With its bubble cockpit forward and its arsenal of ballast tubes, the Johnson Sea-Link I, a 22-foot research submarine, looks like something out of "Star Wars," But this month it is traveling not to the future, but to the past.

At least twice each day it descends from a space age research vessel rolling in the legendary Hatteras seas 16 miles offshore to a century-old shipwreck on the ocean floor.

There is the errie blue twilight 210 feet down it peers with floodlight eyes into the history-laden wreck of the USS Monitor -- the Civil War ironclad that launched a modern Navy.

The Sea-Link forms part of what government officials call the most ambitious underwater archeological excavation in this century -- a 28-day, $275,000 effort to unlock the mysteries that were sealed inside the Monitor when she foundered in a gale Dec. 31, 1862.

The Monitor was less than a year old when she sank, but with her flush decks, rotating sun turret and screw propeller, she already had revolutionized naval warfare.

Easily outmaneuvering a ship more than twice her size, bearing 18 guns to her two, she battled the Confederate ironclad Virginia (formerly the Merrimack) to a historic stalemate in Hampton Roads on March 9, 1862, thus preserving the naval blockade that ultimately won the Civil War and saved the Union. Confederate forces scuttled the Virginia in Norfolk two months later.

Military observers from Prussia, Russia, Britain and France flocked to view and copy the plucky little Union warship that sealed the end of naval battles by broadside in the age of sail. By the Civil War's end, the U.S. Navy had more than 60 monitors under construction or on order, some of which would see duty as late as World War I.

The original ship, however, remained lost for 111 years until a Duke University expedition in 1973 found her capsized on the ocean floor, her hull plates shattered by World War II depth charges and her characteristic turret askew beneath the wreckage.

Later expeditions confirmed her identity and two years ago divers retrieved a 60-pound section of armor plate and the red lantern that had signaled her final message of distress.

The current effort, however, aims for much more.

Divers tethered to the Sea-Link have set up permanent base reference points for the wreck and have begun to excavate portions of the captain's cabin near the forward part of the vessel.

They are searching clues not only to the ship's last hours -- and the fate of the 16 men lost with her -- but technical details of her structure and design as well.

Many of the original plans for the Monitor were lost after her hasty 100-day construction, and though individual drawings keep turning up, the complete plans are believed to be scattered all over the world.

North Carolina state archeologist Gordon Watts also hopes to obtain samples of deck timber which could give clues as to whether the ship remains strong enough to be raised.

Most of those involved on the current expedition, however, think proposals for raising the ship show less immediate promise than studying her where she lies.

Watts points out that the Monitor lies in both better and worse shape than scientists originally hoped to find her.

Propped upside down on her turret and foredeck pilothouse, he notes, the Monitor supports at least 50 percent of her own weight, indicating the ship retains some frame stability.

But many of the armor plates lay broken and scattered and in some sections the Monitor's frame itself lies bare.

Watts, one of the Monitor's 1973 discoverers, said at the time the ship may well have been depth-charged when U.S. ships fought a life-and-death struggle against German U-boats during World War II.

The Germans decimated Allied shipping off Cape Hatteras in 1942, and often hid from sonar searchers among the nearly 700 wrecks that cluttered the ocean floor here in "The Graveyard of the Atlantic."

Ernest W. Peterkin of Camp Spring, Md., generally conceded to be the foremost scholar of the Monitor, says he has turned up records of a depth-charging of a suspected submarine in the area near the Monitor wreck by U.S. Navy ships in 1943. Watts still hopes to find brass detonators from that attack in or around the wreckage.

So far the artifacts turned up have been older and more mysterious. They include:

A small octagonal bottle, embossed with "mustard" on one side and "U.S. Navy" on another, apparently a relic of salt beef dinners in the Monitor wardroom.

A green glass, hand-blown wine bottle of a type made between 1840 and 1870. "It appears," said Watts dryly, "to have contained champagne."

Other less obvious artifacts litter the wreck site but the researchers' time on the bottom is so restricted that the expedition has concentrated almost entirely on excavating one 25 square foot area into the captain's cabin.

The divers work one at a time, rubber-suited against water temperatures that range from the low 60s to the mid 70s as the warm Gulf Stream eddies back and forth across the site.

The workers breathe a mixture of 90 percent helium and 10 percent oxygen to ward off the disorienting "rapture of the deep," nitrogen narcosis. For each hour on the bottom they must spend four hours under pressure purging their tissues of nitrogen that can bring the "bends," and agonizing paralysis of death.

It is not an environment for the claustrophobic.

"I once had a guy freak out in here," said diver Richard Roesch as he tugged shut the pressure hatch of the Johnson Sea-Link's tomblike aluminum diving chamber. "Tore his fingernails off trying to claw his way out."

The 1979 Monitor expedition is a joint project of the state of North Carolina, the National Oceanic and Atmospheric Administration, which made the Monitor wreck site the nation's first marine sanctuary, and the Harbor Branch Foundation of Fort Pierce, Fla., a private nonprofit ocean research and development foundation underwritten largely by the Johnson and Johnson Band-Aid fortune.

Harbor Branch has made possible most of the current effort, not only with money but with its equipment and personnel that rank among the most sophisticated in the world.

NOAA hopes other groups, public and private, will sponsor suitable research at the site in the future.

That seems likely, for the Monitor seems to hold enduring fascination for a wide assortment of people.

They include:

Peterkin, a retired satellite projects manager at Washington's U.S. Naval Research Laboratory, who has spent 12 years studying the vessel. He whiles away time sketching three-dimensional engineering drawings of things as esoteric as the Monitor's coal scuttles and blower ducts.

Roesch, 29, who deserted the high-profit commercial diving world and took a $20,000 annual pay cut for the chance to dive on the ship that has fascinated him since he read about it as a schoolboy in Indianapolis.

Maria Templeton, Ewing Township, N.J., who has studied the Monitor for 20 years and compiled a 2,000 item collection of Monitor memorabilia ranging from original sheet music of a 19th century Monitor song to a piece of whalebone scrimshaved with scenes of the Monitor-Merrimack battle.

"I was a science fiction artist even as a child," she said, "and when I first saw a movie on television about this ship I was absolutely fascinated. It even looks like something out of science fiction. I couldn't believe until I read the story of her building and her battles that I could ever find anything in real life as heroic and larger than life as the things I'd dreamed.

"The Monitor just has so much charisma, don't you think?"