太空漂一年，身体会怎样？

By Marina Koren

What One Year of Space Travel Does to the Human Body

Scott Kelly and Mikhail Kornienko have done a lot this past year.

In the 340 days they spent on the International Space Station， the American astronaut and Russian cosmonaut orbited Earth 5，440 times， conducted hundreds of experiments， and floated out in space in bulky suits， secured only by a tether， to maintain one of humanitys most sophisticated pieces of engineering.1

There are also some things they didnt do， like walk or shower， or feel the wind against their skin， or sleep in a bed that didnt hang from a wall， or drink water that wasnt recycled urine2 and sweat.

“Even after Ive been here nearly a year， you dont feel perfectly normal，” Kelly said in a press conference3. “Theres always a lingering4 something you feel. Its not necessarily uncomfortable， but it is a harsh5 environment. For instance， having no running water6. Its kind of like Ive been in the woods camping for a year.”

Kelly and Kornienko returned to Earth lately. For the United States， it was record-breaking： Kellys mission marks the longest spaceflight of an American astronaut.7 The Russians hold the world record； Valery Polyakov spent nearly 438 days on the Mir space station in the 1990s.8 The last time anyone spent a year in space was in 1999.

The goal of the yearlong expedition is to better understand how the human body reacts to microgravity for long durations.9 Researchers say they hope the data acquired in this mission will help them figure out how to send humans on even longer missions， like one to Mars， which would take two-and-a-half years， roundtrip.10

These days， scientists know generally what astronauts should expect when they leave Earths atmosphere. The most common physiological11 changes result from the lack of gravity. When astronauts first experience weightlessness， their sensorimotor system becomes immediately disrupted.12

“Your inner ear thinks youre tumbling：13 the balance system in there is going all over the place… Meanwhile your eyes are telling you youre not tumbling； youre upright，” Leroy Chiao， a retired NASA astronaut who flew three shuttle missions and spent six months on the ISS in the mid-2000s， told The Atlantic last year.14 “The two systems are sending all this contradictory15 information to your brain.” Cue nausea that takes a few days to subside.16

Without the forces of gravity to help circulate air inside the orbital laboratory， the carbon dioxide its residents exhale can form an invisible cloud around their head， which can lead to headaches.17 In weightlessness， the fluids in the human body float upward and clog the sinuses， making astronauts heads feel congested and their faces appear puffy.18 Their skeletons become useless； bones dont need to support muscles in microgravity， so they start losing minerals and regenerating cells at a slower pace.19 Astronauts can lose one percent of their bone density20 a month. Back on Earth， it takes a year for aging men and women to lose the same amount of bone mass21. In an environment that requires little strength to move around and work， muscles atrophy， their fibers shrinking.22

These effects can be remedied23. Astronauts wear compression cuffs on their thighs to keep the blood in their lower body from pooling upward， and take vitamin D supplements.24 They maintain muscle and bone strength by exercising for two-and-a-half hours a day， six days a week， guided by strength coaches. The stations fans help spread the exhaled carbon dioxide around.

But scientists are still learning. Astronauts have complained of vision problems since the first missions in the 1970s， but it was only in the last decade that scientists discovered such problems were an occupational hazard.25 In 2009， two NASA astronauts noticed they started having trouble seeing things close up26. Eye exams and high-tech cameras revealed their eyeballs had become a bit squashed and their optic nerves had swelled， leading to farsightedness that persisted post-mission.27 Researchers suspect the change in vision is caused by cerebrospinal fluid in the skull，28 free from gravity， pushing on the back of the eyeballs， but they dont know for sure. NASA keeps the ISS stocked with29 glasses just in case.

Still， scientists have managed to figure out how to keep humans alive and relatively well for months at a time， a remarkable feat that now appears routine to those watching from the ground.30 But on a trip to Mars， its distance from Earth， not duration of spaceflight， that becomes the bigger enemy. The ISS orbits about 200 miles away， just within Earths protective magnetic field31. There， astronauts receive 10 times the usual amount of radiation， high-speed particles from the sun or other parts of the galaxy that tear through DNA molecules， that increase their risk of dying from cancer.32 Farther out， the exposure would get much worse.33

Human bodies were not made for outer space34. Neither were their minds， which is why NASA astronauts talk to psychologists35 once every two weeks， and write in their personal journals at least three times a week. The living and working quarters of the ISS are about the size of a six-bedroom house—spacious by manned satellite standards， but certainly very， very cozy.36 On a voyage to Mars， no amount of Instagramming could stave off the potentially harmful effects of months of confinement with only a handful of people， in an environment so isolated from the rest of humankind it would make Sartre cringe.37

