Countdown Starts for Discovery Mission

NASA began the countdown Sunday for the first shuttle flight of the year, a laboratory research mission by Discovery that will examine the effects of weightlessness on people, plants and bugs.

“This should be a great mission for science,” Ronald Grabe, the mission commander, said as he and the flight’s six other astronauts arrived here.

“We’re looking forward to quite a bit of significant scientific return from this flight, and, obviously, the prospect of just going up and flying ourselves--that’s really exciting to us personally,” Grabe said.

The clock began ticking early Sunday afternoon in preparation for the National Aeronautics and Space Administration’s 45th shuttle flight. The liftoff was scheduled for 5:53 a.m. PST Wednesday.

Forecasters put the chance for good weather at 70%. The main concern was a low cloud cover. The temperature at launching time is expected to be in the mid-40s.

The Discovery astronauts will spend most of their time in orbit conducting experiments inside Spacelab, a pressurized module that fills nearly half the cargo bay.

The crew of six men and one woman will split 12-hour work shifts for seven days while Discovery flies 187 miles above the Earth. They will monitor the growth of oat and wheat seedlings, lentil roots and thale cress, as well as the development of fruit flies, roundworms and walking stick insects.

Other laboratory specimens include yeast, bacteria, slime mold, frog eggs and sperm, fetal mouse bones and human blood cells.

Scientists hope the human medical tests will provide a better understanding of space motion sickness and back pain, frequently suffered by astronauts in orbit.