'A city that mourns'

It's one minute into Sept. 11, 2003, and the first commemoration of the day is underway. Sixteen construction workers walk up a newly poured concrete ramp from the bowels of what was the World Trade Center. They cross the rim of the North Tower site, then round the corner of the South, and pause before the rusted cross, melded of steel girders, now enshrined in a concrete base at the southern edge of Ground Zero.

Hardhats come off, heads bow. Some kneel at the foot of the cross, and a long moment of silence follows. These Port Authority workers labor in round-the-clock shifts under deadline to complete a new transportation hub at least 10 stories below street level.

The main ceremony to commemorate the second anniversary of the Sept. 11 attacks is eight hours away. Already hundreds of family members have made the pilgrimage. They wear special identity badges that will allow them into the below-ground areas of Ground Zero in just a few hours when surviving children begin calling the long roll of victims' names. Thousands of family members will walk down the same ramp where the construction crew surfaced to lay bundles of roses over the capped rubble in remembrance of the 2,792 who died.

Later, under the heady end-of-summer sunshine of Sept. 11 a children's choir will sing The Star-Spangled Banner. Bagpipers and drummers will play Amazing Grace. And Mayor Michael Bloomberg will declare, "Today again we are a city that mourns."

These cannot wait, but make hushed memorial rounds of the complex in the wee morning hours of the second anniversary. Some stand back, wide-eyed, trying again to comprehend how two buildings once stretching a quarter-mile into the air were reduced to dust in just a few hours' time. Others move close, pressing teary faces into the fence, poking flowers and family mementos through openings in the grillwork.

One young burly policeman stands at stolid attention, his eyes focused on the air where the buildings once were and his face suddenly full of tears. A man in a suit, fiftyish, sidles up and throws an arm over his shoulders. He thanks the policeman for his loyalty and service: "We'll always remember." He says his daughter lost her husband here, and his two grandchildren lost their father. He doesn't want to give their names.

Nearby a group of families from Colombia congregate. Most have made the trip from Bogota to be with the relatives of 34 Colombians who perished here Sept. 11. Villoria Duque says she, like others, has more questions than answers on the two-year anniversary. "Why would they do this to the United States? Everybody wants to come here. Why does everybody hate the United States, and want to stay here? Everybody needs help, and who helps? The United States."

Two years later, Ground Zero is a centripetal shrine that pulls in victims and rescuers, suits and slackers, warriors and pacifists, strangers and friends, the near and the far-off.

Lower Manhattan's resurgent prosperity is like a paper membrane over the not-too-distant memory that here, on a Tuesday morning, the greatest nation on earth was brought to its knees.

Charles Pellegrino brings both scientific mind and emotional attachment to Ground Zero. At midnight he has come to stroll the perimeter with firefighters who assisted him in what he calls "forensic physics" in the weeks after the 2001 attacks.

Mr. Pellegrino, a physicist, paleontologist, archaeologist, sci-fi author, and sometime oceanaut, is best known for theories on ancient DNA that underpinned the novel and film Jurassic Park. In the real world, his expeditions into the wreckage of the Titanic are yielding discoveries about ocean life that could lead to whole new strains of medicine.

At Ground Zero he wears a family-member badge. His cousin died working on the 98th floor of the North Tower. Another friend also worked there but survived because she reported in sick that day; she is now Mr. Pellegrino's fiancŽe.

Mr. Pellegrino was in a deep-diving submersible in the north Atlantic exploring the deck of the Titanic when two planes flew into the Twin Towers. He learned about the attack from astronauts aboard the space station. "We could get through to the space station but not to New York," he says. The space station collected high-resolution satellite photos showing a black plume cloud stretching from Manhattan out 150 miles across the Atlantic. Astronauts e-mailed those to the Titanic crew with a note reading, "Tears do not flow the same way in microgravity."

Mr. Pellegrino says, "Archaeology is about the people who were there, and so it is never unemotional." With a resumŽ filled with extensive archaeological research at other disaster sites, like Mt. Vesuvius and Nagasaki, he was reluctant to enter Ground Zero, particularly after learning of his cousin's death. "But I have this background only a few Americans have," he explains, and so in the fall of 2001 he became a round-the-clock resident forensics specialist at the site.

His job was to map the surge cloud created by the collapse of both towers, to chart both the path of destruction and what physicists call a "shock cocoon," areas of safety in the midst of the destruction.

So he spent weeks in parts of the South Tower, and in stairwell B of the North Tower, places only a few feet wide where people somehow survived. He examined intact phone books embedded in car roofs and discovered a pile of 300 law books, charting their safe trajectory out of one of the buildings. An unscathed Beanie Baby, he says, "is still giving me nightmares."

In between expeditions into the smoldering rubble, he rested at nearby St. Paul's, where he says parishioners tried to persuade him out of his agnosticism. "If you are a scientist, you follow St. Thomas. You believe only what you can see," he tells WORLD.

What he did see went undetected by many rescue workers: steel girders jutting from the building wreckage twisted "identically" to the way he found the stern of the Titanic.

"Every new piece, every new bend in the metal changes the picture. I have a good photomosaic of this building in my mind," he says a little regretfully. But his research is now being applied to predict and minimize the destruction of future manmade and natural disasters.

"What we are learning about the physics of the downblast and the surge cloud could one day save more lives than the terrorists took," he says.

Surrounded by Sept. 11 memorabilia, Mr. Pellegrino is the rare pilgrim who spies a future in Ground Zero's past.