Rosetta Ends Its Comet Journey

Rosetta has ended its pioneering mission to explore a comet.  On September 30, the orbiter made a planned crash-landing into the surface of 67P/Churyumov-Gerasimenko, concluding its 12-year voyage.

I had blogged previously about Rosetta here and here.

Agilent provided five gas chromatography columns for the Philae lander deployed by Rosetta.  As noted by American Laboratory, “these columns were specifically chosen to meet the unique task of carrying out GC in a completely foreign environment, away from the support of laboratory personnel.”

What did we learn from gas chromatography and mankind’s first trip to a comet?  Among the highlights…

The comet is singing!  It is emitting oscillations at 40-50 millihertz.  You can hear the comet’s song here (increased by a factor of 10,000 to be audible to humans).  Scientists believe that the sound is being produced as neutral particles become electrically charged.  But they’re not really sure.

The comet also stinks!  As scientist Kathrin Altwegg wrote on the Rosetta blog, “The perfume of 67P/C-G is quite strong, with the odour of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odour of formaldehyde.”

Scientists have detected key organic compounds in the gas and dust cloud surrounding the comet.  These include glycine (an amino acid used by living organisms to make proteins) and phosphorus (a key element in all living organisms).  This supports the theory that building blocks of life may originally have been brought to Earth by comets.

On the other hand, scientists are increasingly doubtful that water was originally brought to Earth by comets.  The water on 67P has a different isotopic ratio than Earth water.  (Of 11 comets previously examined, only one had an isotopic ratio matching Earth water.)

Scientists were surprised to detect an abundance of molecular oxygen for the first time in a comet.  Though oxygen is a common element in the universe, it usually binds with other elements.  In this pristine form, 67P’s oxygen may be more than 4.5 billion years old!

The comet is spraying dust, water vapor, carbon dioxide, carbon monoxide and other volatile chemicals into space.  This happens as the comet approaches the sun and these gases heat up.

Scientists had expected 67P to be made mostly of ice.  Instead, the comet is covered with smooth dust plains, rocky cliffs, boulders, pits and cracks.  The data do suggest that there’s a layer of ice beneath the surface.

The comet is shaped like a duck, with a “head” and “body.”  Scientists believe that 67P was once two comets that got stuck together.  The comet is also very porous, with a density about half that of Earth ice.  As much as 80 percent of the comet may be empty space.

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