Philae (spacecraft)

Philae (previously known as RoLand) is the lander that accompanies the Rosetta spacecraft. It is designed to land on Comet 67P/Churyumov-Gerasimenko shortly after arrival.[1][2] The lander is named after Philae island in the Nile, where an obelisk was found that was used along with the Rosetta Stone to decipher Egyptian hieroglyphic.

Contents

Design

The lander is designed to touch down on the comet’s surface after detaching itself from the main spacecraft body and “falling” towards the comet along a ballistic trajectory. It also will deploy harpoons to anchor itself to the surface, and the legs are designed to dampen the initial impact to avoid bouncing. Communications with Earth will use the orbiter spacecraft as a relay station to reduce the electrical power needed. The mission duration on the surface is planned to be at least one week, but an extended mission lasting months is possible.

The main structure of the lander is made from carbon fiber, shaped into a plate maintaining mechanical stability, a platform for the science instruments, and a hexagonal “sandwich” to connect all the parts. The total mass is about 100 kg. Its "hood" is covered with solar cells for power generation.[3]

It was originally planned to rendezvous with the comet 46P/Wirtanen. A failure of the Ariane 5 launch vehicle necessitated a change in target to the comet 67P/Churyumov-Gerasimenko. The larger comet mass and the resulting increased impact velocity made modification of the landing gear necessary. Besides the changes made to launch time and target, the mission profile remained unchanged.[1]

Instruments

The science payload of the lander consists of 10 instruments with 26.7 kg making up nearly one third of the mass of the lander.[4]

Mission

Philae's mission is to land successfully on the surface of a comet, and transmit data from the surface about the comet's composition. Unlike the Deep Impact probe, it is not an impactor. A check of the instruments indicated no major problems in 2006.[10] Some of the instruments and the lander were used for the first time as autonomous systems during the Mars flyby on February 25, 2007. ÇIVA, the camera system, returned some images while the Rosetta instruments were powered down; ROMAP took measurements of the Martian magnetosphere. Most of the other instruments need contact with the surface for analysis and stayed offline during the flyby.

References

  1. ^ a b S. Ulamec, S. Espinasse, B. Feuerbacher, M. Hilchenbach, D. Moura, H. Rosenbauer, H. Scheuerle, R. Willnecker (2006). "Rosetta Lander—Philae: Implications of an alternative mission". Acta Astronautica 58 (8): 435–441. Bibcode 2006AcAau..58..435U. doi:10.1016/j.actaastro.2005.12.009. 
  2. ^ J. Biele (2002). "The Experiments Onboard the ROSETTA Lander". Journal Earth, Moon, and Planets 90 (1–4): 445–458. Bibcode 2002EM&P...90..445B. doi:10.1023/A:1021523227314. 
  3. ^ Biele, Jens (2002). Earth Moon and Planets 90: 445. Bibcode 2002EM&P...90..445B. doi:10.1023/A:1021523227314. 
  4. ^ Bibring, J.-P.; Rosenbauer, H.; Böhnhardt, H.; Ulamec, S.; Biele, J.; Espinasse, S.; Feuerbacher, B.; Gaudon, P. et al. (2007). "The Rosetta Lander ("Philae") Investigations". Space Science Reviews 128: 205. Bibcode 2007SSRv..128..205B. doi:10.1007/s11214-006-9138-2. 
  5. ^ Goesmann F., Rosenbauer H., Roll R., Böhnhardt H. (2005). "COSAC onboard Rosetta: A bioastronomy experiment for the short-period comet 67P/Churyumov-Gerasimenko". Astrobiology 5 (5): 622–631. Bibcode 2005AsBio...5..622G. doi:10.1089/ast.2005.5.622. PMID 16225435. 
  6. ^ Wright, I. P.; Barber, S. J.; Morgan, G. H.; Morse, A. D.; Sheridan, S.; Andrews, D. J.; Maynard, J.; Yau, D.; Evans, S. T.; Leese, M. R.; Zarnecki, J. C.; Kent, B. J.; Waltham, N. R.; Whalley, M. S.; Heys, S.; Drummond, D. L.; Edeson, R. L.; Sawyer, E. C.; Turner, R. F.; Pillinger, C. T. (2006). "Ptolemy – an Instrument to Measure Stable Isotopic Ratios of Key Volatiles on a Cometary Nucleus". Space Science Reviews 128: 363. Bibcode 2007SSRv..128..363W. doi:10.1007/s11214-006-9001-5. 
  7. ^ D. J. Andrews, S. J. Barber, A. D. Morse, S. Sheridan, I. P. Wright, G. H. Morgan, (2006). "Ptolemy: An Instrument aboard the Rosetta Lander Philae, to Unlock the Secrets of the Solar System". Lunar and Planetary Science XXXVII: 1937. http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1937.pdf. 
  8. ^ Kofman, W., A. Herique, J-P. Goutail, T. Hagfors, I. P. Williams, E. Nielsen, J-P. Barriot, Y. Barbin, C.Elachi, P. Edenhofer, A-C. Levasseur-Regourd, D. Plettemeier, G . Picardi, R.Seu, V. Svedhem (2007). "The Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT). A short description of the instrument and of the commissioning stages". Space Science Reviews 128: 413–432. Bibcode 2007SSRv..128..413K. doi:10.1007/s11214-006-9034-9. 
  9. ^ Seidensticker, K. J.; Möhlmann, D.; Apathy, I.; Schmidt, W.; Thiel, K.; Arnold, W.; Fischer, H.-H.; Kretschmer, M. et al. (2007). "Sesame – An Experiment of the Rosetta Lander Philae: Objectives and General Design". Space Science Reviews 128: 301. Bibcode 2007SSRv..128..301S. doi:10.1007/s11214-006-9118-6. 
  10. ^ Biele, J; Willnecker, R; Bibring, J.-P.; Rosenbauer, H (2006). "Philae (Rosetta Lander): Experiment status after commissioning". Advances in Space Research 38 (9): 2025. Bibcode 2006AdSpR..38.2025T. doi:10.1016/j.asr.2006.09.016. 

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