This TerraSAR-X image, acquired 30 November 2013, shows Kiritimati atoll in the Pacific Ocean.
Kiritimati atoll is a unique place - here, major European cities or entire countries become tiny hamlets, and where you might find that Paris is abandoned, 235 people live in Poland and London has about 1829 inhabitants. This remote Pacific island, where the seafarer James Cook and his crew celebrated Christmas back in 1777, is quite literally in deep waters. It has a land area of 321 square kilometres, and a lagoon roughly 324 square kilometres. If current forecasts prove accurate, climate change and the consequent rise in sea levels in the Pacific could mean the disappearance of the island state of Kiribati and the island of Kiritimati by around 2070. Viewed through the 'eyes' of the German Aerospace Center's (Deutsches Zentrum für Luft- und Raumfahrt; DLR) TerraSAR-X radar satellite, orbiting at an altitude of over 500 kilometres, the atoll looks like a porous, fragile structure.
When James Cook anchored there in 1777 and named the atoll 'Christmas Island', it was still uninhabited. Today, about 5100 people live on Kiritimati - out of a population of roughly 102,000 in the entire island state of Kiribati with its more than 30 atolls and archipelagos. If one takes its expanse as the basis of calculation, the Republic of Kiribati is among the largest countries in terms of the area it occupies. However, its actual land area of just 811 square kilometres places it firmly in the group of microstates.
The radar satellite TerraSAR-X is particularly capable of imaging this type of location from space: "The areas located above water are particularly good at reflecting the radar signals back to the satellite," explains Stefan Buckreuß, Mission Manager at the DLR Microwaves and Radar Institute. In the radar images shown here - acquired on 30 November 2013 - these areas are discernible as a light-coloured frame stretching round the lagoon of St Stanislas Bay on the Kiritimati atoll. The differing green and yellow colours indicate differences in the roughness of the land surface. "The areas in yellow are particularly rough – so they could be rock formations, trees or even man-made structures."
In contrast, the calm waters of the lagoon are visible in dark green - a sign that the ocean is particularly smooth, as the signals are mainly reflected away from the satellite with only weak returns being received. Such surfaces appear dark in radar images; however, the slightly smudged lines along the coast clearly show that the Pacific is anything but quiet around the outer reaches of the atoll. The motion of the spray flying through the air as the breakers pound the coast prevents TerraSAR-X from imaging this area.
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