The airlock of the International Space Station (ISS) was turned into a laboratory last week. In a station with as much space as a 747, that may seem a bit odd, but its purpose was part of a study of the lungs of space travelers by monitoring the effects of one the astronauts' most surprising hazards: dust.
In zero gravity, dust is particularly nasty. Instead of settling to the floor and waiting patiently for the next pass of the vacuum, it floats about, getting into ventilation systems, equipment and, worst of all, lungs and eyes. Learning how to cope with this dust is a high priority if manned space exploration is to continue. Moondust, for example, is sharp, abrasive, and the utterly dry conditions of the Moon make it cling to everything. So when the Apollo astronauts returned to the Lunar Module they looked like they'd taken a stroll in a coal mine – and scientists suspect that Mars may be just as bad.
As part of the effort to determine just how harmful dust is, ESA astronaut Samantha Cristoforetti and NASA astronaut Terry Virts are taking part in the Airway Monitoring experiment, which measures exhalations of nitric oxide, a chemical found in cigarette smoke and car exhausts, and in human breath, where it acts as an important "signalling" molecule to help diagnose inflamed lungs and asthma.
Nitric oxide is a simple molecule with a surprising range of biological functions. It's a vasodilator (widens blood vessels), helps people living at high altitudes avoid hypoxia, protects the liver against ischemia, and works with the immune system to ward off infection. Doctors use it to treat pulmonary embolisms and ischemic pain, and it's used to diagnose asthma and lung inflammations. It's this last fact that makes it of interest to space medicine specialists because it helps to assess the health of the lungs and the effects of dust on them.
According to ESA, last week the two astronauts went into the Quest airlock module (PDF) on the ISS. Once inside, the airlock pressure was reduced 30 percent, or the equivalent of an altitude of 3,000 m (9,800 ft), while scientists back on Earth monitored their breathing and especially their nitric oxide levels.
ESA says that the astronauts will carry out four test sessions, which will be compared to pre-flight tests, and a total of eight astronauts will undergo similar tests. It's hoped that the data will not only help future space explorers, but also the 300 million people suffering from asthma on Earth who would benefit from a simple lung test, as well as the possibility of developing new drugs.
"In the future, it is quite likely that drugs could be designed based on exhaled nitric oxide measurements, to find the most effective molecules to treat inflamed airways and lungs" says Lars Karlsson, lead investigator at the Karolinska Institutet of Sweden. "This type of research is a first step down this road."
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