LOUISVILLE, Ky. (AP) _ An experiment scientists hope will shed light on the cause of motion sickness in zero gravity and the loss of bone mass in astronauts continues this week as more ''space chicks'' hatch.

The first of a group of baby chicks to hatch from eggs that took a five-day space ride aboard the space shuttle Discovery pecked through his shell Friday night at Kentucky Fried Chicken headquarters here.

Kentucky Fried Chicken is the sponsor of the experiment that is the brainchild of Purdue University senior John Vellinger.

The first space chick hatched less than a week after the eggs took their ride. Seven more space chicks and eight from a control group that remained on the ground also hatched Friday and Saturday. Another eight eggs that traveled in space and eight more control eggs are to hatch this Saturday.

Vellinger said the experiment was designed to measure the effects of a weightless environment on embryo development.

Vellinger, 23, designed an incubator that was launched aboard Discovery on March 13. It carried 32 chicken eggs. A similar incubator with a control group of 32 eggs was kept on the ground during the period that Discovery was in space.

Vellinger and a group of scientific advisers will study the chicks during the next year and then prepare a paper assessing the results.

The other half of the 64 eggs - from space and the control group - were opened by Vellinger and his five advisers after the shuttle landed to examine the embryos at that stage in their development.

Ronald Hullinger, a professor of veterinary medicine at Purdue, said it is possible the experiment could provide clues about human reproduction during generations-long voyages as well as the differences in cartilage, bone, tissue and internal organs between the space chicks and their Earthbound contemporaries.