Volume XXVII Number 1
Photo courtesy IU Home Pages
Photo © Tyagan Miller
Rats in Space
Imagine, for a moment, that you are an astronaut aboard the International Space Station.
Given the challenges of living, eating, sleeping, and every other typically ordinary thing made extraordinary in space, the last thing you might expect to deal with is vermin. After all, it's hard enough floating through the lifeless vacuum of space for months at a time, let alone sharing limited living space with a bunch of rats. Or is it?
If Jeffrey Alberts has his way, by 2007, the Space Station will be crawling, or more accurately, floating, with rats. This will come as no surprise to NASA. For the past decade and a half, the space agency has been working with Alberts, professor of psychology at Indiana University Bloomington, and his company, STAR Enterprises ("star" is rats spelled backward), to develop habitats to house rats in microgravity. Nor will the astronauts on the station be particularly averse to their rodent stationmates. Specially trained to work with experimental rats, they will participate in what Alberts hopes will be groundbreaking research on the effect of gravity, and lack of gravity, on the development of life.
"It's a huge, fundamental question," says Alberts, who even after 15 years spent on putting rats in space speaks with fresh enthusiasm about the topic. "Since the beginnings of life on Earth, all living things have been continually exposed to gravity, yet we know very little about how gravity affects the development of life. The only way to learn more is to study organisms that develop without it."
Although he earned his undergraduate and graduate degrees during the late 1960s and early 1970s--the era of moon exploration--Alberts never gave much thought to being an astronaut or working for NASA. He devoted his professional life to studying the behavior and neural development of rats. Soon enough, however, space-related science came looking for him.
By the mid-1980s Alberts's expertise in the postnatal development of rats had attracted the attention of the Soviet space program, which was working jointly with NASA to study the effect of space flight on pregnant rats. Before long Alberts was working alongside Soviet scientists behind the Iron Curtain, having designed a portable laboratory and brought it to Moscow to study the effects of microgravity on rats born shortly after returning from flight in an unmanned Russian satellite. Working with both space programs was intoxicating and dramatically altered the trajectory of Alberts' career.
"I was exposed to the space bug, and I got it bad," recalls Alberts, who describes seeing the Space Shuttle up close as a near-religious experience.
Impressed with his work on the Soviet experiment, NASA hired Alberts to design and build habitats to house rats aboard the Space Shuttle and the future Space Station. The idea was to allow researchers such as Alberts to study the effects of microgravity throughout the course of rat life cycles. Rather than being limited to collecting data on rats and their offspring that had spent at most two weeks in space, harboring rats on the Space Station for three months at a time would allow adult rats to mate and give birth, and allow their offspring to mate and give birth, all within a gravity-free environment. For the first time, scientists could study animals that had never experienced the effects of gravity.
Alberts energetically embarked on the project, but soon financial constraints got in the way. After working with Alberts for nearly a year, NASA, citing a strapped budget, attempted to build the habitats themselves. Kept on as a consultant, Alberts watched the project implode, as first NASA and then several large aerospace companies failed to make significant progress on the habitats. Meanwhile, in the mid-1990s, Alberts signed on as a p rincipal investigator overseeing experiments involving pregnant rats housed in NASA-built habitats aboard two Shuttle missions. The goal was to test the effects of microgravity on the development of rat pups who had spent the week before their birth aboard the Shuttle.
"There's a rule in neurobiology that a sensory system depends on appropriate stimulation to develop properly," Alberts explains. "For instance, if you're not exposed to patterned light as an infant, then the visual parts of your brain don't develop appropriately. Or if your ears are plugged from birth, the brain won't properly develop its hearing capacities."
The hypothesis, Alberts continues, was that the vestibular system--an inner ear structure that, like a carpenter's level, helps the brain to maintain and regain balance and orient the body in space--worked like any other sensory system. In other words, it wouldn't develop properly in the absence of gravity. The first Shuttle experiment provided corroborating evidence. Tested immediately after birth, the pups born to the space rat mothers had significantly underdeveloped vestibular systems. Alberts pops in a videotape to demonstrate.
"This pup is part of the control group (rats not exposed to microgravity)," Alberts says, pointing to an infant rat held above a water-filled tank. A latex-gloved hand releases the pup, belly up. It quickly rights itself under water before sinking too far. "See how the rat almost immediately turns itself right side up," says Alberts, as the rat pivots gracefully and begins swimming toward the surface. "Its vestibular system allows it to regain balance and understand where its body is in relation to gravity and the surrounding space."
The video then cuts to another rat, one born to a space-going mother, suspended at the water's surface. When the rat pup is released, it moves its legs but doesn't turn over. "Because this rat spent a week in the womb without gravity," Alberts says, "it can't tell up from down; its brain doesn't understand how to regain balance."
