It's been a tumultuous year at the National Zoo--deaths, investigations, resignations--but you wouldn't know it from watching Tian Tian and Mei Xiang happily eating bamboo in their $3-million home in Rock Creek Park.

The world has changed since we got our first pandas. Six presidents have come and gone. Soviet-style communism has crumbled. China is an emerging economic giant. But since April 20, 1972, pandas have brought smiles to the faces of millions of Washingtonians and tourists. This spring and summer will be no exception.

For nearly three decades Washington was the only place in the United States where you could see pandas. Our originals, the female Ling-Ling and male Hsing-Hsing, came as gifts of the Chinese government when outsourcing was the least of our international problems--and rapprochement was our goal with the secretive Asian power.

The two pandas symbolized hope that the Cold War one day might end. Even as that hope was realized, the pandas' annual attempt at breeding became a reminder of the frustration and uncertainty of life itself. Over the years, Ling-Ling gave birth to five panda cubs, but none lived.

The pandas' very public attempts to breed became a ritual of spring. When the zoo decided to import a rough-edged stud from London to impregnate Ling-Ling, he was sent packing with headlines blaring BRUTE GETS BOOT.

For their first ten years in Washington, Ling-Ling and Hsing-Hsing lived separately. The Chinese had told the National Zoo that the pandas would be likelier to reproduce if they were together only when Ling-Ling was in heat. But it wasn't until they were allowed to live together that Ling-Ling started getting pregnant.

By then it was too late--her best childbearing years were gone. When she finally started having cubs, they didn't survive. Embarrassing as the failures--and the media coverage--were, Ling-Ling and Hsing-Hsing grew ever larger in the hearts of Washingtonians.

On December 31, 1992, Washington's beloved Ling-Ling toppled from her platform and fell dead to the ground. A heart attack was blamed. Hsing-Hsing carried on for seven years until he was euthanized in 1999 by then-chief veterinarian Lucy Spelman, who is soon to be the zoo's former director. Hsing-Hsing was believed to be 28, very old for a panda.

The politics of panda-giving are now very different. China is no longer inclined to give away animals as state gifts. In fact, the giving of wild animals as state gifts has become politically incorrect. Some conservationists believe the world's 1,000 remaining pandas should remain in their natural habitat.

By the 1990s, Washington was no longer the only place in America where you could see pandas. In 1996, San Diego got two pandas on a research loan from the Chinese. The Atlanta zoo did the same. Money from the leases was going back to China to support conservation efforts in panda habitats. Zoos argue that allowing Americans to see pandas in captivity supports Chinese efforts to conserve them in the wild.

It didn't take long after Hsing-Hsing's death in 1999 for Smithsonian head Larry Small and other officials to realize that Washington's National Zoological Park, minus the pandas, would not be a happy place. For almost 30 years, the National Zoo had been the nation's panda home.

A deal was done. The Smithsonian agreed to spend $5 million to refurbish and upgrade the zoo's panda house, adding ponds and two "cool spot" grottoes in the yard so the pandas could get out of the sun. New quarters for keepers and a bamboo-storage facility are also under construction.

The Zoo agreed to pay China $1 million a year for ten years in exchange for a pair who might breed and produce little pandas. In December 2000, Mei Xiang (pronounced may-zhawng) and Tian Tian (pronounced tyen tyen) were carted onto a Federal Express jet. It took off from Chengdu in China's central province of Sichuan and landed 17 hours later at Dulles International Airport.

Ling-Ling and Hsing-Hsing had been born in the wild. The new pandas were born in semi-captivity at the Wolong National Reserve, where China operates its Research and Conservation Center for the Giant Panda.

These two were slightly older on arrival than Ling-Ling and Hsing-Hsing were believed to have been. Tian Tian was born on August 27, 1997, Mei Xiang almost a year later, on July 22, 1998.

Even rookie panda watchers can tell the new pandas apart. Mei Xiang has a pale black bar across the bridge of her nose, while Tian Tian has black dots. The black area across Mei Xiang's back is wider than Tian Tian's.

Mei Xiang's name means "beautiful fragrance." Tian Tian's name means "more and more."

Mei Xiang is shy and gentle--nothing like Ling-Ling, her female predecessor, who was aloof and prone to temper tantrums. From a male-female perspective, the pandas seem to have switched roles. The late male Hsing-Hsing was a relaxed and loveable panda, easy to take care of. Tian Tian, the new male, has the intensity and impatience of Ling-Ling.

"When Tian Tian wants something, he is very driven," says head panda keeper Lisa Stevens.

Unlike their predecessors, the new pandas have been trained to accept human contact. This means that medical procedures, such as blood tests, can be done without the risks of anesthesia.

Each winter day each of the two pandas dined on nearly 60 pounds of bamboo, the main staple of the panda diet. They eat less in the summer. Pandas in the wild live almost exclusively on bamboo; Mei Xiang and Tian Tian also get treats like biscuits, apples, and carrots. It costs the zoo $20,000 a year to cut and transport bamboo from a grove in Maryland.

Like pandas everywhere, Mei Xiang and Tian Tian are not bundles of energy. Pandas tend to eat, then sleep. Then they sleep some more, perhaps dreaming of eating.

The best time to catch the pandas is early in the morning, when they are most likely to be eating. Mei and Tian usually come outside at 7:30. Their bamboo awaits them. Ling-Ling and Hsing-Hsing had strict feeding schedules, but Mei and Tian eat whenever they want.

The pandas' laid-back lifestyle has done nothing to diminish the excitement people experience on seeing them. Nearly a million people a year visit the panda house. On a typical summer weekend, the pair receives more than 15,000 visitors a day.

On a lucky day, zoogoers will see them wrestling or playing. On a very lucky day, they might see them mate. Pandas don't care for hot weather. As temperatures rise, they are likely to spend more time inside their air-conditioned house, although officials hope they will like the cool new grottoes built for them outside. For the best chance of seeing them rolling around in a barrel or playing with their toys, go to the zoo on the coldest day possible. Pandas love the cold.

But you don't have to go to the zoo to see them. You can monitor their activities, complete with crowd noise, via Webcam at www.natzoo.si.edu/animals/giantpandas.

While the Internet is good for many things, I find it's no substitute for the thrill of seeing the real thing. The lines of fans who have poured through the Olmsted walks of the National Zoo for the last 32 years are abundant proof of that.