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An international team of astronomers using NASA's Swift satellite and the Japanese/U.S. Suzaku X-ray observatory has discovered a new class of active galactic nuclei (AGN). By now, you'd think that astronomers would have found all the different classes of AGN - extraordinarily energetic cores of galaxies powered by accreting supermassive black holes. AGN such as quasars, blazars, and Seyfert galaxies are among the most luminous objects in our Universe, often pouring out the energy of billions of stars from a region no larger than our solar system.

But by using Swift and Suzaku, the team has discovered that a relatively common class of AGN has escaped detection...until now. These objects are so heavily shrouded in gas and dust that virtually no light gets out.

"This is an important discovery because it will help us better understand why some supermassive black holes shine and others don't," says astronomer and team member Jack Tueller of NASA's Goddard Space Flight Center in Greenbelt, Md.

Evidence for this new type of AGN began surfacing over the past two years. Using Swift's Burst Alert Telescope (BAT), a team led by Tueller has found several hundred relatively nearby AGNs that were previously missed because their visible and ultraviolet light was smothered by gas and dust. The BAT was able to detect high-energy X-rays from these heavily blanketed AGNs because, unlike visible light, high-energy X-rays can punch through thick gas and dust.

To follow up on this discovery, Yoshihiro Ueda of Kyoto University, Japan, Tueller, and a team of Japanese and American astronomers targeted two of these AGNs with Suzaku. They were hoping to determine whether these heavily obscured AGNs are basically the same type of objects as other AGN, or whether they are fundamentally different. The AGNs reside in the galaxies ESO 005-G004 and ESO 297-G018, which are about 80 million and 350 million light-years from Earth, respectively.

Suzaku covers a broader range of X-ray energies than BAT, so astronomers expected Suzaku to see X-rays across a wide swath of the X-ray spectum. But despite Suzaku's high sensitivity, it detected very few low- or medium-energy X-rays from these two AGN, which explains why previous X-ray AGN surveys missed them.

According to popular models, AGNs are surrounded by a donut-shaped ring of material, which partially obscures our view of the black hole. Our viewing angle with respect to the donut determines what type of object we see. But team member Richard Mushotzky, also at NASA Goddard, thinks these newly discovered AGN are completely surrounded by a shell of obscuring material. "We can see visible light from other types of AGN because there is scattered light," says Mushotzky. "But in these two galaxies, all the light coming from the nucleus is totally blocked."

Another possibility is that these AGN have little gas in their vicinity. In other AGN, the gas scatters light at other wavelengths, which makes the AGN visible even if they are shrouded in obscuring material.

"Our results imply that there must be a large number of yet unrecognized obscured AGNs in the local universe," says Ueda.

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The Planetary Society's silica-glass DVD is ready to launch to Mars on board Phoenix, NASA's newest Scout mission led by Principal Investigator Peter Smith at the University of Arizona. Attached to the deck of the Phoenix lander, the DVD includes Visions of Mars, a collection of 19th and 20th century stories, essays and art inspired by the Red Planet, as well as the names of over a quarter million inhabitants of Earth. The disk will appear in some of the calibration images that Phoenix sends back from the Martian surface.

"Since The Planetary Society's disk should last for centuries on Mars, we hope astronauts at some future date will enjoy the visionary works we have sent in this first Martian library," said Louis Friedman, Executive Director of The Planetary Society, who conceived the idea for Visions of Mars. "These tales and images have inspired generations about the wonder of space, including many men and women who are now researchers and engineers in the space program."

This first library on Mars contains materials that represent 20 nations and cultures. Visions of Mars includes works by The Planetary Society's co-founder Carl Sagan, Isaac Asimov, Ray Bradbury, Kim Stanley Robinson, Arthur C. Clarke, Percival Lowell and many more.

Phoenix will be the first lander to explore the Martian arctic, landing near 70 degrees north latitude. Designed to search for and study water ice, the spacecraft is a fixed lander with a suite of advanced instruments and a robotic arm that can dig up to half a meter into the soil. The Phoenix team hopes to uncover clues in the icy soil of the Martian arctic about the history of near surface ice and the planet's potential for habitability. Tune into a Planetary Radio interview about Phoenix with Peter Smith.

The first possible launch date for Phoenix is August 3, 2007, with a landing slated for 2008.

This will be The Planetary Society's second attempt to send Visions of Mars to its namesake planet. It was originally created by the Society to launch aboard Russia's Mars 96 spacecraft, which failed shortly after launch. The library has been updated and risen from the ashes for its Phoenix flight. It should be able to last at least 500 years on Mars, so there will be plenty of time for a future generation to discover and enjoy the works included on the DVD.

