SHUTTLE TO PROBE MYSTERIES OF ZERO GRAVITY.

Byline: The New York Times

The space shuttle Columbia rose on yellow blasts of flame Friday into a deep blue sky, carrying a crew of seven on a 16-day mission to explore the subtleties of a lack of gravity.

The shuttle liftoff, witnessed by tens of thousands of people who crammed the roads and beaches around the Kennedy Space Center during the spring break from school, was about 20 minutes behind schedule because of a problem with a small seal in a cabin door.

Loren Shriver, a shuttle launching manager, told a news conference that the liftoff would have been ``almost on time, except for the misbehaving of a perhaps 70-cent O-ring at the end of our oxygen probe.'' A small, rubber O-ring seal through which technicians insert a probe to check pressure in the crew cabin popped loose during a final check and had to be replaced, officials said.

Engineers added extra oxygen to the cabin to compensate for leaking when the seal was replaced, and later this extra oxygen was vented into the cargo bay. This additional oxygen, in turn, set off hazardous gas detectors in the bay, and mission controllers had to wait about 20 minutes for the oxygen to drop to acceptable levels before proceeding with the flight, officials said.

The Columbia, the oldest of NASA's four shuttles, was two hours into its 22nd flight when astronauts activated the pressurized laboratory in its cargo bay and moved inside shortly afterward to begin round-the-clock operations. The crew of five men and two women was divided into two teams, allowing one to work while the other slept or attended to other duties.

The mission, the third of the year, focuses on the effect of minimum gravity in space on fire and combustion, and on the physics of making new materials and growing protein crystals for medical research. The shuttle is also carrying equipment, like a new experiment rack that can be moved from place to place on the ship, that is intended for the planned international space station.

Of the 33 major experiments on the mission, all studying phenomena without the influence of gravity, the major ones involve fire research. The astronauts are to set as many as 200 small fires inside special, insulated chambers designed to contain any dangers.