The vestibular systems of the infant space rats were clearly disrupted by their exposure to microgravity, but their sense of balance recovered completely within a short time. The vestibular system's rapid recovery, Alberts says, tells us something basic: the system is not fixed by early experience but is continually adapting.
The second rat-bearing Shuttle flight, launched a year later, produced more surprising results. To investigate the effects of microgravity on fetal vestibular development, pregnant rat mothers were taken directly to the operating room upon touchdown. There, Alberts and his team removed the rat fetuses from the mothers' wombs and, while they were still attached umbilically, measured the fetuses' sensitivity to movement. As predicted, the fetuses were insensitive to pure gravity forces. But compared to the control group, they were hypersensitive to angular accelerations, created by rolling movements.
"We were stunned when we analyzed the data," Alberts says. "Then we compared videos of the earthbound, pregnant control-group rats and the pregnant rats on the Shuttle and figured out what was probably happening. While the Earth rats only walked across the floor and reared up and down, the space rats, freed from gravity, were able to move across all surfaces. In effect, they were constantly pitching and rolling in unusual ways, so the fetuses inside them had an enriched set of vestibular experiences, based on the kinds of movement only possible in zero gravity."
The unexpected findings have helped Alberts better understand how the vestibular system works. Like other sensory systems, inhibiting one type of input can strengthen response to another. Just as a blind person may develop unusually acute hearing to compensate for lack of sight, the rat fetuses aboard the Shuttle acquired unusual sensitivity to movement-based forces in the absence of gravitational forces.
Alberts's findings so far represent a potentially significant step toward better comprehending how gravity affects the development of life on earth. In practical terms, learning more about the relationship between gravity and the vestibular system could lead to advances in treatments for Parkinson's and other diseases that effect motor control and balance. The more deeply we know the workings of the vestibular system, Alberts argues, the more likely we'll be able to reduce the enormous costs--monetary and physical--of broken hips and other bone breaks often suffered by the elderly.
Although engrossed by the theoretical and experimental elements of studying rats in space, Alberts is currently engaged in the practical challenge of designing and building habitats for the space-bound rodents. Having witnessed the failure of NASA and other companies to produce optimally designed habitats, Alberts and STAR Enterprises, together with another Indiana company called Space Hardware Optimization Technology (SHOT), submitted a proposal to NASA to finish the project Alberts had begun nearly a decade and a half earlier. NASA accepted the proposal and set a timetable of three years, with the goal of housing rats in the newly designed habitats aboard the Space Station by 2007.
The existing prototypes, stashed in a small, machine-filled room in the back of Alberts's campus laboratory, appear deceptively simple. The approximately 3 by 4 feet blue plastic and metal boxes contain titanium wire cages in which the rats will live for three months at a time. The boxes within which the cages rest will house lights, video cameras, food dispensers, and waste collection systems; devices to monitor the rats' vital signs and other physical properties; and mechanisms to regulate airflow, temperature control, and carbon dioxide levels. The prototypes represent significant advances over the NASA-built habitats used aboard Shuttle flights, which were not designed for housing rats long term.
For Alberts, the central challenge has been conceiving a habitat that will comfortably and effectively house rats not only in microgravity, but also in the varying increments of gravitational force to be created by the Space Station's centrifuge--a device that, by spinning, can simulate gravity. Finally, unlike the habitats used aboard the Shuttle flights, which did not allow for human interaction with the rats, the habitats designed for use aboard the Space Station are meant to allow the astronauts to remove the rats and conduct experiments. Ideally, the habitats will not only keep the rats alive and well but eventually also encourage them to breed successfully and give birth to a slightly altered species--the weightless, gravity-free rat.
Making rats comfortable in weightless spaceflight may seem challenging enough, but Alberts has done so while balancing academic work with university administrative responsibilities and business obligations. A professor at IUB since 1974, Alberts served the university for many years as associate dean for research, making the step up to associate vice president for research in 2001. So far, he has handled what he describes as a "slightly schizophrenic exist-ence" with aplomb--STAR Enterprises is a winner of the Tibbetts Award, a prize given annually by the U.S. Small Business Administration to outstanding small businesses. Experiencing the business world has also opened Alberts's eyes to the rewards of applying academic knowledge in broader fashion.
"This has been a chance for me to take part of my expertise as an academic researcher in animal behavior and translate that into something tangible that can be sold to a customer," he says. "The hardest part is being careful to preserve the values of the academy while at the same time meeting business obligations and keeping a company afloat."
As the 2007 deadline approaches, Alberts hopes that his habitats will prove not only to be a successful business venture, but also an important advancement in the ongoing investigation of gravity and its impact on life.
Jeremy Shere, a freelance science writer, is completing his Ph.D. in English at IU Bloomington.