Remote Sensing
Program Information
Series: NASA ConnectProgram: Hidden Treasures: Landscape Archeology
Segment Number: 2 (Watch entire program)
Duration: 00:05:40
Year Produced: 2005
Description:
Second segment of NASA Connect Hidden Treasures defines remote sensing and explains how researchers use satellites to observe the Earth from space. This segment defines the electromagnetic spectrum and explains how satellites use different sensors to measure the invisible light reflected from Earth's surface. This segment also explores the definition of Geographic Information Systems or GIS.
NASA CONNECT™ is a series of Emmy®-award-winning, math-focused programs. Each program supports the national math, science, and technology standards and has three components that include (1) a 30-minute television broadcast; (2) a companion educator's guide; and (3) an online activity that further explores topics presented in the broadcast. These programs establish a connection between the math, science, and technology concepts taught in the classroom to those same concepts used everyday by NASA researchers.
For more information visit: http://connect.larc.nasa.gov/Transcript
So how did you do
with the questions?
Great job, everyone.
Have you ever heard of the term
remote sensing?
Well,
it's a rather simple activity
that we do every day
of our lives.
In fact, as you're watching
this program right now,
you are actively engaged
in remote sensing.
Coming from the screen is energy
in the form of visible light.
The radiated light is detected
by sensors in our eyes,
which collect data
about the energy
and transmit that information
to the brain.
In the brain,
those data are interpreted,
and meaning is attached to it.
We experience such sensations
as heat.
We react to chemical signals
from food.
We understand the textures
of different surfaces
all without coming
in direct contact.
Now, this can be called
remote sensing.
Now, at NASA,
remote sensing has
a slightly more technical
definition.
So let's talk to an expert
in that field,
Dan Irwin at NASA Marshall
Space Flight Center.
Thanks, Jennifer.
Remote sensing
is gathering information
about the Earth from a distance.
Information can be collected
about the land
using special cameras
or instruments
located just a few feet
above the Earth's surface
or an airplane
flying hundreds to thousands
of feet above the ground
or even from a satellite
orbiting hundreds of miles
above the Earth.
Now that you know
what remote sensing means,
let's talk about
terrestrial remote sensing.
"Terrestrial" refers
to the Earth,
so terrestrial remote sensing
means gathering information
about the Earth from a distance.
This involves the detection
and measuring
of electromagnetic energy
coming from different objects
made of various materials.
The spectrum of sunlight
reflected by the Earth's surface
contains information about
the materials it is made of.
Since sand, rocks, crops,
and dense vegetation
each have different temperatures
and reflect the light
in different ways,
sensors can reveal clues
about past human activities,
such as agriculture,
that our eyes
may not be able to detect.
Most of the universe
is invisible to humans.
In fact, the only part
that we can see
with our detectors, or our eyes,
is the part
of the electromagnetic spectrum
known as visible light.
If the entire
electromagnetic spectrum
were scaled to the same size
as the Earth's circumference,
the portion of visible light
would be as wide as a pencil.
But scientists have been able
to build sensors
that can see portions
of the electromagnetic spectrum
that we cannot.
For example, Norbert is standing
next to a hot stove.
He cannot see the infrared
energy coming from it,
but the sensors in his skin
send data to his brain
that's interpreted as heat.
He knows to move away.
We know to protect our skin
from ultraviolet radiation.
While we cannot see this energy
with our eyes,
we can see its effects
on our skin.
So what is
the electromagnetic spectrum?
The electromagnetic spectrum
is just a name
that scientists give to a bunch
of types of radiation
when they want to talk
about them as a group.
Radiation is energy that travels
and spreads out as it goes.
Visible light that comes
from a lamp in your house
or radio waves that come
from a radio station
are two types
of electromagnetic radiation.
Other examples
of electromagnetic radiation
are microwaves,
infrared and ultraviolet light,
X-rays, and gamma rays.
Hotter, more energetic objects
create higher energy radiation
than cooler objects.
Visible satellite images
are similar
to pictures
a photographer might record
in that they relay and display
reflected light
just as our eyes
would see the scene.
As long as light is available,
land features like mountains,
river courses, lakes,
silt run-off from rivers
into the sea,
and coastlines
are clearly visible.
But what about the energy
that we cannot see?
Infrared images
display gradients
of temperature differences.
Infrared sensors pick up data
both day and night.
They show the pattern of heat
released from the Earth.
Heat-producing areas
such as warm-water currents
or cities with heat-absorbing
concrete and asphalt
and heat-producing cars,
people, and factories
are bright spots
on the infrared images.
Archeologists use data
collected by sensors
located on satellites
to reveal clues
about the past temperature
and chemical composition
to find potential agricultural
and other areas
of human occupation.
For example, let's take a look
at a satellite image
of the Sahara Desert in Africa.
Right now, you're looking
at an image in visible light
as if you were in an airplane
or a spacecraft,
looking out the window.
A 50,000-wide path from the
Shuttle Imaging Radar mission
over the Sahara
is now shown superimposed
on the previous image.
The radar penetrated
a few meters
beneath the desert sand
to reveal
a prehistoric river system.
Archaeologists have found
artifacts and animal remains
showing that this was once
a moist
and densely vegetated area.
While each of these instruments
creates a different image,
imagine
if they could be combined
to give scientists
and researchers
new information
about a particular area.
That's what GIS does.
GIS stands for Geographic
Information System.
GIS is a system
of computer software,
computer hardware, data,
and humans
that help manipulate, analyze,
and present information
about a specific
geographic location.
The human part of this system
is the thinking explorer,
who's key to the power of GIS.
Simply put, GIS combines layers
of information about a place
to give you
a better understanding
of that place.
What layers of information
you combine
depends
on what you want to know.
If you want to find
the best location
for a new sporting goods store,
you might want to know
the traffic pattern
and population density.
You might also want to know
if there are any potential
customers living nearby.