Thursday, 22 November, 2018

Nasa declares elite planet-hunting spacecraft dead

NASA Administrator Jim Bridenstine in a file image the US space agency's Kepler space telescope has run out of fuel and is being retired after nine years The Kepler space telescope's end has finally come
Sandy Nunez | 02 November, 2018, 00:59

Only Kepler has discovered more than 2.6 thousand planets outside the Solar system.

Kepler showed us that "we live in a galaxy that's teeming with planets, and we're ready to take the next step to explore those planets", she said.

NASA's most prolific planet-hunter is powering down after almost a decade of revealing the diversity of our galaxy's planets.

The far more advanced James Webb Space Telescope, scheduled to lift off in 2021, should be able to reveal more about planets' mass, density and the makeup of their atmosphere - all clues to habitability.

Kepler allowed astronomers to discover that 20% to 50% of the stars we can see in the night sky are likely to have small, rocky, Earth-size planets within their habitable zones - which means that liquid water could pool on the surface, and life as we know it could exist on these planets.

Several of them are rocky and Earth-sized in the so-called Goldilocks or habitable zone of a star - an orbit where temperatures are neither too cold nor too hot, but just right for the existence of water, which is considered a key ingredient for life.

"When we started conceiving this mission 35 years ago, we didn't know of a single planet outside our solar system", said Borucki. "Now we know because of the Kepler Space Telescope and its science mission that planets are more common than stars in our galaxy". At the time of its launch, the telescope featured the largest digital camera ever tasked with space observation.

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Kepler has studied more than 500,000 stars in this way.

"The Kepler mission has paved the way for future exoplanet studying missions". "It was an extremely clever approach to doing this kind of science", said Leslie Livesay, director for astronomy and physics at NASA's Jet Propulsion Laboratory, who served as Kepler project manager during mission development.

Four years into its mission, mechanical failures briefly halted observations. But the mission team managed to devise a fix, switching the spacecraft's field of view roughly every three months. After completing its initial mission, NASA tasked Kepler with its extended K2 mission, which resulted in the spacecraft having surveyed more than half a million stars. It's also illuminated the tantalizing mysteries and possibilities among the stars.

NASA scientists are expected to spend the next decade trawling through data provided by Kepler in search of new discoveries.

"We know the spacecraft's retirement isn't the end of Kepler's discoveries", said Jessie Dotson, Kepler's project scientist at NASA's Ames Research Center in California's Silicon Valley.

In a briefing with reporters, agency officials said that Kepler ended operations after exhausting the last of its hydrazine fuel used for attitude control. A new planet-hunter, named TESS, was launched in April and Kepler has been left drifting around the Sun more than a hundred-and-fifty-million kilometres from Earth. Like Kepler, TESS looks for very small, periodic dips in brightness of stars caused when planets pass in front of, or transit, those stars.

Planetary exploration is going through a wider-ranging changing of the guard: For example, NASA's Dawn mission to the dwarf planet Ceres is ending, due to the same empty-tank issue that Kepler faced. It is created to cover an area 400 times larger than Kepler could manage and is expected to find some 20,000 or more exoplanets during the course of its mission.