VOA慢速英语2009年-EXPLORATIONS - 2009: A Year of Discove

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VOICE ONE:

I'm Mario Ritter.

VOICE TWO:

And I'm Steve Ember with EXPLORATIONS in VOA Special English. This week, we tell about some of the biggest space stories of two thousand nine. First, there was the American space agency's discovery of water on the moon. We also talk to a NASA expert about the discovery of methane¹ gas on Mars. And we hear about the test flight of NASA's newest rocket.

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VOICE ONE:

An artist's picture of LCROSS

Possibly the biggest space story this year was the discovery of water on the moon. The best evidence was provided by a dramatic experiment carried out on October ninth. NASA used its Lunar Crater² Observing and Sensing Satellite, or LCROSS, to look for water deep beneath the lunar surface.

To get below the ancient lunar rocks, NASA crashed a rocket into the moon's south pole. The crash caused soil to be expelled many kilometers above the lunar surface. LCROSS studied the soil before it too crashed into the moon. The experiment pushed the search for water several meters below the lunar surface—much deeper than had been possible before.

VOICE TWO:

LCROSS scientists Anthony Colaprete and Kim Ennico study early results from the lunar impact experiment

In November, Anthony Colaprete, a leading scientist with the LCROSS project, spoke³ about information gathered by the spacecraft. He said about one hundred kilograms of water had been found in the material ejected by the moon crash. Water has now been confirmed in amounts much greater than had been thought.

In September, NASA scientists had announced the discovery of water molecules⁵ mainly in the moon's extreme northern and southern areas. They noted⁶, however, that they could also be seeing evidence of another molecule⁴, hydroxyl.

VOICE ONE:

Instruments on three separate spacecraft gathered that evidence of lunar water. NASA's Moon Mineralogy Mapper made the most recent observations. It was one of eleven scientific devices carried by the Chandrayaan-One spacecraft of the Indian Space Research Organization.

The Mapper is a spectrometer, which measures reflected light wavelengths⁷. The device shows scientists what an object is made of from great distances. Similar devices on NASA's Cassini and Epoxi spacecraft also reported water.

But those observations were made years ago. NASA scientists had not trusted the results without clear confirmation⁸.

The Moon Mineralogy Mapper could only examine lunar soil to a depth of a few millimeters. And the amount of water found in that layer was very small. Now, LCROSS has shown that large amounts of water could exist on the moon. And it raises even more questions.

Was water brought to the moon by space rocks and icy bodies called comets? Or could processes deep within the moon produce water? If that is the case, it may be possible that the moon could hold enough water for future explorations or even colonies.

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VOICE TWO:

An image showing methane on Mars

The presence of water on the moon was not the only major solar system discovery NASA made this year. In January, a team of NASA and university scientists announced that they had found methane gas on Mars. The group used NASA's Infrared⁹ Telescope Facility and the W.M. Keck telescope. Both instruments are in Mauna Kea, Hawaii. Methane is better known as natural gas. On Earth, it is mainly produced by processes linked to biology.

This raises the exciting possibility that life may have existed in the past on Mars. Or it may still exist deep below the surface. Michael Meyer is lead scientist for NASA's Mars Exploration Program in Washington. He spoke to us about the finding.

MICHAEL MEYER: "It really means that the planet is more active than we thought, and more active--and that can be geologically or maybe even biologically."

VOICE ONE:

On Earth, biological activity is very effective in making methane. But Michael Meyer notes that methane also can come from a purely¹⁰ non-biological process called serpentinization. He says the methane discovery presents scientists with a mystery because it is still not clear how the gas is being produced.

Martian methane is also unusual because it is not evenly spread over the planet. It can become concentrated in small areas and then disappear. This suggests processes that both supply and remove methane from the atmosphere in certain places. Currently, the best explanation for the loss of methane is that it chemically reacts with dust in the atmosphere. The gas may then turn into something else such as carbon dioxide.

VOICE TWO:

An artist's picture of how methane could be formed under the Martian surface

NASA plans to send the Mars Science Laboratory to the red planet in the autumn of two thousand eleven. The exploration vehicle will be able to measure methane even at very low levels in many places on the surface.

Michael Meyer also says NASA is developing an orbiter with European scientists. It will be able to measure small amounts of many different gases. The orbiter could finally provide evidence about how methane on Mars is created and destroyed. Michael Meyer says planetary scientists often study processes that are very different from ones on Earth. But he says understanding these differences can help discover how some complex processes on our own planet really work.

(SOUND: NASA Rocket Launch)

VOICE ONE:

The Ares 1-X launch at the Kennedy Space Center in Florida

On October twenty-eighth, NASA took an important step into the future. The agency carried out a test flight of its next-generation launch vehicle for astronauts.

NASA is developing two separate rockets for the Ares program. Phil Sumrall is the Ares Project Office Advanced Planning Manager. He says this was done for safety reasons.

The loss of the space shuttle Columbia in February of two thousand three led to an investigation¹¹ by the Columbia Accident Investigation Board. The group recommended that human life must not be risked simply to send equipment into space. The result was a design in which safety was the top concern.

PHIL SUMRALL: "We designed the Ares One to be the absolute safest possible vehicle that we could conceive."

VOICE TWO:

Space scientists designed Ares One with a system that would rescue astronauts whether there was a failure of the rocket in the launch area or during flight. Mister Sumrall says NASA estimates the new Ares One will be twenty to thirty times safer than the Space Shuttle.

The other Ares launch vehicle is the huge Ares Five rocket. It will be the biggest rocket ever built. The Ares Five will be one hundred sixteen meters tall and weigh three point seven million kilograms. It will be able to lift nearly forty percent more than the Saturn¹² Five rocket that sent Apollo astronauts to the moon.

VOICE ONE:

Much of the Ares technology has been developed from existing vehicles. Versions of the solid fuel rockets that are used on the Space Shuttle today will serve as the first stage of the Ares One and booster rockets on the Ares Five. An engine first developed for the Saturn Five moon rocket has been updated to be used on Ares.

Existing manufacturing technologies are also being used in new ways on Ares. The tanks of the Ares rockets will be made of aluminum¹³ lithium. This is a strong and light metal alloy¹⁴ that has been used on the Space Shuttle. But Ares will use new methods in metal-working science such as friction¹⁵ stir welding. This method uses heat and pressure to join pieces of metal together. Friction stir welding can be used to make complex curved and domed¹⁶ structures out of aluminum lithium and similar alloys¹⁷. And, friction stir welding uses fewer workers at less cost than other methods.

Scientists developed the new welding technology at the Marshall Space Flight Center in Montgomery, Alabama. It will be used when Ares is built at the Michoud Assembly Facility in New Orleans, Louisiana.

VOICE TWO:

Phil Sumrall says NASA's estimate to keep the Ares program going forward as planned calls for three billion dollars in additional spending a year.

He says if money is available, Ares Five could be ready for a test flight by two thousand seventeen. We asked Phil Sumrall how NASA expects to use Ares in its space exploration plans.

PHIL SUMRALL: "It's not just for going to the moon or near Earth objects. It's what we'd use to go to, eventually, to Mars or to the moons of Mars."

NASA named the new rocket system Ares, the Greek name for Mars. The name suggests the goal for a future generation of space explorers. They may be the first humans to set foot on another planet.

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VOICE TWO:

I'm Steve Ember with Mario Ritter who also wrote and produced our program. You can find links to the NASA Web site at voaspecialenglish.com. You can also find transcripts¹⁸, MP3s and podcasts of our programs. Join us again next week for EXPLORATIONS in VOA Special English.