Space Bugs
Scientists are pondering over the problem of man inadvertently carrying microbes to space:
Artist’s impression of the Phoenix Lander
If man has charted his way into space, can microbes be far behind? Life in outer space indeed seems an absolute certainty, given that ever since the beginning of the space age scientists have sent more than just satellites and astronauts into that realm, say researchers studying microbial colonisation of locations beyond earth.
“Wherever man boldly goes, his microbial fauna are sure to follow,” says Lewis Dartnell, an astrobiologist at University College London. Dartnell focuses on the microbiology of the closed artificial environments created for the exploration of the cosmos — such as the International Space Station (ISS) — and minimisation of the risks of inadvertently transporting terrestrial contamination into space.
Recently writing in Microbiology Today, Dartnell says that despite our scientific advancements, spacecraft are not routinely decontaminated and are teeming with bugs. The first proper investigation into microbial diversity was conducted following the launch of the Russian space station Mir in 1986. Mir, which spent 15 years in orbit, was humanity’s first consistently inhabited long-term research station in space and was internationally available to astronauts of many countries. Numerous studies were conducted on the microbial life surviving in different regions of the station, such as the dining area, sleeping quarters and hygiene facilities. “Widespread bacterial colonisation was noted, but fungal levels typically remained low throughout space missions, probably owing to the low humidity of the recycled air,” Dartnell writes in his paper.
In 1998, however, a unique observation was made during a Nasa mission to Mir. Several large free-floating blobs of water were discovered behind the service panels of one of the habitation modules. These were later analysed and found to contain many Enterobacteriaceae such as Escherichia coli (that causes gastroenteritis) and Yersinia species (another group of bacteria that causes disease in humans). Researchers believe that these microbes were almost certainly supplied by the human occupants of the station. Apart from the bacterial fauna, the free-floating condensates contained fungi, amoebae, protozoa as well as dust mites.
But what was most worrying, writes Dartnell, was that “the researchers isolated several opportunistic pathogens and what they suspected to be a Legionella species, although this identification could not be confirmed as subculturing failed.” Some species of this genus cause Legionnaires’ disease, an often fatal infection, he adds.
Things have, however, improved greatly over the years. Today’s ISS is much cleaner than Mir was 20 years ago, thanks to special filters, weekly cleaning and biweekly disinfecting regimes. Nonetheless, many contaminants from human occupation have been found on ISS, such as Staphylococcus epidermidis.
So what are the consequences of microbial infection on astronauts? Diseases, mainly respiratory infections, occur in a quarter of space shuttle flights. Adverse microbial effects also include allergies and toxicity of air and water supplies as well as biodegradation of critical spacecraft components. “Prolonged exposure to cosmic radiation and microgravity is believed to have a negative effect on the immune system, and disease transmission is enhanced within the closed environment of recycled air and water,” says Dartnell.
A few days ago, the Phoenix Lander touched down on Mars to take the first ever direct measurements of Martian water and organic molecules. “To guarantee the cleanliness of this robotic arm, and thus the validity of any organic detection, it was enclosed in a biobarrier bag — effectively an interplanetary condom,” writes Dartnell.
But once scientists decide to send humans to the Red Planet, such biological containment will be near impossible. Our microbial entourage will inevitably begin leaking out onto Mars. What’s more, microbes have an uncanny ability to survive as spores, resistant to heat, cold and radiation. In such a scenario, “how could we ever be totally certain that any subsequent biological discoveries weren’t simply signs of our own dirty sleeves?” asks Dartnell.
The problem of contaminating other solar systems with earth life must be dealt with seriously, says Charles Cockell of the Centre for Earth, Planetary, Space and Astronomical Research at Open University in Milton Keynes, the UK. “Interstellar contamination could endanger a distant biosphere or even interfere with an origin of life occurring on another planet,” he told KnowHow.
But despite our best efforts at planetary protection, we may never ensure the complete biological isolation of cosmic bodies. The theory of “cross-fertilisation of worlds” has of late been gaining much momentum among scientists. “There may exist a natural process that has been transporting life between neighbouring worlds since the birth of the solar system,” explains Dartnell.
Cosmic processes are bound to continue, but perhaps it’s best to let earth bugs remain on earth and not hitchhike a night flight to Venus.
Sources:The Telegraph (Kolkata, India)