced in Guatemala today, and many researchers like myself feel that this technique of agriculture is affecting local climate today in the area.

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Our computer models suggest that when the forest is completely cut down, the temperature of a region can rise five to six degrees.

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If the Maya had completely deforested the region, the warmer temperatures would have dried out the land, making it very difficult for raising crops.

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Rising temperatures would also have disrupted rainfall patterns.

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During the dry season in the Patan, water is scarce, and the groundwater is too deep, 500 feet deep, to tap with wells.

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The Maya must have relied on rainwater saved in reservoirs to survive, so a disruption in rainfall could have a terrible consequence on their ability to grow food.

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Even when the Maya filled up all their reservoirs, they only had an 18-month supply.

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A two- or a three-year drought would have had a devastating effect on them.

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Remember what I said about the lack of trees causing erosion?

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Archaeologists have also studied samples of soil from ancient lake sediment in the Patan rainforest region.

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In these samples of sediment, they have discovered tree pollen.

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The curious part of all of this is that around 1,200 years ago, just before the Maya civilization's disappearance, tree pollen disappeared almost completely and was replaced by the pollen of weeds.

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In other words, the region became almost completely deforested.

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Did the Maya experience a natural drought that was made worse by the deforestation of their environment?

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A lot of researchers think that this is exactly what happened at 800 A.D.

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However, there is a bigger question.

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The Maya survived for centuries in the delicate tropical forest of Central America.

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Exactly how did they do it?

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An important clue comes from space.

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Data collected from satellites orbiting the Earth show evidence of an ancient system of canals and irrigation ditches in low-lying swamps called bajos, the Spanish word for lowland.

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Today's residents make little use of the bajos.

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For years, archaeologists believe that the Maya hadn't used these swampy areas either.

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During the rainy season from June to December, the bajos are too muddy, and in the dry season, they're parched.

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Neither condition is good for farming.

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Not only do I use data collected from satellites, I also practice what is called ground-truthing.

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Using a coordinate grid system, I am able to create maps of where I think I might find evidence of the Maya canals and irrigation ditches.

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Using satellite images, I explore the Earth up close to see that my data matches what I can observe on the ground.

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Data collected through remote sensing and ground-truthing have led archaeologists to hypothesize that these ancient canals and habitation sites were part of a system devised by the Maya to manage water in the ancient bajos and to use these areas for farming.

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The bajos make up almost half of the region.

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By making good use of the bajos for farming, the Maya would have been able to grow a much larger and more dependable supply of food.

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They could have farmed the bajos during the dry season by draining the water to lower areas into reservoirs.

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This way, they could have had two crops on the elevator bridges during the rainy season and two crops during the dry season in the bajos.

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It is the evidence of these features in the bajos that is leading researchers and environmentalists to help the people of the Bataan Rainforest today.

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One goal of our NASA research is to see if we can rediscover how the ancient Maya used this environment successfully.

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If we can determine the agricultural techniques that they used, we can use those techniques and apply them to modern-day populations who are living in the area today.

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By learning what the Maya did right and what they did wrong, maybe we can help local people find sustainable ways to farm the land while stopping short of the excesses that doomed the Maya.

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Using satellite data to examine Mayan ruins gives Seaver a big-picture view, otherwise impossible from his perspective here on Earth.

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Combining remotely sensed or satellite data with conventional down-in-the-dirt archaeological findings and working with NASA climate scientists,

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he may have uncovered a clue that will solve one of history's greatest mysteries as well as provide clues about what will happen to our Earth in the future.

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Wow. You know, right now as you watch this show, the rainforest is still falling under the axe.

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About half of the original rainforest has been destroyed in the past 40 years, cut down by farmers practicing slash-and-burn agriculture.

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This cycle repeats endlessly, or until the forest is gone.

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By 2020, only 2% to 16% of the original rainforest will remain if current rates of destruction continue.

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Changes in cloud formation and rainfall are occurring over deforested parts of Central America today.

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Is history repeating itself?

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If the residents of the rainforest cannot learn to live with their environment, many scientists believe history will in fact repeat itself.

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The bottom line is, how well do we, can we relate to our environment?

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As we seek to explore new worlds, such as Mars, we are taking our cues from the mistakes of the past.

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Before sending humans to create colonies, NASA has a carefully planned series of uncrewed missions designed to observe the environment of Mars.

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Now these missions are looking for water, testing the atmosphere, and monitoring the cycles of weather.

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Armed with as much detailed information as possible, future explorers and colonists to the Red Planet will have a better understanding of how to work with their environment before they arrive.

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They will be much better prepared for survival than were the Jamestown colonists in 1607.

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In fact, it is very likely that you are sitting among some of the first explorers and colonists of Mars.

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That's right. NASA predicts that they will put humans on Mars as early as 30 years from now.

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So here's my challenge to you, the next generation of explorers.

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How can you learn from the past mistakes we've made here on Earth and apply that information to making better decisions for your future exploration of new worlds?

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Well, that wraps up another episode of NASA Connect. We'd like to thank everyone who helped make this program possible.

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Got a comment, question, or suggestion? Well, then email them to connect at lark.nasa.gov.

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And don't forget to check out this program's student challenge. You can find it on the NASA Connect website.

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So until next time, stay connected to math, science, technology, and NASA. Goodbye for now.

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Music

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Music