[meteorite-list] Rosetta: Landing Site Search Narrows

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 26 Aug 2014 12:51:43 -0700 (PDT)
Message-ID: <201408261951.s7QJphqo011394_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2014-289

Rosetta: Landing Site Search Narrows
Jet Propulsion Laboratory
August 25, 2014

The European Space Agency's Rosetta mission has chosen five candidate
landing sites on comet 67P/Churyumov-Gerasimenko for its Philae lander.
Philae's descent to the comet's nucleus, scheduled for this November,
will be the first such landing ever attempted. Rosetta is an
international mission spearheaded by the European Space Agency with
support and instruments provided by NASA.

Choosing the right landing site is a complex process. It must balance
the technical needs of the orbiter and lander during all phases of the
separation, descent and landing, and during operations on the surface,
with the scientific requirements of the 10 instruments on board Philae.
A key issue is that uncertainties in navigating the orbiter close to the
comet mean that it is possible to specify any given landing zone only in
terms of an ellipse - covering up to six-tenths of a square mile (one
square kilometer) - within which Philae might land.

"This is the first time landing sites on a comet have been considered,"
said Stephan Ulamec, Philae Lander Manager at the German Aerospace
Center, Cologne, Germany. "The candidate sites that we want to follow up
for further analysis are thought to be technically feasible on the basis
of a preliminary analysis of flight dynamics and other key issues - for
example, they all provide at least six hours of daylight per comet
rotation and offer some flat terrain. Of course, every site has the
potential for unique scientific discoveries."

For each possible zone, important questions must be asked: Will the
lander be able to maintain regular communications with Rosetta? How
common are surface hazards such as large boulders, deep crevasses or
steep slopes? Is there sufficient illumination for scientific operations
and enough sunlight to recharge the lander's batteries beyond its
initial 64-hour lifetime without causing overheating?

The potential landing sites were assigned a letter from an original
pre-selection of 10 possible sites, which does not signify any ranking.
Three sites (B, I and J) are located on the smaller of the two lobes of
the comet and two sites (A and C) are located on the larger lobe.

"The process of selecting a landing site is extremely complex and
dynamic; as we get closer to the comet, we will see more and more
details, which will influence the final decision on where and when we
can land," said Fred Jansen, Rosetta's mission manager from the European
Space Agency's Science and Technology Centre in Noordwijk, The
Netherlands. "We had to complete our preliminary analysis on candidate
sites very quickly after arriving at the comet, and now we have just a
few more weeks to determine the primary site. The clock is ticking and
we now have to meet the challenge to pick the best possible landing site."

The next step in preparation for landing operations is a comprehensive
analysis of each of the candidate sites, to determine possible orbital
and operational strategies that could be used for Rosetta to deliver the
lander to any of them. At the same time, Rosetta will move to within 31
miles (50 kilometers) of the comet, allowing a more detailed study of
the proposed landing sites. By September 14, the five candidate sites
will have been assessed and ranked, leading to the selection of a
primary landing site. A fully detailed strategy for the landing
operations at the selected site will be developed, along with a backup.

The landing of Philae is expected to take place in mid-November when the
comet is about 280 million miles (450 million kilometers) from the sun.
This will be before activity on the comet reaches levels that might
jeopardize the safe and accurate deployment of Philae to the comet's
surface, and before surface material is modified by this cometary activity.

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 since arriving at comet 67P/Churyumov-Gerasimenko
earlier this month 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 through 2015, as it sweeps past the sun.

Comets are time capsules containing primitive material left over from
the epoch when the sun and its planets formed. Rosetta's lander will
obtain the first images taken from a comet's surface and will provide
comprehensive analysis of the comet's possible primordial composition by
drilling into the surface. Rosetta also will be 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.

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. NASA's Jet Propulsion Laboratory in
Pasadena, California, a division of the California Institute of
Technology, manages the U.S. participation in the Rosetta mission for
NASA's Science Mission Directorate in Washington.

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

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

Dwayne Brown
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

2014-289
Received on Tue 26 Aug 2014 03:51:43 PM PDT