The federal Urban Renewal Administration has approved a 42-acre Kendall Square renewal project, paving the way for construction next spring on the first phase of the $60 million National Aeronautics and Space Administration research laboratory.

Cambridge gave its approval for the project on August 30, and the federal government will new provide a $15.3 million grant to help purchase 42 acres, clear the land, and make improvements preparatory to construction. NASA will use 29 acres of the area, which is adjacent to M.I.T., and the other 13 will go for private development.

State Decision Due

Still remaining is a decision from the state -- it's expected before next Thursday. If the state approves the project, as pro-NASA forced predict, opponents may try to block construction by appealing to the courts.

"Sure, we will go to court," John Brennan, a leader in the light against NASA, said last night.

However, Robert Rowland, director or the Kendall Square project for the Cambridge Urban Renewal Authority, doubted that court action would materially delay" construction.

Businesses Opposed

Opposition to NASA has come almost, entirely form 94 business firms located on the urban renewal site. They have claimed that the area is not "blighted" and therefore should not be developed under urban renewal. One problem cited by many of the businesses is the high cost of relocating.

However, included in the $15.3 million federal grant is $2.5 million for relocation. The federal government would pay all relocation costs up to $25,000 and then would split with the city on a 2-1 basis anything above that. Legislation is now pending in the Massachusetts General Court (the state legislature) to permit the city to pay its third of the costs.