When Jack Nicklaus discovered the American space shuttle launch had been delayed until almost the exact minute he would tee off in the second round of the Masters this morning, he joked to a friend: "Good, we're both going to blast off at the same time."

Only Nicklaus got off the ground, and if U.S. officials want no more postponements, they will ship him to Cape Canaveral very early Sunday and let him launch Columbia with a seven-iron. On the back nine of his life, or ever since he turned 40, Nicklaus has been in another golf galaxy during the tournaments he most covets.

At 40, he won the U.S. Open by four shots -- matching or setting every record worth having along the way -- and the PGA by seven. At 41, he rocketed past everyone here today, the masters and disasters in the field of 82, and reached the Masters' midpoint with a four-shot lead.

Nicklaus was almost casual about it, the seven-under 65 that could have been a record 62 if putts less than the length of his shadow had fallen. Most golfers would be clicking their cleats in ecstasy after such a feat. That Nicklaus was not helps explain how greatly he bestrides his sport at the moment.

The truth, of course, is that Nicklaus shot a better round (64) here 16 years ago, when Tom Watson was 15 and some of the amateur players here now were nearly as short as their clubs. That had been easier, he said. Today, he hit a few bad shots. And was getting reacquainted with the zillionth changes in his game.

"The 64 was a breeze," he said. Nicklaus admitted that while today's masterpiece might have beaten that record he shares with five others, it also might have been something mortal, like 70. Yep, the worst Nicklaus probably could have shot today was two under par.

"Obviously, I'm satisfied," he said.

As a purist, Nicklaus said the round Thursday that ended at 70 was superior to today's 65. The approaches were better today, the chips either almost going into the hole or leaving tap-ins and the putts mostly wonderful. He is delighted about his short game, the one he tinkers with constantly to the bafflement even of players his peers for brief stretches.

"In '75," said Johnny Miller, "he told me that every week he's always trying something different. Imagine, the best player in the world still trying something new. You can take that too far, of course, but that's the mark of a great player."

Whether out of fear that his game might be eroding in ways nobody else would notice or simply to keep from being bored, Nicklaus retools his game as Richard Petty might his racing car. His latest way of staying excellent at what cripples most of us in middle age, short putting, is a stance that allows him to see the ball and the hole at the same time.

Hackers are bright enough to think of that; Nicklaus had forgotten it, until a club pro reminded him of it a few weeks ago.

"And I began holing everything," he said.

And getting close enough with the lofted tools so his knuckles are not so white so often any more. The shorter the putt the easier, and Nicklaus chipped exceptionally today. His motto these days with a wedge in hand: when in doubt whether to chip or pitch, chip every time. Loft the ball instead of playing bump and run.

"And my chipping game, for me, is outstanding," he said.

That is what exasperates the young turks who thought Nicklaus might be finished a few years ago. "When Jack's working on his short game, you know he's in trouble," one fine player said in the late '70s."It used to be Jack wouldn't miss a green in three years."

Let's join him 15 yards from the pin at the 12th hole today. He has pulled his eight-iron tee ball on the par-3 hole and now is facing the golfing equivalent of brain surgery. If his chip is too hard, the ball will roll past the pin and off the green into a sand trap. If he is too delicate, the ball might not even get onto the steeply banked green.

Dr. Nicklaus smacks the ball into the bank, lets that stop the momentum enough so the ball only trickles seven feet beyond the cup. Then he strokes in a save to a savor.

"I did that four other times," he said. He only missed the follow-up putt at 15.

Before his round, Nicklaus was one of 27 players within three shots of the lead. Then he made four birdies in a row on the front nine and all of a sudden became compelling once again.

"I was going to watch someone else," a fellow huffing down a fairway said, "but I can't leave that man alone."

Once being a driver of near-legendary length, Nicklaus lately has not been exceptional off the tee. Until today. Even he was impressed at the howitzers suddenly in his arsenal. At No. 8, when Nicklaus outdrove Crusher Don Pooley and then put his second shot on the uphill, 535-yard hole on the green, a fan mimicked him talking to this sudden weakling of a playing partner, saying:

"Son, I only bring the thunder down from the mountain when I need it."

Nicklaus has more sense than to assume he was won his 20th major title, to mentally fit himself for his sixth green coat with two rounds to play. He has several fine players on his heels, which makes his performances of late even more special. The masters of the generation before him -- Hogan, Snead and Nelson -- had only themselves to beat in most tournaments.

Nicklaus may have an even tougher foe than the growing number of course killers: himself. His unique motivation comes from trying to convince himself that some golfer, perhaps unborn, will take a whack at his record in the major tournaments and he wants to make it nearly impossible for him to exceed.

Nicklaus showed us a rare glimpse inside his mind when a nervous young reporter rose after a press conference today and asked him how it felt to come so close to breaking that one-round record of 64 "when you might not ever get such a chance again in your career."

Dumbfounded, Nicklaus looked at him and said:

"I've got tomorrow and the next day."