As he sat chewing on a specially-formulated popsicle, 12 year-old Tian Tian looked very happy and very satisfied with himself.
"This is a surprisingly big weekend because panda breeding started early at the National Zoo," says zoo spokesperson Pamela Baker-Masson.
Baker-Masson says 11 year-old Me Xiang went into heat on Friday, several months earlier than expected.
It's an event that only happens once a year and lasts just 48 hours.
But Tian Tian, and the zoo scientists, were ready.
"He knows that she's gone into heat," Baker-Masson says. "They were very active yesterday and mated. Because we didn't believe it was a competent mating, that's when we decided to perform the artificial insemination last evening and again this morning."
Scientists have tried to inseminate Mei Xiang at least eight different times in the last seven years. The only success resulted in 4 Â½ year old Tai Shan, the first panda cub ever successfully bred at the National Zoo, born after scientists artificially inseminated Mei Xiang using Tian Tian's sperm in 2005.
Tyson Eakman and his family are visiting from Albuquerque and say they came to the zoo just so they could see the pandas.
"I think it's great," Eakman says. "I think anytime they can mate in captivity it's a miracle."
But his seven year-old son Caelin says he's sad that Tai Shan is going back to China in the next few weeks. "I really wanted to see the pandas for a long time," Caelin admitted.
Tian Tian and Mei Xiang are next, scheduled to go back to China in December.
Even though it's a done deal for Tai Shan, zoo officials might be able to keep his parents a bit longer.
Baker-Masson says they plan to renegotiate their contract with China this spring and it's highly unlikely that anyone will want to move Mei Xiang if she gets pregnant.
Meaning all eyes are on Tian Tian to see if he, and his human helpers, got the job done.