As American astronauts overhauled the aging Hubble, European scientists launched an even larger space telescope toward a far-flung orbit, hoping to help answer two questions: How did the cosmos begin and are we alone in it?

"We are seeking the origins of the universe," said Jean-Yves Le Gall, chairman and CEO of French satellite launcher Arianespace, which on Thursday launched the Herschel space telescope and a companion spacecraft from French Guiana.

The Herschel space telescope, the largest ever launched, will observe chunks of ice and dust left over from the formation of planets, playing a "complementary" role to the versatile Hubble, said Andreas Diekmann, director of the European Space Agency's Washington office.

• Click here to visit FOXNews.com's Space Center.

A companion spacecraft called Planck separated from the Ariane rocket soon after launch on a mission to measure radiation from the Big Bang.

Unlike Hubble, which has become famous for its breathtaking images of the heavens, Herschel and Planck work in non-visible wavelengths of light. But they will provide scientists with crucial information about planet and star formation.

The Herschel telescope will allow scientists to study the birth of stars and galaxies and analyze the dust-clouds around stars. Astronomers will also look for the presence of water in deep space.

"One could get an impression on how life began in the universe and how widely it might be distributed, or whether we are totally alone," said Martin Harwit, a Washington-based mission scientist for Herschel. The telescope could also pinpoint molecules that serve as building blocks for primitive organisms.

"It will also be looking at very large distances across the universe, where the first stars and galaxies were beginning to form and tell us how those processes took place," Harwit said.

The Planck, which carries its own telescope, will be capable of observing radiation that could help astronomers understand the universe as it appeared when it was 380,000 years old.

As the Herschel telescope hurtled farther away from Earth on Friday, spacewalking astronauts from the shuttle Atlantis installed a refurbished pair of gyroscopes and fresh batteries aboard Hubble.

In all, five spacewalks are planned to repair the observatory so it can last another five to 10 years.

The Herschel telescope and Planck will need several weeks to reach their separate orbits nearly a million miles from Earth. The telescope will map the cosmos for up to three years. Planck will stay in orbit for 1 3/4 years.

Herschel is "the biggest telescope ever sent to space," bragged Jean Clavel, science director of the ESA, referring to the telescope's mirror, which has a diameter of 11.5 feet. The mirror on the Hubble has a diameter of 7.9 feet.

Data collected from the Herschel telescope could help answer questions such as what the universe was made of, how it has evolved and the rate at which it is expanding.

"Scientists will be able to explore the unknown," ESA director Jean-Jacques Dordain said.

To ensure accurate readings of tiny microwaves, equipment aboard the Planck and Herschel will be kept at nearly absolute zero (minus 273 degrees Celsius) using helium.

When the helium is used up, both instruments, worth a total of $952 million, will overheat and become inoperable.

"We are going toward discoveries that will surprise us," said Roger-Maurice Bonnet, who worked on the project for years when he was science director for the ESA.