Activity 3: Remote Sensing

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Concept
Learning Objectives
Set-Up
How To Demonstrate
Questions To Ask
Sample Dialogue
What's Next?


Concepts
  • Remote sensing can be active or passive and can be performed with different types of scientific instruments, including different types of satellites. Different methods and equipment produce different data.
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Learning Objectives
  • The visitor will use a digital camera on a tablet to take a picture passively and actively, comparing the data collected. Using the tablet, the visitor will explore different types of satellite and information they collect.
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Set-Up
  1. Take out the remote sensing box and place it on the cart.
  2. Make sure the tablet is charged and have the camera app ready with the flash off.
  3. If desired, have the metal cube with solar panels attached ready inside the cart.

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How To Demonstrate
  • Attract visitors by asking them questions like, “Want to take a picture with me?” or “Want to find out about Earth from space?”
  • Ask the visitor how they think we can find out about something that is far away. We can use equipment like telescopes, which allow us to see things that are far away. Many telescopes have equipment that can detect things we can't even see. Ask the visitor whether we would ever want to look at Earth from space, encouraging them to discuss how we would do that and why.
  • Show the visitor the black box, asking what they think is inside it. Show them how to use the camera on the tablet, explaining that taking pictures can give us a lot of information. Ask whether they think cameras just take pictures of what exists, or whether they add anything that might change what is already there.
  • Have them place the tablet on the black-tape corners on the remote sensing box, then press the button to take a picture. Take the tablet off and ask them what they see. Ask them if we can add anything inside the box to change the information we got.
  • Turn the flash on the camera, and have them take another picture. Ask how the information they got changed.
  • Explain that the flash shines a light on what the camera is taking a picture of. This adds something that wasn't originally there--there was no light in the box. However, by adding light, we got a lot more information about what was in the box. This is a demonstration of passive versus active sensing. For passive sensing, we simply collect what data is there. For active sensing, we add or change something so we can get more information.
  • Ask them if they can think of any examples of active versus passive sensing. Let them know about active versus passive sensing of carbon dioxide. (If they have not yet done the carbon cycle activity, transition to explain what carbon dioxide is.) We can look at the sunlight absorbed by carbon dioxide, but at night we wouldn't be able to do this. If we shone a laser down on Earth and then measured wavelengths absorbed by the laser, we could measure the elements in the atmosphere. (If they have not yet done the spectroscopy activity, transition to explain how a spectrometer can be used to detect carbon dioxide.)
  • Encourage the visitor to think about what equipment could be used to find out about the Earth from space, leading them to a discussion about satellites. Open the Earth Now app and give them the tablet, explaining that there are two different kinds of satellites.
  • Show them the polar orbiting satellites, explaining that polar orbiting satellites orbit the poles of the Earth. Discuss the pros and cons of this. Polar orbiting satellites can cover a lot of territory, but this takes time. They can't look at the same spot for a long time, or see very much of the Earth at once.
  • Show them the geostationary satellites, explaining that geostationary satellites aren't actually stationary. They move at the same speed that the Earth rotates so that they can always have the same view of the Earth. Discuss the pros and cons of this. They can get a lot of great information about one place over time, but they can't see the other side of the Earth. Also, usually geostationary satellites are positioned quite far away so they can see a lot at once, but this usually means the quality of images is quite low.
  • Brainstorm other equipment and methods that could be used to collect data about Earth from space.
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Questions To Ask
  • Have you heard of remote sensing?
  • What equipment do we use to look at something far away?
  • Why would we want to look at the Earth from far away?
  • What could we see or measure on Earth from far away?
  • What equipment could we use for remote sensing?
  • What are different ways you can measure things in your own life?
  • What are the advantages and disadvantages of passive sensing? Active?
  • What are the advantages and disadvantages of polar orbiting satellites? Geostationary satellites?
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Sample Dialogue

Key:
  • P    Presenter
  • G    Guest
  • Bold italics indicate action.
  • Italics indicate a note to the presenter.
  •    □ indicates a cue


