Satellites Destroyed In Orbital Collision

一家美国公司的商业卫星在与一颗已报废的俄罗斯军用卫星发生的碰撞中遭到破坏。美国国家航空及太空总署(NASA)说，这是太空轨道中首次发生此类事件，进一步增加了人们对太空碎片危险的担忧。据美国政府和卫星业人士说，少数人持股公司铱星公司(Iridium Satellite LLC)拥有的一颗卫星和多年前就已明显失灵的一颗俄罗斯军用卫星周二在近地轨道发生了碰撞。Iridium一位画家描绘的铱星通讯卫星此次碰撞在西伯利亚上空约480英里的地方产生了两大片碎片云，这也促使空间科学家和工程师开始评估未来发生更多碰撞的可能性。此次事件可能影响到美国的空间预算和政策，原因之一是五角大楼正在寻求增加设备支出，通过更好地跟踪数千块碎片和环绕地球的其它卫星保护美国的高科技太空设施。随着越来越多的卫星被送入轨道，让它们避免碰到碎片或相互碰撞的难度也越来越大。军事指挥官还担心敌手的干扰破坏甚至是撞击美国的卫星。业内人士说，铱星公司已经确定俄罗斯的卫星是1993年发射“宇宙”系列卫星之一，重量超过一吨，卫星上装有一个核反应堆。碰撞会释放核残留物，但专家多年来一直认为，放射性碎片穿过大气层跌落到居住区的可能性非常小。目前地球轨道上共有220多颗仍在使用的商业卫星，此外还有数百颗军事间谍和科学卫星。商业卫星为企业用户提供从数据和视频传输到银行自动柜员机系统和消费者导航设备支持等各种服务。五角大楼负责跟踪太空碎片的部门一直在监视俄罗斯的卫星，以免轨道内发生的碰撞损坏或破坏商业或政府卫星。美国国家航空及太空总署和五角大楼跟踪着1万多个高速飞行的碎片，其中有些还没有一个足球大。2007年1月时对空间碰撞的担心曾一度升温，当时中国政府用相对简单的反卫星武器摧毁了一颗退役的气象卫星。美国国家航空及太空总署说，此前曾出现过四次轨道内的意外碰撞，但都是火箭部件和其他碎片。整个卫星发生碰撞这还是第一次。当卫星的使用寿命结束后，它们往往会被定位到遥远的轨道，不太可能危及正在工作的卫星。但是，如果卫星上面的计算机或其他系统发生故障，或电池的电能耗尽，地面的操作者可能就难以进行控制。如果没有这样的地面指令，几个月内卫星的运行轨迹可能就变得难以预测。总部在马里兰州的铱星公司使用60多颗卫星，为全球约30万用户提供语音和数据服务。这家公司说，公司有强大的后备能力，碰撞对服务的影响“微不足道”。Andy Pasztor 本文涉及股票或公司document.write (truthmeter('2009年02月12日14:25', 'IDM.XX'));Iridium Satellite L.L.C.总部地点：美国


A commercial satellite owned by a U.S. company was destroyed in a collision with a defunct Russian military satellite in what NASA said was the first such accident in orbit, raising new concerns about the dangers of space debris.The crash, which happened Tuesday in low-earth orbit, involved one of the satellites owned by closely held Iridium Satellite LLC and a crippled Russian military satellite that apparently stopped functioning years ago, according to U.S. government and satellite-industry officials.The collision created two large clouds of debris floating roughly 480 miles above Siberia, and prompted space scientists and engineers to assess the likelihood of further collisions.The accident could have implications for U.S. space budgets and policy, partly because it comes amid a Pentagon campaign to increase spending on systems to protect U.S. high-tech space hardware by keeping better track of the thousands of pieces of debris and other satellites circling the earth.As more and more satellites are blasted into orbit, the challenges of keeping them from hitting debris or each other are growing. Military planners also worry about enemies jamming, disabling or potentially even ramming U.S. satellites.Industry officials say Iridium has identified the Russian craft as a Cosmos series satellite launched in 1993, weighing more than a ton and including an onboard nuclear reactor. A collision could release nuclear residue, though experts have argued for years that the chance of radioactive debris surviving a fall through the atmosphere and reaching inhabited areas is very small.More than 220 active commercial satellites now orbit the globe, in addition to hundreds of military, spy and scientific satellites. Commercial satellites provide businesses with everything from data and video transmissions to support for automated bank teller systems and consumer navigation devices.The Russian craft was being monitored by Pentagon organizations that keep track of space debris in order to prevent in-orbit collisions from damaging or destroying both commercial and government satellites. The National Aeronautics and Space Administration and the Pentagon track more than 10,000 pieces of high-speed debris, some no larger than a football.Space collision worries gained momentum in January 2007, when the Chinese government used a relatively simple antisatellite weapon to knock down one of its aged weather satellites.NASA said there have been four earlier instances of accidental collisions in orbit, generally involving rocket parts and other debris. None involved a full-size satellite.When satellites reach the end of their useful lives they often are parked in remote orbits where they are unlikely to endanger working satellites. But if a satellite's onboard computers or other systems fail, or it runs out of battery power, it can be difficult for ground operators to maintain control. Without such orders from the ground, satellites can act unpredictably over months.Iridium, of Bethesda, Md., uses more than 60 satellites to provide voice and data services for about 300,000 subscribers globally. It said the collision has 'minimal impact' on service due to its backup capacity.Andy Pasztor