NEAR the beginning there was light. And the light travelled across the
expanding Universe for billions of years, carrying with it the secrets of how
the cosmos began. Now, a new satellite promises the best view yet of this
afterglow from the big bang.
NASA will launch the Microwave Anisotropy Probe (MAP) on 30 June. The
$145 million satellite will slingshot around the Moon to boost it to a
point 1.5 million kilometres away called L2. Far from Earthly interference, the
probe can get an uninterrupted view of the light lingering from a mere 400,000
years after the big bang.
That light started its journey when the budding Universe cooled to roughly
3000 kelvin and changed from a light-trapping plasma to a translucent gas of
neutral hydrogen. “We’re talking about the ultimate baby picture of the
Universe,” says Alan Bunner, a science director at NASA headquarters in
Washington DC. MAP’s full-sky map will be the first to look at the microwave
background since NASA’s Cosmic Background Explorer (COBE) in 1992.
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MAP will measure tiny differences in the temperature of the microwaves across
the sky, says Charles Bennett of NASA’s Goddard Space Flight Center in
Greenbelt, Maryland. Over the past few years, balloon and ground-based
experiments have allowed researchers to study these variations. Their data shows
that space is “flat”, and that the Universe consists of roughly 5 per cent
ordinary matter, 30 per cent “dark matter”, and 65 per cent “dark energy”. MAP
will pin down these quantities much more precisely, Bennett says, testing the
theory of “inflation”, which predicts the Universe expanded faster than light
speed just after the big bang.
