On July 24, 1969, the Apollo space capsule, carrying the first men ever to walk on the moon, began its descent through the Earth's atmosphere.
The world held its collective breath waiting to see if the spacecraft would withstand the intense heat of re-entry and deliver the men safely home.
The whole world, it would seem, except Bill Borucki.
"Oh no," Bill says, "there was never any doubt in my mind that they would come back safely."
Bill, a space scientist at NASA Ames Research Center in Mountain View, had done the research that had gone into designing the heat shield protecting the astronauts.
"We knew what we were doing," Bill says. "We dotted all the i's and crossed all the T's. It was going to be a success."
What Bill was displaying at the time was a brand of confidence that would serve him well over the years.
Like in 1984.
That was the year that Bill determined It was possible to create a system of extremely sensitive instruments that, installed on a space-based observatory, could detect the presence of other planets in other corners of our galaxy. It would do so by measuring the diminished amount of light a distant star gave off when a planet passed in front of it.
Bill was convinced it would work. Others were not. "The reception was all very negative, and very uniform."
For the next 16 years, Bill lobbied whomever he could at the higher levels of the space administration. "They'd see me coming and they'd hide," Bill says.
Even after being turned down time after time, Bill still persisted. He eventually managed to cobble together enough money to build something of a prototype in his lab at NASA Ames, to prove that his idea was possible.
It was enpough to eventually convince the right people and, in 2000, he was given the green light to go ahead with his project, named Kepler.
"It really felt wonderful," Bill remembers. "We're finally going to get started building he spacecraft and get started finding those answers."
And find answers they have. The mission launched in 2009 and has been a smashing success. Over the past five years, Bill and his team have confirmed the presence of close to 1,000 planets orbiting stars other than our own.
In their biggest discovery yet, just last week, the team announced the discovery of Kepler 186f, the first Earth-sized planet within what scientists call the "habitable zone" around its star.
Bill is excited that his work, and persistence, have paid off in a way that could one day lead to the discovery of life on distant worlds.
Excited, but not surprised.
Asked if the mission has exceeded his expectations, Bill simply says, "No. It was right at my expectations."