[meteorite-list] Rosetta Comet Outburst Captured

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=4687

Rosetta Comet Outburst Captured
Jet Propulsion Laboratory
August 11, 2015

The European Space Agency's Rosetta spacecraft has been witnessing growing 
activity from comet 67P/Churyumov-Gerasimenko as the comet approaches 
perihelion (its closest point to the sun during its orbit). On July 29, 
while the spacecraft orbited at a distance of 116 miles (186 kilometers) 
from the comet, it observed the most dramatic outburst to date. Early 
science results collected during the outburst came from several instruments 
aboard Rosetta, including the Double Focusing Mass Spectrometer (DFMS), 
which uses NASA-built electronics. The DFMS is part of the spacecraft's 
Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument.

When the outburst occurred, the spectrometer recorded dramatic changes 
in the composition of outpouring gases from the comet when compared to 
measurements made two days earlier. As a result of the outburst, the amount 
of carbon dioxide increased by a factor of two, methane by four, and hydrogen 
sulfide by seven, while the amount of water stayed almost constant.

"This first quick look at our measurements after the outburst is fascinating," 
said Kathrin Altwegg, principal investigator for the ROSINA instrument 
from the University of Bern, Switzerland. "We also see hints of heavy 
organic material after the outburst that might be related to the ejected 
dust.

"But while it is tempting to think that we are detecting material that 
may have been freed from beneath the comet's surface, it is too early 
to say for certain that this is the case."

A sequence of images taken by Rosetta's scientific camera OSIRIS shows 
the sudden onset of a well-defined, jet-like feature emerging from the 
side of the comet's neck. The jet, the brightest seen to date, was first 
recorded in an image taken at 6:24 a.m. PDT (9:24 a.m. EDT, 13:24 GMT) 
on July 29, but not in an image taken 18 minutes earlier. The jet then 
faded significantly in an image captured 18 minutes later. The OSIRIS 
camera team estimates the material in the jet was traveling at 33 feet 
per second (10 meters per second), at least.

A composite of the three images taken by Rosetta's OSIRIS is online at:

http://rosetta.jpl.nasa.gov

On Thursday, Aug. 13, the comet and Rosetta will be 116 million miles 
(186 million kilometers) from the sun -- the closest to the sun they will 
be in their 6.5-year orbit. In recent months, the increasing solar energy 
has been warming the comet's frozen ices -- turning them to gas -- which 
pours out into space, dragging dust along with it. The period around perihelion 
is scientifically very important, as the intensity of the sunlight increases 
and parts of the comet previously cast in years of darkness are flooded 
with sunlight. The comet's general activity is expected to peak in the 
weeks following perihelion.

Comets are time capsules containing primitive material left over from 
the epoch when the sun and its planets formed. Rosetta's lander, Philae, 
obtained the first images taken from a comet's surface and will provide 
analysis of the comet's possible primordial composition. Rosetta is the 
first spacecraft to witness at close proximity how a comet changes as 
it is subjected to the increasing intensity of the sun's radiation. Observations 
are helping scientists learn more about the origin and evolution of our 
solar system and the role comets may have played in seeding Earth with 
water, and perhaps even life.

Rosetta is a a European Space Agency mission with contributions from its 
member states and NASA. The Jet Propulsion Laboratory, Pasadena, California, 
a division of the California Institute of Technology in Pasadena, manages 
the U.S. contribution of the Rosetta mission for NASA's Science Mission 
Directorate in Washington. JPL also built the MIRO instrument and hosts 
its principal investigator, Samuel Gulkis. The Southwest Research Institute 
(San Antonio and Boulder) developed the Rosetta orbiter's IES and Alice 
instruments, and hosts their principal investigators, James Burch (IES) 
and Alan Stern (Alice).

For more information on the U.S. instruments aboard Rosetta, visit:

http://rosetta.jpl.nasa.gov

More information about Rosetta is available at:

http://www.esa.int/rosetta


Media Contact

DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle at jpl.nasa.gov 

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov 

Markus Bauer
European Space Agency, Noordwijk, Netherlands
011-31-71-565-6799
markus.bauer at esa.int 

2015-266