Het is een passend besluit, vlak na het eerste lustrum van de
unieke prestatie met de landing van de Huygens-sonde op de
maan Titan. Het verhaal van ScienceGuide daarover leest u
hier.
NASA will extend the international Cassini-Huygens mission to
explore Saturn and its moons to 2017. The agency's fiscal year 2011
budget provides a $60 million per year extension for continued
study of the ringed planet.
"This is a mission that never stops providing us surprising
scientific results and showing us eye popping new vistas," said Jim
Green, director of NASA's planetary science division at NASA
Headquarters in Washington. "The historic traveler's stunning
discoveries and images have revolutionized our knowledge of Saturn
and its moons."
Cassini launched in October 1997 with the European Space Agency's
Huygens probe. The spacecraft arrived at Saturn in 2004. The probe
was equipped with six instruments to study Titan, Saturn's largest
moon. Cassini's 12 instruments have returned a daily stream of data
from Saturn's system for nearly six years. The project was
scheduled to end in 2008, but the mission received a 27-month
extension to Sept. 2010.
"The extension presents a unique opportunity to follow seasonal
changes of an outer planet system all the way from its winter to
its summer," said Bob Pappalardo, Cassini project scientist at
NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Some of
Cassini's most exciting discoveries still lie ahead."
This second extension, called the Cassini Solstice Mission, enables
scientists to study seasonal and other long-term weather changes on
the planet and its moons. Cassini arrived just after Saturn's
northern winter solstice, and this extension continues until a few
months past northern summer solstice in May 2017. The northern
summer solstice marks the beginning of summer in the northern
hemisphere and winter in the southern hemisphere.
A complete seasonal period on Saturn has never been studied at this
level of detail. The Solstice mission schedule calls for an
additional 155 orbits around the planet, 54 flybys of Titan and 11
flybys of the icy moon Enceladus.
The mission extension also will allow scientists to continue
observations of Saturn's rings and the magnetic bubble around the
planet known as the magnetosphere. The spacecraft will make
repeated dives between Saturn and its rings to obtain in depth
knowledge of the gas giant. During these dives, the spacecraft will
study the internal structure of Saturn, its magnetic fluctuations
and ring mass.
The mission will be evaluated periodically to ensure the spacecraft
has the ability to achieve new science objectives for the entire
extension.
"The spacecraft is doing remarkably well, even as we endure the
expected effects of age after logging 2.6 billion miles on its
odometer," said Bob Mitchell, Cassini program manager at JPL. "This
extension is important because there is so much still to be learned
at Saturn. The planet is full of secrets, and it doesn't give them
up easily."
Cassini's travel scrapbook includes more than 210,000 images;
information gathered during more than 125 revolutions around
Saturn; 67 flybys of Titan and eight close flybys of Enceladus.
Cassini has revealed unexpected details in the planet's signature
rings, and observations of Titan have given scientists a glimpse of
what Earth might have been like before life evolved.
Scientists hope to learn answers to many questions that have
developed during the course of the mission, including why Saturn
seems to have an inconsistent rotation rate and how a probable
subsurface ocean feeds the Enceladus' jets.