VOA慢速英语2019--专家们为可能的小行星撞击举行地球演习

NASA, World Experts to Hold Exercise for Possible Asteroid¹ Strike

We sometimes hear news reports warning of asteroids² passing close to Earth, with the possibility for disastrous³ results if there was a direct hit.

But most experts agree there is only a small likelihood that a large asteroid or other space object will crash into Earth and cause great destruction.

Many organizations do recognize the real risk of such an event. One example is NASA, the United States government’s space agency. NASA and its international partners continuously search the skies for what scientists call near-Earth objects (NEOs). Such objects include asteroids and comets that come within 50 million kilometers of Earth’s orbit.

This week, NASA is teaming up with the U.S. Federal Emergency Management Agency (FEMA) and international experts to study the possibility of a NEO hitting Earth. At a conference near Washington, D.C., scientists will simulate a made-up asteroid to explore what might happen when defending against a real-life hit.

What is an asteroid?

An asteroid is a rocky, airless object. Asteroids are sometimes called minor⁴ planets. They are left over from the early formation of our solar system about 4.6 million years ago. Most asteroids can be found orbiting the Sun between the planets Mars and Jupiter. NASA reports that, in all, scientists have identified more than 795,000 asteroids.

A comet is a small, at times active object that contains ice. In sunlight, the ice can vaporize to form an atmosphere of dust and gas.

NASA reports that about once a year, an asteroid about the size of an automobile⁵ enters Earth’s atmosphere. Such objects turn into a fireball and burn up before reaching Earth’s surface.

About every 2,000 years, a much larger object strikes the Earth and causes major damage. However, NASA experts say an object large enough to threaten Earth’s civilization only comes along once every few million years.

Asteroid simulation

The gathering⁶ this week – from April 29 to May 3 - is called the Planetary Defense⁷ Conference. Attendees from NASA, FEMA and other government agencies and experts from around the world will take part in a simulated test exercise.

The “tabletop exercise” will consider a false threat from an asteroid invented by NASA’s Jet Propulsion Laboratory (JPL). Groups will explore possible emergency and defensive⁸ measures to deal with the manmade asteroid threat.

Lindley Johnson is a planetary defense officer for NASA. He said the exercise will be a chance to create better international preparation and response processes in case of a real threat. "This … will help us develop more effective communications with each other and with our governments," he added.

The exercise is based on the made-up discovery of a NEO, one that conference organizers say is set to hit Earth in 2027. The exercise estimates a 1-in-100 chance of the NEO striking the planet.

NASA officials say the international community has decided⁹ that in real life, a 1-in-100 chance would be great enough to consider taking defensive and emergency measures.

Organizers noted¹⁰ in a press release that a real-life asteroid is set to pass close to the Earth in 2029. This asteroid, called Apophis, is one of the most important NEOs ever discovered.

NASA predicts Apophis will pass by Earth on Friday, April 13, 2029, within 31,300 kilometers above Earth's surface. That is closer than where weather satellites orbit our planet.

Apophis is estimated to be around 340 meters long from end to end. Experts say if such an asteroid were to hit Earth, it would cause major damage to the planet’s surface and our civilization.

But NASA has clearly stated it does not believe that Apophis will hit Earth in 2029. However, the close flyby will provide a great chance for scientists to study the asteroid, NASA says.

In the future, the world community could also decide to send a spacecraft to observe Apophis, the press release said.

I’m Bryan Lynn.

Words in This Story

asteroid – n. a rocky object that goes around the sun like a planet

simulate – v. create something that behaves or looks like something real but is not

vaporize – v. to turn from a solid or liquid into a gas

1 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

2 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

3 disastrous   

adj.灾难性的，造成灾害的；极坏的，很糟的

参考例句：

• The heavy rainstorm caused a disastrous flood.暴雨成灾。
• Her investment had disastrous consequences.She lost everything she owned.她的投资结果很惨，血本无归。

4 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

5 automobile   

n.汽车，机动车

参考例句：

• He is repairing the brake lever of an automobile.他正在修理汽车的刹车杆。
• The automobile slowed down to go around the curves in the road.汽车在路上转弯时放慢了速度。

6 gathering   

n.集会，聚会，聚集

参考例句：

• He called on Mr. White to speak at the gathering.他请怀特先生在集会上讲话。
• He is on the wing gathering material for his novels.他正忙于为他的小说收集资料。

7 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

8 defensive   

adj.防御的；防卫的；防守的

参考例句：

• Their questions about the money put her on the defensive.他们问到钱的问题，使她警觉起来。
• The Government hastily organized defensive measures against the raids.政府急忙布置了防卫措施抵御空袭。

9 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

10 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。