The Duchess of Palma de Mallorca, the Princess Cristina, the youngest of King Juan Carlos' two daughters, has been named a U.N. goodwill ambassador for next year's World Assembly on Aging in Madrid, U.N. officials said yesterday. The princess, 36, is the second goodwill envoy to be appointed by the world body for the April 8-12 meeting in Madrid. She joins celebrated French mime Marcel Marceau, 78, who was named in April. “Medical advances are enabling people to live longer and more productive lives,” the princess said in a videotaped message accepting the appointment. “As a representative of my generation, I can say that we are grateful to previous generations for these achievements and we look forward to reaping the benefits,” she said. Her task will be to promote awareness of the needs of older people ahead of the United Nation's second assembly on aging. The first was held nearly 20 years ago in Vienna. Her appointment follows a U.N. tradition of turning to prominent figures for help. Among the world body's “messengers of peace” have been Muhammad Ali and actor Michael Douglas.