P   Hi there! Can you help me out?
G   Okay.
P   I'm trying to figure out what's in this box. Any guesses?
G   Maybe a snake.
P   How interesting. For right now, I can't open up this box. What do you think I could use to help me figure out what's inside?
G   A periscope.
P   Great idea, except I don't have one of those. I do have this tablet, though. Do you think there's anything on this that could help me capture an image of what's inside?
G   A camera!
P   Awesome! Have you used one of these before?
G   No, my mom won't let me.
P   Well, if it's cool with your mom, I'll show you how to use this one and we'll use it together while being very careful. Sound good?
G   This is the best day of my life.
P   Fantastic. This is the camera app. To take a picture, just touch this button. Want to try?
G   Okay. I'm going to take a picture of you. Now of me. Now of my shoes. Now of that Sphere--
P   Great. Looks like you've got the hang of the camera. Now let's take a picture of what's in this box. Place the tablet on these black corners so we line up the lens of the camera with the hole.
G   Okay.
P   Now take a picture. What do you see?
G   Nothing.
P   Hm. Maybe there was nothing in the box, or maybe we just can't see what's in the box because there's no light in there. Do you think there's light in the box?
G   No.
P   Want to try adding light?
G   Sure.
P   Okay, I'll turn on the flash. Now try.
G   It's the Earth!
P   Awesome! Okay, now we know what's in the box--but did we add anything to the box to find out what was there?
G   No.
P   Let's think about the first picture you took. That's called passive sensing, because you just took a picture of exactly what was there. Then what did we add to the box so we could get more information?
G   You turned on the flash.
P   Yeah! A flash shines a light on what you're taking a picture of. That's what we call active sensing. Active sensing is when we use a tool to change what we're looking at in some way so we can get more information about it. Can you think of any other examples of active sensing?
G   I use a flashlight to find things in the dark.
P   That's great. We're talking about trying to gather information--so you couldn't gather much information in the dark, but by adding light, you can get more information. But that's you seeing with your own eyes. Do we ever use other equipment to see things?
G   Well, we used a camera.
P   Yeah! That's remote sensing. What would we use if we wanted to see something in space?
G   A telescope?
P   Definitely. That's also remote sensing. So can you think of some remote sensing that is active?
G   No.
P   That's okay. Have you ever heard of radar?
G   Yeah!
P   Right. With radar, we send out a little signal. Then it hits something and comes back. We can measure how long it took to hit something and how long it took to come back, and that will tell us where objects are. You can kind of think about it like echolocation, if you know what that is.
G   Dolphins.
P   Yep! Dolphins echolocate. They use sound for detecting things, and radar uses radio waves. Can you think of other equipment we can use to sense things that are far away?
G   Maybe a space ship.
P   That's a cool idea. The nice thing about remote sensing is we don't have to go somewhere to get information. Do you think we would ever use remote sensing to look at Earth?
G   Maybe.
P   Right. For instance, what if we wanted to look at the whole Earth?
G   You could use a space ship.
P   Definitely. Is there a way we could take pictures of Earth without sending people into space?
G   Like a satellite?
P   Exactly. And just like there are different ways to measure things, there are different satellites for different orbits. Can you take this satellite and show me a way you think it could orbit around the Sphere?
G   Okay.
P   Great! You walked around the Sphere. Now, does the Earth stay still while things orbit it?
G   No.
P   Cool. How does it move?
G   It rotates.
P   Okay, what if you orbited around the Earth at the same rate at which it rotated. Then you'd always be looking at the same spot. Do you think that could be useful?
G   No.
P   Well, but what if I wanted to see how North America changed over time? What could I do?
G   Look at North America for a long time.
P   Right. What kind of information might I be looking for if I just sat there looking at North America?
G   Maybe seasons?
P   Right! Or even how it looks different at night or day, or maybe I'm measuring something in the air that's different at different times. That kind of satellite is called geostationary. Can you say geostationary?
G   Geostationary.
P   Yeah. Geostationary satellites are farther away and move with the Earth to look at the same side of the Earth all the time. What's another way a satellite could make a circle around the Earth?
G   Maybe over the top?
P   Exactly. That's called a polar orbiting satellite, because they orbit the poles. Now, these satellites look at a lot of different parts of the Earth and they're pretty close. Why might we want to look at the Earth that way?
G   So we can see the whole thing.
P   Right. And these satellites are closer, so we get clearer pictures. Thanks for looking at different ways to remotely sense things with me!
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