The ground controllers sent the final orders to the Kepler NASA telescope, disabling the space ship's spacecraft and switching off the automatic recovery software after the planetary observatory ran out of fuel last month.
The last signals to Kepler were broadcast from the control center at the Laboratory of Atmospheric and Space Physics (LASP) at the University of Colorado in Boulder, through NASA's Deep Space Network, on Thursday evening.
The engineers ordered Kepler to turn off the radio transmitters, which is a standard procedure when deactivating a space mission to ensure that erroneous signals do not interfere with communication using the same or similar frequencies. The commands also prevented Kepler's on-board computer from trying to re-engage the transmitters and contact Earth.
"As the spacecraft is slowly spinning, the Kepler team had to carefully extend the time it takes for commands to reach the spacecraft during periods of vital communication," NASA said on Friday. "The team will be monitoring the spacecraft to make sure the commands are successful."
NASA announced on October 30 that Kepler was out of fuel and there was no stability in looking for planets around other stars.
Launched in 2009, Kepler is circling the Sun at a distance of 94 million miles (151 million kilometers) from Earth. On the current path, Kepler flies a bit further from the Sun than Earth and travels around the Sun a bit slower than Earth.
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The spacecraft will be more distant from Earth in the coming decades before the Earth begins to catch again. In 2060 Kepler will return to the Earth – but far beyond the orbit of the Moon – and the gravity of the planet will pull the telescope into orbit slightly closer to the Sun, and the one that moves faster than the Earth.
The reversal will take place in 2117, when Kepler and Earth will converge again, and gravity will push the space ship into a further, slower orbit. As predicted by NASA, it is expected that this scheme will continue in the near future.
In the meantime, the researchers are continuing to analyze the data collected during the nine-year Kepler mission, worth $ 692 million.
Kepler collected the last scientific observations in September, ending the course in which over 530,000 stars were observed and returned 678 gigabytes of data. Kepler's findings have helped astronomers write almost 3,000 scientific publications, the number of which will continue to grow.
Astronomers using data collected by Kepler confirmed the existence of 2681 planets orbiting other stars, with another 2,899 planets that could be confirmed by observations.
"We've found small, potentially rocky planets around some of these bright stars, and they are now the main goals of current and future telescopes so we can go on to see what these planets are made of, how they are formed and what their atmosphere is." said Jessie Dotson, a project scientist at Kepler in Ames.
"While we have ceased to perform space operations, the results of the Kepler data will continue for many years," she said.
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