Passage 5 The West Side of the Moon 067
月球的水源 《纽约时报》2009-11-19
[00:01]There have been 73 missions, manned and unmanned, to the Moon,
[00:06]and understanding its chemical composition, particularly finding water,
[00:11]has always been a priority.
[00:14]So why haven't we seen significant amounts of water until now?
[00:20]The answer lies in the Moon's rotation. Unlike Earth, which rotates
[00:26]on a significant tilt to the Sun, the Moon is barely tilted at all.
[00:32]At the poles, some hills remain in permanent sunlight
[00:37]while some troughs are always in shadow. When water lands in sunny spots,
[00:44]perhaps carried by comets or asteroids, the water transforms directly into gas;
[00:51]if it lands in shadow, the water freezes and can remain indefinitely.
[00:58]The lack of light explains why spectrometers - instruments
[01:02]that can be used for remote water detection but rely on reflected light to do so -
[01:09]never picked up on the water.
[01:13]This changed last month, when NASA shot a satellite into a permanently
[01:19]shadowed region on the Moon's surface,
[01:22]throwing a plume of material containing water up out of the shadow.
[01:29]From the perspective of human space exploration,
[01:33]that water is the most important scientific discovery since the '60s.
[01:39]We can drink it, grow food with it and breathe it -
[01:43]by separating the oxygen from the hydrogen through a process called electrolysis.
[01:50]These elements can even be used to fuel rocket engines.
[01:55]Creating a permanent lunar habitat is important primarily for our species'
[02:01]survival. Humanity needs more than one home because,
[02:05]with all our eggs in one basket, we are at risk of low-probability
[02:11]but high-consequence catastrophes like asteroid strikes,
[02:16]nuclear war or bioterrorism.
[02:20]But it would also lead to valuable technological and other advancements.
[02:26]Consider the side-effects of the Apollo program:
[02:30]it drove the development of small computers,
[02:33]doubled the number of doctoral students in science and math in about a decade
[02:39]and marked a new stage in relations between the Americans and Soviets.
[02:45]Imagine what we could learn from living on the Moon permanently.
[02:50]On its far side, shielded from the Earth's radio noise,
[02:55]there is a quiet zone perfect for radio astronomy -
[02:59]which allows us to see objects we can't see from Earth.
[03:03]Out of necessity we could develop bacteria to extract resources directly
[03:10]from the regolith - a useful technology for Earth as well.
[03:14]And an international venture could open a new era of global cooperation.
