Ice and Trekkers’ Dreams Shattered at Top of World : Arctic: Two Italians feel lucky to be alive after harsh conditions end their polar walk from Siberia to Canada.

In a howling north wind, the temperature stood at minus 42 degrees Fahrenheit. Two explorer brothers had taken shelter in their tent on the restive ice pack that encrusts the Arctic Ocean.

Suddenly, with ominous cracks, ice splintered on three sides of them. The pack began to explode, tossing towering blocks of blue ice into the air.

Some sank into sudden openings of frothing sea. Others rained down, one atop another. One block smashed a sled. Fleeing another, one brother slipped into the water.

Thus, in the black heart of a winter’s night this week did a polar expedition five years in the planning collapse in five hours of terror.

Italian adventurer Reinhold Messner and his pediatrician brother, Hubert, hoped to walk 1,200 miles from Siberia across the North Pole to Canada without outside help. They carried supplies for 90 days in two sleds.

They walked two days--11 miles--and were lucky to get out alive. Responding to their frantic SOS, a Russian military helicopter plucked them to safety Thursday.

“They are OK, but Reinhold was still very agitated when he called by phone from the Russian base,” Marco Milani, one of the expedition coordinators, said Friday.

Messner, 50, who is considered history’s greatest mountain climber, intended the expedition to be his third and last “pole.” He has walked to the South Pole and is the first alpinist to have scaled Mt. Everest alone and without portable oxygen.

Man proposes. Nature disposes.

“I was afraid of dying,” Messner told Milani and fellow coordinator Alessandro Gogna from a Russian base at Sredny Island in the extreme north of Siberia. “There was a moment when Hubert and I thought we wouldn’t make it, surrounded by those towers of blue ice that rose up a few meters away, then fell back onto the ice pack and broke it, opening crevices in the crust. . . .”

Trapped on a thrusting peninsula of ice, the brothers struggled to rescue their equipment and scramble back to the main pack. Ice crushed one sled. Then Hubert, who walked with Reinhold across Greenland in 1993, slipped into water up to his waist. Somehow, he got out.

The loss of the sled with its precious food and supplies doomed the expedition, the first attempt to walk from Asia to North America. Previous expeditions have ended at the North Pole or failed in the attempt.

Once they scrambled back onto safe ice, it was the weather that nearly killed the brothers. It was hours before Reinhold was able to transmit an SOS on a hand-held electronic marvel called Argus that flashed his position to Toulouse, France.

Messner said in an interview with The Times before departing that the expedition was the most difficult he had ever attempted.

He was doing it, he said, “to live a piece of life. . . . If I make it, there’s not a lot to be gained. If I fail, I lose my reputation and a lot of money.”

A resident of the Italian mountain region of Alto Adige, Messner helps support himself by making a major expedition with commercial sponsorship each year.