The Landing of Rosetta's Philae Lander on Comet 67P/Churyumov-Gerasimenko

click to larger farewell images views in the form of a animated gif of the lander seen separating from the Rosetta orbiter. picture ESA

As the landing date was to be confirmed on 26 September after further trajectory analysis and the final Go/No Go for a landing at the primary site following a comprehensive readiness review on 14 October, the landing operations began since Nov. 11, 2014. After a series of Go/No go decisions were made, the Rosetta probe was eventually moved to a point about 14 miles above the comet's surface, and separation was confirmed at ESA’s Space Operation Centre, ESOC, in Darmstadt, Germany at 09:03 GMT as it took the radio signals from Rosetta 28 minutes and 20 seconds to reach Earth. Thence, Philae kept descending without propulsion or guidance, gradually gathering speed in the comet's weak gravitational field during about 7 hours, and eventually reaching a speed of 3 ft per second only. Commands prepared by the German space agency DLR's Lander Control Center had been uploaded via the Rosetta mission control before separation. During the descent, the lander was to take pictures and make science, and it was to begin communications with Rosetta about two hours after separation. All that occurred by 311 million miles from the Earth. By November 2014, the 'Site J' landing site had been renamed for Agilkia Island, a island on the Nile River in the south of Egypt where the Temple of Isis from the island of Philae when the latter was flooded during the building of the Aswan dams

Some troubles hampered the landing of the Philea lander however. First, the cold gas thruster atop of the lander did not appear to be working so the landing had to rely on the lander's harpoons only at touchdown. Those harpoons in turn were not available at landing, which made that the lander bounced off the landing site by 1 kilometer (300 ft), despite touchdown occurred at a walking pace (which is due to the comet's weak gravity with the lander weighing 1 gram only instead of 50 lbs!), and it eventually landed on a inclined terrain, close to a boulder, and in shadow. The lander after landing thus is just anchored with the comet through two of its three ice screws only. With a inclination of 13° and 1 hour and 30 mn of solar light available instead of 12, the lander is hampered in his science but that kept up however. Philae’s Science, Operations and Navigation Centre is at France's CNES space agency, and the Lander Control Centre at DLR, the German space agency

click to a view of the comet's surface closing as seen by the Philae lander's ROLIS instrument. picture ESA

click to a two-image mosaic of the neighbourhood of where the lander touchdowned. One of the lander’s three feet can be seen in the foreground. picture ESA

Confirmation of Philae’s touchdown on the surface of comet 67P/Churyumov–Gerasimenko had arrived on Earth at 16:03 GMT on Nov. 12, 2014. A first touchdown and its signal however occurred as the lander bounced off downrange the planned landing ellipse. Philae touched down again then two hours after as third contact was the charm. The lander however alighted in a crevice about six feet (two meters) in diameter and six feet (two meters) deep and it lied on its side. Despite is landing site position, the Philae lander has completed its planned primary science mission, of which a drill into the soil, after nearly 57 hours on comet 67P/Churyumov–Gerasimenko, performing on its own batteries. The Philae probe has detected organic molecules in the atmosphere of comet 67P/Churyumov-Gerasimenko. The lander’s body was lifted by about 4 cm (less than 2 inches) and rotated about 35° in an attempt to receive more solar energy but Philae’s power rapidly depleted. Descent images show that the surface of the comet is covered by dust and debris ranging from a line in size to 3 feet while post-landing panoramic images show layered walls of harder-looking material. As the illumination at the site is unsufficient to provide more power, the Philae team decided to put the lander into hibernation as they hope they might be able to wake it up when closer to the Sun with enough solar power. The Rosetta orbiter will listen for a signal each time its orbit brings it into line-of-sight visibility with the lander as it is unlikely that contact will be re-established with the lander in the near future. The lander could be woken up on 26 April 2015, but had been unable to send any signals until 13 June. After 13 June, it made a further seven intermittent contacts with Rosetta in the following weeks, with the last coming on 9 July. That awakening is due to that the comet came closer to Sun on its orbits, yielding more power to the landing's solar panels. However, such communications links were too short and unstable to enable any scientific measurements to be commanded. The Philae lander however had managed to complete 80 percent of its planned first science sequence before falling into hibernation. Philae's mission was considered decommissioned by ESA by late Dec. 2015

ESA's Philae Landing Operations Timeline

(this timeline is a one given by ESA; all times subject to change. check abbreviations below)

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