Remote%20Sensing%20

1
Remote Sensing Geodesy
2
(No Transcript)
3
What is Remote Sensing?
the science of deriving information about
Earth's land and water areas from images acquired
at a distance
4

• Starting in 1946, captured V-2 rockets were
  launched to gt 100 km by the U.S. Army
• Launch 13 in the V-2 series contained a motion
  picture camera in its nose cone, which acquired a
  series of views of the Earth's surface as it
  proceeded to a 134 km altitude.

http//rst.gsfc.nasa.gov/
5
The Soviet Union surprised the world when it
launched Sputnik, the world's first satellite, on
October 4, 1957. The U.S. quickly followed suit
Explorer I, was launched into Earth orbit on Jan.
31, 1958 and discovered the Van Allen radiation
belts (above, right). In the 1960s spy planes
and satellites were common (e.g., right Cuban
missile crisis) .
6
Landsat
S.F. Bay Area
http//geo.arc.nasa.gov/sge/landsat/
7
(No Transcript)
8
Satellite Orbits
Geostationary

• Communications satellites use a geostationary
  orbit, in which the satellite is always in the
  same position (above the equator) with respect to
  the rotating Earth.
• Geostationary orbits are high altitude (35700
  km)

9
Satellite Orbits
Polar

• Many remote-sensing satellites use a polar orbit
  to provide a more global view of Earth
• These satellites operate in a sun-synchronous
  orbit at an altitude of 700 to 800 km
• .

10
Multispectral Imaging Systems

• MSI systems are passive devices that measure
  electromagnetic waves (e.g. light, infrared) at
  different wavelengths, then combine the results
• Example Landsat Thematic Mapper (TM) images are
  produced using 7 different spectral bands

http//www.classzone.com/books/earth_science/terc/
content/investigations/esu101/esu101page07.cfm
11
Multispectral Imaging Systems
http//www.classzone.com/books/earth_science/terc/
content/investigations/esu101/esu101page07.cfm
12
Global Positioning System

• The Global Positioning System is a network of 24
  satellites placed into orbit by the U.S.
  Department of Defense.
• The satellites circle the earth twice a day in a
  very precise orbit and transmit information to
  earth.

13
Global Positioning System

• A GPS location is pinpointed using triangulation
  from 3 or more satellites.
• Today, GPS is used extensively for navigation
  and geodetic studies.

http//pasadena.wr.usgs.gov/office/hudnut/scec/97_
SCEC_E_summary.html
14
Satellite Radar Systems

• Radar satellites (e.g., ERS2, Radarsat) are
  active systems that reflect radar beams from
  Earths surface.
• Radar waves can pass through clouds and so
  provide more continuous coverage of the surface

15
Satellite Radar Systems

• Since the satellite orbits approximately repeat,
  radar images of the same region can be compared
  (radar interferometry)
• Interferometric synthetic aperture radar (InSAR)
  techniques are used to study dynamic systems
  (e.g., Indian earthquake on right)

http//www.gfz-potsdam.de/ pb1/pg5/research/method
s/insar/insar_uk.html
16
Satellite Gravity Systems

• CHAMP (CHAllenging Minisatellite Payload),
  launched July 15, 2000, is a German small
  satellite mission that measures Earths gravity
  using precise GPS orbital data

17
Satellite Gravity Systems

• The Gravity Recovery and Climate Experiment
  (GRACE) March 2002 mission detects changes in
  Earths gravity field by monitoring the distance
  between the two satellites
• The trailing spacecraft is actually about 220
  kilometers behind the lead spacecraft.

18
Satellite Gravity Data

• New data from satellite gravity missions is
  being used for plate tectonic research
• Note improvement in the resolution of gravity
  anomalies in Tonga trench region

http//www.csr.utexas.edu/grace/gravity/solid_eart
h.html
19
http//www.gfz-potsdam.de/pb1/op/champ/
20
Geodesy Study of Earths shape

• The Earth is not quite a perfect sphere
• This shape is called the reference ellipsoid
  (RE)
• RE has the shape of a drop of ideal fluid
  rotating at same velocity as Earth!

http//earth.leeds.ac.uk/dynamicearth/internal/sha
pe.htm
21
Geodesy Study of Earths shape

• Geoid The hypothetical Earth surface that
  coincides with sea level everywhere.
• Usually, the Reference Ellipsoid is used for a
  datum.
• Large-scale Geoid anomalies reflect the mass
  distribution in Earths mantle.

22
Geoid