Many people remember Sept. 11, 2001, as a day of helplessness and heartbreak. Carl Schroeder remembers it as the day he began to learn how much he could do to help.

Schroeder's searingly beautiful orchestral elegy, "Christine's Lullaby," in memory of the tragedy's youngest victim, will receive its world premiere today at Orchestra Hall. The extended family of the late Christine Hanson has flown to Minneapolis from the East Coast for the occasion. This will mark the second reunion visit between the family and the softspoken 21-year-old Minneapolis composer, who finds it strange to think that before Christine's passing, they were all complete strangers.

On Sept. 11, Schroeder was just days into his freshman year at St. Olaf College, a prospective music-composition major. As he struggled, along with other Americans, to grasp the enormity of the tragedy, one small corner of it began to pull at him.

He'd read in Newsweek magazine about 2 1/2-year-old Christine Hanson. A passenger on United Airlines Flight 175, Christine had left her home in Groton, Mass., that morning with her mom, Sue, and dad, Peter, bound for a Disneyland vacation. Their plane struck the south tower of the World Trade Center at 9:03 a.m.

"I wasn't able to forget that story," Schroeder said recently from his dorm room in Northfield, Minn.

"It all became symbolic for me. Christine became a symbol of the senselessness of human violence. It seemed to me the story was being made so complicated -- about a clash of civilizations and about the event reshaping the world -- when what really happened on September 11 was the death of innocence, the loss of our innocent future," Schroeder said.

He sifted through news of her family's story and found a Web site dedicated to the memory of Christine and her parents, packed with remembrances and condolences. Reading them, he said, "It felt like Christine had become a little more real."

Schroeder holed up for the following three days in a music studio on campus, where he set to work composing the five-minute piece, his first work for full orchestra.

He'd learned that Christine's favorite tune was the "Barney and Friends" song. So to start, he took the descending minor third from the opening of the TV show's theme song, "This Old Man," and gave it to a lonely harp, expanding it to sound a lot more like late Romanticism than TV kitsch.

He went on to incorporate the strong, hopeful sound of woodwind choirs, soaring violin lines doubled by flutes, and the solemn trumpet calls and soft, intermittent snare-drum rolls of a proud nation hobbled by grief. In closing, chimes symbolize the wind in which Christine had been traveling when she died, Schroeder said.

What makes the piece exceptional, said Schroeder's composition teacher, Timothy Mahr, is its "serene calm."

"I can't tell you the effect this music had on both my wife and myself," said Christine's paternal grandfather, Lee Hanson, 70. He and his wife, Eunice, and their daughter, son-in-law and two grandchildren are in the Twin Cities to hear the work performed by the Minnesota Youth Symphonies in today's concert at 2 p.m. in Orchestra Hall.

The Hansons first heard "Christine's Lullaby" last spring, when Schroeder sent them a recording made by the orchestra under the direction of Manny Laureano.

"We couldn't listen to it at first without crying," Hanson said. "In the first part, you can actually see a little child playing. It's almost as if Christine was there with him when he was writing it."

Schroeder explained: "What I wanted to do was create something that was an antithesis of what happened that day. . . . I wanted to bring back to life some of what was lost."

Visit to ground zero

Last summer Schroeder accepted an invitation to visit the Hansons at their home in Easton, Conn. He and Lee Hanson and Hanson's brother-in-law went to ground zero for the first time.

Standing in the observation area, facing the gaping pit below, Schroeder and Hanson felt compelled to look heavenward. "Maybe that's man's condition," Hanson said. "We are meant to look up."

Later, they took in other sights -- Times Square, St. Patrick's Cathedral, a boat tour. "We felt lucky we'd been sent this wonderful person, a wonderful young man, and he was here with us now," Lee Hanson said.

Eunice Hanson also spoke of how her granddaughter lives on, thanks to Schroeder. "In Carl's music I see her, I can feel her presence. It's beautiful. So beautiful."

Among the many condolences they've received, "this music is unquestionably the most special," Eunice said.

She is looking forward to the balm and comfort of this afternoon's music. On first hearing "Christine's Lullaby," she recalled, "I felt that she had come back to us through Carl. It was like she was sitting here giving us the message: 'I'm all right. Hey, I'm all right.' "

Gwendolyn Freed is at gfreed@startribune.com.