The European Space Agency announced Tuesday that its historic comet-chasing mission Rosetta had been extended until the end of September 2016.

"The adventure continues," the ESA declared.

"ESA's Science Programme Committee has given formal approval to continue the mission for an additional nine months."

In a final flourish, the spacecraft Rosetta may be "landed" on 67P/Churyumov-Gerasimenko, the comet it has been shadowing, the agency said.

In doing so, the mothership would rejoin the tiny lab it has nurtured in an odyssey spanning billions of kilometres (miles).

Launched in 2004, the mission has been applauded as a milestone in space exploration.

It comprises an orbiter, Rosetta, carrying a robot lab, Philae, which seek to unveil the secrets of comets -- primordial clusters of ice and dust that may shed light on the formation of the Solar System and on how life developed on Earth.

After a 10-year chase, the pair caught up with 67P last August.

In November, Philae was landed on the comet surface, and in a dramatic 60-hour episode carried out a range of experiments before its stored battery power gave out.

But the plucky 100-kilo (220-pound) lander has now revived, thanks to sunlight bathing its solar panels as the comet hurtles towards the Sun.

Both Rosetta and Philae will have a grandstand view when 67P reaches perihelion, its closest point to the Sun, on August 13, scientists hope.

The comet will then loop back into deep space, beginning another six-and-a-half-year trek around our star.

- 'Fantastic news' -

Rosetta project scientist Matt Taylor said the extension was "fantastic news."

"We'll be able to monitor the decline in the comet's activity as we move away from the Sun again, and we'll have the opportunity to fly closer to the comet to continue collecting more unique data.

"By comparing detailed 'before and after' data, well have a much better understanding of how comets evolve during their lifetimes."

The mission had been nominally funded until the end of December 2015, and its extension was not a surprise.

By the end of September 2016, "as the comet moves far away from the Sun again, there will no longer be enough solar power to run Rosetta's set of scientific instrumentation efficiently," ESA said.

"At (this) point, the spacecraft will most likely be landed on the surface of Comet 67P/Churyumov-Gerasimenko."

The idea would be to have Rosetta -- which is not designed for a landing -- spiral down to the comet over three months, using up its last drops of propellant to get unique closeups of the surface.

"But there is still a lot to do to confirm that this end-of-mission scenario is possible," cautioned mission manager Patrick Martin.

"We'll first have to see what the status of the spacecraft is after perihelion and how well it is performing close to the comet, and later we will have to try and determine where on the surface we can have a touchdown."

As of Tuesday, Rosetta was 294,739,926 kilometres (183,136,684 miles) from Earth, and 207,880,198 kilometres from the Sun, ESA said on its website (http://sci.esa.int/where_is_rosetta/).

Since the launch from ESA's base in Kourou, French Guiana, the mission has travelled 7.015 billion kilometres.