Four shuttle astronauts walked on rails, stood in a barrel and rode a spinning chair Saturday as scientists studied how quickly Columbia's crew adjusted to gravity after nine days in orbit.
"Each of them got a good night's sleep and they were ready to go this morning," said Mel Buderer, project scientist for the shuttle's Spacelab mission.The shuttle was in good condition, with only 118 "dings" to its heat-shield tiles and minor heat damage to a door where the external fuel tank attaches to the orbiter during launch, said Bascom Murrah, Columbia processing director for the National Aeronautics and Space Administration.
Columbia landed Friday at this Mojave Desert military base. Spokesman Mitch Varnes said agency officials will meet this week to decide if future shuttles will land routinely at Kennedy Space Center in Florida.
He also said 15 of Columbia's 29 experimental rats were killed by decapitation so they could be further studied. The others will lose their heads in eight days.
"That's the most humane way," Varnes said. "That's the way scientists do it - little guillotines."
Columbia's flight, its rat and jellyfish experiments and on-the-ground tests for four of its seven crew members will help researchers learn how well future astronauts can endure zero-gravity during long trips on a space station or spacecraft to other planets.
Columbia commander Bryan O'Connor, pilot Sid Gutierrez and mission specialist Tamara Jernigan flew home to Houston after Friday's landing. Remaining for a week of tests are cell biologist Millie Hughes-Fulford and Drs. James Bagian, F. Andrew Gaffney and M. Rhea Seddon.
In one test Saturday, the astronauts stood in "a vertical gurney," which spun as scientists watched how the crew members' eyes rolled, Buderer said.
The astronauts' balance was measured by having them walk narrow rails. They also closed their eyes while trying to point at objects with a light-emitting pen - a test similar to one for drunken-driving suspects.
In another experiment, astronauts stood in a barrel-shaped device that exposed the waist and legs to low atmospheric pressure. Researchers checked cardiovascular function and the body's ability to respond to gravitational-like stress, Buderer said.