GOOD MORNING: Steven Spielberg calls it “the coolest set in town.” And with good reason. Before I set out for Stage 36 at Universal, where “Apollo 13″ is filming, I was warned to dress warmly because the stage temperature would be 38 degrees. On my arrival, I was told my scarf and earmuffs would not provide enough warmth. I was given a heavy parka. Inside, the stage temperature was indeed set at near freezing. Director Ron Howard, producer Brian Grazer and the entire “Apollo 13″ crew were also packed in parkas, gloves and assorted headgear. Between takes, hot soup was passed up to Tom Hanks and Bill Paxton, who are portraying the Apollo 13 astronauts Jim Lovell and Fred Haise, respectively. Why the cold-storage stage? To simulate conditions in the module following the deep space explosion, which set in motion the great drama that had 400,000 (you heard right) global outer space workers trying to figure a solution to save the astronauts from freezing, poisoning by carbon monoxide, suffocation or incineration on re-entry into the earth’s atmosphere. As the players spoke their lines, their breath steamed forth. Hanks was floating about weightlessly, connected to a special device (which will not be seen on-camera). However, he and his fellow astronaut cast members, Paxton and Kevin Bacon, will be photographed in true weightlessness in scenes to be shot next month aboard a KC- 135 (affectionately called “the vomit comet”) out of Houston, thanks to an OK given the filmmakers by NASA. The space moguls think highly enough of the moviemakers’ integrity to give them full cooperation and equipment as well. Producer Grazer told me the module on the stage was made of parts from actual space travel equipment … Grazer and Howard said plans are already afoot for an “Apollo 13″ ride to follow in the park. And coincidentally, the Imagine team of Grazer and Howard said their “Apollo” is budgeted at about the same as “Backdraft”–”under $ 40 million.”TOM HANKS NOTED THERE IS NO gunplay or car chase, but more dramatic action, as well as suspense in this movie. Howard showed me some of the explosive, into-outer-space scenes that will be counteracted by the infinitely personal drama inside the module, which is no bigger than the interior of a sports car. Ron Howard told me the challenge is to show the inner feelings of the endangered trio … Oscar winner Hanks has regained the 40 pounds lost for “Philadelphia” and some dropped for “Forrest Gump.” But Bacon and Paxton told me they will all now have to lose about 16 pounds as their suspenseful hours in space pass. Bacon had also regained weight he lost for his just-wound “Murder in the First” prison-set movie …”Apollo” is being shot in sequence, thus allowing the men’s daily diet to show effectively. Of course makeup will help … The special effects are handled by Digital Domain … And post by Imagine’s regular team of Dan Hanley and Mike Hill. They all want this movie to be great — and a tribute to our men in space. Astronaut Dave Scott, who was aboard the Apollo IX and XV and drove on the moon with the lunar rover vehicle, is on the “13″ set training the thesps and guarding for accuracy. He told me, “Tom Hanks goes beyond accuracy and asks me ‘Why?’ The actors are digging into stuff I had forgotten! This movie will be a pyramid — a history lesson for the world.” Bacon, the hateful heavy in “The River Wild,” is now heroic. “I am proud to be in this movie ,” he told me … Howard and Grazer’s Imagine will be shooting “No Fear” with James Foley directing, same time “Apollo” is before the cameras. They follow with “Sergeant Bilko,” starring Steve Martin. Then, “Friday Night Lights” for U, about football in an Odessa, Texas, high school, with Brian Levant directing, Alan Pakula exec producing, Grazer producing. Imagine’s readying the far-out “The Nutty Professor” for Universal and Paramount with Eddie Murphy’s banner. They showed me a 15-minute test tape Murphy made as the 300-pound professor — thanks to Rick Baker’s body and face makeup magic. Murphy once again demonstrates the comedy genius that launched his career … Brian Grazer’s lady friend, former TV exec Gigi Levangie, joins the feature world, as she has sold her screenplay “Stepmother” to Wendy Finerman and TriStar. IT’S A THANKSGIVING DAY wedding for director Tony Scott and actress/model Donna Wilson in Cabo San Lucas … Steve Allen makes his return to B’way — after 40 years — to title role “The Mikado” for the N.Y. Gilbert & Sullivan Players Jan. 5-15 at Symphony Space …”Swanson on Sunset,” a musical about Gloria S.’ attempt to produce a B’way musical of “Sunset Blvd.” in 1955, bows Dec. 7 at the Cinegrill. Dickson Hughes, who wrote the original show for her, plays himself. Richard Leibell plays Richard Stapley, Laurie Franks is Swanson. Luke Yankee directs.