Clearing the Air: Smaller Detectors Needed for Moon, Mars Missions
NASA astronaut Don Pettit, Expedition Six NASA ISS science officer, holds a Grab Sample Container (GSC) in the International Space Station's Zarya module. The sample container is used for collecting air samples as part of ISS environmental monitoring.
Credit: NASA/JSC.

No matter what mission astronauts will carry out on the moon and Mars during future planetary expeditions, they will certainly have to breathe.

To make sure their air is clean, a team of NASA researchers and Spacehab engineers have teamed up to develop miniaturized detectors which, they hope, will lead to a compact, real-time air monitoring system for future spacecraft.

"It will be increasingly important as we get past the space station on to the moon or Mars," said John James, NASA's chief toxicologist at Johnson Space Center, in a telephone interview. "Right now, we don't have space shuttles going back and forth to the station, so it is difficult to get air samples back down for analysis."

NASA's space shuttle fleet has been grounded since the Columbia disaster in 2003, in which the Columbia orbiter and its seven-astronaut crew were lost during reentry. The space agency is planning to launch its first return to flight mission, STS-114 aboard the shuttle Discovery, no early than July 13. In the meantime, Russian Soyuz spacecraft have returned archival air samples to scientists on Earth.

But it is a new space-based system that James and Spacehab hope to develop.

Under a two-year partnership between NASA and Spacehab, researchers will test miniature mass spectrometers, instruments that detect and measure the amount of pollutants in a given environment, in order to develop better spacecraft life support systems.

 "Air pollutants can affect your health, and some people are more susceptible than others," James said, adding that the effects of contaminated air can also vary. "Sometimes they're non-specific, and only cause reports of headache or mild, flu-like symptoms."

Spacecraft air is recycled repeatedly, which could lead to an accumulation of harmful compounds, researchers said. The possibility of leaking equipment, such as the chemical halon from onboard fire extinguishers, is also cause for concern, they added.

Bringing down the weight

Most mass spectrometers on the market today weigh about 100 pounds (45 kilograms) and can be as large as a car trunk, much too big and heavy for spaceflight, NASA officials said. The mass spectrometer inside the nitrogen-oxygen air quality system aboard the International Space Station (ISS) is about the size of a large suitcase, but James hopes future versions can be even smaller still.

A separate instrument, the volatile organic analyzer (VOA) uses a method called gas chromatograph ion mobility spectrometry to track the slow build-up of trace contaminants onboard the ISS on a monthly basis. That instrument, a 96-pound (43-kilogram) tool about the size of a mid-deck locker, failed in July 2003.

"That technology is not going to get us to the moon," said Nigel Packham, manager of NASA's environmental factors office for the station at JSC. "It is too big, and it is too heavy."

Spacehab officials are calling upon the nanotechnology-expertise of the Richardson, Texas-based company Zyvex to scale down mass spectrometer size.

"These little things [would] have an advantage in that you could deploy three, four or five of them around as a kind of first-alert system," James said. "I see that as very valuable for a lunar or Mars [human] habitat."

A real-time system would also be vital since lunar and Mars astronauts would be too far from home to send an air sample back to Earth for analysis, NASA officials said.

Packham said ISS astronauts currently use devices called grab sample containers and dual absorbent tubes to collect station air samples and send them back home to Earth. The most recent batch of samples arrived home with the crew of ISS Expedition 10, whose Russian Soyuz spacecraft landed in Kazakhstan on April 24.

"We have no current real-time monitoring system in place," he said, adding there are also other projects underway to minimize instrument weight. "For example, [the Jet Propulsion Laboratory] is working on a miniature gas chromatograph mass spectrometer."

A captive environment

Space-bound astronauts, such as the six-month crews assigned to the ISS, can be more sensitive to air pollutants because of their contained environment.

"It's magnified in the sense that your exposure is continuous," James said. "Workers with industrial exposures on Earth are exposed between six and eight hours a day, but in space habitat you can't just go home."

In February 2002, ISS Expedition 4 astronauts had to confine themselves temporarily to the Russian segment of the space station after detecting a foul odor in the U.S.-built Quest airlock. The offending, but non-toxic, smell originated in a recyclable metal oxide (Metox) canister used to clean and recharge air scrubbers for U.S. space suits, NASA officials said.

"We call it the 'Metox Incident,'" James said. "Basically, we went to desorb some filters used in the air scrubbers and they released some noxious compounds."

A fire aboard the Russian space station Mir in 1997 also gave NASA researchers samples of contaminated air, which were collected by astronaut Jerry Linenger after a faulty oxygen-generating canister sent flames and smoke billowing through the orbital outpost. Linenger and the rest of Mir's crew also contended with rising carbon-dioxide levels and leaking antifreeze fumes.

James said that one of the major hurdles facing mass spectrometer miniaturization is how small engineers can push the device without losing performance. Retaining reliability too, will be a focus.

"Honestly, I think the technology is to the point that there's some good opportunity for spin-off on Earth," he said, adding that simple carbon monoxide monitoring in homes is just one of many potential uses. "There are Homeland Security opportunities and perhaps some specials applications where you might want to monitor high risk areas."