In retirement, Nobelist takes up moon bouncing

If the moon is up, there’s a good chance Joseph Taylor is on his ham radio, using a homemade antenna in his backyard to bounce signals off the moon’s pockmarked face. It’s a skill Taylor began cultivating in 2003, shortly before he retired from Princeton University, where he used radio waves to probe the secrets of pulsars, the spinning, magnetized neutron stars that emit bursts of radiation with clocklike regularity.

The work earned Taylor and his Princeton colleague Russell Hulse the Nobel Prize in physics in 1993, for detecting a new kind of pulsar that shed light on the nature of gravity. In his Nobel lecture, Taylor said that scientific goals motivated him, but so did his affinity for “a good intellectual puzzle, and the quiet satisfaction of finding a clever solution.”

The same attitude has driven Taylor, now 74, to spend his retirement moon bouncing. “It’s possible, but it’s difficult,” he says. “If you succeed, it’s fun.” The task entails reflecting a radio signal off the moon rather than off the upper atmosphere, as regular ham transmissions do. Taylor calls it the Mt. Everest of amateur radio.

“You need to have a very sensitive receiver, the biggest antenna that you can manage and as much power as is legal,” Taylor says. (People often gawk at the contraption that soars above his garage on a 70-foot-tall telescoping tower not far from the university.)

The purpose is to communicate with fellow ham users, so Taylor usually sends a broadcast appeal using the radio shorthand CQ for “seek you.” He’s gotten more than 3,000 replies — reflected off the moon — from about 900 people. It’s just the latest phase of his lifelong radio hobby; Taylor got his amateur license at the age of 13.

When he’s not moon bouncing, Taylor goes to his Princeton office and still studies pulsars. In 1974, Taylor and his colleagues found the first pulsar locked in orbit with another object using a radio telescope at Puerto Rico’s Arecibo Observatory. The cosmic tango of the pulsar and its companion provided evidence for the existence of gravitational radiation, a central prediction of general relativity.

Taylor says his radio hobby offers much of the same excitement and reward of doing frontier science. Both require learning something new, he says. “So much the better if a good technical challenge is involved!”