Rosetta Arrives at Target Comet
 
August 6, 2014:  Today, after a decade-long journey chasing its target, the
European Space Agency's Rosetta probe, carrying three NASA instruments,
became the first spacecraft to rendezvous with a comet,
67P/Churyumov-Gerasimenko.
 
"After 10 years, five months and four days travelling towards our
destination, looping around the sun five times and clocking up 6.4 billion
kilometers, we are delighted to announce finally we are here," said
Jean-Jacques Dordain, ESA's director General.
 
http://www.nasa.gov/content/rosettas-target-up-close/
 
Comet 67P/Churyumov-Gerasimenko by Rosetta's OSIRIS narrow-angle camera on
August 3, 2014, from a distance of 177 miles (285 kilometers). Credits:
ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA Full
image and caption
 
The latest images of the comet taken by Rosetta are available at
http://www.nasa.gov/rosetta
 
Comet 67P/Churyumov-Gerasimenko and Rosetta are 252 million miles (405
million kilometers) from Earth, about halfway between the orbits of Jupiter
and Mars. The comet is in an elliptical, 6.5-year orbit that takes it from
beyond Jupiter at its farthest point, to between the orbits of Mars and
Earth at its closest to the sun. Rosetta will accompany the comet for over
a year as it swings around the sun and back out towards Jupiter again.
 
Rosetta is 62 miles (100 kilometers) from the comet's surface. Over the
next six weeks, it will fly two triangular-shaped trajectories in front of
the comet, first at the 62-mile (100-kilometer) altitude and then down at
31 miles (50 kilometers). At the same time, the spacecraft's suite of
instruments will provide a detailed scientific study of the comet, scanning
the surface to identify a target site for its comet lander, Philae.
Eventually, Rosetta will attempt a close, near-circular orbit at 19 miles
(30 kilometers) and, depending on the activity of the comet, may come even
closer.
 
"Over the next few months, in addition to characterizing the comet
nucleus and setting the bar for the rest of the mission, we will begin
final preparations for another space history first: landing on a
comet," said Matt Taylor, Rosetta's project scientist from the
European Space Agency's Science and Technology Centre in Noordwijk, The
Netherlands.
 
As many as five possible landing sites will be identified by late August,
before the primary site is identified in mid-September. The final timeline
for the sequence of events for deploying Philae -- currently expected for
Nov. 11 -- will be confirmed by the middle of October.
 
http://www.nasa.gov/content/rosettas-target-up-close/
 
Close up detail focusing on a smooth region on the `base' of the `body'
section of comet 67P/Churyumov-Gerasimenko. The image was taken by
Rosetta's Onboard Scientific Imaging System (OSIRIS) on August 6, 2014.
Credits: ESA/Rosetta/MPS for OSIRIS Team  Full image and caption
 
Comets are considered to be primitive building blocks of the solar system
and may have helped to "seed" Earth with water, perhaps even the
ingredients for life. But many fundamental questions about these enigmatic
objects remain, and through a comprehensive, in situ study of the comet,
Rosetta aims to unlock the secrets within.
 
The three U.S. instruments aboard the spacecraft are the Microwave
Instrument for Rosetta Orbiter (MIRO), an ultraviolet spectrometer called
Alice, and the Ion and Electron Sensor (IES). They are part of a suite of
11 science instruments aboard the Rosetta orbiter.
 
MIRO is designed to provide data on how gas and dust leave the surface of
the nucleus to form the coma and tail that give comets their intrinsic
beauty. Studying the surface temperature and evolution of the coma and tail
provides information on how the comet evolves as it approaches and leaves
the vicinity of the sun.
 
Alice will analyze gases in the comet's coma, which is the bright envelope
of gas around the nucleus of the comet developed as it approaches the sun.
Alice also will measure the rate at which the comet produces water, carbon
monoxide and carbon dioxide. These measurements will provide valuable
information about the surface composition of the nucleus.
 
The instrument also will measure the amount of argon present, an important
clue about the temperature of the solar system at the time the comet's
nucleus originally formed more than 4.6 billion years ago.
 
IES is part of a suite of five instruments to analyze the plasma
environment of the comet, particularly the coma. The instrument will
measure the charged particles in the sun's outer atmosphere, or solar wind,
as they interact with the gas flowing out from the comet while Rosetta is
drawing nearer to the comet's nucleus.
 
NASA also provided part of the electronics package for the Double Focusing
Mass Spectrometer, which is part of the Swiss-built Rosetta Orbiter
Spectrometer for Ion and Neutral Analysis (ROSINA) instrument. ROSINA will
be the first instrument in space with sufficient resolution to be able to
distinguish between molecular nitrogen and carbon monoxide, two molecules
with approximately the same mass. Clear identification of nitrogen will
help scientists understand conditions at the time the solar system was
formed.
 
U.S. scientists are partnering on several non-U.S. instruments and are
involved in seven of the mission's 21 instrument collaborations. NASA's
Deep Space Network is supporting ESA's Ground Station Network for
spacecraft tracking and navigation.
 
Launched in March 2004, Rosetta was reactivated in January 2014 after a
record 957 days in hibernation. Composed of an orbiter and lander,
Rosetta's objectives upon arrival at comet 67P/Churyumov-Gerasimenko in
August are to study the celestial object up close in unprecedented detail,
prepare for landing a probe on the comet's nucleus in November, and track
its changes as it sweeps past the sun.
 
Credits:
Production editor: Dr. Tony Phillips | Credit: Science{at}NASA
 
The scientific imaging system, OSIRIS, was built by a consortium led by the
Max Planck Institute for Solar System Research (Germany) in collaboration
with Center of Studies and Activities for Space, University of Padua
(Italy), the Astrophysical Laboratory of Marseille (France), the Institute
of Astrophysics of Andalusia, CSIC (Spain), the Scientific Support Office
of the European Space Agency (Netherlands), the National Institute for
Aerospace Technology (Spain), the Technical University of Madrid (Spain),
the Department of Physics and Astronomy of Uppsala University (Sweden) and
the Institute of Computer and Network Engineering of the TU Braunschweig
(Germany). OSIRIS was financially supported by the national funding
agencies of Germany (DLR), France (CNES), Italy (ASI), Spain, and Sweden
and the ESA Technical Directorate.
 
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. JPL, a division of the California Institute of Technology,
Pasadena, manages the U.S. participation in the Rosetta mission for NASA's
Science Mission Directorate in Washington.
 
Web links:
European Space Agency home page
 
Rosetta -- from the ESA
 
Rosetta -- from NASA
 
NASA Instruments on Rosetta
 
Rosetta Comet Comes Alive -- from Science{at}NASA
 
 
Regards,
 
Roger

--- D'Bridge 3.99