Overcoming years of repeated rejections, a persistent William Borucki conceived, designed and now is leading NASA’s Kepler space mission that will bring the world a step closer to knowing whether life exists on other planets orbiting distant stars.
The Kepler space observatory launched in 2009 and still in operation today is the culmination of Borucki’s nearly 30 years of pioneering work demonstrating a technique for discovering thousands of planets orbiting distant stars in our region of the Milky Way. Many of these planets are the size of Earth or larger, and a small portion of these exist in the habitable zone—the region around a star where water may exist.
While the scientific objective of the Kepler mission is to explore the structure and diversity of planetary systems as far as 1,200 light years away from Earth, the ultimate outcome could be even more profound.
“The result of this mission will be one of the most important scientific discoveries of any century and will forever change humanity’s perception of our place in the cosmos,” said S. Pete Worden, director of NASA’s Ames Research Center. “Kepler is showing that planets are common in our galaxy, opening up the very real possibility that life exists elsewhere in the universe.”
Worden said Borucki’s intense personal commitment, scientific knowledge, exhaustive mastery of many technological challenges and sheer persistence won over skeptical astronomers and NASA managers, making the idea for the Kepler mission an extraordinarily successful reality.
By the spring of 2013, the Kepler orbiting telescope had catalogued more than 2,700 planet candidates and confirmed 114 as planets. It has discovered the first rocky planet in the habitable zone of another star; a tightly compacted six planet system; the first pair of planets orbiting a double star; several planets in the habitable zone of sun-like stars; and planets as small as the size of Earth’s moon.
Borucki initially published a seminal paper in 1984 that discussed the requirements for detecting presumed planets outside our solar system using photometry. This technique involves measuring the total light from many stars and looking for small and periodic dips in total luminosity that occur when a planet crosses in front of its star, the signature of a possible but unseen planetary body. As described in the paper, the project required high precision space-borne imaging detectors which had not yet been developed.
In 1992, NASA solicited ideas for mission concepts that could be developed at a moderate cost. Borucki’s idea was rejected because the necessary detectors were thought not to exist. Borucki and his colleagues then demonstrated that detectors could accomplish the mission goals when corrected for systematic errors, but his second proposal was rejected in 1994 because NASA said it would be too expensive.
Undeterred, Borucki refined the mission to reduce its complexity and cost, but his plan was rejected for a third time in 1996 because he had not proven that the proposed instrument could make high-precision measurements of thousands of stars simultaneously.
Borucki and a NASA team spent the next two years building the needed instrumentation and demonstrating that it could observe 6,000 stars simultaneously. A fourth proposal was submitted in 1998, but that too was rejected because of concerns the system could not get the required precision in the presence of on-orbit noise. Borucki solved this problem, and on his fifth attempt in 2001, the Kepler mission was finally selected for flight—a process that took another eight years of work before the launch could take place.
“Bill Borucki is a hero. He has singlehandedly developed the idea to detect Earth-like planets orbiting other stars,” said Geoff Macy, a Kepler science team member from the University of California at Berkley. “When he came up with the idea years ago, people thought he was crazy. He didn’t mind the criticisms and just kept going.”
“You must be persistent and really show people that it can be done and convince them to join your team,” said Borucki. “I knew that the photometric detection of Earth-size planets would work, and I knew the results would be extremely valuable. Therefore there was no reason to ever give up. No matter what the obstacles, you must always push on.”
Borucki said the mission has involved hard work and dedication by many scientists and will “help mankind learn whether or not there are other Earths.”
“The next step will be to determine the composition of their atmospheres, and only then can we go there—but first we have to know what is out there. It’s like building the foundation for a cathedral. We are making discoveries that our children will build upon.”
Borucki has been with NASA for more than 50 years and worked on some of the agency’s most compelling projects that include the Apollo space program’s heat shields for returning spacecraft. The Kepler mission is the culmination of an interest in space that started as a boy observing the dark night skies and launching homemade rockets in Wisconsin.
Michael Bicay, director for science at the Ames Research Center, said Borucki found a way to “make his dream come to fruition.”
“The findings of this mission will fundamentally rewrite our textbooks and have a philosophical and theological impact on our society,” said Bicay. “We will be essentially one step closer to finding out whether we aren’t alone in our galaxy.”