The Phoenix Mission is led by Principal Investigator Peter H. Smith of the University of Arizona, with project management at NASA's Jet Propulsion Laboratory and a development partnership with Lockheed Martin Space systems. International contributions for Phoenix are provided by the Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen, and the Max Planck Institute in Germany.

To date, only NASA has succeeded in sending a rover to explore our neighboring planet Mars. That is about to change. In 2011, the European Space Agency will send ExoMars to the Red Planet in search of signs that Mars is, or was, a living world. Astrobiology Field Research Editor Henry Bortman recently interviewed the ExoMars project scientist, Jorge Vago. In this, the second part of a two-part interview, Vago explains why ExoMars will focus on looking for fossil evidence of ancient life and why such evidence may be easier to find on Mars than it is on Earth.

Astrobiology Magazine: It's my understanding that the instruments on ExoMars will be looking for biomolecules typical of terrestrial life. You don't plan to look for indicators or patterns that could be caused by biology with a different chemical basis than that of terrestrial life. Is it true that ExoMars will focus on looking for Earth-like life, and if so, why?

Jorge Vago: Well, there are two answers to that. One is that, in reality, what we're looking for is organic molecules, carbon-based. And that is of course based on what we know about life on Earth. The other thing we do know for sure is that there has been a very large exchange of meteoritic material between the two planets. So we can be pretty sure that Mars was in some way seeded with organic matter that came from Earth in the early period of the planet. Would this give rise to life on Mars as we know it or not? - well, I don't know.

On the other hand, we know that carbon is a very able atom when it comes to producing complex molecules, under the thermodynamic conditions that we know to prevail on Earth and on other terrestrial planets, including Mars. We have no evidence that point to more exotic chemistry being active on Mars. And when you have to design a mission, you have to be practical. So we go for the things we know. If we don't find any organics - we should at least be able to find the organics that we know are delivered to Mars daily by cometary and meteoritic dust - if we don't find that, even in the subsurface, then at that point we will have moved the bar for trying to find life on Mars much, much higher. The next mission that will try this will have to probably go much, much deeper.

AM: Finding fossil life is also tricky. There's a lot of debate about the oldest fossils on Earth, in which there are supposedly traces of life. There are questions about what you can really see, how easy it is to distinguish ancient fossils from the effects of purely chemical processes, what are reliable biomarkers. If it's that hard to find ancient life on Earth, how are you going to do it on Mars?

JV: Well, actually, it might be easier to find reliable biomarkers for very ancient life on Mars than on Earth. Because on Earth you have had all these plate-tectonics and reformation processes and volcanism that have made it extremely hard for us to find old rocks, older than 3.5 billion years, where you can say, Yeah, I'm looking at a rock that is more or less in the same state it was in when it was formed 3.5 billion years ago. This is simply not possible on our planet. Now Mars seems to have gone into a dormant stage very early in its history, so it is likely - and this will depend, of course, on our landing site - that we can access a place that is very, very old, where the rocks will be more or less in the same state that they were in when they were deposited there, 3.5 or even 4 billion years ago. What are we going to find there? Nobody knows. But chances are that whatever organics might be encased in those rocks will be in a much better state than you would hope to find in Earth rocks of a similar age.

AM: You're developing the capability to look both for extant life and for fossil life. How do you find a landing site that provides you with both opportunities?

JV: That would be very, very hard. My guess is that we will target some formation that we can definitely say is related to the past presence of water on old Mars. A site that may be of more interest for present life, is one where the Odyssey gamma-ray spectrometer indicates there may be water ice within one meter from the surface. Off course, water ice doesn't mean there's life there. It's really, really cold, but it's interesting. If anybody were to find some sort of heat in the next couple of years associated with the presence of water ice, then that would be interesting for a possible site for present life. I would say that from the point of view of the objectives of the mission, if we want to maximize the chances of finding something, the priority will be on targeting fossil life, or past life. And if we can get to a site that also has the potential for present life, that would be a bonus.

AM: Do you think Mars is, or ever was, a living world? What do you expect ExoMars to find?

JV: What I would like to answer with this mission is the question of where are the organics that we know should be there from the meteoritic delivery, and I think we have the instrumentation to do that. Hopefully these oxidants do not extend so deep into the subsurface that we are unable to find anything.

Now, regarding the possible emergence of life on Mars, I think if it happened, it happened very early, more or less at the same time when it did on Earth, and it will be very, very hard to prove with a single mission that there was life on Mars. But maybe we can at least plant a seed with this mission, and find a few strong indications that there could have been life there. To establish for sure that there was life on Mars may require more than one mission. But we can get started, and that would be a good thing.

