ORLANDO, FLA. -- Long before Walt Disney turned Orlando into one of the world's major vacation meccas, a Maryland defense contractor bought 6,700 acres of swamp south of town and launched a key part of Florida's economy.

An evolution of the area's high-technology industry began in 1956 when a 50-person work force for Glenn L. Martin Co. started operating out of leased airport space a year before permanent facilities opened.

This month, what is now known as the Martin Marietta Electronics & Missiles Group, a subsidiary of Martin Marietta Corp. in Bethesda, Md., marks its 30th anniversary, with 15,000 employes in central Florida and two new multibillion-dollar military equipment contracts.

The Orlando plant oversees projects in Baltimore, and the parent corporation has aerospace operations in Denver and builds NASA's space shuttle external fuel tanks at Michoud, La.

"Orlando's modern history really begins with Martin Marietta," said Mayor Bill Frederick. "The Martin operation marked the first important diversification of our area's economy."

Martin Marietta began Orlando operations on Dec. 4, 1957, with 2,700 workers on about $200 million in orders for missiles and antiaircraft guidance systems for the Marines, Air Force, Army and Navy.

Some 40,000 Bulltop air-to-surface missiles were produced over the next eight years at the 627,000-square-foot facility that is now five times that size.

And last year alone, Martin Marietta's Orlando operation processed $2.4 billion in orders, said company spokesman Tom Duncan.

The contractor's presence has not been without controversy.

Environmentalists this year attempted to block building of a laser test range because the facility threatened an endangered species of woodpecker.

And dozens of workers were hospitalized briefly on several occasions when they complained of an illness that still can't be explained by doctors or work safety consultants.

But Martin Marietta also has deeded more than 1,000 acres of its land to local government for roads, wetlands preservation and public facilities.

The company played a large role in establishing and expansion of the University of Central Florida, andThe original plant now employs 6,700 people. corporate and employe contributions to the United Way charity average $3 million annually.

The original plant now employs 6,700 people. Another facility in east Orlando, opened in 1985, employs nearly that number; and 1,600 people work at an Ocala plant opened in 1970.

Martin Marietta retains vast land holdings in Orange County, developing industrial parks near its headquarters, and has a 50 percent interest in the year-old Peabody hotel adjacent to the city-county convention center.

"Martin has spawned the growth of a wealth of new business and has directed or funded a host of community projects," Mayor Frederick said.

Since 1979, Martin's Florida payroll has been $2.15 billion, and state and local taxes paid over the 30 years exceed $100 million, according to corporate figures.

Goods and services bought in Florida reached a level of $160 million in 1986.

On Nov. 30, the Army awarded Martin a contract expected to be worth $97 million through 1989 for supplying a surface-to-air missile system designed for deployment near front troop lines to protect soldiers against aircraft or tank attack.

And the Army has an option to order an additional $1.7 billion worth of the air defense anti-tank systems from the company.

The Air Force on the same day contracted for continuing production of Martin Marietta's "Lantirn" targeting and navigation jet fighter equipment, which enables an F-16 or F-15E to fly up to 500 miles per hour in total darkness 200 feet above ground.

Three hundred Lantirn systems are in the works with another 400 expected to be ordered from the company during the next five years, making the project worth more than $3 billion.endqua