A series of images taken over the last six weeks by Rosetta’s OSIRIS camera system revealed that its target comet, 67P/Churyumov–Gerasimenko, developed a long dusty tail (a “coma”) as its orbit has approached the Sun. The tail is approximately 808 miles (1,300 kilometers) long. The spacecraft, a European Space Agency (ESA) project with participation from its member states and NASA, is scheduled to approach its target comet in August; its Philae lander is set to land on the comet in November. Months after Rosetta infamously “woke up,” its comet is now beginning to wake up.
The images were taken by the spacecraft’s Optical, Spectroscopic and Infrared Remote Imaging System (OSIRIS). While the comet is still very far away from the Sun (to be approximate, 1.24 million miles, or 2 million kilometers), as it approaches its surface is warmed up, which allows gas to escape its nucleus, forming a long tail. Rosetta and 67P/Churyumov–Gerasimenko will come closest to the Sun in August 2015, several months after the spacecraft approaches its intended target.
Holger Sierks, principal investigator for OSIRIS at the Max Planck Institute for Solar System Research in Germany, underscored the excitement surrounding Rosetta’s—and the comet’s—next steps. “It’s beginning to look like a real comet. It’s hard to believe that only a few months from now, Rosetta will be deep inside this cloud of dust and en route to the origin of the comet’s activity,” he enthused.
Scientists and researchers have studied the changing nature of the coma prior to the spacecraft’s approach. In addition, the spacecraft’s cameras (including its navigation cameras) have been determining Rosetta’s relative trajectory to the comet, which will further aid in its approach later this year. According to the ESA, measurements have been made concerning changes in brightness, which have revealed that the comet’s nucleus rotates every 12.4 hours (20 minutes shorter than expected). Sylvain Lodiot, ESA Rosetta spacecraft operations manager, discussed the significance of such discoveries.
“These early observations are helping us to develop models of the comet that will be essential to help us navigate around it once we get closer,” Lodiot related. The spacecraft is currently making its first maneuvers that will bring it closer in line with the comet.
These images come months after the spacecraft was reactivated successfully from a 2.5-year-long “slumber.” Rosetta’s journey to 67P/Churyumov–Gerasimenko started with its launch over a decade ago; it was launched from the Guiana Space Centre near Kourou, French Guiana, on March 2, 2004. A January AmericaSpace article by Ben Evans detailed the “awakening” of the spacecraft.
Moreover, the article discussed the selection of the spacecraft’s target comet. Evans wrote: “In its first incarnation, Rosetta was not destined for Churyumov-Gerasimenko at all. Originally scheduled to begin in January 2003, the mission was targeted for an eight-year voyage to rendezvous with Comet 46P/Wirtanen – which measures only about 0.75 miles [1.2 km] in diameter – but an Ariane 5 failure in December 2002 grounded Rosetta’s launch for almost 14 months. As a result, Churyumov-Gerasimenko, which, at 2.5 miles [4 km] is significantly larger than Wirtanen, was selected instead.”
On March 28, it was announced that the Philae lander had been successfully reactivated, which was also detailed in a previous AmericaSpace article. Rosetta and Philae are planned to study the comet until the conclusion of their science missions in December 2015.