中国太空网

       北京时间8月6日消息　据国外媒体报道，数百年来，全世界的天文学家们一直在尝试着研究和查明土星光环的结构。同时，这些光环的成因则更显得神秘莫测。不过，“卡西尼”号探测器传回的最新观测数据最终揭开了土星光环的“身世”－－它们在数亿年前均曾是土星的卫星，最终发生分解并演化为现在的带状结构。

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　　作者：任霄鹏 (科学时报)

　　本报讯 最近，美国天文学家利用Hobby-Eberly大型望远镜，在宇宙中新发现了一颗红巨星(氢元素消耗殆尽的恒星)和围绕着它的行星。根据这一发现，科学家预测，当太阳膨胀成为一颗红巨星时，它的表面甚至能够达到地球轨道，从而与我们的地球发生“亲密接触”。相关论文将发表在11月的《天体物理学杂志》上。

　　科学家早已预言，太阳在50亿年后会膨胀成一颗红巨星。此次新发现的一个重要意义就在于使天文学家通过对比研究，加深对太阳系未来的认识和理解。科学家表示，太阳膨胀会使地球的生物生存区域重新分布。大约20亿年后，太阳就会使地球变得不再适合生存。因为在太阳演化为红巨星的膨胀过程中，地球将变得越来越热。太阳的扩张将影响地球等行星的轨道以及整个太阳系的动力学，引起轨道交叠乃至行星碰撞。

　中国日报网环球在线消息: 芭芭拉·摩根曾经是美国爱达荷州的一名教师，在等待和准备了22年后，她将于下周乘坐“奋进”号航天飞机飞往太空，完成自己的宇航梦。更重要的是，她希望能通过自己的行动告诉学生们，坚持和耐心是取得成功的最重要因素。

　　1985年，摩根报名参加了美国航空航天局(NASA)教师宇航员选拔计划，并成功从上千名报名者中脱颖而出，成为NASA宇航员的预备人员。同时被选中的还有来自康科(Concord)地区的社会研究教师克丽斯塔·麦奥利弗(Christa McAuliffe)。

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                                     凤凰号任务标志

新浪科技讯 北京时间8月5日消息，据美国宇航局太空网报道，卡尔·萨根、亚瑟·克拉克、赫伯特·乔治·韦尔斯、金·斯坦利·鲁宾逊等著名科幻作家对火星充满了幻想。4日，他们“遨游”太空的夙愿终于实现，但不是这些科幻作家本人，而是他们的代表作品。

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       据美国宇航局太空网8月4日报道，美宇航局“凤凰”号火星探测器于当地时间4日拂晓在佛罗里达州卡纳维拉尔角发射升空，踏上了飞往火星的漫漫征程。“凤凰”号此行的主要任务是寻找支持火星上原始生命存在的必要条件。

　　“凤凰”号成功发射

　　美国东部时间4日5时26分34秒(北京时间4日17时26分34秒)，美国发射联盟的一枚德尔塔2型火箭搭载“凤凰”号火星探测器从佛罗里达州卡纳维拉尔角空军基地17A发射台发射升空。“凤凰”号将在火星北极附近的瓦斯蒂塔斯-伯勒里斯(Vastitas Borealis)北部平原着陆，接着，“凤凰”号将使用8英尺(2.4米)的机械臂凿开火星土壤取样，探寻火星生命迹象。

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A NASA robotic explorer equipped to dig up and analyze icy soil on Mars sits atop a 13-story tall stack of rocket engines prepared for liftoff before sunup on Saturday. A Delta II launch vehicle will carry the Phoenix Mars Lander into Earth orbit and, about 90 minutes later, give it the push needed to send it to Mars. A three-week period when planetary positions are favorable for this launch begins with an opportunity at 2:26:34 a.m. PDT (5:26:34 a.m. EDT) on Aug. 4. A second opportunity the same day, if needed, will come at 3:02:59 a.m. PDT (6:02:59 a.m. EDT).

"We have worked for four years to get to this point, so we are all very excited," said Barry Goldstein, Phoenix project manager at NASA's Jet Propulsion Laboratory, Pasadena. "Our attention after launch will be focused on flying the spacecraft to our selected landing site, preparing for surface operations, and continuing our relentless examination and testing for the all-important descent and landing on May 25 of next year."

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A US space probe embarked Saturday on a 10 month journey to Mars, where it will dig through Martian soil in a search for signs of life in a frigid region of the Red Planet. The Phoenix Mars Lander separated from a Delta II rocket after blasting off into the dark sky at 5:36 am (0936 GMT) from the Kennedy Space Center in Cape Canaveral, Florida. Powered by solar panels, Phoenix, whose launch was delayed by one day following bad weather, is scheduled to land on Mars on May 25, 2008, after traveling 680 million kilometers (422 million miles) through space.

The National Aeronautics and Space Administration hopes to land the probe on flat ground with few or no rocks at a Martian latitude equivalent to northern Alaska on Earth.

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The Phoenix spacecraft has separated from the Delta II rocket and ground controllers at NASA's Deep Space Network have acquired its signal and begun assessing its health. The solar panels that will power the mission's cruise phase will be deployed and Phoenix will be pointed to best receive solar power and communicate with Earth.

The spacecraft has oriented itself to the sun as it was programmed to do. It will use solar panels to generate electricity during the nine-month coast to Mars. A separate set of solar arrays is attached to the lander itself.

The Phoenix Mars lander's assignment is to dig through the Martian soil and ice in the arctic region and use its onboard scientific instruments to analyze the samples it retrieves.

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