Space Shuttle Endeavour is ready to fly, NASA managers concluded July 26 after wrapping up the two-day flight readiness review at Kennedy Space Center in Florida. Launch of Endeavour on the STS-118 mission is officially set for August 7. "On behalf of all the people that work on Endeavour, both here and really across the country, it's a great, great feeling to have Endeavour back on the pad," said Shuttle Launch Director Mike Leinbach. "We're looking forward to a great launch."

Launch preparations continue at Launch Pad 39A. Hypergolic propellant has been loaded into the solid rocket booster hydraulic power units, as well as Endeavour's orbital maneuvering system, forward reaction control system and auxiliary power units.

The suits to be worn on the mission's spacewalks have been stowed, and flight crew equipment and supplies are being loaded into the crew cabin. Payload closeouts include camera tests on the shuttle's robotic arm and orbiter boom sensor system.

The 22nd flight to the International Space Station, STS-118 will be the first flight for Endeavour since 2002, and the first mission for Mission Specialist Barbara Morgan, the teacher-turned-astronaut whose association with NASA began more than 20 years ago.

NASA试验新型飞机

　　北京时间7月29日消息，据国外媒体报道，美国宇航局表示，尚处于试验阶段的“翼身合一”飞机第一次试飞成功，这种飞机的外形就像一个飞行翼，它的问世有望催生一种燃料消耗更低、噪音更小、容量更大的新型飞机的诞生。

　　美国宇航局德莱顿飞行研究中心表示，这是一种遥控的喷气式飞机，重500磅，有3个 发动机，翼展21英尺。它在7月20日进行了试飞，爬升到海拔7500英尺的高空，飞行了大约半小时后成功降落。地面站的飞行员控制X-48B“翼身合一”飞机的飞行。美国宇航局和波音公司表示，它们正在将这次飞行资料与风洞试验资料进行比较。波音公司幻影工程部与美国宇航局和俄亥俄州赖特-帕特森空军基地的空军研究实验室合作，设计出这种飞机和它的复制品，由英格兰贝德福德的克兰菲尔德航空航天有限公司制造，现在飞机的尺寸只有未来完整版的飞机的8.5%。

　　美国宇航局和波音公司表示，X-48B很像一个飞行翼，但是飞机的机翼与宽大、扁平且无尾的机身融合在一起。与传统飞机的圆柱形机身相比，这个设计提高了飞机的抬升力，减少了空气阻力，降低了飞行时的燃料消耗。发动机安装在飞机的后面，因此飞行时机体的内部会更加安静，到达地面的噪音也更少。测试开始时，这架飞机以很慢的速度飞行，以便研究人员获得有关它的设计稳定性和飞行控制特征的资料，尤其是在起飞和降落期间。另一架用作风洞测试的X-48B还能当作飞行测试的候补飞机。

据美国《科学》杂志在线报道，天文学家利用钱德拉X射线天文望远镜发现了一些特大质量的黑洞，在7月24日公布的这幅由艺术家绘制的图画(如上图)中，一个黑洞正在加速运转的过程中吞噬周围的物质。与今天的黑洞相比，110亿年前的黑洞体积要大20倍。这可能是由于它们当时的“伙食”很好——这些怪物在早期星系团中出现的频率要比今天高6倍，因为后者中包含大量的气体，从而为黑洞的生长提供了更多的物质基础。

　新华社南京7月29日电 江苏、天津两地天文学会通报，8月公众可赏英仙座流星雨、海王星冲日和月全食等三大天象。

　　英仙座流星雨将在8月13日晚间从天空划过，届时公众用肉眼就能观测。根据预报，今年该流星雨将发生两次极大值，分别是北京时间8月13日13时至15时30分和当天晚上23时，第二次极大值的出现最适合我国公众观测。按农历计算，当日是七月初一，整晚观测流星雨都不会有月光的干扰，观测条件相当不错。

　　英仙座流星雨刚落幕，海王星便登场。8月14日海王星冲日，此后的20多天，海王星离地球的距离最近，天文爱好者可借助望远镜一睹这颗神秘星球。冲日期间，太阳落山后，海王星从东方地平线升起，直到第二天太阳升起后才从西方落下，因此整夜都能观测。在望远镜中，海王星是一个有着深蓝色视圆面的天体。

　　8月28日将发生月全食，虽然我国各地公众都无法看到本次月食的全过程，但如果天气晴好，很多地区还是可以看到“带食月出”的景象。月全食发生的具体时间为28日16时52分—20时24分。

凤凰号火星探测器

　　北京时间7月30消息，据《星期日泰晤士报》报道，8月3日，美国宇航局将向火星发射“凤凰”号探测器，决心为“外星球是否真的存在生命？”这一地球人都关注的问题，给出一个确定的答案。

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