CAPE CANAVERAL, Fla., July 11— 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.
Astronauts tend to grow two or more inches in space because the spine becomes elongated in the absence of gravity. The phenomenon is often accompanied by back pain.
Mr. Hieb and Dr. Chiaki Naito-Mukai, a Japanese heart surgeon, are measuring themselves each morning aboard Columbia so researchers can compare growth to soreness. There is no word yet on Dr. Mukai's height, but she started out at 5 feet 2.
Aspiring astronauts must be at least 4 feet 10 1/2 inches to be accepted into the program and at least 5 feet 4 to be a shuttle pilot. The National Aeronautics and Space Administration requires that astronauts be able to reach the controls and fit into the space suits. If they were too tall, they would be cramped in their seats.