Smooth launch for probe

The American space agency's (Nasa) $145m (�103m) spaceprobe will construct a full-sky picture of the oldest light in the Universe.

It is designed to capture the afterglow of the Big Bang, which comes to us from all directions in space and from a time when the Universe was a very different place.

Map will look for faint patterns imprinted within this afterglow that carry the answers to many mysteries such as:

• What happened during the first instant after the Big Bang?
• How did the galaxies form?
• Will the Universe expand forever?

Preparing for launch

"We are tremendously excited about this mission because it will help answer basic questions that people have been asking for ages," said Dr Charles Bennett, Principal Investigator for the Map mission at Nasa's Goddard Space Flight Center, Maryland, US.

"Map's unprecedented accuracy and precision will allow us to determine the nature and destiny of the Universe."

According to the Big Bang theory, currently the only one seriously considered by astronomers, the Universe began about 14 billion years ago as an unimaginably hot and dense fog of light and exotic particles.

Since then, the Universe has expanded and cooled. Today, the entire Universe is bathed in the afterglow light from the Big Bang. The light has been travelling for about 14 billion years, thus allowing Map a look back through time to see the early Universe.

Map's unprecedented accuracy and precision will allow us to determine the nature and destiny of the Universe.

Charles Bennett, Nasa

"The cosmic microwave light is a fossil," said Professor David Wilkinson, Princeton University, Princeton, US. "Just as we can study dinosaur bones and reconstruct their lives of millions of years ago, we can probe this ancient light and reconstruct the Universe as it was about 14 billion years ago."

Map has a range of sensors that will collect radiation and measure the tiny temperature variations in different parts of the sky.

The Map mission will build on the 1992 Cosmic Background Explorer (Cobe) satellite that discovered a faint tiny pattern, or "anisotropy", in the CMB.

"Nothing has ever been built like it before," said Nasa's Dr Edward Wollack: "To measure the cosmic glow reliably to a part in a million, to millionths of a degree, has been the grand challenge. That's like measuring the weight of a cup of sand down to the resolution of a single grain."

From the begining: The Cosmic Background Radiation

About a month after its launch on a Delta II rocket from Cape Canaveral, Map will swing past the Moon, boosting its orbit to the Earth's second Lagrange Point, or L2. This is the first time a spacecraft will be in orbit around the L2 point.

It has been chosen because L2 is four times further than the Moon in the direction away from the Sun and a spacecraft there requires very little fuel to maintain its position.

"I can't wait," said Professor Frenk. "These are exciting times in astronomy and Map will be one of the most exciting."