EXPLORATIONS - Space Digest（在线收听）

EXPLORATIONS - Space Digest
By Paul Thompson

Broadcast: Wednesday, August 04, 2004

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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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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.

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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:

 
A false color picture of the Columbia Hills area of Meridiani Planum.
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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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:

 
A color picture of the rings of Saturn from Cassini.
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.

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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:

 
Graphic Image
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.

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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.