NASA’s Kepler telescope will end its search for exoplanets
Harmanjeet Singh Gurm
NASA’s Kepler telescope is running low on fuel after nine years of discovering exoplanets beyond our solar system.
“The Kepler telescope was launched in 2009 and its primary role was to search for planets orbiting other stars,” said Paul Delaney, director of the York University Astronomical Observatory.
“It had initially a four-year planned lifetime and we were going to be looking for about 100 to 150,000 stars … in the constellations of Cygnus and Lyra,” he said.
To observe the exoplanets, Delaney said Kepler used transit technique, which relies on the changes in the light intensity of stars when a planet passes between the star and the telescope.
“The spacecraft normally keeps itself oriented using reaction wheels basically known as spinning gyroscopes,” he said.
Delaney said a telescope needs fuel to operate these spinning gyroscopes, which helps it to point its antenna towards the Earth and send signals.
“In 2013, two of the four reaction wheels failed and that left the spacecraft unable to orient itself as carefully in space as NASA wanted,” he said.
Delaney said the failure of the two wheels gave birth to the K2 mission, Kepler’s second-generation mission where NASA used the two remaining reaction controller wheels and the thrusters to operate it.
“Now in 2018 after about three years of this K2 mission, we have now reached the point where the on-board fuel to help orient the spacecraft is all but exhausted,” he said.
Raymond Carlberg, a professor of the Department of Astronomy and Astrophysics at the University of Toronto, said after the failure of two gyroscopes, Kepler used solar panels to sail and direct itself, but it still needs rocket fuel to make the adjustments, which is gradually running out.
Delaney said NASA has turned off the data gathering capability of the spacecraft so they can turn it on one last time in August to download all of the data from its last observing run.
“We suspect that Kepler will run out of fuel in August, which basically means we are no longer able to maintain the pointing accuracy of Kepler, either towards the Earth for data transmission or towards a star field for observation,” he said.
“So running out of fuel is basically like a car running out of gas. You no longer have the capability of controlling the vehicle,” Delaney said.
Delaney said Kepler was absolutely fundamental and it revolutionized our understanding of how common exoplanets are.
“We were finding exoplanets, but it was a fairly slow process,” he said. “But what Kepler found in its first four years was nearly 4,000 exoplanets. It found something close to 5,000 exoplanets throughout its lifetime.”
Carlberg said Kepler increased mankind’s knowledge of other planets and was more successful than ever expected.
“I think in the case of Kepler, they will just abandon it into space because it is far enough that there is no danger that it will hit the Earth,” he said. “It will just wander around the space like an asteroid.”
Delaney said the Kepler telescope will be replaced by Tess, another telescope which was launched about three months ago.