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科学家建议改良航天器杀菌技术
http://www.sina.com.cn 2005/07/28 15:56  国际在线

  Is there life on Mars? If there is, NASA might be contaminating it with microbes from Earth.

  The concern prompted the Washington, D.C.-based National Research Council (NRC) to issue an advisory yesterday urging the U.S. space agency to adopt more stringent spacecraft-sterilization techniques.

  Microbes (microscopic organisms that humans live with every day) can survive in much more extreme environments than previously believed—places of superheated temperatures, radiation, freezing cold, high salt concentrations, or extreme dryness.

  "The science we've been operating on, gathered during the Viking 1 and 2 missions in the 1970s, is completely outdated," said University of California planetary scientist David Paige. Paige is also a member of the private, nonprofit NRC.

  NASA's Viking landers were the first spacecraft to land on Mars and conduct scientific research. Viking 1 and Viking 2 landed on July 20 and September 3, 1976, respectively.

  "The planetary protection policies that we have are rooted in the era of Viking. … ," Paige said. "Since then we've found that microbes are a lot more rugged than we originally thought," he added. "In addition, Mars might be more hospitable to life than we originally thought." For example, scientists have found evidence that there could be liquid water—which is necessary for life on Earth—at many places on the Mars.

  The early spacecraft that landed on Mars were thoroughly sterilized. But as money for the space program got tight, the expensive cleansing process was cut back.

  Now that more is known about both Mars and microbes, the NRC is advising NASA to develop and implement new methods and rules to detect and eliminate microorganisms on robotic spacecraft.

  The techniques currently used to clean spacecraft only detect heat-resistant and spore-forming bacteria. The scientists are concerned that NASA's screening-and-cleaning process does not detect all the microbes that might be present on the spacecraft.

  The advisory, which is based on a NASA-funded report by the NRC, recommends that all future landers be 100 percent sterilized. The NRC also suggests that NASA undertake a research program to find and test improved techniques within the next three years.

科学家建议改良航天器杀菌技术

  火星上有生命吗?如果有的话,或许也已经被宇宙飞船带去的地球细菌所污染了。目前,这种担心已经促使总部设在华盛顿特区的美国国家研究委员会向该国有关部门提出建议,希望能采取更为严格的航天器杀菌技术。

  据美国《国家地理》杂志网站7月26日报道,细菌能够在超出人们以前认为的更加恶劣的极端条件中存活,如超高温、辐射、冰冻环境,还有高盐度环境或者极度干燥的环境中。

  美国加州大学行星科学家、非营利组织国家研究委员会成员大卫·佩奇表示:“现在我们所从事的科学,是上个世纪70年代由美国“海盗1号”(viking 1)和“海盗2号”(viking 2)探测器收集到的,已经完全过时了。

  美国宇航局的“海盗号”登陆车是登陆火星,并从事科学研究的第一个航天器。“海盗1号”和“海盗2号”分别于1976年的7月20日和9月3日登陆火星。

  “我们目前的行星保护政策基于‘海盗号’时代,”佩奇说,“从那时以后,我们就发现细菌的生命力要比我们最初认为的更顽强。”另外,他还补充说道:“对待生命体,火星可能也比我们原来想像得更加‘热情好客’。”他说,比如,科学家曾经在火星上的很多地方发现曾有液态水存在的证据,而这是生物生存的必要条件。

  早期登陆火星的航天器都经过了彻底杀菌,但是当用于太空计划的资金变得紧张起来的时候,这种花费高昂的清洁程序就被削减了。

  现在,人们对于火星和细菌的了解越来越详细,美国国家研究委员会因此建议美国宇航局开发和实施新的方法、规则,以发现并排除航天器上的微生物。而目前所使用的航天器清洁技术仅能发现耐热的和孢子形成的细菌。科学家们担心,美国宇航局所使用的检查和清洁程序并没有发现所有可能出现在航天器上的细菌。

  报道说,美国国家研究委员会建议未来的火星登陆者应该100%地进行杀菌。该委员会还建议说,在未来3年内,美国宇航局应采取一项研究计划,以便研究出改良后的航天器清洁技术。(文/王高山)


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