[meteorite-list] Rosetta's MIRO Instrument Maps Comet Water

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=4632

Rosetta's MIRO Instrument Maps Comet Water
Jet Propulsion Laboratory
June 19, 2015

Since last September, scientists using NASA's Microwave Instrument for 
Rosetta Orbiter (MIRO) on the European Space Agency's Rosetta spacecraft 
have generated maps of the distribution of water in the coma of comet 
67P/Churyumov-Gerasimenko, as the comet's orbit brings it closer to the 
sun.

MIRO is able to detect water in the coma by measuring the direct emission 
from water vapor in the coma and by observing absorption of radiation 
from the nucleus at water-specific frequencies as the radiation passed 
through the coma.

On Sept. 7, 2014, when Rosetta was 36 miles (58 kilometers) from the center 
of the comet, the MIRO team obtained their first map of the nucleus of 
67P/C-G and its surroundings. They discovered the highest density of water 
just above the comet's neck, close to the north pole of the comet's rotation 
axis. In this narrow region, the number of water molecules is up to two 
orders of magnitude higher than elsewhere in the coma. Lower but still 
substantial amounts of water were detected over on the day side of the 
nucleus up to the terminator between the illuminated and dark side. The 
lowest amounts of water are found on the comet's night side -- particularly 
over its southern polar regions. This could be due to either local outgassing 
or circulation effects within the coma, causing water to flow from the 
day to the night side.

A European Space Agency blog post on the MIRO data is online at:

http://blogs.esa.int/rosetta/2015/06/19/miro-maps-water-in-comets-coma/

For a deeper dive into the science the blog post is based on, please visit:

http://www.aanda.org/component/article/?access=doi&doi=10.1051/0004-6361/201526094

The MIRO instrument is a small and lightweight spectrometer that can map 
the abundance, temperature and velocity of cometary water vapor and other 
molecules that the nucleus releases. It can also measure the temperature 
up to about one inch (two centimeters) below the surface of the comet's 
nucleus. One reason the subsurface temperature is important is that the 
observed gases likely come from sublimating ices beneath the surface. 
By combining information on both the gas and the subsurface, MIRO is able 
to study this process in detail.

Comets are time capsules containing primitive material left over from 
the epoch when the sun and its planets formed. 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 will help 
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 an ESA mission with contributions from its member states and 
NASA. Rosetta's Philae lander is provided by a consortium led by the German 
Aerospace Center, Cologne; Max Planck Institute for Solar System Research, 
Gottingen; French National Space Agency, Paris; and the Italian Space 
Agency, Rome. NASA's 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 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, Califorina
818-393-9011
agle at jpl.nasa.gov

Dwayne Brown
NASA Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

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

2015-214