Philae

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Launch data: Designation  28169 / 04006A Launch date  02 Mar 2004 - 07:17:44 UTC Launch site  Kourou, ELA3 Launch vehicle  Ariane-5G+ (V158) Mission  Comet lander Operator   Ejected date from Rosetta  12 Nov 2014 - 08:35 UT Landing date  12 Nov 2014 - 17:33 UT The Philae lander was attached to the Rosetta sonde.

The Rosetta spacecraft with Philae added, is illustrated in this artist's concept. Credit: EADS Astrium

Spacecraft data:

Prime contractor German Aerospace Research Institute (DLR) Customer   Platform  Rosetta Mass at launch  100 kg Dry Mass   kg Basic shape  cube Dimension   Solar array   Design lifetime

Flight model of the Rosetta spacecraft being transferred within the ESTEC Test Centre for acoustic and vibration testing in April 2002. Its folded solar wings can be seen on either side of the main box-shaped hull, with the Philae lander folded up on the front side. Credit: ESA

Technicians work on the lander during pre-flight activities. Credit: EADS Space

An artist's concept shows the Rosetta orbiter and its lander. Credit: EADS Astrium

Description:

• Rosetta is a spacecraft intended to rendezvous with Comet 67P/Churyumov-Gerasimenko and deploy a small lander called Philae on the nucleus of the comete 67P/Churyumov-Gerasimenko.
• The 100-kilogram Philae lander is provided by a European consortium under the leadership of the German Aerospace Research Institute (DLR). Other members of the consortium are ESA and institutes from Austria, Finland, France, Hungary, Ireland, Italy and the UK.
• The box-shaped lander is carried on the side of the orbiter until it arrives at Comet 67P/Churyumov-Gerasimenko. Once the orbiter is aligned correctly, the lander is commanded to self-eject from the main spacecraft and unfold its three legs, ready for a gentle touchdown at the end of the ballistic descent.
  On landing, the legs damp out most of the kinetic energy to reduce the chance of bouncing, and they can rotate, lift or tilt to return the lander to an upright position.
  Immediately after touchdown, a harpoon is fired to anchor the lander to the ground and prevent it escaping from the comet’s extremely weak gravity. The minimum mission target is one week, but surface operations may continue for many months.
• The lander structure consists of a baseplate, an instrument platform, and a polygonal sandwich construction, all made of carbon fibre. Some of the instruments and subsystems are beneath a hood that is covered with solar cells.
  An antenna transmits data from the surface to Earth via the orbiter. The lander carries nine experiments, with a total mass of about 21 kilograms. It also carries a drilling system to take samples of subsurface material.
  
  
  
• Instruments:
  • APXS: Alpha Proton X-ray Spectrometer (studying the chemical composition of the landing site and its potential alteration during the comet's approach to the Sun) CONSERT: COmet Nucleus Sounding Experiment by Radiowave Transmission (studying the internal structure of the comet nucleus with Rosetta orbiter)
  • COSAC: The COmetary SAmpling and Composition experiment (detecting and identifying complex organic molecules)
  • PTOLEMY: Using MODULUS protocol (Methods Of Determining and Understanding Light elements from Unequivocal Stable isotope compositions) to understand the geochemistry of light elements, such as hydrogen, carbon, nitrogen and oxygen.
  • MUPUS: MUlti-PUrpose Sensors for Surface and Sub-Surface Science (studying the properties of the comet surface and immediate sub-surface)
  • ROLIS: Rosetta Lander Imaging System (providing the first close-up images of the landing site)
  • ROMAP: Rosetta Lander Magnetometer and Plasma Monitor (studying the magnetic field and plasma environment of the comet)
  • SD2: Sampling, drilling and distribution subsystem (drilling up to 23 cm depth and delivering material to onboard instruments for analysis)
  • SESAME: Surface Electric Sounding and Acoustic Monitoring Experiment (probing the mechanical and electrical parameters of the comet)

Mission details:

• The Ariane 5 rocket fired up at 0717:44 GMT (2:17:44 a.m. EST), exactly when the booster could place the probe on the first leg of its ten-year course to comet Churyumov-Gerasimenko.
• The lander Philae is attached on the side of Rosetta.
• The 85 kg Philae lander was ejected from the Rosetta probe 22 km from Comet 67P/Churyumov-Gerasimenko at 0835 UTC Nov 12, 2014. Philae's thruster was not working, and at 1533 UTC on contact with 67P's surface at the Agilkia landing site the harpoons intended to lock it to the surface apparently did not deploy. The lander bounced off the surface gently and settled down in another location at 1726 UTC, for a second briefer bounce that resulted in final touchdown at 1733 UTC, with the lander tilted, with one of its three legs off the surface. The lander is in the shadow of a crater cliff and not receiving enough sunlight to recharge its 2.5-day-life batteries. Science data is being received, but at the moment it looks like a race against time.
  
  

  Philae on comet.Credit: ESA

  This photo from the European Space Agency is the Philae lander's view of its landing site on Comet 67P/C-G's surface. Image release Nov. 13, 2014. Credit: ESA

• It is the first landing of a probe on a comet
• On comet 67P/Churyumov-Gerasimenko, the Rosetta lander Philae, awoke from hibernation on Jun 14, 2015 and began sending data back to Earth. Rosetta remains in orbit around the comet.