Richard J. Hieb, the payload commander of the space shuttle Columbia, is growing in orbit, and he now exceeds N.A.S.A.'s height limit for astronauts.

Mr. Hieb started the two-week laboratory mission on Friday at 6 feet 3 inches. Today, he topped 6 feet 4, the limit for someone on a space shuttle.

"According to my quick calculations here, I seem to have grown about an inch or so. So I'm now too tall to fly in space," Mr. Hieb informed payload controllers after measuring himself. "And that's without slipper-socks."

A ground controller in Alabama said, "I just hope the flight director's not listening."

"We heard that," answered a voice from Mission Control in Houston.