一颗高速飞行的彗星即将要与火星来一场近距离接触。赛丁泉彗星预计将在美国东部时间下午2点27分时进入与火星不到八万七千英里的距离，对于一颗低空飞行的彗星来说，这一距离已经非常近。太空陨石的飞行速度约为12万6千英里每小时（56千米每秒）。
美国国家航空和宇宙航行局认为该颗彗星不会和火星相撞，但彗星会喷射出一道尘埃与气体，这些尘埃与气体可能会对围绕火星运行的航天器造成损害。
“火星会正好处于一片碎片云的边缘，所以它有可能会与某些颗粒冲撞——也有可能不会，”美国国家航空和宇宙航行局喷射推进实验室中火星探险项目的首席科学家里奇·楚雷克在媒体发布会中表示。
“在56公里每秒的速度下，一个0.5毫米大小的颗粒就可以损坏这些航天器中的某一台。”近地天体项目办公室主任唐·约曼斯在美国国家航空和宇宙航行局的录像中说。
安全起见，美国国家航空和宇宙航行局将在彗星靠近时将火星奥德赛号，火星勘测轨道飞行器和新火星大气与挥发物演化任务移动到星球的另一边。
“我们会躲在火星后面，”火星项目工作室轨道飞行器研究项目负责人罗波·洛克说，“就像发生地震或者碎玻璃漫天飞舞的时候躲到桌子底下一样。”
人造卫星会在彗星呼啸而过时拍下照片并记录下数据。一些地基望远镜和太空望远镜，包括哈勃太空望远镜，也会拍照。
那么火星表面的探测器又如何呢？美国国家航空和宇宙航行局表示火星漫游车在火星大气的保护下，非常安全。
A comet is speeding toward a close-encounter with Mars.Comet Siding Spring is expected to come within 87，000 miles of Mars at about 2：27 p.m. ET on Sunday -- very close for a comet flyby. The space rock is moving at about 126，000 mph （56 kilometers per second）.
NASA thinks the comet will miss the Red Planet， but comets spew out a trail of dust and gas， and that could damage the fleet of spacecraft orbiting Mars.
"Mars will be right at the edge of the debris cloud， so it might encounter some of the particles -- or it might not，" Rich Zurek， chief scientist for the Mars Exploration Program at NASA"s Jet Propulsion Laboratory said in a press release.
"It only takes a half-a-millimeter-sized particle traveling at 56 kilometers per second to injure one of these spacecraft，" Don Yeomans， manager of the Near Earth Object Program Office said in a NASA video.
Just to be safe， NASA will move the Mars Odyssey orbiter， Mars Reconnaissance Orbiter （MRO）， and the new Mars Atmosphere and Volatile EvolutioN （MAVEN） to the other side of the planet as the comet approaches.
"We"re going to hide behind Mars，" said Rob Lock， Orbiter Studies Lead in the Mars Program Office. "Kind of like diving under your desk if there"s an earthquake and flying glass around."
The orbiters will take pictures and collect data on the comet as it zips by. Several Earth-based and space telescopes， including the Hubble Space Telescope， also will take pictures.
What about the probes on the surface of Mars？ NASA says the rovers are safe and will be protected by Mars" atmosphere.
http：//edition.cnn.com/2014/10/17/tech/innovation/mars-spacecraft-comet-siding-spring/index.html