 |
|
|
 |
 |
|
|
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The Extreme 2008 scientists will begin their research expedition on November 10, 2008, when they leave port in Manzanillo, Mexico, for the 9North site along the East Pacific Rise. Their first Alvin dive will be Nov. 12, followed by a dive each day through Nov. 19. Later in the day on Nov. 19th, they will set sail for the Sea of Cortés (Gulf of California), where another series of Alvin dives will be conducted.
The scientists' home for 21 days will be the 274-foot research vessel Atlantis. Besides containing quarters for the scientific party and crew, the Atlantis carries fully equipped research laboratories, a library, and the deep-sea sub Alvin, which will be deployed almost daily on eight-hour dives once the scientists reach their first dive site.
How do mariners find their way on the seas?
Modern-day sailors rely on several high-tech tools such as the Global Positioning System (GPS), a satellite-based radio navigation system initiated in 1973 by the U.S. Department of Defense for military applications. Today, GPS is widely used in many different applications, from navigating ships like R/V Atlantis or even your car, to studying earthquakes, to name only a few.
Between 24 and 32 GPS satellites orbit Earth some 10,000 miles above us twice a day, transmitting microwave signals that enable GPS receivers to determine their current location, the time, and their velocity. GPS receivers compare the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. By taking distance measurements from several more satellites, the receiver can compute latitude, longitude, altitude, and time.
The U.S. Coast Guard requires mariners to know celestial navigation to operate a vessel more than 200 miles offshore. By using a traditional navigational tool such as a sextant, mariners can determine their location by measuring the vertical angles between two or more stars and the horizon line. This sighting process is called "shooting a star."
The Earth's longest mountain range is underwater. Called the Mid-Ocean Ridge system, it is over 56,000 kilometers (35,000 mi) long and snakes around the globe like a zipper or the stitching on a baseball.
The East Pacific Rise is part of this system. This ridge is in a geologically active area, where the Earth's tectonic plates are moving apart and new seafloor is being born, giving rise to hydrothermal vents, volcanoes, and earthquakes.
The East Pacific Rise was discovered during the Challenger expedition in 1875. Over 100 years later, in 1979, the submersible Alvin made its first trip to the East Pacific Rise and revealed "black smokers" spewing super-heated water.
The East Pacific Rise is one of the fastest-spreading sections of the Mid-Ocean Ridge system. While many tectonic plates move about as fast as your fingernails grow, the plates here move an average of 14.2 cm (5.6 inches) each year. The area of the East Pacific Rise near Easter Island in the South Pacific currently has the fastest rate of tectonic plate movement at more than 15 cm (6 inches) a year.
