The Tuamotu Archipelago
is part of French Polynesia, and forms the largest chain of atolls in
the world. This astronaut photograph features Mataiva Atoll, the
westernmost atoll of the Tuamotu chain. An atoll is a ring-shaped island
that encloses a central lagoon. This distinctive morphology is usually
associated with oceanic islands formed by volcanoes; coral reefs become
established around the partially submerged volcanic cone. Over geologic
time the central volcano becomes extinct, followed by erosion and
subsidence beneath the sea surface, leaving the coral reefs as a ring
around (or cap on) the submerged island remnant. Coral reefs exposed
above the sea surface in turn experience erosion, sedimentation, and
soil formation, leading to the establishment of vegetation and complex
ecosystems—including in many cases human habitation.
Mataiva Atoll is notable in that its central lagoon includes a
network of ridges (white, image center) and small basins formed from
eroded coral reefs. Mataiva means “nine eyes” in Tuamotuan, an allusion
to nine narrow channels on the south-central portion of the island. The
atoll is sparsely populated, with only a single village—Pahua—located on
either side of the only pass providing constant connection between the
shallow (light blue) water of the lagoon and the deeper (dark blue)
adjacent Pacific Ocean. Much of the 10-kilometer- (6-mile-) long atoll
is covered with forest (greenish brown). Vanilla and copra (dried
coconut) are major exports from the atoll, but tourism is becoming a
larger part of the economy.
Astronaut photograph ISS024-E-11914 was acquired on August 13, 2010, with a Nikon D2Xs digital camera using a 400 mm lens,
and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center.
The image was taken by the Expedition 24 crew.
The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed.
The International Space Station Program supports the laboratory as part of the ISS National Lab
to help astronauts take pictures of Earth that will be of the greatest
value to scientists and the public, and to make those images freely
available on the Internet. Additional images taken by astronauts and
cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth.
Caption by William L. Stefanov, NASA-JSC.