President Reagan appointed a high-powered, 11-member bipartisan Commission on Strategic Forces yesterday to review the nation's nuclear weapons programs and to help him try once more to decide what to do with the controversial new MX missile.

The commission, which includes former Carter administration defense secretary Harold Brown, former Nixon administration CIA director Richard Helms and Reagan's first secretary of state, Alexander M. Haig Jr., faces a Feb. 18 deadline for reporting its findings to Reagan.

It is the third panel asked by the Reagan administration in two years to help find a basing plan for the MX that has enough support to win approval from a skeptical Congress.

Last month, Congress refused to approve production money for the MX, made clear that it did not like the administration's most recently proposed "Dense Pack" basing plan for the intercontinental nuclear weapon, and directed the White House to reevaluate all possible basing plans and report back to Congress by March 1.

Although the new commission undoubtedly will review the possibility of dropping the MX entirely in favor of perhaps a new and much smaller missile that could be moved around the countryside, many defense and military officials doubt it would recommend killing MX.

They say they believe some compromise basing plan may emerge, combining elements of Dense Pack and the Carter administration's original plan to build numerous dummy silos to make it more difficult to locate MX missile silos.

In such a compromise, officials speculate that the 100 MX missiles Reagan wants still could be bunched closely together in the Dense Pack scheme, on the theory that Soviet missiles would blow each other up trying to attack such a small area. But to further confuse the Soviets and make it more costly for them to contemplate an attack, a few hundred or more deceptive silos could be added.

When he took office, Reagan rejected the Carter plan to shuttle 200 missiles among 4,600 shelters in Utah and Nevada.

Officials say the only quick alternative to MX would be to improve many of the existing 1,000 U.S. Minuteman missiles further. The newest Minuteman carries the same basic atomic warhead in its nose as the MX and could be modifed with the new MX guidance system. But officials worry that the old missiles will be less reliable and more vulnerable to attack.

The commission role is advisory. But, although Reagan does not have to follow its advice, many officials believe the White House will adopt the panel's recommendations.

The president has urged that the MX, each of which would carry 10 individual nuclear bombs in its nose, be deployed to help preserve the nuclear deterrent. But he has failed thus far to convince Congress that his plans for basing the MX will keep it safe from attack by Soviet missiles, as he once claimed was essential.

Congress has rebuffed Reagan twice in the past year on MX deployment plans. Before Dense Pack was proposed, Congress rejected a plan to put MX in existing Minuteman and Titan missile silos.

The new commission has a very broad charter that allows it to look into the whole $180 billion Reagan program to modernize U.S. long-range land- and submarine-based missiles and bombers carrying nuclear weapons, and to review possible alternatives to the MX.

Several key members of the panel, however, are on record as favoring the new missile, although a number of them have been critical of the basing ideas thus far put forward by the Reagan administration.

The commission chairman, retired Air Force Gen. Brent Scowcroft, who also was White House national security assistant under President Ford, told reporters yesterday that he felt "MX is a very important part of our future defense posture." Stressing this was "a purely personal" opinion, Scowcraft said the commission had an unrestricted charter to look into all alternatives.

The vice chairman of the new commission is Thomas Reed, a special assistant to Reagan on national security and a former secretary of the Air Force who was been one of the prime advocates of Dense Pack in the administration.

Other members include Bill Clements, the former governor of Texas and deputy secretary of defense in the Nixon administration; Nicholas Brady, the former Republican senator from New Jersey; Dr. John Deutch, the dean of science at the Massachusetts Institute of Technology; John Lyons, a vice president of the AFL-CIO and chairman of its defense subcommittee; retired Vice Adm. Levering Smith, the former director of the Navy's Polaris missile-firing submarine program, and James Woolsey, former under secretary of the Navy in the Carter administration.

The executive secretary of the commission is Dr. Marvin Atkins, director of the Pentagon's office of offensive and space systems.

In a statement that accompanied signing of the executive order setting up the commission, Reagan said the panel "will review the strategic modernization program with particular focus on our land-based intercontinental ballistic missile system and basing alternatives for that system. An important part of the commission's work will be to consider carefully the views of Congress."

Reagan said, "I cannot overemphasize the importance of the complex task facing the commission" and how much success hinges on cooperation with experts in Congress, the Pentagon and outside of government.

"In undertaking this vital mission," the statement said, "I ask that we all keep the fundamental objective in view--to preserve an effective deterrent while moving forward with negotiations to reach equitable and verifiable arms reductions." The administration has also argued that failure to approve the MX will weaken the U.S. ability to bargain successfully with Moscow at arms control talks.

The MX missile has been under study and development for 10 years, and the Air Force has studied more than 30 different basing modes for it. But none of them has ever been greeted with much enthusiasm because land-based missiles have become increasingly vulnerable, at least in theory, to being knocked out in an initial attack by more accurate and numerous enemy missiles.

The Reagan administration, however, wants to keep land-based missiles in the mix of U.S. weapons, and specifically wants the silo-busting potential of MX as a balance to the first-strike threat posed by Moscow's existing missiles.

The Feb. 18 deadline means that the new commission will have very little time to review this history. As of yesterday, no schedule of meetings had been set up. Officials said they hoped to be organized by the end of this week.

Aside from Scowcroft and Reed, Brown and Haig also have supported the need for the MX, although Brown and Scowcroft have expressed serious reservations about Dense Pack.

Scowcroft and Woolsey served on an earlier panel last year to try to find a home for MX that was headed by a Nobel-prize winning physicist, Dr. Charles Townes of the University of California. Townes, who had privately expressed his doubts about Dense Pack to Secretary of Defense Caspar W. Weinberger, is noticeably absent from this latest commission.

The earlier Townes panel had reported there was no longer any practical system for basing missiles on land that could guarantee a high survival rate. It said that putting the MX on planes that could stay in the air for days might be a promising answer, but that idea also was ultimately rejected. A second panel headed by Townes later last year gave a limited vote of confidence to Dense Pack after the Air Force came up with that scheme.

Reagan campaigned on the necessity of closing the "window of vulnerability" to Soviet missile attack, and castigated the Carter administration for allowing it to open. But Reagan administration officials, including Weinberger, have now acknowledged that "there isn't any perfect ground-based system," as Weinberger put it last week.

"It's a very difficult issue," Scowcroft told reporters yesterday, because obviously the MX problem has gone on for years without being solved and "whatever we come up with is unlikely to meet with unanimous approval. . . . "