Space Fungus: A Menace to Orbital Habitats

by Yuri Karash : Moscow Contributing Correspondent
Posted: 07:00 am ET July 27, 2000

Now that the Zvezda service module has docked and the International Space Station will soon be habitable, a growing number of cosmonauts and astronauts could soon face a new threat -- space fungus.

During a recent mission, Mir crew members noticed that the view from the station's porthole was deteriorating due to an unknown film that was spreading like some horror-movie scum.

"During 20 years of research, the IBMP scientists have discovered up to 250 species of microorganisms which live inside manned spacecraft, including fungi and bacteria."

The porthole was examined carefully after the crew returned to Earth, with the results shocking researchers and engineers. Although the porthole and other windows were made of extra-hard quartz glass and mounted on titanium covered with enamel, they were partly destroyed by a colony of fungi and bacteria visible to the naked eye.

A communications device on Mir was damaged by space fungi during the 24th main mission.

Engineers later learned that the fungi also damaged electronic equipment on Mir, including a control block for a communications device used on the outpost from 1997 to 1998 during the 24th main mission to Mir.

The microorganisms crept under the steel cover of the block and sat on electrical contacts and polyurethane pieces. As a result, parts of copper cables located nearby also were oxidized.

Subsistence for the microorganisms was certainly not the metal, glass and plastic of those devices, said Natalia Novikova, a deputy chief of the Department at the Institute of Biomedical Problems (IBMP

) in Moscow.

"They consume organic stuff which consists of skin epithelia, lipids and other products of human activity," Novikova said. "These products get into the station atmosphere from human breath, sweat etc..and stick to the station's surfaces."

"Bacteria and fungi eat this stuff and generate products of metabolism, particularly organic acids which can corrode steel, glass and plastic."

A mysterious strain

The IBMP has been on the trail of space microorganisms since 1980, when the crew of the fifth main mission to the former Soviet Union's

Salyut 6 space station found a white deposit on parts of the station's interior and exercise machines.

Samples of this deposit were delivered to Earth. Having examined them, IBMP researchers determined that the deposit was left by Aspergillus, Penicillium and Fusarium.

The unwelcome visitors made it to the Salyut 7 station as well. In 1985, the crew members of the last mission to this station were alarmed by fungi destroying the inner plastic surfaces of panels covering the walls of the orbital outpost.

"During 20 years of research, the IBMP scientists have discovered up to 250 species of microorganisms which live inside manned spacecraft, including fungi and bacteria," said Elena Deshevaya, an IBMP researcher. "107 species of fungi were found onboard Mir. The most frequently met fungus is Penicillium chrysogenum."

More fungi from beyond

Not only do space microorganisms thrive inside spaceships, but they actually procreate there. Some fungi found inside Mir in 1995 were descendants of the fungi discovered in the station in 1988, Novikova said.

"All the space microorganisms found inside spaceships originated on Earth

she said. "Most of them got into spacecraft on Earth and some of them were brought aboard with the visiting crews. So, you would expect them to behave like 'normal' Earthly fungi and bacteria."

This is not the case, however. Microorganisms in space significantly mutate. One of the reasons for their mutation could be the level of radiation on Mir, which is 500 times more intense than on Earth.

"Fungi and bacteria are dormant for a number of years and than suddenly become active. Then they may become passive again, but overall their aggressiveness exceeds this of the same type of microorganisms on Earth," said Novikova.

"We don't know what triggers their activation in space," Novikova said. "Based on some observations we can say that the older the plastic is, the more likely it will be used by microorganisms as their feeding ground. They also become more aggressive after the increase of solar activity."

Storing fungi

All the samples of space-grown microorganisms brought back to Earth are kept at IBMP in sealed ampoules stored in safe places. "We don't know how they will behave if they get back into regular Earth conditions," Novikova said.

There is one more reason, however, for keeping space mutants in specially secured places. "If you take a space-grown microorganism which used metal as a part of its habitat and keep cultivating it by increasing the content of metal in its habitat, you can potentially get a destructive biological weapon which will literally 'eat' arms," said Novikova.

Preventing future outbreaks

A number of precautionary measures have been taken to minimize the risk of spacecraft contamination.

All cargo destined to go to a space station is carefully disinfected. A spacecraft is often filled with a gas mixture of ethylene oxide with methyl chloride that is lethal to microorganisms. A few days before launch, public access to cosmonauts is severely restricted to avoid possible transfer of microbes to the crew.

During flight, the crew vacuum-cleans the station once every two weeks and wipes the outpost's surfaces with special wet disinfecting cleaners. Mir also has a special equipment that cleans the station's atmosphere of microorganisms.

IBMP also has developed "Fungistat" which has proved to be an effective killer of fungi.

A metabolic product of space fungus created a small hollow in this aluminum piece of space equipment

Such precautions bring their fruits. "None of Mir crew members has ever got any infectious disease in space," stressed Deshevaya.  But even the most effective disinfecting measures, like filling spacecraft with an extremely toxic gas mixture, do not kill all the fungi and bacteria.

"Microorganisms get inside plastic where this mixture cannot reach them. Than at some point during flight, the contaminated plastic just emits its inhabitants into the station's atmosphere," said Novikova.

It came from the United States

The upcoming international operations on the ISS present extra challenges for microbiologists.  "Space-shuttle crews brought some microorganisms to Mir which had not been found aboard the station before, particularly Penicillium expansum," Novikova said. "This is quite natural, taking into consideration the peculiarities of [the] U.S.' environment. There is a greater variety of fungi and bacteria in a warm climate than in a cold one, like in Russia."

Novikova totally agrees with the strict measures adopted by NASA to avoid possible contamination of Jupiter's moon Europa by robotic spacecraft.  "Regular and relatively harmless microbes can dramatically change their characteristics in extraterrestrial conditions. For this reason the Russians thoroughly decontaminated the Mars 96 spacecraft before sending it to Mars," said Novikova

Deshevaya said that decontamination was done for the sake of future human missions to Mars. "We don't want future Mars voyagers to bring back to Earth mutated microorganisms which could pose a potential threat to humanity," she said.  "With the International Space Station and future human mission to Mars in view," Novikova said, "it is especially important to study space microbiology."