US Spacecraft to Probe Origin of Gamma Rays

 

By David McAlary

The U.S. space agency, NASA, launched a satellite Saturday that scientists hope will help them locate the sources of mysterious gamma ray explosions, the brightest most energetic bursts in the universe. This is a nearly 40-year-old puzzle.

If your eyes could see gamma rays, you would see frequent flashes in different parts of the sky, as if camera bulbs were popping. NASA astronomer¹ Anne Kinney says the fleeting² bursts are unpredictable, never occurring in the same place twice.

"When we look at the sky with gamma ray glasses, we see 10 second messages from the distant universe,which we call camera bulbs " she said Anne Kinney. "We never know which direction these messages are going to come from, but we know they will be brief - more like postcards than letters."

Astronomers³ say nothing is more powerful than a gamma ray burst. Just one emits more than 100 billion times the energy that the Sun does in a year.

"How can you produce so much energy in such a short period of time?"

That question is asked by NASA gamma ray expert Neil Gehrels. He says no one knows what causes the flashes, but one view is that they might signal the formation of black holes, pockets of collapsed⁵ stars so dense⁶, with such powerful gravity, that not even light can escape.

"The gravitational energy of the collapse⁴ is a huge amount that could power a gamma ray burst," said Neil Gehrels. "So we think that perhaps bursts are the birth cries of black holes and we're seeing these throughout the universe."

Gamma ray bursts were first detected in 1967 by U.S. military satellites monitoring Soviet⁷ compliance⁸ with the Nuclear Test Ban Treaty. A nuclear blast emits gamma radiation. No treaty violations⁹ were detected, but satellite data released in the early 1970s revealed that mysterious flashes were occurring outside our solar system.

In the 1990s, spacecraft such as NASA's orbiting Compton Gamma Ray Observatory¹⁰ and the Italian BeppoSax satellite revealed that the bursts occur in all directions and come from distances up to billions of light years away, far beyond our galaxy¹¹.

The fleeting flashes fade quickly, impeding¹² the quest for more knowledge about them, especially since the detection process is cumbersome¹³. Typically after BeppoSax detects a burst, the information is processed and ground controllers re-command the satellite to observe the portion of the sky where the flash originated. Ground telescopes are alerted to observe in x-ray and optical wavelengths¹⁴. This entire process can take up to one day.

The telescope just launched, called SWIFT, is designed to react instantly. SWIFT mission operations director John Nousek of Pennsylvania State University says the telescope's detectors¹⁵ can sense a gamma ray burst as it begins, causing the spacecraft to spin around rapidly to focus on the event in progress and its afterglow in all the necessary wavelengths.

"SWIFT has this tremendous advantage, and it in fact, that was the whole concept of SWIFT of building these all in together, so the amount of latency we have is basically about 20 seconds between when the gamma ray burst occurs and one the satellite finishes analyzing¹⁶ its data set," said John Nousek. "From a scientist's point of view, this is exactly what you are looking for to make progress in a new field."

SWIFT's speedy reaction to gamma ray bursts means that the network of ground telescopes can be alerted immediately to provide backup observations.
Mr. Nousek says SWIFT's unique rapid detection technology is too important to be left to gamma ray observations alone. It will eventually be available to researchers looking at other astronomical¹⁷ phenomena¹⁸.

"This responsiveness, that can be useful in a great number of fields of astrophysics," he said. "So that, I like to tell my mission operations people, 'Be ready for that phone call,' because I suspect that phone call may be more important than the whole rest of the mission."

As for gamma ray detections, Mr. Nousek says SWIFT will observe 500 to 1,000 events during its initial two-year mission.

David McAlary , VOA NEWS, Washington.

