They hardly seem proper shipmates on something so grand as a journey into space. But there they are, side by side aboard the space shuttle Columbia _ noble man, ignoble rat.
They've flown together before, man and rodent, but not always with happy results. In 1985, astronauts aboard Challenger were horrified when what appeared to be rat droppings escaped from the cages and began floating about the cabin. They quickly donned masks, lest they breath in the tiny particles.
"I'm not exaggerating," radioed angry astronaut William J. Thorton. "It is a literal flood of these things." It was later learned the "droppings" were almost exclusively rat food, but a lesson had been learned.
Columbia _ carrying new and improved rat cages _ is scheduled to lift off between 8 a.m. and 10 a.m. today, weather permitting, on a nine-day mission to study how the heart, blood vessels, lungs, kidneys and hormone-secreting glands react to the weightlessness of space.
Extensive testing will be done on the rats, a couple of thousand jellyfish and the seven members of the crew.
The effects of weightlessness must be understood if men and women ever are to fly safely to faraway places such as Mars, a journey of about nine months. Muscles atrophy without gravity to make them work, and the body's chemistry changes in subtle but important ways, too.
That's where the 30 rats come in. They are Norway albinos, bred to be free of all germs potentially harmful to humans _ the healthiest, hardiest most nearly perfect rodents NASA can get.
They are fit (a trim 250 grams), trained (in the use of their feeding equipment) and ready.
And they are doomed.
When they return to Earth they will be killed so that scientists can begin a detailed study of what happened to their muscles during weightlessness.
One of several who will do these studies is Kenneth Baldwin, associate dean of the College of Medicine at the University of California at Irvine. He'll have access to the animal's thigh muscles.
They are well-studied, he said, but the main reason concerns the way muscle tissue in all animals degrades and is re-made many times. Since the lifespan of a rat is only about three years, the process of change is accelerated. Thus, there is more change to observe in a rat during the nine days of flight than there is in a human.
And they are tough, said Kenneth Souza, a space life-sciences expert for NASA. One need not worry about them surviving the rigors of launch, for example.
"No problem," Souza said. "They just ride it out in their cages. This species is well-tested for vibration and stress. They can take far more than a human can."
About 2,400 jellyfish will make the journey, too. Since some of the developing structures of jellyfish resemble developing structures in humans, scientists hope to use jellyfish to make predictions about effects on more complicated organisms.
The flight is to be the first in a series of life-science missions that are to someday support longer efforts aboard a space station. The experiments will be conducted inside Spacelab _ a 23-by-16-foot module that rests in the shuttle's payload bay.
A tunnel connects the module to the crew's quarters.
Commanding the crew will be Bryan D. O'Connor. The pilot is Sydney M. Gutierrez. Mission specialists are Tamara E. Jernigan, Margaret Rhea Seddon, James Bagian, Francis Andrew "Drew" Gaffney and Millie Hughes-Fulford.
CNN plans coverage
The launching of space shuttle Columbia, scheduled for between 8 a.m. and 10 a.m. today, will be covered live by CNN. ABC, CBS and NBC said they do not plan live coverage.