of all the mysteries that scientists
investigate the greatest riddle is life
itself what caused a planet like Earth
to form around our Sun what sparked
chemicals to burst forth into life to
help answer these questions
astronomers are studying celestial
fossils from the solar system's earliest
times
the planets and the Sun were created
four and a half billion years ago from a
whirling cloud of dust and gas
heat from the young Sun and the pressure
of the solar wind swept clean nearby
planets like the earth
but farther away the cold outer regions
preserve giant gas balls like Jupiter
and Saturn comets were to remain frozen
fossils holding secrets of the chemical
makeup of the solar system's birth
life itself is found only on earth but
clues to its origins may be found in the
distant reaches of giant planets moons
and comets the NASA missions to the
outer solar system are named comic
rendezvous asteroid flyby or craft and
Cassini craft and Cassini are the first
missions in Mariner mark to a new series
of spacecraft being designed to explore
the outer solar system dr. Tobias Owen
of the state university of new york the
inner planets are small they've been
heavily bombarded reworked from within
that early history is more or less gone
it's been very very changed with time
but in the outer solar system the low
temperature out there has preserved the
chemistry in a primitive state from the
time the solar system formed comets took
shape billions of miles from the Sun
they are likely composed of the same
primitive chemicals as the ancient
nebula of gas and dust that formed the
Sun and solar system 1986 a fleet of
international spacecraft track Halley's
Comet and reveal a snowball of dust and
ice and the hint of organic compounds in
1995 craft will be launched to a typical
comet named cough on its outward flight
the spacecraft first investigates an
asteroid
in August 2000 it reaches its
destination as craft travels alongside
the comet it fires a penetrator lander
equipped with a laboratory of
instruments
these instruments will directly sample
chemicals that could be relics of an era
billions of years old
comets must have impacted the earth with
considerable frequency shortly after the
planet itself was formed so the Comets
were bringing in this rich mixture of
organic material which would have been
available to give life a sort of
headstart the chemical reactions for
life ahead start as we proceed down the
path towards increasing complexity and
ultimately to life itself so we want to
know what are those compounds what are
the chemical missing links in Earth's
past while crafts studies the comet for
three years
Cassini search will take it to Saturn
Cassini is an international mission that
teams an orbiter spacecraft built by
NASA's Jet Propulsion Laboratory and a
probe provided by the European Space
Agency ISA Cassini was named for the
17th century astronomer John Dominique
Cassini here in the Paris observatory he
discovered four of Saturn's moons and
the division in Saturn's rings dr.
Danielle Gautier is the chief scientist
for the Titan probe but louis xiv invite
him to come here and he discover all
four satellites of Saturn yeah you can
see the notes by Cassini where he put
discoveries the spacecraft Cassini will
orbit Saturn for at least three years
giving scientists an extended look at
the ringed planet and its elaborate
system of moons the most tantalizing of
those moons is Saturn's largest Titan
Titan is larger than the planet Mercury
and is the only moon with a major
atmosphere in 2002 Cassini will launch
its european-built probe to descend to
Titan
the most important I think the most
important project of the title pub will
be the measurement of complex molecules
which are expected to be present in the
upper atmosphere Titan including the
organic molecules which has used to
build life we don't believe that the
life exists on Titan because it's of
course but obviously there is a complex
chemistry detailed measurements will be
made of the thick nitrogen methane
atmosphere believed to contain the
chemical precursors to a life supporting
environment huge lakes of liquid methane
and ethane may exist on Titan the probe
will analyze compounds on the surface
and relay the information back to the
orbiting spacecraft Titan has an
atmosphere that is denser than our own
consisting primarily of nitrogen but
with a lot of carbon rich compounds as
well now what's fascinating about that
atmosphere for us is that it allows us
to do a kind of cosmic time traveled as
if we could go back in time and see what
the earth was like shortly after it
formed because Titan being at such a low
temperature has preserved those original
conditions so the kinds of chemical
reactions taking place in Titan's
atmosphere today we think resemble the
kinds of things that happened on the
very early earth which ultimately led to
the formation of life here raff and
Cassini are a new series of spacecraft
being designed at the Jet Propulsion
Laboratory to explore the outer solar
system the spacecraft to be launched on
expendable rockets streamlined design
and operations to save costs
what we're trying to do with these two
spacecraft is to gain information about
two of the biggest questions that people
have ever asked themselves one is where
did the solar system come from the
second is where did we come from how did
life on earth begin time has obliterated
remnants of the past the celestial past
on our planet by exploring comets
asteroids Saturn and its moons we are
looking backwards in time
the astronomical equivalent of being the
first to open an ancient vault it is an
inquiry that may lead us back to our
distant beginnings
you