THERE'S water, water, everywhere in the cosmos, but how it comes
about in the interstellar clouds that give birth to stars,
planets and even life is a bit of a mystery. The answer, it
seems, may lie on the surface of frosty dust grains. When
hydrogen and oxygen exist as gases water forms easily, but
models of interstellar clouds suggest that this route is
unlikely to produce the abundance of water seen in them. Most of
the water we see has formed icy sheaths around tiny grains of
dust in the clouds, and it is believed oxygen atoms accumulate
on the grains and react with hydrogen to form water. Akira
Kouchi and colleagues at Hokkaido University in Sapporo, Japan,
tested the idea by freezing oxygen onto a nucleation surface
held at 10 degrees above absolute zero. When they fired atoms of
hydrogen onto the oxygen, hydrogen peroxide was produced, which
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