Communications Satellite Corp. lost $47.3 million ($2.58 per share) in 1987, with the disposal of money-losing divisions, an aborted merger and a $39 million refund to overcharged customers helping push the Washington-based company deeply into the red.

But company officers said yesterday they expected a strong rebound in 1988, with profits probably exceeding the $50 million earned in 1986. The turnaround would come, they said, because Comsat has shifted gears strategically, slimmed down and is now founded on profitable businesses.

Representing the United States in a global satellite consortium, Comsat channels most of the country's overseas data and voice traffic. This business accounted for 55 percent to 60 percent of its $333.7 million in revenue in 1987, with the rest coming from maritime communications, video entertainment and information services and other operations. Comsat had revenue of $304.9 million in 1986.

In the fourth quarter, Comsat earned $4.1 million (22 cents), down 80 percent from a year ago, on revenue of $82.2 million, an increase of 4.7 percent. Comsat's biggest losses for the year were recorded in the second quarter, when it took major charges against earnings in connection with the restructuring. Overall, the company cut its work force from 2,400 to 1,400.

Comsat was also shaken during the year by the collapse of a merger pact with Contel Corp., the third largest independent U.S. telephone company. Contel pulled out of the deal in the spring, citing refunds that the Federal Communications Commission subsequently ordered.

Comsat lost $3 million in legal and other fees connected with the merger. But it got a consolation prize, Contel's agreement to buy two unwanted divisions that manufactured small satellite dishes and provided international private lines. In addition, Comsat sold to another buyer a wing that made microwave and defense components.