November 15, 2007, Darmstadt, Germany--This striking composite image of Earth by night shows the illuminated crescent over Antarctica and cities of the northern hemisphere. The images were acquired with the OSIRIS wide-angle camera (WAC) during Rosetta's second Earth swing-by on November 13.
This image showing islands of light created by human habitation was taken with the OSIRIS WAC at 19:45 CET, about two hours before the closest approach of the spacecraft to Earth. At the time, Rosetta was about 80,000 km above the Indian Ocean where the local time approached midnight (the angle between Sun, Earth, and Rosetta was about 160°). The image was taken with a five-second exposure of the WAC with a red filter.
This image showing Earth's illuminated crescent was taken with the WAC at 20:05 CET as Rosetta was about 75,000 km from Earth. The crescent seen is around Antarctica. The image is a color composite combining images obtained at various wavelengths.
ESA's Rosetta spacecraft will be the first to undertake the long-term exploration of a comet at close quarters. It comprises a large orbiter, designed to operate for a decade at large distances from the Sun, and a small lander. Each of these carries a large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted. The Rosetta orbiter has eleven scientific instruments. OSIRIS is Rosetta's Orbiter Imaging System.
After entering orbit around Comet 67P/Churyumov-Gerasimenko in 2014, the spacecraft will release a small lander onto the icy nucleus, then spend the next two years orbiting the comet as it heads toward the Sun. On the way to Comet Churyumov-Gerasimenko, Rosetta will receive gravity assists from Earth and Mars, and fly past main-belt asteroids.
This is the second Earth flyby on Rosetta's journey. The first was in November 2005, and the third and final Earth fly-by will be in November 2009. The spacecraft will then be in deep-space hybernation until it approaches Comet Churyumov-Gerasimenko in 2014.
--V.C.