Activity—Radar Image Analysis
Materials
Copies of the following image sets (found
in the binders):
•Earth Image 1 and 2
•“LASESAT_(1978)” image
•“LAZoomIn_(1978)” image
•“LASIRC_image”
Purpose
• In this activity, we will compare visible,
infrared, and radar images using data sets
from various spacecraft
Background
• Visible Light—allows to see color variations
• Limitations: can only see the surface…what is
below the surface that we cant see?
Part 1—Viewing Earth from Space
• Brainstorming (10 min)
– What I know
• Describe what you think you know about infrared, or IR
energy
• NOTE:
– You may or may not know what infrared (IR) energy is.
– Remember, you are just putting down your ideas on paper.
– IR waves are not visible to the human eye
What is a wavelength?
• Wavelength is the
distance from one wave
crest to the next wave
crest
Electromagnetic Spectrum
• Using a cell phone camera, you can actually see IR waves
from a remote control.
• Heat is a form of Infrared energy
Galileo—Jupiter Mission 1989
• Path allowed
for additional
views of Earth
with its
cameras
Part 2: Comparing IR images and Vis images
• Earth Image 1 and 2
– What are some of the similarities and differences you are seeing in the images?
– What sort of instrument do you think took Earth Image 1?
– What aspects of Earth Image 1 would lead you to guess that there might be life
on this planet?
• Now, look at the image called Earth Image 2.
– What is the most notable difference between the two images (Earth Image 1
and 2)?
– Now look for more subtle differences. In which image can you see more land?
Earth Image 1 and 2 details
• The Earth Image 1
– Visible image
• The Earth Image 2
– Infrared image
– This records "Heat Waves" and is able to penetrate clouds and haze much more easily.
– Only one infrared wavelength was used in this image. Thus, it is only possible to show the image as
shades of gray ranging from black to white.
The Earth Image 1
The Earth Image 2
What I Learned (full version)
• Describe something new that you learned about
infrared.
• Look back at your ideas in the “What I Know”
section.
• How many more things can you add?
• Did any of your original ideas change?
Part 3—Viewing Earth from space using radar
images
• We’ve looked at a “data set” using visible energy
and IR energy.
• Now we'll take a look at images that use radar
energy to give us a closer view of the earth
• Brainstorm (10 min)
• What I Know
– Describe what you know about radar and radar imaging
Vocab Strategy: Kate Kinsella
• Kate Kinsella
– websites found at the end of the worksheet
Vocab
• Electromagnetic Spectrum
– The range of wavelengths or frequencies
over which electromagnetic radiation
extends.
• Wavelength
– the distance from one wave crest to the
next wave crest
• radar
– Radio Detection and Ranging
RADAR
• Where does radar fall on the electromagnetic spectrum?
– Microwave region of the spectrum (Mini-RF images at 4.2 and 13 cm
wavelengths)
Background: Seasat
• Launched in 1978
• Included an imaging radar
• Its mission was to
understand the physical
processes taking place on
the ocean surface through
analysis of its radar images
Background--Why radar?
• The SEASAT radar images gave scientists an
invaluable tool for looking at the Earth, over both
ocean and land.
• Since the radar instrument uses energy generated
by the instrument itself, radar has capabilities that
visible cameras do not:
– radar imaging can produce images at night
– radar has the capacity to transmit through even the
heaviest cloud cover.
How does radar imaging work?
• Since the radar impulses are sent at an angle toward the Earth's surface, flat
surfaces such as streets, parking lots, and calm water reflect the energy away from
the receiver, like so:
• All of the structures generally appear as dark areas in radar images.
• The angled roofs and uneven surfaces of vegetation and land surfaces tend to
reflect a greater amount of energy back at the radar antenna and thus appear as
lighter areas.
What I learned (full version)
–What I learned about the radar energy
–Describe something new that you learned
about radar energy.
–Look back at your ideas in the “What I
Know” section. How many more things can
you add? Did any of your ideas change?
