One of my favorite sketches on the original Muppet Show as “Pigs in Space,” in which the intrepid crew of the starship Swine Trek faced danger, excitement and bad writing while exploring the final frontier. As far as I know, no real pigs have yet flown into space, but many other animals have made the trip. In fact, at this very moment there are 2,052 of them in orbit aboard the Space Shuttle Columbia: oyster toadfish, freshwater snails, swordtail fish, molting crickets, adult rats, baby rats and pregnant mice.
Unlike the pigs on the Swine Trek, they’re not being asked to fight aliens or explore strange new worlds: they’re just being asked to be themselves. They’re being studied to better understand the affect of weightlessness on the neural system of living things. So are the seven human members of the crew, although they have one big advantage over the animals: nobody’s planning to dissect any of them.
The animal and human experiments are all part of Neurolab, Columbia’s main payload this time around. NASA says it’s the most complex life sciences mission ever flown, and its very important: the data gathered through Neurolab’s experiments will help future astronauts deal with the effects of long-duration space flights (to Mars, for example) and will provide insight into the treatment of neurological disorders here on Earth.
Neurolab was developed by scientists at 26 universities in seven countries and at the National Science Foundation, Office of Naval Research and National Institutes of Health in the U.S., the space agencies of Canada, Japan, France and Germany, and the European Space Agency.
Twenty-six Neurolab experiments are being conducted during the 16 or 17-day mission, which got under way on Friday. Some of the questions to which Neurolab is seeking answers include:
How do the inner ear, cardiovascular system and muscles learn to cope without gravity? Why do astronauts’ sleep and biological rhythms change in space? Will the inner ears of embryos that develop in space function the same as those of embryos that develop on Earth? Does the lack of gravity affect the development of basic motor skills like walking?
Eight teams are overseeing the various experiment. Four of them are focusing on the human members of the crew. For example, the Autonomic Nervous Sytem Team is interested in blood pressure and gravity. If you stand up to fast, you sometimes feel dizzy. For some people, mainly elderly people, the condition is chronic, and is called orthostatic hypotension. Astronauts suffer from the same thing when they first return to Earth. By analyzing blood and urine samples and recording muscle nerve activity in the legs, scientists hope to trace the changes in the autonomic nervous system brought on by low gravity and better understand how respiration, blood pressure and muscle nerve activity relate to the flow of blood to the brain.
Meanwhile, the Sensory Motor and Performance team is studying how the lack of gravity affects astronauts’ performance of simple, everyday movements, through simple experiments such as testing the ability of the crew members to catch a ball. Data gathered through these experiments may also be helpful to scientists on Earth studying neurological diseases such as Parkinson’s.
Many astronauts report trouble sleeping in space, so the Sleep Team will be focusing on that. One scientist on the team will focus on respiration, to see if irregular breathing patterns and greater difficulty obtaining sufficient oxygen (due to the specialized on-board atmosphere) might be the root cause. Another scientist is testing melatonin, a naturally occurring hormone that influences our sleep patterns on Earth, to see if it can be administered to help astronauts sleep better. On Earth, the data may be useful in work focusing on insomnia.
Finally, the Vestibular Team is studying the spatial disorientation suffered by many astronauts, the result of conflicting signals between eyes and the inner ear and other organs that tell us the difference between up and down here on Earth.
Another four teams are overseeing the animal-based tests, beginning with the Neurobiology Team, which is the team dealing with the crickets. (The one-day delay in the shuttle’s launch last week cost the original batch of crickets their chance to go into space: a whole new batch was put on board because of fears that the first batch, many of whom were in the egg stage, might hatch prematurely.)
The Neurobiology Team wants to know how much of normal development, especially of the senses, is preprogrammed in the genes and how much is modified by the environment. Crickets were chosen for this study because it they develop rapidly and because they possess a complex gravity sensor system that includes hair-like cells called cerci in their legs and tail. Located close to the cerci are other sensory receptors used to detect air currents. Each sensory system has its own neural pathway.
The crickets will be housed in BOTEX, a special unit that has some compartments in which gravity is simulated (by spinning) and some that are subject to microgravity as usual. Some of the crickets will mature in the simulated gravity, some in the microgravity. By comparing the devlopment of the gravity sensors of the two different groups, the team hopes to uncover some clues about the relative importance of environmental factors to normal development.
How do you measure how well a cricket’s gravity sensors are working? Three ways: by monitoring its behavior (even when its body is at an angle, a cricket normally keeps its head as close to vertical as possible–the better it does so, the better its gravity sensors are working); by assessing the ability of the cricket to regenerate cerci when they’re damaged, in gravity and out of gravity; and by analyzing the speed at which the neural pathways transmit information, data which can be obtained using electrodes.
The Aquatic Team, as you can guess from the name, is the one examining fish and snails on the shuttle. The Aquatic Team’s focus is similar: they want to see how the inner ear of snails and swordtail fish develop in the absence of gravity. As well, they’ll be monitoring the signals sent from the inner ear of a toadfish to its brain in the absence of gravity. The information gathered may help future astronauts deal with motion sickness brought on by weightlessness, and may also someday help those of us (like me!) who suffer from it here on Earth.
The Mammalian Development Team wants to understand the effect that lack of gravity has on the development the nervous system in animals and how the nervous system of adult animals adapts to microgravity; they’ll be examining mice and rats at various stages of development, from fetuses to youngsters to adults. Exposure to microgravity, for instance, may alter the physical structure of the nerve fibers in the heart that monitor blood pressure, which could account for the blood pressure changes suffered by astronauts in orbit. By examining the hearts of rats that have been exposed to microgravity, the team hopes to see if that’s true.
The Neuronal Plasticity Team will also be taking a close look at adult rats, to see how their brains reorganize themselves in microgravity, a capability called “neural plasticity” (the same ability that enables people to regain at least some of its normal function after an injury or stroke). The scinetists involved are examining the brains of adult rats to see how they are changed by their time in space, and studying living rats behavior to see if and how their internal clocks are disrupted by their new environment. On Earth, data from these studies may be beneficial in developing treatments for such disorders as jet lag and winter depression.
Aside from the Earth-bound applications, all of the Neurlab experiments are important because, even after almost 40 years of human spaceflight, scientists don’t completely understand how and why the lack of gravity affects the body. With the International Space Station due to begin construction within months and serious discussions beginning of missions to Mars, that lack of information could one day prove deadly. If we’re going to live and work in space effectively and safely, we need to know all we can.
And, of course, one day humans will live and work in space on a regular basis. If pigs can manage it, so can we.
