NASA Rats: Victims Of Their Cage?

When the space shuttle Columbia landed on May 3, one unanswered question was why so many of the neonatal rats on board died. Payload commander Richard Linnehan, a veterinarian, said he was surprised, then seriously concerned that 55 out of 96 rats onboard had died or had to be put to sleep.

"There were some unfortunate happenings there on the animal side in that we had some deaths of neonate rats that flew in the research animal holding facilities," he said. "It turns out it was an unforeseeable event and it's regrettable that it happened. However, we still get back most of the primary science for all the PIs [principal investigators]."

News About Animals

At a post-flight news conference 10 hours after landing, Linnehan thanked his crewmates for helping hand feed and care for the sick rats, saying "we had a veterinary ICU going in the [Spacelab] module for about a week. We checked these animals every night."

CBS News space consultant Bill Harwood reports that while it's not yet known what caused the higher-than-expected mortality, Linnehan feels it might have been caused by the design of the cages used to house the animals.

"It may be just a function of the way the cages were built and the way the mothers moved around in the cages," Linnehan said. "Some of the animals were not able to maintain a hold or get to a mother at the certain times they needed to. We actually saw them free floating and they appeared to be doing well but I just don't think they could figure out the environment well enough to get to the mother and nurse. And so they became dehydrated. And as you know, when you become dehydrated you become depressed and that just is a cyclical thing that builds and builds and you get to the point where some of them just succumb to that."

Harwood explains that while the cage design was tested prior to launch, it is only possible to be in a zero gravity environment for about 25 seconds on earth, essentially a free fall simulated in an airplane. The Columbia mission was 16 days long.

"It's not like the spacewalking simulations done in a water tank", said Harwood. "There, you are still being pulled down by gravity", and he added: "It's one thing to predict what you think will happen in weightlessness and its another to actually fly it and see how it performs"... Harwood explains that for Apollo 13, all the zero gravity scenes were filmed in 25-second spurts.

Harwood also notes that the 9-day-old rats were the only ones to die; older ones were OK. He adds that the only other space flight to take neonatals experienced no deaths.

Scientists will be dissecting the rats to see if there ere any physiological changes to further explain the deaths.

NASA managers, meanwhile, decided not to relaunch Columbia and its crew in August to carry out additional Neurolab research so as not to not interfere with planned launches for the international space station.

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