A special lab that allows test subjects to live and be observed in altered conditions recently opened in Cologne. It's an ideal testing ground both for spaceflight and medicine.
Envihab - a combination of "environment" and "habitat" - is the latest research lab to open up at the German Aeronautics and Space Research Center (DLR) in Cologne. Doctors working there can simulate and study how a particular environment affects people's health.
The core of Envihab is a section where test persons can be locked in for weeks at a time.
"We can barricade people in here," quipped Rupert Gerzer, director of the institute. "We can close off the windows so that no daylight comes in - only artificial light."
Those who agree to be locked in here consent beforehand to participating in a long-term experiment - often under difficult conditions.
"We make people lie down on a bed with a head-down position of six degrees. That corresponds precisely to zero gravity," said aerospace physiologist Bergita Ganse.
Medical observation 24/7
The test subjects must stay in this position in bed for weeks at a time. They eat and shower while lying down, and medical exams are also performed in this position - allowing doctors to study how a longer spaceflights affect the body's circulatory system.
Lying in the head-low position for weeks on end helps to simulate the body's circulatory system during a space flight
The test subjects can be observed around the clock in the facility. Melanie von der Wiesche, director of the study, points to a hatch on the wall.
"We can draw blood from the test subjects through this hatch during the night," she said.
The researchers are particularly interested in melatonin levels in these exams - the hormone that helps regulate sleep. Daylight affects the amount of melatonin the body produces. In the morning, when the sun rises, bright, blue light inhibits the production of melatonin - and the body wakes up. In the evening, as the sun goes down and the light changes to a warm reddish hue, people become sleepy as the body releases melatonin.
The same effect can be simulated in the DLR lab using a special overhead lighting system. It's a highly complex system that allows the entire spectrum of light to be adjusted precisely.
"We can use it to create every kind of lighting situation, intensity and atmosphere, allowing us to study how light affects sleep," said von der Wiesche.
Noise and stress impact sleep
The scientists can also expose their test subjects to noise - either the kind found around the clock at the International Space Station, or in a big city during the day, when shift workers want to try to catch some sleep with their windows open, for instance. The test subjects are also woken up after four hours of sleep, which causes stress to the body.
"If that keeps happening over the course of a week, they get quite irritable, and the body then acts differently," said Gerzer.
Humidity and air composition can also be altered in the Envihab, permitting the scientists to study whether or not people can live with less oxygen in certain situations, or can deal with more carbon dioxide and nitrogen. All of these elements can affect astronauts' health, and also that of pilots and plane passengers. Researchers in the lab can simulate an atmosphere at 10,000 meters above ground level; for instance, they can study a drop in air pressure in a plane.
Understanding changes in organs at higher gravity
Researchers at Envihab are also able to adjust gravitational forces using short-arm centrifuge. The test person sits at the end of a cross-shaped carousel.
"We ca induce abnormal accelerations - in other words, up to six times the Earth's gravity," said Guido Petrat, one of the researchers.
One of the four centrifuge seats is equipped like an intensive care unit in a hospital. Its special feature is a robot arm, to which an ultrasound machine is attached at the end. The machine is controlled externally. While a test person is spun around in the centrifuge, researchers can view his or her heart or other organs and glimpse changes in vascular density.
"We can see how veins in the feet, legs and thighs react when exposed to this intense pressure and whether they could become damaged in the process," Petrat said.
Alexander Gerst will be participating in the studies. The German astronaut is scheduled to fly to the International Space Station in 2014, but a bed in the Envihab is already reserved for him for when he comes back.
"As an astronaut, I'm also a scientist, but in this case, I'll be a test subject, too," he said. "I'm looking forward to it!"