NASA’s SOFIA telescope, aboard a jumbo jet, detects water on the moon. NASA
Does water exist on the moon? In 2018, scientists confirmed the presence of water in the form of ice in the moon’s polar regions. Now, NASA scientists have detected water in more places than expected.
月球上有水存在吗？2018年，科学家们证实，在月球的极地水以冰的形式存在。如今，美国国家航空航天局的科学家们在比预期更多的地方发现了水。
For the first time, scientists have identified water on the moon’s sunlit surface. The water was found in and around the southern hemisphere’s sunlit Clavius crater, one of the largest craters on the moon.
科学家们首次在月球的太阳照射面发现水。这些水在月球南半球的克拉维斯环形山 —— 也是月球最大的环形山一带被发现。
Scientists made this discovery using data from NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) airborne telescope. It is a 2.5-meter telescope that rides aboard a jumbo jet to get clear views of the sky. In August 2018, SOFIA detected 6-micrometer infrared light coming from a region near the Clavius crater. After analysis, scientists confirmed that this wavelength of light is generated by the vibrations (振动) of sunlight-heated water molecules.
科学家们通过使用美国国家航空航天局的平流层红外探测天文台“索菲亚”空运望远镜的数据，得出了这一发现。这架口径2.5米的望远镜被架设在了一家巨型喷气式飞机上，从而能够获得天空的清晰视角。2018年8月，“索菲亚”在克拉维斯环形山一带发现了6微米的红外波段。经过分析，科学家们证实这段光波长源于受阳光加热后的水分子振动。
“This is the first unambiguous detection of molecular water on the sunlit moon,” said study co-author Casey Honniball, a lunar scientist at NASA. “This shows that water is not just in the permanently shadowed regions – that there are other places on the moon [where] we could potentially find it.”
“这是月球光照区存在水分子的首个明确发现，”该研究的联合作者、美国国家航空航天局的月球科学家凯西·霍尼鲍尔表示。“这表明，水不仅存在于常年阴暗的月背 —— 月球上的其他地方也可能发现水。”
Based on the brightness of the observed infrared light, Honniball’s team figured out the water exists at around 100 to 400 parts per million around the Clavius crater. That’s less than half a liter (升) of water per ton of lunar soil. As a comparison, the Sahara desert has 100 times the amount of water than that. This is basically what the researchers expected, based on past spacecraft observations.
根据观测到的红外波段亮度，霍尼鲍尔的团队认为克拉维斯环形山附近水的浓度大约为百万分之100至400。这也就是每吨月球土壤中的含水量少于半升。作为对照，撒哈拉沙漠的含水量是月球的100倍。从以往的航天观测来看，这一结果与研究人员的预期基本相符。
Interestingly, these water molecules are so far apart that they are in neither liquid nor in frozen ice.
有趣的是，这些水分子之间的间隔太大，因此并不是以液体或者固态冰的形式存在。
“To be clear, this is not puddles of water,” Honniball said. Instead, scientists think the water molecules are bound inside some other material on the lunar surface. They could be covered in glass created by the crash of micrometeorites, or “sandwiched” between soil grains that protect the water from solar radiation.
“要明确的是，这并不是水坑，”霍尼鲍尔表示。科学家们认为这些水分子被储存在了月球表面的一些其他物质中。它们或许被包裹在微小陨石撞击所形成的玻璃中，或者被夹在了土壤颗粒之间，从而避免被太阳辐射带走。
Scientists believe the water came from comets, asteroids, interplanetary dust, the solar wind or even lunar volcanic eruptions. It is too soon to know if the water would be accessible. Without knowing how hard the surface is, there is a risk of damaging equipment. But the finding expands the possible landing spots for robots and astronauts alike. It is “opening up real estate previously considered ‘off limits’ for being bone dry”, according to assistant professor Paul Hayne of the University of Colorado, US.
科学家们认为这些水来自彗星、小行星、星际尘埃、太阳风甚至是月球上的火山喷发。目前能否采集这些水还是个未知数。在并不了解月球表面硬度的情况下，存在着损坏设备的风险。但这一发现扩大了机器人及宇航员可能的着陆范围。美国科罗拉多大学的助理教授保罗·海尼认为，这“打开了以往因干燥而被‘禁入’的区域”。
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