Part 4: Radar Image Analysis
• For this section, you will need the following images (in your teacher
binder):
LASESAT (1978)
LASIRC image
LAZoomIn (1978)
LASEASAT (1978) image
• Look at the image labeled
LASEASAT (1978).
• This is an image of Los
Angeles and the surrounding
area as taken from the
SEASAT satellite in 1978.
• The image was taken from
the West (to the left of the
image)
Burbank
LASEASAT
LASEASAT (1978) image
• Locate the city of Burbank.
• Notice the darker area just
underneath the white
square.
• These are the Hollywood
Hills which reach towards the
left (West) into the Santa
Monica Mountains.
• The famous HOLLYWOOD
sign is located here.
Burbank
LASEASAT
Feature ID
1. List five features of the
city that you can readily
make out, such as
streets and mountains.
2. Why does Burbank
stand out as a white
square?
Burbank
LASEASAT
What’s wrong with Burbank?
• Burbank is unique in this image in
that its streets are oriented
differently from the remainder of
the cities in Los Angeles.
• The streets are lined up in such a
way that the incoming radar
pulses are able to bounce off the
streets and then bounce again off
the buildings (called a doublebounce) and directly back
towards the radar instrument.
• Dark = smooth surfaces
• Light = rough/angled
surfaces
LASEASAT (1978) image analysis
• This image of Los Angeles and
its surrounding cities was taken
from the west (left on the
image).
• The Pacific Ocean is visible on
the left of the radar image and
the San Gabriel Mountains are
clearly shown in the upper right
corner.
• The more impulses returning to
the radar receiver, the lighter
the image.
LASEASAT
Image comparison
• Now look at the LAZoomIn (1978) image. This image is a close up of downtown Los
Angeles, with Dodger stadium featured at the top center.
• What features can be identified in both the LASEASAT and LAZoomIn images?
Dodger Stadium
Burbank
LASEASAT (1978)
LAZoomIn (1978)
LAZoomIn (1978) image analysis
LAZoomIn (1978)
• This image is of Dodger Stadium and the
surrounding L.A. community.
• Downtown Los Angeles in the center of the
image, ringed by freeways.
• The stadium itself appears darker than the
surrounding areas because the flat surfaces
of the playing field and parking lots reflect
the radar impulses away from the radar
receiver.
• The other image is a visible image.
• Notice how the radar image looks different
than the visible image
Google Earth
Then and now…
• Next, look at the LASIRC image.
• This is a RADAR image of Los
Angeles collected by an instrument
called SIR-C radar in October 1994,
16 years after the SEASAT image.
• This instrument flew on the space
shuttle.
• This is again a black-and white
image of Los Angeles, taken using
the same type of radar (same
wavelength and polarization) as the
one flown on SEASAT.
LASIRC
Compare LASIRC with LASEASAT
– LASEASAT and LASIRC were taken 16 years apart, but they were also taken at different
angles.
– SEASAT flew in a near-polar orbit, observing Los Angeles at it flew from South to North.
– SIR-C flew in a different orbit, observing Los Angeles at it flew from almost South-East to
almost North-West.
– When you look at things from different directions they tend to appear different.
LASIRC (1994)
LASEASAT (1978)
Perspective
• When radar energy “bounces” off certain objects, those objects
may show up brighter or darker, depending upon the angle they
bounce off the object.
• Lets say for example, the radar signal bounces off a building, or a
tree from one angle, scientists will get a specific view of that object,
from a particular angle.
Wrap up
• How can our view of the surface of a
planet change, depending upon the type
of imaging device being used?
• What other places might we use radar
images?
– Mini-RF uses radar to make images , and
the Magellan spacecraft looked
“through” the thick clouds of Venus to
map the surface.
• What other kinds of features can
scientists possibly see using radar?
– Buried geologic features in desert
regions, surface features below thick
vegetation (that is how scientists were
able to uncover extensive surface
features of the ancient civilization of the
Mayans beneath the thick jungle cover.)