Largely unnoticed by all but the wildlife and a handful of wilderness wanderers, the U.S government has, for decades now, been slamming rockets into the Arctic National Wildlife Refuge of northern Alaska.

The bombing, the National Aeronautics and Space Administration says, is nothing to worry about; it's merely a little fallout from science. Hikers who have stumbled on the debris, though, say it is more than a little unsettling. "These rockets would kill anyone near the impact site and would destroy a cabin," said Brad Meiklejohn, who found the tail end of a rocket in the Wind River drainage of the Brooks Range this summer and then started examining the debris field. "There was thick, half-inch metal shrapnel over a 100-foot radius around the rockets."

Not to worry, say the scientists. The rockets come from the University of Alaska Fairbanks' Poker Flat Research Range and are used almost entirely for auroral research, which means they only go up and come down in the winter when the aurora borealis is active over the North.

Rare is the traveler in ANWR in the winter, but Poker Flat doesn't take even that for granted, said Kathe Rich, operations controller at the launch facility. "We also do flyovers," she said.

Launch trajectories are calculated so that the landing zones for spent rockets will keep them away from cabins, camps, traplines or any sign of travelers in the Brooks Range Mountains, she said. Statistically, Rich said, NASA rocket scientists have calculated that there is a greater likelihood someone will be hit dozens of times by lightning than that they will be hit once by a rocket. The conclusion is one with which it is hard to argue. There is lots and lots of nothing in ANWR, especially in winter. The refuge covers about 19 million acres, but it attracts only about 1,000 visitors a year -- nearly all of them in the summer.

Rich said she couldn't provide the exact odds on someone being hit by a spent rocket. "That's a more complicated question than it sounds on the surface," she said. The main complication is that a variety of missiles of different size are fired from Poker Flat. They have different trajectories and fall back to earth as different size objects. NASA scientists back on the East Coast have done calculations for all the missiles in the Poker Flat inventory, however, and all the numbers are infinitesimally small.

"We're very careful about this," Rich said. "We have a standoff area around those areas" with people. Those areas would include villages, of which there are only a few; fish camps; trapper cabins; established camping areas and any other sign of humans.

No matter how logical this might sound, the people who report having stumbled into the remains of missiles in the middle of one of America's last great wildernesses admits to being a little shocked.

"It didn't seem real," said Dori McDannold, who encountered a missile on a gravel bar near the headwaters of the Canning River. "It just seemed so out of place. It was like you entered into some sort of time warp."

McDannold, like Meiklejohn, found the aft section of a missile about 10 feet long. Meiklejohn said it appears the spent rockets hit nose-down and the front part shattered on impact, sending pieces of metal spraying everywhere. McDannold said it was clear what would have happened if she'd been on the ground when the missile landed.

"I would have been squashed," she said. Meiklejohn had the same thought and more. "My reaction on finding the first rocket was disbelief," he said.

"My reaction on finding the second one two hours later was outrage and fear."

Not to worry, say the scientists, who can point to two rockets in the same general vicinity as a good indication that they're calculations as to where the rockets will land are pretty good. The rocket scientists aren't too worried about hitting anyone or anything. They are, however, a little concerned about the litter. Rich said that when people report the locations of spent missiles, Poker Flat does its best to retrieve them.