A new opera for children, with music and libretto by Gian Carlo Menotti, will have its world premiere at the Kennedy Center in mid-April as part of the sixth annual "Imagination Celebration," a national children's arts festival. "We're hopeful that it may be picked up for television and produced in other places," said Jean Kennedy Smith, who commissioned the opera in the name of the Kennedy family as a gift to the Kennedy Center in honor of her brother, John.

Titled "A Bride From Pluto," Menotti's opera has a moral, lots of action and color, and a theme in which visitors from outer space intrude into the life of an American family. "I've read the script and seen a sort of preview of the high points," said Smith, a trustee of the Kennedy Center. "I like it very much, and I think Jack would have liked it, too."

The idea originated two years ago, when Smith was the chairman of the Kennedy Center's education committee. She had met Menotti at the Spoleto Festival in South Carolina, and when she read an interview about his interest in children's opera, she thought that an opera would be a good gift from the Kennedy family for the Kennedy Center's 10th anniversary. Details were worked out in a meeting between Smith, Menotti and Roger Stevens.

The opera will be directed by Menotti and produced by Jack Kukuk, director of education for the Center. No details are available on the designer, music director and cast, on which final decisions will be made when Menotti returns from a vacation in Europe.

The production will include exotically clad creatures from outer space, notably the Queen of Pluto, whom a plot synopsis describes as "a very peculiar young woman with a costume of bulbs that light up and buttons to push." Using a device that allows her to see what is happening anywhere in the universe, she has scanned all available suitors and decided to choose a young earthling named Billy (who is engaged to another earthling named Rosie) as her husband. Billy accepts the proposal, but gets cold feet when he discovers a condition for the marriage: He must undergo an operation to replace his heart and soul with an electronic machine. The faithful Rosie finds a way out of this problem, and once again wins the hand of her fickle fiance'. From the outline provided, it seems to meet Menotti's specs for a children's opera, which include action, pageantry, slapstick comedy amd psychological simplicity. "An audience of children is a merciless one," according to the composer. "Inside the theater, just as they are quickly enchanted, children become easily bored and do not forgive boredom."

"A Bride From Pluto" will be the third Menotti opera for children to reach the stage, not counting "Amahl and the Night Visitors." The others were "Help, Help, the Globolinks!," which also has an outer-space theme, and "Chip and His Dog." Another opera for children is scheduled for a premiere in Wilmington later this year.