Experiments designed by scientists from Vanderbilt University Medical Center and other research institutions around the world are scheduled to depart on the space shuttle Columbia when it thunders from the pad at Kennedy Space Center and hurtles into space this week.
On Thursday, April 16, seven astronauts will leave the earth and its gravity behind to perform the Neurolab Mission - a series of life-sciences experiments designed to evaluate the effects of weightlessness on the human nervous system.
VUMC's team of investigators - along with scientists from 25 other universities in seven countries as well as the National Science Foundation, Office of Naval Research, NIH, the space agencies of Canada, Japan, France and Germany, and the European Space Agency - have spent the last four years designing and refining Neurolab.
VUMC scientists, under the direction of Dr. David Robertson, professor of Medicine, director of the Clinical Research Center and co-director of Vanderbilt's Center for Space Physiology and Medicine, are part of Neurolab's Autonomic Nervous System Team, which is focusing on blood pressure regulation, gravity and a condition known as orthostatic intolerance.
"Our interests and concerns are with the autonomic nervous system and the changes and adaptations that take place during space flight," said Andrew C. Ertl, Ph.D., assistant professor of Medicine. "These adaptations that are appropriate in space turn out to be mal-adaptations when astronauts return to earth and its gravity."
According to Robertson, the VUMC experiments are the most complex human experiments ever to be attempted in space. Two years ago, NASA payload specialists spent two months here training to be able to properly perform the VUMC experiments.
A mental picture of the VUMC team's area of interest, orthostatic intolerance, is easy to conjure up: Television images of weak-kneed astronauts struggling to keep their balance following a trip into space.
"The majority of astronauts returning to earth are incapacitated to some degree, especially when standing" Ertl said. "The concern for NASA is that astronauts may not be able to perform an emergency egress to get away from the shuttle if there's a problem."
Orthostatic intolerance isn't limited only to astronauts returning from space, however. The condition - chronic and sustained periods of dizziness and disorientation - afflicts nearly a half-million people in the United States. It's causes remain a mystery.
"We hope if we can understand how micro-gravity mimics this problem maybe we can figure out how to help astronauts and patients," Ertl said.
Orthostatic intolerance is one of several disorders of the autonomic nervous system currently under investigation at VUMC's Clinical Research Center. VUMC's experiment on Neurolab is just one of 26 experiments scheduled to be performed during the shuttle crew's 17 days in space. The test's three basic components include:
- microneurography, a technique used to measure the electrical activity of sympathetic nerve fibers that control the size of blood vessels;
- norepinephrine spillover, which uses a radioactive isotope tracer to more accurately measure catecholamine levels released in the body during times of stress; and
- lower body negative pressure testing, which involves a device that draws body fluids downward to simulate, in a micro-gravity environment, the effects of standing up.
At launch minus sixty, a short two months before Columbia and Neurolab were scheduled to light up the south Florida sky, Ertl and the VUMC team passed a major pre-flight hurdle. They completed their baseline data collection.
"The reason this was so important was that if we didn't have good pre-flight data, we wouldn't have anything to compare with the in-flight and post-flight data," Ertl said. "All the money was on this one. It had to be successful."
One hitch in collecting the baseline data involved microneurography and the excruciating sensitivity needed to monitor electrical activity in some of the smallest nerve fibers in the body.
This electrical activity may have to be amplified more than 100,000 times, at which point it becomes highly susceptible to EMI, or electromagnetic interference.
"Overhead lights, cords from other equipment, batteries - all these types of things can be a problem, and are a problem on earth," Ertl said. "We had to address over and over again how to prevent that interference in space." Finally, on the very last day for baseline data collection and after several weeks of preparation, the EMI problems were resolved.
Now Robertson, Ertl and the rest of the VUMC team - which includes Dr. Andre Diedrich, visiting scientist from the German Space Agency; Dr. Italo Biaggioni, associate professor of Medicine; Dr. Rose Marie Robertson, professor of Medicine; Lynda D. Lane, senior associate in Medicine; and Sachia Paranjape, research assistant - can concentrate on the mission itself. Immediately following the launch, part of the team will head for Houston, where they will spend the following 17 days monitoring the experiments as they are conducted in space. Neurolab's science monitoring headquarters are located in the room which used to serve as mission control during the heady days of Apollo flights and moon walks.
One team of VUMC scientists will stay in Florida while another heads to Edwards Air Force Base in California. It isn't known yet at which of these two sites the shuttle will land, so two separate, complete laboratories have to be set up to collect the post-flight data.
Once Columbia settles into its orbit, testing begins. During the first two days, autonomic nervous system function testing takes place. On days seven and eight, experiments will include autonomic nervous system plus lower body negative pressure. Days 11 and 12 will be busy for Columbia's crew.
That's when testing will include autonomic nervous system plus lower body negative pressure as well as microneurography and norepinephrine spillover. This battery of experiments duplicates the crucial baseline data collection that took place at launch minus 60.
The experiments will be duplicated again immediately after Columbia touches down in either Florida or California.
"They call it 'R + 0,' which is return plus zero, or the day they return," Ertl said. "They come in on the crew transportation vehicle, or CTV, to where we will do the post-flight data collection, and, hopefully, they will not have been upright at all to that point.
"Astronauts historically like to walk off the shuttle as a sign that they are okay, but we want to study them without them having experienced any gravitational stresses due to upright posture."
The work won't end at that point. In many ways that's when it begins. Then the VUMC team and the teams from the other 25 research institutions can begin analyzing the data, reviewing the information collected from an environment that can't be duplicated on earth.
"We are extremely excited," Ertl said. "This has been a huge commitment for Vanderbilt. This allows us to do science in a completely different environment than what's done in our hospital on earth. The potential benefits of this research are enormous."