The preservationists are grumbling, as they always will. This time their target is the Port Authority, which yesterday unveiled plans to preserve Eero Saarinen’s famed TWA terminal at Kennedy airport by assimilating it to a new JetBlue terminal that will be completed in 2009.

Let us begin by allowing that any fate the building might suffer as a result of renovations probably will be better than what we see today: a darkened, desolate hulk that was useless even before the demise of TWA in 2001. The building will receive a brand-new lease on life as the grand entrance to a far larger terminal that will loop around it but will generally be lower and humbler in feeling than Saarinen’s masterpiece.

There is something very good about the whole affair: An icon of the Mod strain of Modern architecture is preserved and reanimated, while JetBlue, the no-frills carrier, has gained a signature building with which it will be identified. That the rest of the project is overseen and designed by the omnipresent if unsung firm of Gensler suggests the whole affair will be as cost-efficient as the airline itself.

The projected revival of the famed Butterfly building, as it has long been known, is part of a decade-long re-examination of the Modern movement in architecture. Having lived through the convulsions of the first phase of Post-modernism, which declared war on Modernism, we can now look with greater calm and objectivity at the artifacts of both movements, without a blanket rejection or adulation of either.

Much that was built in obedience to both tastes was bad,but some were good and the TWA terminal is among the best. In fact, it is almost unique in that it has been not only respected but loved since its creation in 1962. The Postmodernists, sensing perhaps a kindred spirit in the swerving allusiveness and rich contextuality of the terminal, never included it on their hit list. They had bigger fish, like Mies and Gropius, to fry.

On a personal note, I fondly remember being whisked into this building as a 5-year-old and greatly enjoying it, as did my brothers. I adduce this testimony because, in this instance, the opinion of children is worth heeding. Children tend not to take to Modern architecture as they do to other styles, but Saarinen’s building struck us as beautiful, interesting, and fun.

Not for nothing was it used in Steven Spielberg’s recent movie, “Catch Me if You Can”: It enshrined the thrill of airtravel that was new to the 1960s, the sense that airplanes were no longer the exclusive privilege of the very rich but a possibility open to everyone. The world had suddenly opened up, and Saarinen’s building was the gate through which access was allowed. It would appear to be the aim of JetBlue, that fresh upstart among airlines, to restore to air travel some of the effervescent excitement it had back then.

To that end, it has enlisted David Rockwell, renowned designer of hotels, restaurants,and Broadway stages,to reconfigure strategic parts of the terminal beyond Saarinen’s building. After you have passed through the elaborate security apparatus, you will be ushered into the large arrivals and departures area. The renderings released yesterday are hard to read, but the dominant aesthetic seems to be that of the Russian Constructivist revival, the reborn engineering aesthetic that inspires so much of the work of Santiago Calatrava. This is expressed most emphatically in a variety of wired ornaments along the ceiling.

Another part of Mr. Rockwell’s plan is a large stairway. “It’s going to be dramatic,” the designer said yesterday. “It’s not going to be anonymous.There’s a series of step platforms that in some ways relate to the steps in front of the Met, where you can sit and grab a bite to eat. The typical sort of anonymous airport symmetry’s been banished and hopefully it will suggest the freshness and the newness of JetBlue.”

The success of Mr. Rockwell’s designs will become clearer in the fullness of time. For now, though, there is some reason for optimism.

jgardner@nysun.com