ROSETTA: The Challenge of Escorting a Comet and Landing on Its Surface

One of the most interesting places in our solar system was 2014/2015 moving between the orbits of Jupiter and Earth, when the European space probe ROSETTA had a rendezvous with the comet 67 P Churyumov-Gerasimenko. In November 2014 the PHILAE lander separated from the mother spacecraft and landed by a combination of autonomous reactions and remote controls from a distance of 500 Mio km with high accuracy on the surface of the comet. The unconventional landing ended due to actuator malfunctions in a very interesting cliff, where the foreseen measurements were nevertheless well performed. ROSETTA escorted the comet in near distance during the year 2015, including its passage of closest distance to the Sun in order to observe the development of its tail. This way sublimated pristine materials from the core of the comet could be characterized, providing information from the period when our solar system formed. Scientific journals like Science and nature selected the pioneering ROSETTA mission as scientific top event of the year 2014. This presentation addresses the software and control background of this complex and challenging mission, which started about 25 years ago and had to respect ambitious technical as well as international challenges. The fascination of space exploration will be illustrated by pictures from this bizarre comet.