NASA鈥檚 Microwave Anisotropy Probe, which promises the best view yet of the afterglow of the big bang, launched without problems on 30 June.
The space probe was sent into space on a Boeing Delta 2 rocket from Cape Canaveral Air Force Station in Florida. 鈥淲e鈥檙e off to a fantastic start,鈥� said Clifton Jackson, MAP mission systems engineer at NASA鈥檚 Goddard Space Flight Center.
The $145 million satellite will orbit the Earth for several weeks, before a slingshot manoeuvre around the Moon boosts it to a point in space called L2. This is 1.5 million kilometres away, where the Earth鈥檚 and Sun鈥檚 gravity balance.
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MAP can orbit L2 without using much fuel and get an uninterrupted view of the light left lingering from a mere 400,000 years after the big bang.
The light MAP hopes to trap originated when the budding Universe cooled to roughly 3000 Kelvin and changed from a light-trapping plasma to a translucent gas of neutral hydrogen.
Since then, the expansion of the universe has stretched this light into microwaves. 鈥淲e鈥檙e talking about the ultimate baby picture of the Universe,鈥� says Alan Bunner, a science director at NASA headquarters in Washington DC.
MAP鈥檚 full-sky map will be the first since NASA鈥檚 Cosmic Background Explorer (COBE) studied the microwave background in 1992.
The probe will measure tiny differences in the temperature of the microwaves across the sky, says Charles Bennett of NASA鈥檚 Goddard Space Flight Center. These differences are evidence that the infant Universe was more dense in some places than others, and these dense spots seeded the formation of galaxies.
Flat space
Since 1998, researchers working with balloon- and ground-based experiments have measured the size of the hot and cold spots. Their data show that space is 鈥渇lat鈥�, and that the Universe consists of roughly five per cent ordinary matter, 30 per cent 鈥渄ark matter鈥�, and 65 per cent 鈥渄ark energy鈥�.
MAP will pin down these quantities much more precisely, Bennett says. This will test the theory of 鈥渋nflation鈥�, which predicts the Universe expanded at greater than light speed just after the big bang.
The satellite will also measure variations in polarisation of the microwaves, which could yield evidence of gravity waves in the early Universe, says David Spergel of Princeton University in New Jersey. 鈥淩egarding polarisation, MAP should be like COBE was for temperature fluctuations,鈥� Spergel says. 鈥淚t should give us the first big picture.鈥