Not that one needs an excuse to hold a moon-bounce, but this one is being held as a kind of advance celebration of the 40th anniversary next month of the Apollo 11 mission.

Image Michael Cousins, an engineer at SRI International, a non-profit that operates the dish, center, in the control room, with Ham operators Lance Ginner, left, and Jim Klassen. Credit... Jim Wilson/The New York Times

Moon-bouncing, also known as Earth-Moon-Earth communications, or E.M.E. requires a higher grade of ham-radio technology than that used for traditional earth-bound communication across parts of the radio spectrum approved by governments for amateur use. Only about 1,000 hams worldwide have stations capable of moon-bouncing.

Skill and luck also help. As the hams say, the moon is a poor sounding board, since it is spinning and has a rough surface that can disrupt signals. The hams’ voices must survive atmospheric interference over the long round-trip journey in a discernible form.

“It’s the equivalent of climbing Mount Everest in amateur radio,” said Joseph H. Taylor Jr., a Nobel Prize winner and retired physics professor from Princeton University who has written software to help radio buffs communicate via weak signals. “It’s possible, but only barely possible.”

Large dishes like those owned by the government and communications companies can solve many of these problems by making it easier to send and receive signals. That’s why the hobbyists have searched out retired or rarely used dishes. So far, operators of about 20 large dishes in the United States, Australia and Europe have agreed to participate in the event.