ESA's Philae "Go" for Landing Tomorrow on Comet 67P

ESA's Philae "Go" for Landing Tomorrow on Comet 67P

The European Space Agency (ESA) made the first “go” of four planned “go/no-go” decisions this afternoon commanding its Rosetta spacecraft to get ready to separate the Philae lander for its trip down to the surface of Comet 67P.  Landing on the comet is expected tomorrow morning (November 12) Eastern Standard Time (EST).  It takes 28 minutes 20 seconds for a signal to get from Rosetta to Earth during which time scientists and people around the world will be waiting with baited breath for confirmation that the landing was successful.   ESA expects the confirmation signal about 11:02 am EST plus or minus 40 minutes.

Rosetta, with Philae aboard, arrived at Comet 67P/Churyumov-Gerasimenko (or 67P for short) in August after a 10 year journey.   It has been orbiting the comet over the past several months getting steadily closer to the surface to shorten the descent for Philae.   If successful, this will be the first time a spacecraft has landed on a comet nucleus.

Comet 67P and Rosetta/Philae are currently about 510 million kilometers from Earth, though the spacecraft took a circuitous route to get there, travelling more than 6.5 billion kilometers to date.

ESA is providing extensive live coverage of the go/no-go decisions and other events leading up to the landing.  A list of the critical moments is posted on its website. 

NASA will cover the landing on NASA TV tomorrow from 9:00-11:30 am EST.  NASA contributed three of the instruments on Rosetta — ALICE, MIRO and IES — and part of the electronics for a fourth, ROSINA.

Comet 67P is approximately 4 kilometers in diameter, though it has an irregular shape — often described as looking like a duck, though that takes some imagination.   ESA narrowed down potential landing sites to one, which it named Agilkia.  

Comet 67P/Churyumov-Gerasimenko taken by ESA’s Rosetta spacecraft at a distance of 1,000 kilometers,
August 1, 2014. Photo credit:  ESA/Rosetta/MPS for OSIRIS Team. 
ESA notes that the dark spot is an image artifact.

Philae has 10 instruments that will analyze the composition and structure of the comet’s surface and subsurface.  A drill will allow samples to be obtained down to 23 centimeters below the surface.  The samples will be analyzed by a spectrometer to determine the chemical composition.   Other instruments will measure near-surface strength, density, texture, porosity, ice phases and thermal properties.  Gravity on the comet is almost non-existent so Philae will “touch down at no more than a walking pace” and use a harpoon to anchor itself to the comet, according to an ESA fact sheet.

ESA says Rosetta and Philae “aim to unlock the mysteries of the oldest building blocks of our solar system — comets” and hence the names are connected to the deciphering of hieroglyphics. 

  • Rosetta is named after the Rosetta Stone that allowed the deciphering of hieroglyphics and therefore an understanding of Egyptian civilization.
  • Philae is the name of an island in the Nile river where an obelisk was found with the final clues to enable the decryption.
  • Philae was flooded when the Aswan dams were built in the 20th century and a complex of Ancient Egyptian buildings, including the Temple of Isis, were moved to another island, Agilkia,   ESA held a contest to name Philae’s landing site on 67P and of 8,000 entries, more than 150 suggested Agilkia and that was the winner.

The comet is named after the two Kiev, Ukraine astronomers who discovered it in 1969, Klim Churyumov and Svetlana Gerasimenko, while conducting comet observations at the Alma-Ata Astrophysical Institute in Kazakhstan.

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