Space Digest

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VOICE ONE:

This is Steve Ember.

VOICE TWO:

And this is Doug Johnson with EXPLORATIONS in VOA Special
English. Today we tell about a new satellite that will be used to
examine the health of Earth's atmosphere. We report about thousands
of meteors that have already begun to provide a show in the night
sky. We report about beautiful color photographs of the rings that
surround the Planet Saturn. And we begin with the latest news from
the two American Space Agency devices that are exploring the planet
Mars.

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VOICE ONE:

The NASA exploration vehicles on Mars continue to provide
information about the red planet. The vehicle named Spirit is
climbing an area called the Columbia Hills.

Spirit has already traveled more than three-and-one-half
kilometers across the surface of Mars. This is more than six times
the distance NASA had planned for Spirit to travel. The increased
distance has led to some problems with Spirit's right front wheel.
The wheel does not turn as freely as Spirit's other five wheels.

VOICE TWO:

NASA scientists who control Spirit have decided to make it travel
backwards on five wheels to rest the problem wheel. The sixth wheel
now will only be used to cross very difficult surface areas.

Joe Melko is a NASA engineer with the Jet Propulsion Laboratory
in Pasadena, California. Mister Melko says using only five wheels
will make Spirit travel much more slowly. However, he says this
method will permit NASA to continue doing science work with the
vehicle much longer than was thought possible.

VOICE ONE:

As Spirit continues to drive up
the Columbia Hills, the exploration vehicle named Opportunity is
traveling deeper into a large hole. The hole is called Endurance
Crater. It is in the area of Mars called Meridiani Planum.

Instruments on Opportunity show the element chlorine is present
in the huge hole. Scientists want to know how it got there. They
also want to know which elements the chlorine is linked to.

Opportunity will continue on this path to discover more about the
chlorine. Scientists also want Opportunity to inspect a row of sharp
rocks that look like teeth. Scientists believe this unusual area was
formed when liquid moved over the ground.

VOICE TWO:

NASA officials are also preparing the two exploration vehicles
for the coming of the Martian winter. The middle of winter on Mars
is in September. There is less daily sunshine during winter. This
means the rovers' solar cells will be able to collect much less
sunlight to make electric power.

NASA officials say they must plan now for longer rest periods for
the vehicles if they are to keep working through the winter. NASA
officials say the two vehicles will work a little less each day to
permit them to collect more sunlight for energy. Or perhaps the
vehicles will work every other day while their solar cells produce
and store electric power during a longer rest period.

The two Mars rovers, Spirit and Opportunity, landed on the planet
in January.

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VOICE ONE:

The Cassini spacecraft has sent back to Earth beautiful color
photographs of the famous rings of the planet Saturn. Cassini made
the photographs on June twenty-first, a few days before it flew into
orbit around the huge planet.

The photographs show that the famous rings are many different
colors. They include the color of sand and many shades of brown,
gray and pink.

Scientists have color photographs of the rings that were taken in
the past. These include some taken by the Hubble Space Telescope and
the Voyager spacecraft. In the nineteen-eighties, two Voyager
spacecraft flew near Saturn. So did Pioneer Eleven in
nineteen-seventy-nine.

The photographs sent back to Earth by those spacecraft raised
many questions for scientists. The questions include: How many rings
surround the planet? What effect do Saturn's many moons have on the
rings? The scientists had to wait twenty-five years for a chance to
answer these questions.

The photographs sent to Earth by Cassini are the beginning of a
four-year study of Saturn, its rings and its moons. Scientists say
many questions about the planet will be answered soon.

VOICE TWO:

Scientists say most evidence shows
that the many rings of Saturn are made mostly of water ice. But pure
water ice is white. So scientists believe that the many colors of
the rings are the result of different amounts of other materials.

They say the colors could be caused by small amounts of rock,
carbon or other materials. In the near future the scientific
instruments on Cassini will be able to help scientists learn what
the rings are really made of.

VOICE ONE:

If you have a computer than can link with the Internet, you too
can see the Cassini photographs of the huge rings. You can also see
photographs of some of Saturn's moons. The Internet address is
www.nasa.gov/cassini. That Internet address again is
www.nasa.gov/cassini.

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VOICE TWO:

A spacecraft named Aura was
launched from the Vandenberg Air Force Base in California July
fifteenth. Aura is NASA's newest Earth-observing satellite. NASA
hopes it will help scientists understand and protect the air we
breathe.

Aura was designed to send back information about the quality of
air in our atmosphere. It will also be used to study the changes in
Earth's climate and how weather affects the atmosphere.

The launch of Aura completes the first series of NASA's Earth
Observing System satellites. The other satellites are Terra, which
observes the land, and Aqua, which observes the water on Earth.

VOICE ONE:

The new satellite carries four instruments. They are designed to
study different parts of Earth's atmosphere. Aura will study the
atmosphere from the area where humans live to the stratosphere. This
is the area where the ozone layer protects life on Earth. The
protective ozone layer has been damaged in the past. Scientists hope
the new Aura satellite will provide information to help them answer
three important questions. The scientists want to find out if the
ozone layer is repairing itself. They want to learn the process that
controls air quality.And they want to learn how the Earth's climate
is changing. NASA expects the first answers to these questions
within thirty to ninety days.

The Aura satellite joins a total of twelve other science
satellites that have been placed in orbit in the past ten years. All
are now gathering information about the Earth.

Ghassem Asrar is a NASA official for Earth Science. He said the
new Aura satellite will lead to a much better understanding of
Earth. Mister Asrar says it will also help us understand other
planets in our solar system.

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VOICE TWO:

In the middle of July, Earth entered an area of space that is
filled with very small pieces of rock, ice and other material. The
comet named Swift-Tuttle is leaving behind this material as it
passes near Earth. Millions of pieces of this material are hitting
the Earth's atmosphere. When they do, they appear as a quickly drawn
line of light moving across the night sky. Each bright line of light
is the material burning up in Earth's atmosphere.

VOICE ONE:

The event happens each year and is called the Perseid Meteor
Shower. It began slowly in the middle of July and will reach full
strength about the eleventh or twelfth of August.

Bill Cooke is with the NASA Marshall Space Flight Center. He says
there is something added to the show this year. He says Earth will
also pass through material left behind by the Swift-Tuttle comet
long ago. He says this material was left in space in about
eighteen-sixty-two – during the American Civil War.

Mister Cooke says the Earth will move into this cloud of material
on the night of August eleventh. He says observers in Europe and
Asia will see as many as two-hundred of the small lines of light
each hour if they watch closely. The show will begin at about
twenty-one-hours Universal Time. This show can only be seen by
people who live well north of the Equator.

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VOICE TWO:

This program was written by Paul Thompson. It was produced by
Mario Ritter. This is Doug Johnson.

VOICE ONE:

And this is Steve Ember. Join us again next week for EXPLORATIONS
in VOA Special English.