http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=44249

NASA and ESA prioritize outer planet missions
European Space Agency
18 Feb 2009

At a meeting in Washington last week, NASA and European Space Agency
officials decided to first pursue a mission to study Jupiter and its
four largest moons, and plan for another mission to visit Saturn's
largest moon Titan, and Enceladus.

The proposed projects are grand endeavors that set the stage for
future
planetary science research. These outer planet flagship missions could
eventually answer questions about how our Solar System formed and
whether habitability conditions exist elsewhere in the Solar System.

The missions, called the Europa Jupiter System Mission and the Titan
Saturn System Mission, are the result of NASA and ESA merging their
separate mission concepts. NASA originally studied four mission
concepts
during 2007, which were narrowed down to two proposals in 2008. One
finalist was the Europa Orbiter to explore that icy moon of Jupiter
and
its subsurface water ocean. The other was a Titan Orbiter to visit the
Saturn moon. Meanwhile, in 2007, ESA also initiated a competition to
select their flagship mission for the Cosmic Vision 2015-2025 slot of
the ESA scientific programme. Two finalists, called Laplace and
Tandem,
were selected for further study. Laplace was proposed as a set of
spacecraft to orbit Jupiter and eventually orbit and possibly land on
Europa. Tandem was proposed as a set of spacecraft to orbit Titan,
explore its surface, after exploring the surface of Saturn's moon
Enceladus.

NASA and ESA engineers and scientists carefully studied these missions
in preparation for last week's meeting. Based on studies and stringent
independent assessment reviews, the US Europa Jupiter System Mission,
called Laplace in Europe, was the most technically feasible to do
first.
However, ESA's Solar System Working Group concluded the scientific
merits of both missions could not be separated. The group declared,
and
NASA agreed, that both missions should move forward for further study
and implementation.

"The decision means a win-win situation for all parties involved,"
said
Ed Weiler, associate administrator for NASA's Science Mission
Directorate in Washington. "Although the Jupiter system mission has
been
chosen to proceed to an earlier flight opportunity, a Saturn system
mission clearly remains a high priority for the science community."

Both agencies will need to undertake several more steps and detailed
studies before officially moving forward. "This joint endeavour is a
wonderful new exploration challenge and will be a landmark of 21st
Century planetary science," said David Southwood, ESA Director of
Science and Robotic Exploration. "What I am especially sure of is that
the cooperation across the Atlantic that we have had so far and we see
in the future, between America and Europe, NASA and ESA, and in our
respective science communities is absolutely right. Let's get to
work."

New exploration challenges at Jupiter and Saturn

The Jupiter System Mission will use two robotic orbiters to conduct
unprecedented detailed studies of the giant gaseous planet Jupiter and
its moons Io, Europa, Ganymede and Callisto. NASA will build one
spacecraft, which is initially named Jupiter Europa Orbiter. ESA will
build the other spacecraft, initially named Jupiter Ganymede Orbiter.
The two spacecraft are scheduled to launch in 2020 on two separate
launch vehicles from different launch sites. They will reach the
Jupiter
system in 2026 and spend at least three years conducting research.

Europa, with its putative ocean, is a unique target to study
habitability around the gas giant. Ganymede, the largest moon in the
Solar System, is the only moon known to have its own internally
generated magnetic field and is also suspected to have a deep
subsurface
water ocean.

Scientists long have sought to understand the causes of the magnetic
field. Io, the most volcanically active body in the Solar System, and
Callisto, whose  surface is heavily cratered and ancient, providing a
clear indication of a record of events from the early history of the
Solar System, are also key targets of the Jupiter System Mission.

The two orbiters will spend nearly a year orbiting Europa and
Ganymede,
respectively. They will both address, in synergy, Jupiter system
science
in order to better understand the formation and evolution of the
Jovian
system.

The Titan Saturn System Mission would consist of a NASA orbiter and an
ESA lander and research balloon. The complex mission possesses several
technical challenges requiring significant study and technology
development. NASA will continue studying and developing those
technologies. The National Academy in Washington is beginning to piece
together the plan that will be the roadmap for new NASA planetary
missions to begin after 2013. On the European side, the interested
community of scientists will have to re-submit the Titan mission at
the
next opportunity for mission proposals in the Cosmic Vision programme
in
the years to come.

ESA's Directorate of Science and Robotic Exploration will manage the
European contribution to the Jupiter mission. NASA's Jet Propulsion
Laboratory in Pasadena, California, will manage NASA's contributions
to
the projects for NASA's Science Mission Directorate in Washington.

Contact

Monica Talevi
ESA Science & Robotic Exploration Programme Communication Officer
Email: monica.taleviesa.int

Dwayne Brown
NASA Headquarters Public Affairs Officer
Email: dwayne.c.brownnasa.gov
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