Plan for planet-hunter to refocus on black holes, exploding stars
New lease of life A joint Australian-US proposal could see NASA's Kepler space telescope turn its sights from hunting planets to studying supermassive black holes and exploding stars.
The proposal, by Dr Brad Tucker of the Australian National University's Mount Stromlo Observatory and the University of California, Berkeley and colleagues, follows a call from NASA to find a new use for the partially-crippled $US530 million ($AU557 million) spacecraft.
"The project I came up with is to study objects in galaxies outside of our own ... including exploding stars, otherwise known as supernovae, and supermassive black holes," says Tucker.
Since it was launched in 2009, Kepler has spent most of its time searching for planets orbiting stars.
But the spacecraft became crippled earlier this year limiting its ability to precisely pinpoint planets.
Under the proposal by Tucker and colleagues Kepler will spend more time looking at subtle changes in the brightness of stars, known as shock waves, that may occur just before it is about to explode.
"With Kepler we can see the evolution of a supernova event as it's exploding," says Tucker. "What we see during the event will provide clues about the composition of the star before it exploded."
The other part of the proposal will see the space-based telescope focus on supermassive black holes that exist at the centre of most galaxies in more detail.
Currently, when astronomers watch black holes destroying stars or consuming clouds of gas, they usually only see big events that can last from anywhere between a year to hundreds of years.
"What we've been wanting to do is find out if these black holes are active every single day, doing things that we can't see," says Tucker. "We know when black holes have a big dinner, but we also want to know when they're snacking."
He says this will allow them to see the moment that a black hole swallows a star, an event that only lasts for a few hours and can't be seen by ground-based telescopes.
Unlike ground-based telescopes, Kepler can survey large slabs of the sky, and repeat those observations every ten minutes.
"We can't monitor these things continuously from the ground," says Tucker. "But because Kepler is staring at the same patch of sky, if things happen we will see them."
He says Kepler's wide field of view - the amount of sky it can see without moving - means it can monitor more objects at the one time.
"It's kind of like your headlights when you're driving your car in the dark," says Tucker. "Kepler shines out and lights up a larger patch as you're driving ... it's like the fog lights of astronomy."
Tucker and colleagues won't have Kepler all to themselves. NASA plans to continue planet-hunting operations, albeit in a slightly different way.
"Kepler is still going to search for some transiting planets," says Tucker. "It will also use a technique called gravitational microlensing to search for planets."
Tucker says the proposal has the support of the Kepler science team but the final decision rests with NASA, which is expected to make a decision early next year.