2004-7-13
(MUSIC)
VOICE ONE:
This is Faith Lapidus
VOICE TWO:
 |
| A false color image of Saturn's rings. |
And this is Steve Ember with
EXPLORATIONS in VOA Special English. Today we tell about NASA's
Cassini-Huygens spacecraft that is now in orbit around Saturn. The
spacecraft has already started sending back exciting information and
photographs of Saturn's famous rings and its moon, Titan.
(MUSIC)
VOICE ONE:
 |
| A picture of Saturn from Cassini Huygens. |
The Cassini-Huygens spacecraft
arrived at the planet Saturn on July first. It flew into orbit from
below the famous rings that circle the planet. Carefully, Cassini
crossed through a large space between two of the huge rings at
speeds close to eighty-seven-thousand kilometers an hour. Cassini
flew to within one-hundred-fifty-eight-thousand kilometers of
Saturn's center. That is the closest Cassini will come to Saturn.
After passing through the rings, Cassini fired its rocket
engines. This slowed the spacecraft, permitting it to be captured by
Saturn's gravity. In this way, the Cassini spacecraft entered an
orbit around Saturn. It had taken Cassini almost seven years to
reach Saturn after traveling more than three-thousand-million
kilometers through space.
VOICE TWO:
It did not take long for Cassini to start making discoveries.
Cassini took photographs of Saturn's giant moon Titan in its first
few days of orbit. These photographs provided details of Titan's
surface that had never been seen before.
Dennis Matson is a scientist for the International
Cassini-Huygens project. He says the photographs sent back by
Cassini are difficult to understand.
He says the photographs do provide the first clear images of
Titan's surface, but will require a great amount of study. Titan has
a thick atmosphere that usually looks almost white in photographs
taken with telescopes. However Cassini has special cameras that can
see through the giant moon's atmosphere to study the surface.
Elizabeth Turtle is a scientist with the University of Arizona.
She says Cassini's first photographs of Titan's surface have shown
unusual features. Mizz Turtle says they do not know what some of
these features mean. She says it will take a great deal of work to
understand the surface of Titan.
VOICE ONE:
Cassini-Huygens carries a total of eighteen scientific
instruments. It used several of these to photograph and make maps of
the surface of Titan. It also used several instruments to study
minerals and chemicals on the surface of the huge moon.
Kevin Baines is a science team member of the Cassini-Huygens
project. He says Cassini provided evidence of pure water ice in some
areas of the surface.
He said it also showed areas of non-ice materials such as
hydrocarbons. Mister Baines said the evidence was much different
from what scientists had expected. Mister Baines also said Cassini
showed clouds of gas made of methane near the moon's south pole. He
said the clouds showed good evidence that Titan has a very active
atmosphere.
VOICE TWO:
The science team for Cassini says these first images of Titan are
just the beginning. It is only the first information gathered in a
four-year study of Saturn and its moons. In the future, the Cassini
spacecraft will fly closer to Titan and be able to use radar to
gather much better details of the moon's surface.
The study of Titan is one of the major goals of the
Cassini-Huygens flight. Cassini's first trip near Titan was still
more than three-hundred-thirty-nine thousand kilometers away. Future
plans call for Cassini to make more than seventy orbits around
Saturn. Forty-five of these will include passing close to Titan.
The closest flight will be only nine-hundred-fifty kilometers
away from the giant moon. This very close flight will permit
extremely detailed mapping of the surface.
VOICE ONE:
 |
| Scientists prepare the Huygens probe. |
The Huygens part of the spacecraft
will cut its link to Cassini on December twenty-fourth. It will then
fly down through the atmosphere of Titan to the surface. As it
passes into the atmosphere, it will deploy a large parachute. The
Huygens instrument will send information back to Cassini. Cassini
will then transmit the information back to Earth.
The Huygens instrument will land on the surface of Titan on
January fourteenth, two-thousand-five. It will be the first
scientific instrument to land on the surface of a moon of another
planet.
(MUSIC)
VOICE TWO:
 |
| A real color image of Titan. |
Saturn's moon, Titan, is very
large. In fact, it is larger than the planets Mercury and Pluto.
Scientists are very interested in Titan because it is the only known
moon in our solar system to have an atmosphere. It also has large
amounts of nitrogen similar to Earth. And scientists believe it has
large amounts of carbon material.
This is the same material needed to form life as we know it on
Earth. However, scientists are quick to say this does not mean there
is life on Titan.
VOICE ONE:
The exploration of Titan is exciting for many scientists.
Scientists believe evidence found on Titan may help to answer the
question of how life began on Earth. Most experts agree this
question is hard to answer because not enough is known about the
atmosphere when Earth was a young planet.
Scientists say they need to know what materials were present at
the beginning of life on Earth. They say some of these answers may
be present on Titan. The carbon material methane on Titan may have
been easily found on Earth when it was young.
VOICE TWO:
Cassini carries more scientific instruments and can do more
science work than any spacecraft ever sent to explore a planet. It
carries twelve science instruments on the Cassini spacecraft and six
more on the Huygens exploration device.
Cassini is six-point-seven meters high, four meters wide and
weighs almost six-thousand kilograms. Electric power for the
spacecraft is supplied by thirty-three kilograms of the nuclear
fuel, plutonium.
The flight to Saturn represents the work of two-hundred-sixty
scientists from the United States and seventeen European nations.
The flight of the Cassini-Huygens spacecraft cost more than
three-thousand-million dollars.
(MUSIC)
VOICE ONE:
The Cassini-Huygens spacecraft is expected to carry out many
tasks. There is much to learn about Saturn. First, there are the
seven huge rings that circle the planet. They are made of water ice,
rock and dust.
Only minutes after it arrived in orbit, Cassini made sixty-one
photographs of the beautiful rings. Cassini's radio sent the
pictures to Earth. Radio signals travel at almost the speed of
light. But even at that great speed, it took almost eighty-five
minutes for the information to arrive on Earth. What scientists saw
excited them.
They saw unusual designs and structures in the rings they had
never seen before. Cassini's photographs provided evidence that the
rings are not a solid mass of objects, but many individual lines
that circle the planet. These thin lines are held together and kept
in orbit by gravity. Scientists now believe there may be more than
one-thousand different lines or rings that make up the seven great
rings.
VOICE TWO:
The huge moon Titan is not alone in its orbit around Saturn.
Saturn has thirty-one known moons. Thirteen of these moons were
discovered after Cassini was launched on October fifteenth,
nineteen-ninety-seven. Scientists want to learn more about how these
moons affect the rings. New photographs already show that the
gravity of the moons has a great effect on the rings. Scientists
hope Cassini will provide more information about this in the future.
The Cassini spacecraft is named for astronomer Jean Dominique
Cassini. He was born in Italy in the sixteen-hundreds. He later
became a French citizen. He made important observations of Saturn
and discovered four of its moons. The Huygens exploration device is
named for Dutch astronomer Christiaan Huygens who also lived during
the seventeenth century. He discovered the moon Titan.
VOICE ONE:
If you have a computer that can link to the Internet, you too can
see the photographs of Saturn. You can see the moon Titan and the
rings that make Saturn such a beautiful planet. Have your computer
link with www.nasa.gov. Then follow the links to Cassini-Huygens.
(MUSIC)
VOICE TWO:
This program was written by Paul Thompson. It was produced by
Mario Ritter. This is Steve Ember.
VOICE ONE:
And this is Faith Lapidus. Join us again next week for another
EXPLORATIONS program in VOA Special English.