爱丽丝摄谱仪获得彗星表面的远紫外光谱.docx

NASA's Alice ultraviolet (UV) spectrograph aboard the European Space Agency's Rosetta comet orbiter has delivered its first scientific discoveries. Rosetta, in orbit around comet 67P/Churyumov-Gerasimenko, is the first spacecraft to study a comet up close. As Alice began mapping the comet's surface last month, it made the first far ultraviolet spectra1 of a cometary surface. From these data, the Alice team discovered that the comet is unusually dark at ultraviolet wavelengths2 and that the comet's surface -- so far -- shows no large water-ice patches. Alice is also already detecting both hydrogen and oxygen in the comet's coma3, or atmosphere.

"We're a bit surprised at both just how very unreflective the comet's surface is, and what little evidence of exposed water-ice it shows," says Dr. Alan Stern, Alice principal investigator4 and an associate vice5 president of the Southwest Research Institute (SwRI) Space Science and Engineering Division.

Developed by SwRI, Alice is probing the origin, composition and workings of the comet, gaining sensitive, high-resolution compositional insights that cannot be obtained by either ground-based or Earth-orbital observations. The ultraviolet wavelengths Alice observes contain unique information about the composition of the comet's atmosphere and the properties of its surface.

"As the mission progresses, we will continue to search for surface ice patches and ultraviolet color and composition variations across the surface of the comet," says Dr. Lori Feaga, Alice co-investigator at the University of Maryland.

Alice is one of three instruments funded by NASA flying aboard Rosetta. Alice has more than 1,000 times the data-gathering capability6 of instruments flown a generation ago, yet it weighs less than 4 kilograms and draws just 4 watts7 of power. A sister Alice instrument was developed by SwRI and was launched aboard the New Horizons spacecraft to Pluto8 in January 2006 to study that distant world's atmosphere. It will reach Pluto in July 2015. SwRI also built and operates Rosetta's Ion and Electron Spectrograph (IES), another instrument with miniaturized electronic systems. With a mass of 1.04 kilograms, IES achieves sensitivity comparable to instruments weighing five times more.

To reach its comet target, the Rosetta spacecraft executed four gravity assists (three from Earth, one from Mars) and a nearly three-year period of deep space hibernation9, waking up in January 2014 in time to prepare for its rendezvous10 with Churyumov-Gerasimenko. Rosetta also carries a lander, Philae, that will drop to the comet's surface in November 2014, attempting the first-ever direct observations of a comet surface.

Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. Airbus Defense11 and Space built the Rosetta spacecraft. NASA's Jet Propulsion Laboratory (JPL) manages the U.S. contribution of the Rosetta mission for NASA's Science Mission Directorate in Washington, under a contract with the California Institute of Technology (Caltech). JPL also built the Microwave Instrument for the Rosetta Orbiter and hosts its principal investigator, Dr. Samuel Gulkis. SwRI (San Antonio and Boulder12, Colo.) developed the Rosetta orbiter's Ion and Electron Sensor13 and Alice instrument and hosts their principal investigators14, Dr. James Burch (IES) and Dr. Alan Stern (Alice).

词汇表：

1 spectra
n.光谱
参考例句：
The infra-red spectra of quinones present a number of interesting features. 醌类的红外光谱具有一些有趣的性质。
This relation between the frequency and the field spectra was noted experimentally. 实验上已经发现频率和场频谱之间的这种关系。
2 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
3 coma
n.昏迷，昏迷状态
参考例句：
The patient rallied from the coma.病人从昏迷中苏醒过来。
She went into a coma after swallowing a whole bottle of sleeping pills.她吃了一整瓶安眠药后就昏迷过去了。
4 investigator
n.研究者，调查者，审查者
参考例句：
He was a special investigator for the FBI.他是联邦调查局的特别调查员。
The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。
5 vice
n.坏事；恶习；[pl.]台钳，老虎钳；adj.副的
参考例句：
He guarded himself against vice.他避免染上坏习惯。
They are sunk in the depth of vice.他们堕入了罪恶的深渊。
6 capability
n.能力；才能；(pl)可发展的能力或特性等
参考例句：
She has the capability to become a very fine actress.她有潜力成为杰出演员。
Organizing a whole department is beyond his capability.组织整个部门是他能力以外的事。
7 watts
（电力计量单位）瓦，瓦特( watt的名词复数 )
参考例句：
My lamp uses 60 watts; my toaster uses 600 watts. 我的灯用60瓦，我的烤面包器用600瓦。
My lamp uses 40 watts. 我的灯40瓦。
8 Pluto
n.冥王星
参考例句：
Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。
Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。
9 hibernation
n.冬眠
参考例句：
Bears wake up in the spring after a winter of hibernation.熊经过一个冬天的冬眠后在春季苏醒。
The tortoise spends the winter months in hibernation.乌龟在冬眠中度过寒冬季节。
10 rendezvous
n.约会，约会地点，汇合点；vi.汇合，集合；vt.使汇合，使在汇合地点相遇
参考例句：
She made the rendezvous with only minutes to spare.她还差几分钟时才来赴约。
I have a rendezvous with Peter at a restaurant on the harbour.我和彼得在海港的一个餐馆有个约会。
11 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。
12 boulder
n.巨砾；卵石，圆石
参考例句：
We all heaved together and removed the boulder.大家一齐用劲，把大石头搬开了。
He stepped clear of the boulder.他从大石头后面走了出来。
13 sensor
n.传感器，探测设备，感觉器（官）
参考例句：
The temperature sensor is enclosed in a protective well.温度传感器密封在保护套管中。
He plugged the sensor into a outlet.他把传感器插进电源插座。
14 investigators
n.调查者，审查者( investigator的名词复数 )
参考例句：
This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》

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