Scientists have always believed that snails are not able to find their way home. But Briton Ruth Brooks, a retired teacher, has found that it is not true.

    Brooks began an experiment on snails after she got mad with the snails in her garden.

    The snails had eaten her vegetables. She didn't want to kill them, so she took them to another place. But she found they always seemed to come back.

    Brooks did an experiment. She marked the snails in her garden with nail polish(指甲油).

    She placed the snails in the area around her home and made notes of their movements.

    She found that snails have a strong homing instinct (本能); the longest returning snail traveled back 90 meters. Brooks has been named Britain's best amateur (业余的) scientist after her work won the BBC Radio 4 project, So You Want To Be A Scientist.

    She said, "I've always wanted to know whether the snails that eat my plants just come back when I move them, and if they do, what is their homing distance?

    "I would say on the evidence (证据) that it would be safe to take your snails away beyond 100m or even further. If you put them somewhere nice with some food, you can be almost certain that they won't come back."

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                                                                                 “神七”技术设计揭秘
        ①在神舟飞船原有技术特点的基础上，“神舟七号”根据航天员开展太空行走以及个别技术的发展，设计上进行了多项改动，各种试验达80多项。
        ②飞船轨道舱具备气闸舱的功能。“神舟七号”飞船长9．19米，总重近8吨，仍为推进舱、返回舱、轨道舱的三舱结构。与以往不同的是，“神五”和“神六”的轨道舱仅作为航天员在太空中的生活舱，吃喝拉撒睡都在这里进行。按照计、划，“神七”飞行时，航天员将从这个舱进入太空。因此，它增加了作为气闸舱的功能。“神舟七号”飞船副总设计师潘腾解释说，其原理类似于潜水艇的闸门装置，通过泄压和复压过程实现空间环境和飞船栽人环境的过渡。
       ③泄复压设备组件安装在轨道舱前端，由5支高压气瓶和管路、阀门等组成。泄压不能过快，必须循序渐进，与此同时航天员也有一个吸氧排氮的过程。航天员在穿航天服时吸纯氧，用大概半个小时的时间来置换血液里的氮，这样再减压就安全了。与出舱过程相反，航天员从太空回到飞船内，则需要经历一个“复压”步骤——将舱内的气压从“零”恢复到一个大气压状态。“神七”飞天前，在地面做了将近百项试验，保障气闸舱性能状态比较稳定，从而确保航天员能够安全、顺利地完成出舱任务。
        ④此外，科研人员还在轨道舱的装潢上颇下工夫。每个航天员的坐椅都是量体特制，舱内色彩搭配柔和，让航天员有“家”的感觉。
        ⑤飞船有效栽荷增加。“神舟七号”飞船系统总设计师张柏楠说，从“神五”搭载一位航天员，到“神六”两名航天员，再到“神七”满载三人，这不仅仅是简单的人数增多，还意味着飞船提供的各项有效载荷的相应增加。比如携带更多的食品、水等消耗品，提高供气、供氧的流量，等等。
       ⑥更重要的是，围绕出舱活动，飞船还增加了不少新的元器件，包括泄复压设备、两套舱外航天服、数据话音传输设备以及其他舱载设备等。
       ⑦为了避免生活物品及大量仪器过多占用航天员活动空间的情况，工作人员通过计算机进行仿真设计，科学布置轨道舱的格局，将必要的设备尽量集中摆放，或装载在类似货架的格框上，提高空间使用率，将航天员活动空间保持在7立方米以上。
        ⑧飞船首次安装中继卫星终端。细心的人不难发现，与前两次载人飞行相比，飞船推进舱外部多了一个银色的小装置，这就是中继卫星的终端天线。据“神舟七号”飞船副总指挥、副总设计师秦文波介绍，我国于今年4月成功发射了首颗中继卫星“天链一号”，这颗卫星已在“神舟七号”飞行中首次应用。