- Rosetta will be the first spacecraft to orbit a comet and to place a lander on the surface
- ESA says the mission objective is to help understand the evolution of the solar system
- After mapping the comet a lander will be deployed to the surface
- Some believe Earth may have received its water from comets
Scientists are inviting you to take part in "waking up" a comet-chasing probe that has been in hibernation in space for nearly three years.
The spacecraft is due to reactivate itself from an internal alarm clock on Monday but to celebrate the event the European Space Agency (ESA) is asking people to film themselves shouting "Wake up, Rosetta!" and then share their video clips on a dedicated Facebook page.
Visitors to the page can vote for their favorites and the top 10 will be transmitted towards Rosetta and out into the universe beyond.
Behind the fun lies a ground-breaking mission, which, if successful, will notch up a series of notable firsts.
Rosetta will be the first spacecraft to orbit a comet and to place a lander on the surface as it approaches and then swings around the sun.
ESA says the mission's objective is to help understand the origin and evolution of the solar system and investigate the role that comets may have played in seeding Earth with water.
Named after the Rosetta stone --- a block carved with ancient scripts that led to Egyptian hieroglyphs being deciphered -- the €1 billion ($1.36 billion) space mission was launched in 2004.
Since then, ESA says it has been around the sun five times as controllers line it up to meet comet 67P/Churyumov-Gerasimenko in August this year. For the last 31 months it has been in hibernation for the coldest part of the journey that took it close to the orbit of Jupiter.
After mapping the comet's surface it will release the lander Philae in November and monitor changes as it gets closer to the sun.
ESA project scientist Matt Taylor said if the project is successful it will advance the knowledge about comets.
"It's the first time we've made a rendezvous with a comet -- that's never been done before -- and it's going to be the first time we've escorted a comet past its closest approach to the Sun," he told CNN.
"The cherry on the cake is that we also deploy the lander to probe the surface of the comet.
"With these firsts it will enable us to make a quantum leap in our understanding of comets -- where they come from, their consistencies.
"Previous missions have only flown past comets at high speed. Rosetta will get within 5km (3.1 miles) when we deploy the lander and will be in pace with the comet -- we will be really up close and personal with it."
Taylor explained that the spacecraft was designed to be put in hibernation because even with massive solar panels the size of a basketball court, Rosetta would not have enough power to complete its mission without this energy-saving strategy.
The lander is equipped with harpoons to attach itself to the comet, which is about 4km (2.5 miles) long, and then drill about 20cm (8 inches) into the surface to analyze the chemical components.
Often described as "dirty snowballs," comets are known to contain a lot of ice but scientists want to learn more about their exact composition.
Barry Kellett, an astronomer and research scientist at the UK's Rutherford Appleton Laboratory, explained that when comets approach the sun, the ice melts and is turned into an ionized gas tail. The dust produces a separate, curving tail.
"Astronomers believe comets are made of pristine solar system material before the solar system was formed," he said. "They are the left over bits that never became a planet."
Some think that Earth may have received its water from comets, or even the chemicals that make up the building blocks of life on our planet.
"When Earth and Mars formed it would have been very hot so they would have formed dry," said Kellett. "And it was certainly very hot when Earth was hit by something that made the Moon. The only things we know that have a large amount of water on them are comets."
He said if Rosetta can establish the composition of this comet then "the question of where life came from might be better answered than before."
Rosetta's target comet 67P/Churyumov-Gerasimenko is known as a short-period comet. It reappears every six years as its orbit brings it close to the Sun. Halley's comet has a period of about 76 years and is not due to return close enough to Earth to be visible until 2061. Others only return after thousands of years.
Recently, comet ISON was mostly destroyed in its close encounter with the sun in November last year but it did provide scientists with fresh data in the process.