The Channel Tunnel is a 50.5 km-long rail tunnel beneath the English
Channel at the Straits of Dover. It connects Dover, Kent in England with
Calais, northern France. The undersea section of the tunnel is unsurpassed
in length in the world. A proposal for a Channel tunnel was first put
forward by a French engineer in 1802. In 1881, a first attempt was made at
boring a tunnel from the English side; the work was halted after 800 m.
Again in 1922, English workers started boring a tunnel, and advanced 120 m
before it too was halted for political reasons. The most recent attempt
was begun in 1987, and the tunnel was officially opened in 1994. At
completion it was estimated that the project cost around $18 billion. It
has been operating at a significant loss since its opening, despite trips
by over 7 million passengers per year on the Eurostar train, and over 3
million vehicles per year.
With its 14 spectral bands from the visible to the thermal infrared
wavelength region, and its high spatial resolution of 15 to 90 meters
(about 50 to 300 feet), ASTER images Earth to map and monitor the changing
surface of our planet.
ASTER is one of five Earth-observing instruments launched December 18,
1999, on NASA's Terra satellite. The instrument was built by Japan's
Ministry of Economy, Trade and Industry. A joint U.S./Japan science team
is responsible for validation and calibration of the instrument and the
data products.
The broad spectral coverage and high spectral resolution of ASTER provides
scientists in numerous disciplines with critical information for surface
mapping, and monitoring of dynamic conditions and temporal change. Example
applications are: monitoring glacial advances and retreats; monitoring
potentially active volcanoes; identifying crop stress; determining cloud
morphology and physical properties; wetlands evaluation; thermal pollution
monitoring; coral reef degradation; surface temperature mapping of soils
and geology; and measuring surface heat balance.
The U.S. science team is located at NASA's Jet Propulsion Laboratory,
Pasadena, Calif. The Terra mission is part of NASA's Science Mission
Directorate.
Size: 59.4 by 63.1 kilometers (36.0 by 39.1 miles)
Location: 51 degrees North latitude, 1.5 degrees East longitude
Orientation: North at top
Image Data: ASTER bands 3, 2, and 1
Original Data Resolution: 15 meters (49.2 feet)
Dates Acquired: March 14, 2001