PALMDALE, CALIF., NOV. 22 -- With a guard dog standing under each wingtip, the nation's $500 million Stealth bomber was rolled out of the dark of its top-secret hangar here today into the sunshine of open space for its public unveiling.

Shouts and cheers from hundreds of the 2,200 Northrop Corp. workers who built this newest strategic bomber erupted as the hangar doors parted, revealing a black-and-gray radar-evading aircraft that looks like a stingray.

"We are not just rolling out America's newest strategic bomber," said Air Force Secretary Edward C. Aldridge Jr. "We are ushering in a new age of strategic deterrence."

The Air Force secretary said it was "America's enduring hope and prayer that this magnificent aircraft will never fly in anger" but instead will further deter nuclear war between the United States and Soviet Union.

Should deterrence fail, the mission of the Stealth bomber is to fly high over the Soviet Union searching out and destroying missiles that have not already been fired and knocking out command posts untouched by retaliatory waves of U.S. missiles fired earlier from land and sea.

The bomber, designated the B2, looked strikingly sleek and small as it stood on a prairie of cement outside the Air Force factory where it was assembled. Every surface has been smoothed and rounded to slip through rather than reflect radar beams. The flying-wing shape has a rounded cockpit on top, big enough to accommodate the two pilots plus at least one or two extra to serve as relief crew during an exhausting flight from the United States to the Soviet Union and back.

The plane is powered by four jet engines in pods atop the wing, with heavily masked air intakes and exhausts to reduce detection from radar or heat-seeking sensors. The B2 will fly at subsonic speeds, and will need aerial refueling to reach Soviet targets from U.S. bases and return.

Using space-age materials such as carbon composites that absorb radar energy, the plane is designed to offer a tiny radar profile, so it can close in undetected, giving defenders no time to shoot at it. Under development for 10 years, it can carry nuclear and conventional missiles and guided bombs, and depends entirely on computers to maintain stability in flight.

Although the swept-back wing is 172 feet across, about the same as the older B52, the length of the tailless B2 is only 69 feet, about the same as a F15 fighter.

The Air Force plans to build 132 of the bombers, with the one rolled out today scheduled to fly early next year to nearby Edwards Air Force Base, where it will be tested, and become operational in the 1990s. The cost of the fleet of 132 bombers ranges from $60 billion to $70 billion, or from $450 million to $500 million a plane. Aldridge said the Air Force will provide detailed B2 cost estimates when it submits its fiscal 1990 budget in January.

The Air Force until today has cloaked the Stealth bomber program in secrecy. Aldridge said the Air Force decided to reveal what the B2 looks like because it would soon be flying anyway, meaning the service would not be able to hide the plane's appearance from either the American public or the Soviets, who have spy satellites staring down on this countryside of brown desert and sharp hills.

Hundreds of Northrop security police, some leading police dogs, watched reporters and other guests every step of the way as they moved around the Air Force plant here. The bomber was kept 200 feet away from reporters and guests in the grandstand, with its nose pointed toward the guests so the secret features of the flying wing's aft end were not revealed.

In U.S.-Soviet negotiations to reduce the strategic weapons now pointed at each superpower, there has been agreement that each side should be able to look at the weapons of the other through on-site inspection. Critics of the B2 contend the Air Force secrecy imposed on the bomber will undercut those arms-control negotiations.

Asked here today whether he would allow the Soviets to get a close look at the Stealth, Aldridge replied, "We'll let them count it, but we're not going to let them get up close to it." If he had his way, said the secretary, who has announced he will leave office soon, the Soviets would get no closer than the 200-foot range reporters and guests were kept at today.

Another criticism of the B2 is that it could make the Soviets nervous and less willing to hold their nuclear fire in times of tension. Under this theory, espoused by the Union of Concerned Scientists and others, the Soviets would see U.S. missiles such as the MX as a first-strike threat to Soviet missiles. The B2, which would fly as a mop-up operation after the United States had launched its missiles under this scenario, would attack the mobile missiles that the Soviet Union had held back for a second-strike retaliatory blow.

Aldridge dismissed this argument at a news conference after the ceremony today, contending that the B2 would put more of the Soviets' warmaking capability at risk and therefore help convince Soviet planners that a nuclear strike on the United States would be a losing proposition.

Rep. Beverly B. Byron (D-Md.), a member of the House Armed Services Committee and early backer of the Stealth bomber, agreed with Aldridge that deployment of the B2 would not be destabilizing, but said she was not sure all 132 would have to be built to provide this extra measure of deterrence. She said Congress might decide 50 to 100 B2s are enough.

"A lot is going to depend on its test program," she said. She said the future of the B2 fleet will have to be evaluated continually as the program moves into the early 1990s.

The Air Force in the 1960s built a strategic bomber designated the RS70 to perform the same mission as the B2. President John F. Kennedy, after a fierce debate in Congress and elsewhere, canceled that version of the B70 bomber in 1962 on the argument that its added deterrent value was not enough to justify the cost of producing it.

Gen. Larry D. Welch, Air Force chief of staff, mindful of the coming budget crunch, said the B2 "completely warrants continued, unwavering support . . . the overriding purpose of this new bomber is to ensure that we never need employ it."

The flying wing B2 rolled out today looks very similar to the YB49 designed by the late Jack Northrop in the 1940s. The Air Force then was enthusiastic about the flying wing, but canceled its order for 30 after one crashed, money became scarce and then-Air Force Secretary Stuart Symington insisted on a merger of aerospace companies, which Northrop opposed.

Thomas V. Jones, chief executive officer of Northrop Corp., today said that Jack Northrop had been briefed on this new version of the flying wing shortly before he died. In closing his speech hailing the B2, Jones said, "Jack Northrop, we salute you."