Rosetta successfully launched

From SpaceFlightNow.com- no LGM for Al to worry about this time : spaceflightnow.com/ariane/v158/040302launch.html


Embarking on its epic voyage to gain new insights into comets and the
history of our solar system, the Rosetta spacecraft was successfully
launched today to rendezvous with a cosmic snowball and deploy a tiny
lander onto its icy heart.

The Ariane 5 rocket fired up at 0717:44 GMT (2:17:44 a.m. EST),
exactly when the booster could place the probe on the first leg of its
ten-year course to comet Churyumov-Gerasimenko.

The Ariane solid rockets and first stage put Rosetta on an arcing
suborbital ballistic trajectory about ten minutes after launch. The
upper stage's Aestus engine fired nearly two hours after liftoff to
send the 6,700-pound craft out of Earth's grasp and into solar orbit.

Rosetta aims to give scientists a wealth of knowledge about comets,
frozen time capsules from billions of years ago, while helping the
public at large wrestle some of the most fundamental questions that
humans can ask.

"I think it is very hard to imagine that you don't wonder sometimes
what is it all about? Where did it all come from?" says European Space
Agency science director David Southwood. "Once we were all star dust.
How did we turn out to be the complicated beings that we are now? I
think we are looking for some of the clues that will help us put that
story together."

Today's launch has been in the works since the Rosetta project began
in 1993. Since then, the Rosetta team has been thrown a number of
curves -- most recently the decision to delay the launch from January
2003 due to concerns with the reliability of the Ariane 5 rocket.

Delaying the launch from 2003 to 2004 caused managers to change
targets for the probe, which required extensive studies of
Churyumov-Gerasimenko to see if it was suitable to approach with a $1
billion spacecraft and safe to land upon with a tiny robot explorer.

Rosetta will take a circuitous route through the solar system and will
arrive back in the vicinity of Earth next March for its first crucial
gravity assist fly-by. The probe will reach Mars in March 2007,
followed by two additional close approaches of Earth to tweak its
course toward Churyumov-Gerasimenko.

Heading further from the Sun and past the asteroid belt, Rosetta will
fly near several of these space rocks and study them from a distance
of over a thousand miles before entering a hibernation period in mid-2011.

"These brief encounters are a scientific opportunity and also a chance
to test Rosetta's instrument payload," explained Rosetta project
scientist Gerhard Schwehm from the European Space Agency.

For two-and-a-half years, Rosetta's systems will be completely
shutdown with the exception of its primary computer and radio
receivers in order to conserve power. Fitted with two solar wings
spanning almost 100 feet, the spacecraft will be the first to fly near
the orbit of Jupiter and rely entirely on solar power.

"To provide the probe with the power it needs in space, we have given
it the biggest solar panels ever carried by a European satellite,"
said Manfred Warhaut, Rosetta's operations manager.

Rosetta will also undergo a number of other extended periods of
inactivity between key mission events during the journey to
Churyumov-Gerasimenko to relieve manpower and electrical constraints.

Power production is strained for Rosetta because it will be traveling
over 500 million miles from the Sun, where light levels are only four
percent of those found on Earth.

Controllers will bring Rosetta back to life in early 2014 for a
thruster firing to slow the probe's approach to the comet before
entering orbit and beginning its mapping and scientific mission to
characterize the surface.

"Rosetta carries more instruments than any previous scientific
spacecraft -- that makes it challenging and one of the most exciting
missions ever," said Claudia Alexander, U.S. project scientist for the
mission from NASA's Jet Propulsion Laboratory. "We anticipate major
discoveries, just like Galileo and Cassini."

By the end of the summer in 2014, Rosetta will be in orbit around
Churyumov-Gerasimenko and science operations should be in full swing.
A major priority will be the determination of favorable landing sites
for a small 220-pound lander carried aboard Rosetta named Philae.

The three-legged Philae will touch down on the surface in November
2014, firing a harpoon to keep the tiny craft anchored on the comet so
it doesn't float away in the weak gravitational field. It will snap
high-resolution pictures and acquire data about the comet's organic
crust and molecules for transmission up to the orbiter for later relay
to Earth.

Operating at least one week, perhaps significantly longer, Philae's
instrument suite even includes a tiny drill that can bore a few inches
into the comet for subsurface investigations.

Together the orbiter and lander will observe the traits and changes
the comet goes through as it approaches the Sun. Officially, the
mission is slated to come to conclude in late 2015.

"This will be our first ever chance to be there, first hand, so to
speak, as a comet comes to life," Schwehm said. "As we will be
accompanying Churyumov-Gerasimenko for two years, until the comet
reaches its closest point to the Sun and travels away from it, we can
at long last hope to acquire new knowledge about comets."

Comet Churyumov-Gerasimenko was discovered in 1969 and is considered a
dusty comet that is roughly two by three miles in diameter. The Hubble
Space Telescope was chartered to observe the comet for 21 hours in
March 2003 to gather more specific details about Churyumov-Gerasimenko
to allow project officials to decide whether to pursue it as a
potential target.

"This comet has only about three-hundred-thousandths the gravity of
Earth," said Alexander. "The Rosetta spacecraft will be able to make
observations from as close as 2 kilometers (1.2 miles). The data from
our state-of-the-art instruments will be amazing."

Scientists believe comets are made of the very same primitive
materials that were present when the Sun and the solar system were
formed an estimated 4.6 billion years ago.

Comets are balls of ice and rock believed to be formed far beyond the
orbit of Pluto where conditions are cold and dark, much like they were
as the solar system was born. Some of these objects are drawn toward
the inner solar system and they become comets -- giving us a unique
view of almost the same primordial materials that played such
important roles in the formation of the Sun and the planets.

"They are the keys to understanding the way the whole solar system,
the Earth, and how even we came into being. And with Rosetta we will
be able to observe, study and analyze this primordial material up
close for more than a year," said Paul Weissman of NASA's Jet
Propulsion Laboratory.

"We are confident we will come a step nearer to understanding the
origins and formation of our solar system and the emergence of life on
Earth," said Schwehm.

Rosetta gets its name from the stone tablet found by French soldiers
in Egypt in 1799 that contained the key to deciphering Egyptian
hieroglyphics. Scientists hope this mission may unveil the mysteries
surrounding how our planet and life came to be as we know it today.

ESA managers are not lost on the difficulties associated with the mission.

"Rosetta is one of the most challenging missions undertaken so far. No
one has ever attempted such a mission, unique for its scientific
implications as well as for its complex and spectacular interplanetary
space maneuvers," Southwood said.

"This mission will turn science fiction into science fact. Every
aspect of comet Churyumov-Gerasimenko will be analyzed, resulting in
the most comprehensive set of scientific measurements ever obtained of
a comet," said Professor Ian Halliday, chief executive of the Particle
Physics and Astronomy Research Council, which funded two of the
instruments.