REMOTE SENSING IN EARTH & SPACE SCIENCE
WHAT IS REMOTE SENSING?
• Remote sensing is a method of measuring the composition,
temperature, and other properties of an object by means of
electromagnetic radiation emitted, absorbed, or reflected by the
object.
• Electromagnetic radiation includes not only visible light, but
also infrared, microwave, and radio radiation of longer
wavelength and lower energy than visible light, and ultraviolet, xray, and gamma-ray radiation of shorter wavelength and higher
energy.
• Two primary methods of remote sensing are imaging and
spectroscopy.
• Recently, advances in electronic imaging technology have
produced a combination of both of these, known as imaging
spectroscopy.
• They have also extended the wavelength ranges accessible, to
include a much broader range of the electromagnetic spectrum
(ranging from X-rays to the far infrared).
REMOTE SENSING IN EARTH & SPACE SCIENCE
• Satellites in Earth orbit can provide complete global coverage,
at regularly repeating intervals, and over long periods of time.
• Earth observing satellites utilize a wide range of orbital altitudes
and inclinations, depending on the types of observations and time
periods of interest.
• Satellite sensors can observe in wavelength ranges of
electromagnetic radiation that are not transmitted through the
lower atmosphere, such as ultraviolet and some types of infrared
radiation, to make measurements of the upper layers of the
atmosphere (such as the ionosphere and the ozone layer of the
stratosphere).
• Satellites can also make highly accurate, long-term
measurements of the Sun’s output of radiation, in nearly all
ranges of the electromagnetic spectrum, for comparison with
direct atmospheric measurements and predictions of global
climate change.
REMOTE SENSING IN EARTH & SPACE SCIENCE
EXAMPLES OF SPACE-BASED REMOTE SENSING
IN EARTH SCIENCE
• Weather Satellites are the best known, and one of the first and
most important, space-based remote sensing applications.
• Earth Resources Satellites, such as Landsat, are similar to
weather satellites but focus on land and ocean areas and include
techniques for measuring composition, temperature, and other
properties of the objects observed.
• Satellites such as the Upper Atmosphere Research Satellite
(UARS) and the Thermosphere, Ionosphere, Mesosphere
Energetics and Dynamics (TIMED) make observations and
measurements of the upper atmosphere (stratosphere and above)
to determine composition, temperature, and other properties; and
also make observations of solar radiation for comparison.
• The most recently launched set of three satellites, constituting
NASA’s Earth Observing System (EOS), are Terra, Aqua, and
Aura (which are focused on land, water, and atmospheric
measurements, respectively).
Earth Observing Satellites
• Two major types of Earth observing satellites are those in near-polar
orbits, at relatively low altitudes (a few hundred km), and ones in
equatorial orbits at an altitude of about 35,800 km.
• The latter type satellite orbits, known as geosynchronous orbits,
have a period of revolution of 24 hours, the same as the period of
Earth’s rotation on its axis; hence nearly an entire hemisphere of
Earth can be maintained in continuous (day and night) view.
Landsat - 7
Landsat Thematic Mapper Image of the Washington, DC Area
ASTER / Terra Image of Washington, DC Area
Advanced Spaceborne Thermal Emission and Reflection Radiometer
(June 1, 2000)
Mt. St. Helens Volcano, 1980
LandSat View of Mt. St. Helens, Post-Eruption
Hurricane Viewed from a Space Shuttle
Sequence of 3 Images of Hurricane Andrew (1992)
Viewed from Geosynchronous Orbit
View of Earth from Geosynchronous Orbit
Reduction in Antarctic Ozone Due to Chlorine Pollution of the Stratosphere
Polar Aurora as Viewed from Space Shuttle
Extreme-UV Images of Earth’s Plasmasphere
Obtained by the IMAGE Satellite