注释：
gamma ray 伽马射线（γ射线）
formation 形成
dense 不透光的
gravitational 重力的
compliance 遵守
Nuclear Test Ban Treaty《禁止核试验条约》
radiation 射线
Compton Gamma Ray Observatory 伽玛射线观测站
galaxy 星系
cumbersome 棘手的
astronomical 天文的

1 astronomer   

n.天文学家

参考例句：

• A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
• He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。

2 fleeting   

adj.短暂的，飞逝的

参考例句：

• The girls caught only a fleeting glimpse of the driver.女孩们只匆匆瞥了一眼司机。
• Knowing the life fleeting,she set herself to enjoy if as best as she could.她知道这种日子转瞬即逝，于是让自已尽情地享受。

3 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

4 collapse   

vi.累倒；昏倒；倒塌；塌陷

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。

5 collapsed   

adj.倒塌的

参考例句：

• Jack collapsed in agony on the floor. 杰克十分痛苦地瘫倒在地板上。
• The roof collapsed under the weight of snow. 房顶在雪的重压下突然坍塌下来。

6 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

7 Soviet   

adj.苏联的，苏维埃的；n.苏维埃

参考例句：

• Zhukov was a marshal of the former Soviet Union.朱可夫是前苏联的一位元帅。
• Germany began to attack the Soviet Union in 1941.德国在1941年开始进攻苏联。

8 compliance   

n.顺从；服从；附和；屈从

参考例句：

• I was surprised by his compliance with these terms.我对他竟然依从了这些条件而感到吃惊。
• She gave up the idea in compliance with his desire.她顺从他的愿望而放弃自己的主意。

9 violations   

违反( violation的名词复数 )； 冒犯； 违反（行为、事例）； 强奸

参考例句：

• This is one of the commonest traffic violations. 这是常见的违反交通规则之例。
• These violations of the code must cease forthwith. 这些违犯法规的行为必须立即停止。

10 observatory   

n.天文台，气象台，瞭望台，观测台

参考例句：

• Guy's house was close to the observatory.盖伊的房子离天文台很近。
• Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。

11 galaxy   

n.星系；银河系；一群(杰出或著名的人物)

参考例句：

• The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
• The company has a galaxy of talent.该公司拥有一批优秀的人才。

12 impeding   

a.(尤指坏事)即将发生的，临近的

参考例句：

• Fallen rock is impeding the progress of rescue workers. 坠落的石头阻滞了救援人员的救援进程。
• Is there sufficient room for the kiosk and kiosk traffic without impeding other user traffic? 该环境下是否有足够的空间来摆放信息亭？信息亭是否会妨碍交通或者行走？ 来自About Face 3交互设计精髓

13 cumbersome   

adj.笨重的，不便携带的

参考例句：

• Although the machine looks cumbersome,it is actually easy to use.尽管这台机器看上去很笨重，操作起来却很容易。
• The furniture is too cumbersome to move.家具太笨，搬起来很不方便。

14 wavelengths   

n.波长( wavelength的名词复数 )；具有相同的/不同的思路；合拍；不合拍

参考例句：

• I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话，因为我们俩完全不对路。 来自《简明英汉词典》
• Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句

15 detectors   

探测器( detector的名词复数 )

参考例句：

• The report advocated that all buildings be fitted with smoke detectors. 报告主张所有的建筑物都应安装烟火探测器。
• This is heady wine for experimenters using these neutrino detectors. 对于使用中微子探测器的实验工作者，这是令人兴奋的美酒。 来自英汉非文学 - 科技

16 analyzing   

v.分析；分析( analyze的现在分词 )；分解；解释；对…进行心理分析n.分析

参考例句：

• Analyzing the date of some socialist countries presents even greater problem s. 分析某些社会主义国家的统计数据，暴露出的问题甚至更大。 来自辞典例句
• He undoubtedly was not far off the mark in analyzing its predictions. 当然，他对其预测所作的分析倒也八九不离十。 来自辞典例句

17 astronomical   

adj.天文学的，（数字）极大的

参考例句：

• He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
• Houses in the village are selling for astronomical prices.乡村的房价正在飙升。

18 phenomena   

n.现象

参考例句：

• Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
• The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系，如果存在着任何联系的话。