The Columbia astronauts, in the home stretch of a grueling dual-shift 16-day science mission, told reporters today their research is proceeding in fine fashion and that scores of scientists on the ground should be pleased with their results.

"A lot of what we're doing now is really in preparation for future flights aboard the space station," said payload commander Michael Anderson. "A lot of experiments that we have are really just being demonstrated and developed and once they're fully developed, they'll reside aboard the space station and the scientists will have years to conduct the experiments we're trying to do here in a relatively short period of time.

"Science wise, this flight has been absolutely fantastic. I think a lot of our experiments have exceeded our expectations by a hundred percent. We've seen things we never expected to see on board this flight. ... Overall, this flight's been absolutely fantastic, the science has been spectacular and we just can't wait to bring it all home so the scientists can really take a close look at what we've done."

To collect as much data as possible from the more than 80 experiments on board, the astronauts are working around the clock in two 12-hour shifts, sharing bunks on the shuttle's lower deck. Shuttle commander Rick Husband said despite all the hustle and bustle of orbital operations, "we've been sleeping pretty well."

"We've got sleep stations in the middeck and they've got sound suppression padding in there an it's extremely dark," he said. "Some of us wear earplugs as well and so when you get to that level of sensory protection, it's actually pretty quiet and dark in those sleep stations."

Along with seven astronauts, Columbia is carrying a small menagerie of animals and insects, including ants, bees, silkworms and moths, fish, rats and spiders, many of them on board as test subjects for student experiments.

"They're all doing well," Anderson said. "The spiders, the ants, the moths, the rats, they're all doing just great ... and I think we're getting good science from it. Most of those experiments are educational experiments and we're beaming down video to students at schools all around the world. I'm sure they're really excited about what they're seeing and I'm sure they're excited for us to bring their specimens back so they can get a closer look at them."

Ilan Ramon, the first Israeli to fly in space, said he's been struck by the view of Earth from orbit, saying "the world looks marvelous from up here, so peaceful, so wonderful and so fragile."

"The atmosphere is so clean and fragile and I think that everybody, all of us, have to keep it clean and good," he said. "For the people of Israel, I wish we will have a peaceful land to live in very soon."

Ramon is on board in part to operate an experiment known as MEIDEX. Mounted in the shuttle's cargo bay, MEIDEX consists of a multi-spectral camera designed to characterize how dust particles from desert storms affect weather patterns.

"In the first seven days, I believe, we didn't have any dust up in the atmosphere," Ramon said. "But it looks like ... we had a big dust storm over the Atlantic (recently) that lasted for two or three days and I think the scientists were very, very successful with their experiment. Other than that, we had another quite big experiment with MEIDEX, which is called Sprite, which is actually lightning going up from the top of the clouds through the atmosphere and we have a lot of lightning storms recorded."

Columbia is scheduled to land Saturday at the Kennedy Space Center. Touchdown is expected around 9:15 a.m. to close out a 16-day, 6.6-million-mile mission.