Rosetta and Comet 67P Finally Meet Tomorrow – UPDATE

Update, August 6, 2014:  “We’re at the comet!”  The final 6-miinute burn to put Rosetta into its rendezvous position next to 67P occurred nominally today.  ESOC received the confirmatory signal at about 11:30 CEST (09:30 GMT, 5:30 am EDT).  The one-way signal travel time from Rosetta to Earth is 22 minutes 29 seconds at this moment.

August 5, 2014:  After a 10-year journey, Europe’s Rosetta spacecraft will finally arrive at its destination tomorrow, August 6, 2014.   Awaiting it is Comet 67P/Churyumov-Gerasimenko, a roughly 4-kilometer diameter comet nucleus, sometimes described as resembling a duck, though that does require a bit of imagination.  The European Space Agency (ESA) will have a day-long series of press conferences that will be livestreamed to herald Rosetta’s arrival and the beginning of its primary science mission.

Rosetta is not the first spacecraft to visit a comet, but it will be the first to orbit one and accompany it as it travels in towards the Sun and is transformed by the Sun’s heat.   It also will be the first to send a lander, named Philae, to the surface of the comet’s nucleus. The landing is scheduled for November after Rosetta’s instruments are used to select potential landing sites.  The lander will be released from Rosetta when it is only about 1 kilometer above the surface.

The comet is named after the two Kiev, Ukraine astronomers, Klim Churyumov and Svetlana Gerasimenko, who discovered it in 1969 while conducting comet observations at the Alma-Ata Astrophysical Institute in Kazakhstan.  The spacecraft is named after the Rosetta Stone that allowed the deciphering of hieroglyphics and therefore an understanding of ancient Egyptian civilization.  Philae is the name of an island in the Nile river on which an obelisk was found that had the final clues that enabled the decryption.  ESA says its Rosetta and Philae spacecraft “aim to unlock the mysteries of the oldest building blocks of our Solar System – comets.”

The spacecraft will study Comet 67P over the course of a year as it swings around the Sun, mapping the comet’s surface and studying how it changes as the ice in the nucleus melts, creating the familiar comet tail.  Instruments on Rosetta will study the dust and gas particles in the tail and their interaction with the solar wind.  The comet and Rosetta are currently about 540 million kilometers from the Sun or 404 kilometers from Earth.  ESA has a useful “Where is Rosetta” interactive graphic that shows the relative distances of Rosetta from the Earth and Sun at all dates throughout its journey.  The two-way signal travel time right now is about 45 minutes.

Though Comet 67P is “only” 404 million kilometers from Earth at the moment, it took Rosetta a journey of 6 billion kilometers to get there, swinging by Earth three times and Mars once to receive gravity boosts.  Launched on March 2, 2004, the spacecraft survived a record 957 days (about 31 months) in hibernation from June 2011 to January 2014 as it traveled so far from the Sun that its solar panels could not fully power the spacecraft.

Rosetta’s arrival at the comet is expected at about 11:45 Central European Summer Time (CEST) tomorrow (09:45 GMT or 05:45 Eastern Daylight Time), but it has already sent back many photos of its destination.

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.

Rosetta is controlled from the European Space Operations Center (ESOC) in Darmstadt, Germany, which is where ESA will hold a series of press conferences throughout tomorrow.  ESOC’s press center opens at 09:30 CEST and livestreamed events begin at 10:00 CEST (08:30 GMT, 04:00 EDT) with a welcome by Thomas Reiter, Head of ESOC and ESA’s Director of Human Spaceflight and Mission Operations, ESA Director General Jean-Jacques Dordain, and other dignitaries.  Coverage of Rosetta’s arrival at 67P begins at 11:25 CEST (09:25 GMT, 05:25 EDT).  A draft program of those and other press events is posted on ESA’s website.   The events will be livestreamed at www.esa.int/rosetta and www.livestream.com/eurospaceagency.