Philae Lander
Philae is the lander unit of ESA’s Rosetta Orbiter which had the task of landing on a comet, executing scientific measurements and sending the collected data to the Earth. The text on the original Rosetta Stone contained an order of Pharaoh Ptolemy V. and written in three different languages in 196 B.C. This was suitable to solve the secret of Egyptian hieroglyphs in 1922. Philae is the name of the Nile island where an Egyptian obelisk discovered in 1815, and the text on it helped in understanding the text on Rosetta. The analogy comes from this: Rosetta and Philae could help in discovering the secret of comets, learning the process of space genesis.
    The Rosetta spacecraft with Philae on its back had been launched by an Ariane 5 rocket from Kourou, French Guiana on March 2, 2004. After 10 years of maneuvering, at 500 million kilometers from the Earth, it approached the comet 67P/Churyumov-Gerasimenko. On November 12, 2014, it kicked off Philae which started a free fall of 7 hours and landed on the comet’s surface exactly where it was planned. The problem was that the harpoons did not work properly and could not fix the lander to the surface and caused its bouncing two times.  The first bounce was done at the speed of 38 cm/s which was luckily less than the escape velocity of 44 cm/s. Philae rose up to 1 km from the surface and was falling down for 1 hour and 50 minutes, and after this second bump it rose again, flew for 7 minutes and finally landed on the comet’s icy, slippery surface at a rough, rocky and shady ground about 1 km from the original place with only two supporting legs from the three and a 30 degrees deviation from the perpendicular position.

    It started to work here immediately by sending data from all of its scientific instruments for about 60 hours. Then its primary batteries ran out, and owing to its unlucky position and the big distance from the Sun, its accumulators could not be properly charged, and it stopped working. Meanwhile the comet was continuing its move towards the Sun, the solar elements of Philae got more light, they could somewhat recharge the accumulators, and on June 19, 2015, the lander gave life signals. Hopefully, it can remain in live condition. The comet will reach its perihelion point in August, 2015, after that it will turn back and leave the Solar System. If everything goes well, Philae will provide in the near future valuable information about the material of the comet, and the increasing gas and dust radiation caused by the Sun.
    The main structural unit of Philae is a carbon fiber fortified plastic house to which the hexagonal platform is attached for the scientific instruments. The external surface is covered by solar elements. The overall volume is about 1 m3 and the weight is about 100 kg. Its most important component is the control and data processor (CDMS – Command and Data Management System) which was developed by the engineers of SGF Co. Ltd. (Space and Ground Facilities Co. Ltd.) and HAS Wigner Research Center for Physics in Hungary. Its detailed description can be found under the Products link. The intelligent Power Supply Subsystem was developed at the BME (Technical University of Budapest), Hungary.

The onboard scientific instruments of Philae are the following:
  • APXS (Alpha Proton X-ray Spectrometer) analyzes the chemical substance of the comet’s surface. It has been developed by Johannes Gutenberg Universität, Mainz, Germany.
  • CIVA (Comet Infrared and Visible Analyzer). Its 6 micro cameras make panorama pictures about the comet’s surface. A spectrometer analyzes the composition of the samples from the surface. It has been developed by Université Paris Sud, Orsay, France.
  • CONSERT  (Comet Nucleus Sounding Experiment by Radio Wave Transmission) examines the internal structure of the comet core. Radio waves sent by the Orbiter going through the core of the comet and received by this unit are sent back to the Orbiter. Developer: Institut de Planétologie et d’Astrophysique de Grenoble, France.
  • COSAC (Cometary Sampling and Composition Experiment) is a gas analyzer for detecting and identifying complex organic molecules in the samples taken and heated by the SD2 instrument. It has been developed by Max-Planck Institut für Sonnensystem-forschung, Katlenburg-Lindau, Germany.
  • PTOLEMY is another gas analyzer which examines the light elements (carbon, nitrogen and oxygen) in these samples. Developer: Open University, Milton Keynes, United Kingdom.
  • MUPUS (Multi-Purpose Sensors for Surface and Subsurface Science) examines mechanical properties and temperature of Philae’s outer environment. It has been developed by Deutsches Zentrum für Luft- und Raumfahrt, Berlin, Germany.
  • ROLIS (Rosetta Lander Imaging System) is a CCD camera which makes panorama pictures of Philae’s environment during and after landing. Developer: Deutsches Zentrum für Luft- und Raumfahrt, Berlin, Germany.
  • ROMAP (Rosetta Lander Magnetometer and Plasma Monitor) makes magnetic measurements and examines interactivity of the comet to the solar wind. Developers: Technische Universität, Braunschweig, Germany and HAS Centre for Energy Research, Budapest, Hungary.
  • SD2 (Sample and Distribution Device) deeply drills into the surface of the comet and provides the samples for the analyzing instruments. Developer: Politecnico di Milano, Italy.
  • SESAME (Surface Electrical Sounding and Acoustic Monitoring Experiments) consists of three instruments examining electrical and acoustical properties of the comet’s surface. Developers: Deutsches Zentrum für Luft- und Raumfahrt, Berlin and Max Planck Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany, and Finnish Meteorological Institute, Helsinki, Finland.

 2.July 2015

rosett after separation
Rosetta and Philae after separation
(work of artist)

Rosetta Philae at ESTEC
Lander Rosetta Integration
Rosetta Intagration
Rosetta and Philae integration at ESTEC

CIVA Mars image
Image of MARS by the CIVA from Philaee