Walter Cronkite splashed down at 7:28 p.m. EST last night.

The world's most famous reporter--whose most memorable stint came in 1969, when he spent more than 100 hours before the camera describing the flight of Apollo 11--read his last story, appropriately enough an update on America's space shuttle project, and then turned to an estimated 29 million viewers for a moment of reflection.

Dry-eyed and steady-voiced, the 64-year old broadcaster, who will be replaced by Dan Rather as anchor of the CBS Evening News next Monday, said he felt "some sadness" at his departure, but added he feared too much had been made of his retirement.

Assuring his viewers he would continue to report and to broadcast. Cronkite said "Old anchorman, you see, don't just fade away. They just keep coming back for more."

Beginning next week, he said, "I'll be out on assignment and Dan Rather will be here--for the next few years."

Cronkite, who began his reporting career before World War II with the old United Press, included in the broadcast the line--"and that's the way it is--" that has been his signature for years.

Although he has reported the news from Vientiane, Paris, Moscow, China, Greenland and a hundred other countries and cities over the years. Cronkite was in his most familiar spot last nights behind his old-fashioned and slightly beat-up desk at CBS's New York studio.

The broadcast, which opened with an account of President Reagan's second press conference, touched on events in the Mideast, Atlanta, Poland, Afghanistan and Pakistan before concluding with the 64-year old broadcaster's 40-second au revoir to his audience.

Last April, Cronkite told a crowd of cheering Harvard seniors on Class Day that their task was to unseat a "modern Four Horsemen of Apocalyse:" over-population, pollution, scarcity of natural resources and the proliferation of atomic weapons.

A day later, the University awarded him an honorary degree. The official proclamation read, "In an era of instant news, he is a preeminent figure in contemporary journalism, friendly, reliable, percipient, forever telling us 'the way it is,"' and President Bok referred to him as "the most trusted man in America."

Across the campus last night, students gathered in front of T.V. sets to watch Cronkite say his farewells. "Dan Rather's all right, but next to Walter, he looks sleazy," one student said.

Higher praise came from John Chancellor, who concluded the NBC Nightly News with a tribute to his longtime rival: "He brought such distinction to his work as a network anchorman that he made the rest of us look a little better.