Mac Murdo and Howe Islands are 2 of the 300 islands of the remote
Kerguelen Archipelago, located in the southern Indian Ocean. The
islands are part of a larger island group called the French Southern
and Antarctic Lands. The Kerguelen Archipelago is also called the
"Desolation Islands." The coastal regions of the islands support
low-growing vegetation (mainly the genus Acaena),
while elevations above 50 meters are bare rock. There are no permanent
(human) residents on the islands, but a permanent settlement (Port aux
Francais) hosts visiting biologists, oceanographers, and other Earth
scientists. In addition, the settlement maintains a weather station and
a satellite/rocket tracking station.
Weather conditions on the Kerguelen Islands are typical for the
latitude; at 49 degrees South, the islands sit at the crossroads of the
latitude zones referred to as the "roaring forties" and the "furious
fifties." This astronaut photograph was captured on January 6,
2009-early summer in the Southern Hemisphere. That day, the mean daily
temperature was 4.5 degrees Celsius (40.1 degrees Fahrenheit), with
mean westerly winds of 9 meters per second (about 20 miles per hour).
The coastlines of many sub-Antarctic islands, like the Kerguelen Islands, are occupied by highly productive giant kelp beds (Macrocystis pyrifera).
One of the largest marine macroalgaes (seaweeds), the species can grow
to lengths of 50 meters (164 feet), forming undersea forests in
hard-bottom, subtidal areas (nearshore areas that remain underwater at
low tide). Fronds can spread out to form a canopy that totally covers
the water surface; we interpret the black patches surrounding coastal
areas in this astronaut photograph as offshore kelp beds. These kelp
forests are habitat for marine animals, and due to their large biomass
and relatively long survival, they are an efficient sink (storage
location) for atmospheric carbon dioxide.
The surface wave pattern that travels southeastward along the
gray-blue ocean surface and through the kelp beds is visible due to sunglint,
the mirror-like reflection of sunlight off the water. The sunglint also
improves the identification of the kelp beds by creating a different
water texture (and therefore a contrast) between the dark vegetation
and the reflective ocean surface.
Kerguelen Archipelago hosts thousands of marine birds (penguins,
albatrosses, and petrels among others) and seals (elephant and
Antarctic fur species). Whales (humpback) and dolphins (killer whales
and Commerson's dolphin) are very common in the area. Fishing boats
also frequent the Archipelago-including unlicensed, so-called "pirate,"
Astronaut photograph ISS018-E-18110
was acquired on January 6, 2009, with a Nikon D2Xs digital camera
fitted with an 800 mm lens, and is provided by the ISS Crew Earth
Observations experiment and the Image Science & Analysis
Laboratory, Johnson Space Center. The image was taken by the Expedition 18 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 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 Bruno Delille, (Université de Liège, Liège, Belgium) and Susan K. Runco (NASA-JSC).
- ISS - Digital Camera