By any standard, the joining of two of America's most successful businessmen in a venture with the Soviet Union this week is an unusual partnership, indeed.

The contrast is especially marked since both businessmen come from conservative Utah backgrounds, both are religious leaders, and both their companies share a classic capitalistic success story - the rise from one man's modest start to an international conglomerate in a single generation.The agreement calls for Marriott Corp., the world's largest airline catering company, to form a partnership with the Soviet airline, Aeroflot, the world's largest airline, to handle airline food service within the Soviet Union.

The new joint company, to be known as Aeromar, will contract with the Utah-based Huntsman Chemical Corp. to provide trays, utensils, and other food service products for the venture

A remarkable thing about the deal is that it goes deeper than merely providing food service. Marriott will modernize, refurbish, and operate the huge kitchen at Moscow Airport. Huntsman, which has chemical plants in many different countries, will build one in the Soviet Union. Officials for both companies talk as if this were only the beginning. Soviet officials expressed the same hope.

The agreement sends an encouraging message that Soviet leader Mikhail Gorbachev really means it when he talks about "glasnost" and opening the rigid and stagnant Russian economy to more free market ideas and practices.

Soviet officials praised the two American firms, saying that "good human relations" have been established with both.

It may be that those good relations eventually will have more political and social impact and more consequences than a mere business venture. A closed door has been opened. Who knows what else it may lead to?