時差N小時:航天飛機為什么發(fā)光?

During the space shuttle's third flight, back innineteen eighty two, astronauts Jack Lousma and C.Gordon Fullerton saw something remarkable. Abovethe tail of the shuttle, where there should have beenempty space, they saw a faint orange glow instead,flickering with ghostly light. Was the space shuttlehaunted? What was going on?

時光倒轉(zhuǎn)回1982年，在宇航員杰克·洛思馬和查爾斯·戈爾登·福勒頓進行第三次航天飛行時，他們看到了驚奇的一幕。在飛機尾部原應是空白的地方，出現(xiàn)了微弱的橙色輝光，詭異地撲閃著。難道航天飛機上也鬧鬼?這到底是怎么回事?

To understand this phenomenon, known as "shuttle glow," you should know something aboutthe region of space where the shuttle orbits. NASA shuttles stay in low Earth orbit, which isgenerally about a hundred and seventy miles above the Earth's surface. At that height, theatmosphere has tapered away to almost nothing--less than a billionth of the pressure it is atground level--but there are still gasses there. Indeed, low Earth orbit is well within theionosphere, a major part of our atmosphere.

為了弄清楚“航天飛機輝光”這一現(xiàn)象，有一點你應該注意到，那就是航天飛機飛行軌道所在的區(qū)域。美航局的飛機飛行時，一般保持在近地軌道上，即距離地表一百七十英里的地方。在這樣的高度，大氣程錐形逐漸減少——大氣壓力比地表的十億分之一還小——但這里仍然有空氣存在。實際上，近地軌道基本被電離層覆蓋。而電離層是大氣的重要組成部分。

The thin gasses of the ionosphere rush past the space shuttle at about five miles per second,forming a very fast, very thin wind. This wind is so thin you'd never be able to feel it, even ifyou stuck your head out the space shuttle window the way a dog sticks it's head out a movingcar. The wind causes two things to happen.

飛機以每秒5英里的速度駛過之后，電離層稀薄的空氣就會形成一股快速流動的細風。人類無法感覺到這種細風，即使你將頭伸到飛機窗外(像狗一樣將頭伸出飛速行駛的汽車)也感覺不到。這種細風會引起兩件事情。

First, it erodes the surfaces of some materials.The erosion is slight, but it can be significantfor camera lenses or other sensitive equipment. Second, the shuttle's surface can scoop upatoms from this wind, and these atoms can undergo chemical reactions. One reaction,involving nitrogen and oxygen, can produce a luminous orange glow. And that's what theastronauts saw. It wasn't a ghost--it was shuttle glow.

第一，它會侵蝕一些材料的表面。這種輕微的侵蝕用照相機或者其它敏感的設備看很明顯。第二，航天飛機的表面會從細風中捕獲原子，并且這些原子能發(fā)生化學反應。有一種氮和氧的反應就能產(chǎn)生明亮的橙色輝光。這就是宇航員所看到的光。它不是鬼火，而是輝光。