NASA's Planet-Hunting Kepler Telescope Has Officially Run Out Of Fuel

It's the pioneering telescope which, for those of us on Earth, filled the galaxy with planets.

And now after a mammoth nine-and-a-half-year mission in search of potentially life-sustaining planets, NASA's Kepler Space Telescope has officially run out of fuel.

Six months after announcing the spacecraft's fuel stores were beginning to deplete, NASA announced Keplar's day had finally come on Wednesday.

As it orbits some 156 million kilometres from Earth, Keplar's radio transmitters will soon be turned off by mission engineers and the spacecraft will be left to drift forever around the sun.

Since being sent into space in early 2009 the telescope has found 2,681 confirmed exoplanets (planets found outside our solar system) and another 2,899 candidates.

"As NASA's first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond," said Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington.

"Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm."

Kepler's mission was to determine if earth-like planets are common or rare outside our own solar system and was originally intended to only last three-and-a-half years.

An artist's rendition of the Kepler in space. Image: Getty

Just shy of a decade later, the telescope has changed how we see the night sky and pinpointed 50 planets which may be similar to our own.

Four years into its mission, mechanical failures briefly halted observations. The mission team fixed the problem by switching the spacecraft's field of view every three months, giving the mission -- now dubbed K2-- a new life.

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As Dr Andrew Rushby, a former scientist at NASA's Ames Research Centre told ten daily earlier this year, one of Kepler's greatest contributions was the concept there are more planets than stars in our galaxy.

"Around every star in the galaxy, we’re confident now that there’s probably at least one planet -- so more planets than stars without a doubt and that’s something that Kepler has shown us," he said.

Now the telescope has reached the end of its life, Dr Rushby says it's no doubt a "sad milestone".

"It's difficult not to personify a spacecraft that revolutionised how we view the night sky and our place in the galaxy,and that affected my career and life so significantly" he said.

"However, with hundreds of gigabytes of data collected there are still many years worth of exciting science to do with the Kepler dataset and we expect many more planet discoveries, firsts, and weird and wonderful astrophysical phenomena are yet to emerge!"

Kepler's discoveries inspired the Twitter hastag #MorePlanetsThanStars, which NASA began circulating after the initial announcement Keplar's time was coming to an end in March.

Continuing with Kepler's work is NASA's Transitting Exoplanet Survey Satellite (TESS), which launched in April to survey an area of the sky 400 times larger than that observed by its predecessor.