The journey will be eight days over an uncharted realm, alien to prior human endeavor, through extremes of pressure and a potentially hostile and toxic atmosphere.

It will require resilience, patience and power. No one knows if it will succeed. But the voyager has been tested, stressed and analyzed, and years of training and science have been brought to the mission by experts from across the nation.

A journey to the outer limits of sport will be taken during next month's Olympics by one man, a 19-year-old swimmer from Maryland named Michael Phelps. Yet it is also a cosmic test of how far the human body, even one as finely tuned as his, can be pushed.

This week, especially Monday night, as the U.S. Olympic swimming trials draw to a close here, coaches and sports scientists will get a better idea of how Starship Phelps may fare in Athens, "boldly going," as his coach puts it, where no swimmer has gone before.

Phelps, who lives near Towson in Baltimore County, is aiming to win seven gold medals in Athens, matching the feat of Mark Spitz, who did it during the 1972 Olympics in Munich.

But Phelps, if he keeps to his plan, must do much more than Spitz did three decades ago. In 1972, swimmers competed only in a preliminary and final of each Olympic event. And Spitz swam events in the relatively narrow distance range of 100 and 200 meters.

Now most events require a preliminary race, a semifinal and a final, and Phelps's events range from 100 to 400 meters.

"Physically the stress on what [Spitz] was doing is different than Michael because of the volume and the range," said John Walker, assistant director of national team technical support for USA Swimming, the sport's U.S. governing body.

In Athens, Phelps will shoulder an enormous workload, and on one night, Aug. 19, he may have to perform the unheard-of Olympic task of swimming three events -- two of them finals -- in about 50 minutes.

But Walker said Friday that the more punishing physical and psychological burden may be the sheer length of Phelps's program -- 22 potential swims over eight days -- starting on Day One with his most grueling event, the 400-meter individual medley.

"It's the cumulative effect from Day One to Day Eight," he said. "Eight days of consistent swimming. . . . Eight days of incredible stress.

"It's something no one's ever been through," he said. "No one's ever come close."

Though Phelps and his coach, Bob Bowman, 39, are the chief architects of his achievements -- Phelps holds three individual world records, including one he broke last week in making the team -- sports scientists and psychologists at USA Swimming and the U.S. Olympic Committee have for months been devising strategies to help him reach his goal.

His blood, and that of most competitive swimmers, is regularly tested during meets for levels of lactic acid, a byproduct of exertion that can tell scientists how hard an athlete is working and how well he recovers after an event. A buildup of lactic acid can inhibit performance and the traditional postrace "warm-down" is designed to flush it from the system.

The rate of "lactate clearance" is a measure of how quickly a swimmer recovers from one race to the next, said Genadijus Sokolovas, director of physiology for USA Swimming. Phelps's clearance rate is extremely good, an indication of superb conditioning, he said. But that will be severely tested in Athens.

Massage, which increases blood circulation, is also a fast way of clearing lactic acid, and Bowman said the plan is to use intense massage to help Phelps recover from back-to-back races. "They'll probably have one person on each arm," Bowman said.

Phelps's blood has also been tested for levels of cortisol, a stress hormone, Walker said. "It can give you indication if someone's experiencing overtraining or a lot of stress in their life."

With Phelps's cortisol levels, "nothing's been an issue," he said. But "there are times when you want to rule things out."

In addition, Phelps's blood has been tested for iron levels. Iron is a basic building block of hemoglobin, Walker said, which carries oxygen through the blood.

"A lot of athletes under a lot of stress tend to have low iron levels, and that's something that's very detrimental," he said. "It takes a long time to turn around, but it's very easy to prevent."

Phelps has met several times with Charlene Boudreau, a USA Swimming nutritionist who explained to him the art of postrace "refueling."

His sometimes erratic racing starts -- his reaction time and water entries -- have been carefully analyzed with above- and below-water cameras and a high-tech computer program.

Walker and his boss, Jonty Skinner, a former South African world record holder who heads the swimming agency's technical support program, also have conducted performance tests on Phelps to help determine how much swimming his body can stand.

Walker said they have conducted "rehearsals" of Phelps's possible Olympic program, essentially "looking at Michael over a seven- or eight-day period of consistent, peak-performance racing."

"We set up that in practice, or set up that in a competition cycle," he said. Phelps's endurance, performance and recovery were then analyzed.

"Michael's going into uncharted territory," Walker said. "The more information they can get, the better."

The current trials were also designed as a kind of dress rehearsal, and a test, for the Games, Walker said. The events here, which began last Wednesday and conclude this Wednesday, occur on the same sequence of days and in almost the same order as they do at the Olympics.

Monday night's program, in which Phelps is scheduled to swim the final of the 200 backstroke, the final of the 200 individual medley and the semifinal of the 100 butterfly, is almost an exact copy of the Olympic program the night of Aug. 19.

"It's important . . . that this is as much like the Olympic Games as we can get it," Walker said.

There is also a mental component to Phelps's task, which his coach thinks may be the most important of all.

"Can he kind of keep his focus?" Bowman said. "Shifting gears. Just being able to take whatever happens in the first race and leave it and go on to the next one and go on to the next one."

And anxiety consumes energy. The brain burns up about 20 percent of the body's calories, said Jim Bauman, a sports psychologist with the U.S. Olympic Committee.

"When we get people who are stressed and worrying, they're actually burning up emotional calories, and that takes away from the energy they need to swim the races," he said.

But Bowman said Phelps is calm, ready and eager for the challenge. He's doing it "because he can," Bowman said. "He's trained to do it. He grew up doing it. And he's capable of doing it."

"Boldly going," the coach said, "where no man has gone before."

Michael Phelps could swim in 22 races over eight days at the Olympics. "No one's ever come close" to doing that, USA Swimming's John Walker said.Physiologist Genadijus Sokolovas said Michael Phelps will be physically tested at the Olympics.