Communications Satellite Corp. has named Marcel P. Joseph, a vice president of General Electric Corp., to the new post of executive vice president and has given him overall responsibility for managing a newly restructured company.

Joseph, the first outsider to fill such a high post at Comsat, may succeed to the No. 2 spot before the end of the year, replacing Irving Goldstein as president and chief operating officer. Goldstein, 47, is expected to take over as chief executive officer when Joseph V. Charyk, 64, reaches retirement age in September, a company official said.

A 24-year veteran of General Electric, Joseph, 50, has broad experience in running businesses in competitive markets. One company official said that experience will be important as Comsat ventures into a new phase of growth and greater competition.

The appointment is "the first step in a major realignment" of Comsat's corporate structure, Goldstein said. The restructuring, details of which were announced Thursday, is designed to take advantage of a newly deregulated international telecommunications market.

Comsat, created by Congress in 1963, still serves as the only U.S. representative to the International Telecommunications Satellite Organization (Intelsat). However, the Federal Communications Commission has authorized other communications companies, as well as Comsat, to offer new international business services and has ended Comsat's monopoly over the earth stations that transmit and receive satellite signals.

In exchange, Comsat has been permitted "common carrier" status, allowing it to offer Intelsat services directly to business customers, much as American Telephone & Telegraph Co., MCI and other companies provide long-distance phone services in this country.

Last week, Comsat offered some of the details of how it plans to get into the common-carrier business. The company announced it has created a new subsidiary to offer, as a common carrier, international communication services and to manage its earth stations. Comsat International Communications Inc., regarded as the centerpiece of the realignment, will be headed by William C. Taylor, 58. A former ITT vice president, his experience in competitive businesses will be valuable to the new venture, a spokesman said.

In addition to CIC, Comsat has formed two other businesses: Comsat Technical Services, which will handle the parent company's growing consulting business, and Network Products, which will build satellite earth stations for large corporations.