Most powerful space telescope ready to launch

James Webb Space Telescope, the largest and most powerful space telescope ever constructed, will lift off on Christmas.

The USD 10bn project spanning over three decades, a collaboration between NASA, the European Space Agency, and the Canadian Space Agency, hopes to look further back in time than ever before - to find out more about the creation of the first stars and the beginnings of our Universe.

After several technical and weather delays the James Webb Space Telescope will take off on a European Ariane rocket from French Guiana, NASA announced.

"Webb is an extraordinary mission," said NASA administrator Bill Nelson.

"It's a shining example of what we can accomplish when we dream big. We've always known that this project would be a risky endeavour. But, of course, when you want a big reward, you have to usually take a big risk."

The truck-sized telescope aims to peer into the cosmos and farther back in time.

Astronomers will also use the new telescope to probe black holes at the centers of galaxies, search for the chemical signatures of life on extrasolar planets and, closer to home, study the frozen oceans on moons at the edge of our own solar system.

The telescope will answer questions about the solar system, study exoplanets in new ways and look deeper into the universe than we've ever been able to.

Once the telescope launches, it will travel for about a month until it reaches an orbit about 1 million miles (1.6 million kilometres) away from Earth.

Plans call for the spacecraft to orbit the sun at this spot, called the second Lagrange point (L2).

The telescope comes equipped with a segmented mirror that can extend 21 feet and 4 inches (6.5 meters) -- a massive length that will allow the mirror to collect more light from the objects it observes once the telescope is deployed in space.

The more light the mirror can collect, the more details the telescope can observe. Over the course of 29 days, Webb will unfold its mirrors and unfurl a protective sun shield the size of a tennis court. This process involves thousands of parts that must work perfectly in the right sequence.

Fortunately, each step can be controlled from the ground in case there are issues.

The concept for the telescope was first imagined as a successor to Hubble at a workshop in 1989, and construction on Webb first began in 2004.

Since then, thousands of scientists, technicians and engineers from 14 countries have spent 40 million hours building the telescope.

Now, Webb could help researchers understand the origins of the universe and begin to answer key questions about our existence, such as where we came from and if we're alone in the cosmos.