When the Hubble Space Telescope launched in April 1990, it was a miracle of engineering, the best telescope ever built, stationed 332 miles in space above Earth. But soon astronomers at NASA realized there was a problem: The focus was off because the main mirror had been ground just a hair too fine-about 1/50th of the width of a human hair too fine, in fact.
NASA announced this on July 2, 1990. The same day, Bob Gonsalves, E56, then a professor of electrical and computer engineering at Tufts, got a call from the space agency. It was convening a panel of experts to find a fix and wanted him to join.
“I was on vacation at Hilton Head Island in South Carolina but cut it short to make the July 5 meeting in Washington,” says Gonsalves, now retired after teaching for more than 30 years at Tufts.
NASA had called the right engineer. Back in 1976, he had published a paper on what’s called phase retrieval, about how a specific algorithm could be used to correct distorted images. “Phase retrieval is the very last step to make sure that everything is tuned up sharp as can be. It’s sort of like autofocus on a camera,” Gonsalves says. Fast forward to 1990, and “it gave a prescription to fix what was wrong in the telescope.”
