Remote sensing

What Remote Sensing is.
Active and Passive Remote Sensing.
How Remote Sensing works?
Spatial / Spectral / Temporal resolution.
Which instruments are used.
Applications of Remote Sensing.
Gamma Rays
X Rays
Ultraviolet Waves
Infrared Waves
Micro Waves
Radio Waves
NASA’S Satellites and their Latest Mission.
REMOTE SENSINGLearningObjectives

KeyConcepts
Remote sensing is the collection and interpretation of information
about the earth from far away. Information from space, the air and
ships (taking measurements from the ocean depth) significantly
aids our understanding of the Earth. Remote sensing is essential
to accurately model the environment and map the earth for use in
Geography Information Systems (GIS).
What Remote Sensing is
Click on the rocket

KeyConcepts
Active Systems: The sensor creates and emits its own energy,
which is then detected and measured as it is reflected from
objects. An example is radar.
Passive Systems: Sensors detect and measure electromagnetic
energy (energy from the sun) as it is reflected or reradiated from
the Earth’s surface
Active and Passive Remote Sensing
Click on Sun

KeyConcepts
All remote sensing systems such as satellites are dependent on
energy. Energy comes in many forms, yet most traditional remote
sensing systems measure wavelengths from within the
electromagnetic spectrum.
How does Remote Sensing Work?
Humans can only see a small portion of the electromagnetic
spectrum called visible light.
Click on energy

Resolution
Spatial Resolution: a term that refers to the number of pixels
utilized in the construction of digital images. Images with a higher
spatial resolution are composed of a greater number of pixels than
those with a lower resolution.
KeyConcepts
Click on LIDAR
Spectral Resolution: a term that refers to the width of the
wavelength intervals measured in the electromagnetic spectrum.
Remote sensors can collect data in the visible part of the spectrum
(to provide images such as aerial photographs).
Other sensors may collect data in the invisible sector like infrared
and ultraviolet.
Temporal Resolution: also known as a repeat cycle or orbital
cycle, describes the frequency with which images are collected
from the same area. Temporal resolution may be continuous,
several times a day, daily or once every few days

Instruments used in Remote Sensing
Satellite images can be produced from a range of different sensors
found on the remote sensing system, each used for different
purposes.
KeyConcepts
Click on LIDAR

Applications of Remote Sensing.
Conventional radar is mostly associated with aerial traffic control, early
warning, and certain large scale meteorological data. Doppler radar is
used by local law enforcements’ monitoring of speed limits and in
enhanced meteorological collection such as wind speed and direction
within weather systems in addition to precipitation location and intensity.
KeyConcepts
Click on LIDAR
Laser and radar altimeters on satellites have provided a wide range of
data. By measuring the bulges of water caused by gravity, they map
features on the seafloor to a resolution of a mile or so. By measuring
the height and wavelength of ocean waves, the altimeters measure
wind speeds and direction, and surface ocean currents and directions.
Remote sensing has enabled mapping, studying, monitoring and
management of various resources like agriculture, forestry,
geology, water, ocean etc. It has further enabled monitoring of
environment and thereby helping in conservation. In the last four
decades it has grown as a major tool for collecting information on
almost every aspect on the earth. With the availability of very high
spatial resolution satellites in the recent years, the applications
have multiplied.

Applications of Remote Sensing.KeyConcepts
Click on LIDAR
(Light Detection and Ranging: LIDAR) is well known in
examples of weapon ranging, laser illuminated homing of
projectiles. LIDAR is used to detect and measure the
concentration of various chemicals in the atmosphere,
while airborne LIDAR can be used to measure heights of
objects and features on the ground more accurately than
with radar technology. Vegetation remote sensing is a
principal application of LIDAR.

Gamma Rays
Click on the image for the video to play!
Gamma Rays refers to electromagnetic radiation with a very high
frequency. Gamma rays are created by radioactive decay. Scientists use
Gamma rays (A Gamma Ray Spectrometer) to determine what makes up
the surface soils of Mars.

X Rays
X Rays refers to electromagnetic waves with a very short wavelength.
Beams of X Rays are fired at substances to see what elements they
contain. (E.g. They are used to determine the elements contained in rocks
on Mars.) X rays can determine temperature, since temperature
determines the wavelength of the radiation emitted by an object. The
hotter the object, the shorter the wavelength.

Ultraviolet Waves
Ultraviolet Radiation is found in sunlight and causes sunburn. Ozone (O3)
protects us from the sun’s ultraviolet radiation. Ozone monitoring
instruments in satellites monitor the amount of Ozone in the atmosphere.

Visible Light Waves
Scientists can learn the composition of an atmosphere by considering
how atmospheric particles scatter light. Nitrogen and Oxygen are just the
right size to scatter the wavelength of blue light.

Infrared Waves
Long wave infrared radiation emitted by the earth is responsible for
heating the atmosphere. Infrared cameras can penetrate regions with
dense gas / dust particles. NASA’s Spitzer telescope was able to locate
23 000 planet forming discs in the Orion Nebula by sensing the infrared
glow of their warm dust. Our TV remotes use infrared light.

Microwaves
Microwaves are used in Doppler radar, which is used for short-term
weather forecasting. Medium band microwaves can penetrate dust,
smoke and clouds to reveal the earth’s surface. Satellite microwave
measurements reveal the arctic sea ice cover every day even where
clouds exist.

Radio Waves
Many of the greatest astronomical discoveries have been made using
radio waves (Pulsars, Plasma clouds and Quasars). Astronomical objects
with magnetic fields usually produce radio waves (such as our sun).
NASA’S Stereo satellite is able to monitor bursts of radio waves from the
sun’s corona.

credit: NASA/Goddard Space Flight Center Scientific Visualization Studio
NASA SATELLITE FLEET
Satellites
Click on the image for the video to play

NASA Satellites

Landsat
The instruments on the Landsat satellites
have acquired millions of images.
The images, archived in the United States
and at Landsat receiving stations around the
world, are a unique resource for global
change research and applications
in agriculture, cartography, geology, forestry,
regional, planning, surveillance and
education, and can be viewed through the
USGS 'EarthExplorer' website.
Landsat 7 data has eight spectral bands
with spatial resolutions ranging from 15 to
60 meters; the temporal resolution is 16
days.[2]

Recording data: Landsat

Cloudsat
Click on the video play button!

Tropical Rainfall Measuring Mission (TRMM)

NASA’S TERRA Satellite

Orbiting Carbon Observatory: OCO-2
Click on the images for the videos to play!
The earth is on the brink of
a “mass extinction event”
that could be similar to the
one that killed off the
dinosaurs 65 million years
ago, a landmark study by
international scientists has
concluded.
Researchers warned that
deforestation, climate
change and overfishing had
driven the extinction rates
to 1000 times their normal
level, Reuters reported.
Extract from the Sunday Times
Newspaper 22 June 2014.

SMAP: NASA’S Latest Mission
Click here to visit the jet propulsion web site

Remote sensing

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Remote sensing