太空漂一年，身體會怎樣？

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. 美國宇航員和俄國宇航員在國際空間站待了340天，他們圍繞地球軌道走了5，440次，做了幾百次實驗，為了維護人類最復雜的工程之一，他們穿上笨重的宇航服漂浮在太空中，只有一根拴繩保護他們的安全。astronaut： 宇航員；cosmonaut：（俄）宇航員； orbit： 繞……軌道而行；float： 漂浮；bulky： 體積大的，笨重的； tether： 拴繩；sophisticated： 復雜的。

2. urine： 尿液。

3. press conference： 記者招待會，新聞發布會。

4. lingering： 揮之不去的。

5. harsh： 嚴酷的。

6. running water： 自來水。

7. record-breaking： 打破紀錄的；spaceflight： 航天，宇宙飛行。

8. Valery Polyakov： 瓦列里·波利亞科夫 （1942— ），俄羅斯宇航員，曾是人類單次太空旅行時長的紀錄保持者；Mir space station： 蘇聯建造的“和平號”空間站，于1986年成功發射升空，后歸俄羅斯。

9. yearlong： 持續一年的；expedition： 遠征，探險；microgravity： 微重力；duration： 持續的時間。

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

11. physiological： 生理的。

12. weightlessness： 失重；sensorimotor： 感覺運動的。

13. inner ear： 內耳；tumble： 翻跟頭。

14. upright： 直立的；NASA： 美國國家航空航天局，全稱The National Aeronautics and Space Administration；shuttle mission： 航天飛機飛行任務；ISS： 國際空間站，全稱International Space Station；The Atlantic ： 《大西洋月刊》，創立于1857年的美國雜志，是一本文學及文化評論雜志。

15. contradictory： 自相矛盾的。

16. cue nausea： 因暗示所引發的惡心；subside： 減弱，消退。

17. 沒有重力促使軌道實驗室內部空氣的流通，里面的人呼出的二氧化碳會在他們頭部周圍形成一圈看不見的云團，可導致頭疼。circulate： 循環，流通；orbital laboratory： 軌道實驗室；carbon dioxide： 二氧化碳；resident： 居民；exhale： 呼出；invisible： 看不見的。

18. fluid： 液體；clog： 阻塞；sinus： 鼻竇；congested： 充血的；puffy： 浮腫的。

19. skeleton： 骨骼；mineral： 礦物質； regenerate： 再生；cell： 細胞。

20. bone density： 骨密度。

21. bone mass： 骨量，骨質。

22. atrophy： 萎縮，衰退；fiber： 纖維； shrink： 收縮。

23. remedy： 治愈。

24. compression cuff： 壓力套箍；thigh： 大腿；lower body： 下身；pool upward： （血液）向上淤積；supplement： 補充劑。

25. vision： 視力；occupational hazard： 職業危險。

26. close up： 靠近。

27. squashed： 壓扁的；optic nerve： 視神經；swell： 腫脹；farsightedness： 遠視；post-mission： 任務結束后。

28. cerebrospinal fluid： 腦脊液；skull： 顱骨。

29. keep sth. stocked with： 讓……保持存有。

30. feat： 功績，壯舉；routine： 普通的，平凡的。

31. magnetic field： 磁場。

32. 在那里，宇航員接受到十倍于常量的輻射和來自太陽或銀河系其他地方的高速粒子，這些都會破壞他們的DNA分子，增加他們死于癌癥的風險。radiation： 輻射；particle： 粒子；galaxy： 星系；tear through： 撕裂；molecule： 分子。

33. farther out： 再遠一點；exposure： 暴露。

34. outer space： 外太空。

35. psychologist： 心理學家。

36. quarter： 住處；spacious： 寬敞的；manned satellite： 載人衛星；cozy： 舒適的。

37. 在前往火星的旅程中，在一個就連薩特都會畏縮的與世隔絕的環境里，與寥寥幾個人困在一起好幾個月，在Instagram上發再多的圖片都無法消除潛在的有害影響。Instagramming： 此處指在Instagram這個圖片社交網站上發圖；stave off： 避開，延緩；confinement： 禁閉，局限；a handful of： 少數，幾個；isolated： 隔絕的；Sartre： 薩特（1905—1980），法國20世紀最重要的哲學家之一，也是優秀的文學家、社會活動家；cringe： 畏縮。

38. spacefarer： 航天員，宇宙飛行員。

39. undergo： 經歷；a barrage of： 接二連三的；cognitive： 認知的；visual： 視覺的；launch： 發射。

40. moonshot： 登月計劃。

41. glob： （液體的）一滴。