Scientists have until the 2030s—when NASA wants to send humans to Mars—to figure out how to keep long-distance spacefarers38 alive. Kelly and Kornienko spent a year undergoing a barrage of cognitive， visual， and medical tests before they launched to the ISS last year.39 They conducted more tests during their 340 days aboard， and will receive even more in the year after they return—all in the name of space explorations latest moonshot40. When the last test is over， Kelly said hes going to go home and jump into his pool， where water doesnt float around in big globs41. 1. 美国宇航员和俄国宇航员在国际空间站待了340天，他们围绕地球轨道走了5，440次，做了几百次实验，为了维护人类最复杂的工程之一，他们穿上笨重的宇航服漂浮在太空中，只有一根拴绳保护他们的安全。astronaut： 宇航员；cosmonaut：（俄）宇航员； orbit： 绕……轨道而行；float： 漂浮；bulky： 体积大的，笨重的； tether： 拴绳；sophisticated： 复杂的。

2. urine： 尿液。

3. press conference： 记者招待会，新闻发布会。

4. lingering： 挥之不去的。

5. harsh： 严酷的。

6. running water： 自来水。

7. record-breaking： 打破纪录的；spaceflight： 航天，宇宙飞行。

8. Valery Polyakov： 瓦列里·波利亚科夫 （1942— ），俄罗斯宇航员，曾是人类单次太空旅行时长的纪录保持者；Mir space station： 苏联建造的“和平号”空间站，于1986年成功发射升空，后归俄罗斯。

9. yearlong： 持续一年的；expedition： 远征，探险；microgravity： 微重力；duration： 持续的时间。

10. figure out： 想出，解决；roundtrip： 往返航程。

11. physiological： 生理的。

12. weightlessness： 失重；sensorimotor： 感觉运动的。

13. inner ear： 内耳；tumble： 翻跟头。

14. upright： 直立的；NASA： 美国国家航空航天局，全称The National Aeronautics and Space Administration；shuttle mission： 航天飞机飞行任务；ISS： 国际空间站，全称International Space Station；The Atlantic ： 《大西洋月刊》，创立于1857年的美国杂志，是一本文学及文化评论杂志。

15. contradictory： 自相矛盾的。

16. cue nausea： 因暗示所引发的恶心；subside： 减弱，消退。

17. 没有重力促使轨道实验室内部空气的流通，里面的人呼出的二氧化碳会在他们头部周围形成一圈看不见的云团，可导致头疼。circulate： 循环，流通；orbital laboratory： 轨道实验室；carbon dioxide： 二氧化碳；resident： 居民；exhale： 呼出；invisible： 看不见的。

18. fluid： 液体；clog： 阻塞；sinus： 鼻窦；congested： 充血的；puffy： 浮肿的。

19. skeleton： 骨骼；mineral： 矿物质； regenerate： 再生；cell： 细胞。

20. bone density： 骨密度。

21. bone mass： 骨量，骨质。

22. atrophy： 萎缩，衰退；fiber： 纤维； shrink： 收缩。

23. remedy： 治愈。

24. compression cuff： 压力套箍；thigh： 大腿；lower body： 下身；pool upward： （血液）向上淤积；supplement： 补充剂。

25. vision： 视力；occupational hazard： 职业危险。

26. close up： 靠近。

27. squashed： 压扁的；optic nerve： 视神经；swell： 肿胀；farsightedness： 远视；post-mission： 任务结束后。

28. cerebrospinal fluid： 脑脊液；skull： 颅骨。

29. keep sth. stocked with： 让……保持存有。

30. feat： 功绩，壮举；routine： 普通的，平凡的。

31. magnetic field： 磁场。

32. 在那里，宇航员接受到十倍于常量的辐射和来自太阳或银河系其他地方的高速粒子，这些都会破坏他们的DNA分子，增加他们死于癌症的风险。radiation： 辐射；particle： 粒子；galaxy： 星系；tear through： 撕裂；molecule： 分子。

33. farther out： 再远一点；exposure： 暴露。

34. outer space： 外太空。

35. psychologist： 心理学家。

36. quarter： 住处；spacious： 宽敞的；manned satellite： 载人卫星；cozy： 舒适的。

37. 在前往火星的旅程中，在一个就连萨特都会畏缩的与世隔绝的环境里，与寥寥几个人困在一起好几个月，在Instagram上发再多的图片都无法消除潜在的有害影响。Instagramming： 此处指在Instagram这个图片社交网站上发图；stave off： 避开，延缓；confinement： 禁闭，局限；a handful of： 少数，几个；isolated： 隔绝的；Sartre： 萨特（1905—1980），法国20世纪最重要的哲学家之一，也是优秀的文学家、社会活动家；cringe： 畏缩。

38. spacefarer： 航天员，宇宙飞行员。

39. undergo： 经历；a barrage of： 接二连三的；cognitive： 认知的；visual： 视觉的；launch： 发射。

40. moonshot： 登月计划。

41. glob： （液体的）一滴。