Are we sending invasive species to other planets?

We have all seen pictures of engineers and technicians working on spacecraft intended to go to other planets.

The workers wear protective clothing and they work in "clean rooms." This is to minimize the chance of contamination, which includes having stowaway bacteria and other things getting onboard.

Testing a spacecraft in a simulated space environment of savage temperature changes, vacuum and radiation also provides a degree of sterilization. We really do not want any Earthly stowaways on any spacecraft we send to other bodies in the solar system.

The preparations for the Apollo missions to the Moon included a number of robot missions to evaluate the conditions on the lunar surface before people landed there. Some of these were landers named “Surveyor.”

The Apollo 12 lunar module landed close to Surveyor 3, which at that point was a dead spacecraft that had been sitting on the lunar surface for several years. The astronauts brought back a few parts from it, because the engineers wanted to know how the construction materials were affected by their years of exposure to the vacuum, radiation and temperature extremes on the lunar surface.

Scientists were surprised to find earthly bacteria living on those pieces. They had stowed away on the spacecraft and had survived years on the lunar surface.

Although putting living creatures from Earth on the Moon is undesirable, the extreme conditions mean that at best they are unlikely to do more than survive.

For missions to Mars, Europa or Titan, for example, the issue of stowaways is much more important, because there is a chance there could be indigenous life on those worlds, and that some Earthly life could thrive there. Actually, stopping the stowaways is tough.

Every species of living thing has genetic variations, this means when conditions change, there will be some individuals who can accommodate the changes better than others will. The result is that after a few generations the species is matched to its environment.

For bacteria, generations range from minutes to hours, so they can adapt quickly. Therefore, if any bacteria or other things are exposed to space conditions for just a short time, there could be survivors.

Eventually, after many generations of adapting, the spacecraft could head off to another world carrying a collection of tough individuals that could survive the exposure to space conditions and could find the surface of Mars, for example, a perfectly comfortable new home.

The cleanliness and harsh sterilization procedures that are a standard part of space mission preparation are to minimize the chance of that happening.

On Earth we find some form of life almost everywhere we look. There are creatures living in the rocks, kilometres underground. There are things making their lives at the bottom of the deep ocean trenches, living in cold darkness, under pressures thousands of times greater than the air pressure we live with.

Hot, volcanic springs of nearly boiling water contain algae and bacteria. There are other creatures that live in ice.

Basically, here on Earth, wherever life is possible, life is there. Moreover, it is always seeking to spread to anywhere it can live or adapt to. Our battle against the spread of alien species — plants, animals or germs — into our ecosystems shows how hard it is to stop them moving into new environments.

When we complain about invasive species, we do so with a degree of hypocrisy. There is one highly invasive species that now inhabits the whole Earth, from pole to pole, in numbers that are severely impacting ecosystems and even changing global climate. It is homo sapiens, us.

At least though, when one day we meet an alien living creature, we are trying very hard to ensure it is not a descendent of something that came from Earth.

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Mars is low in the southwest after dark. Jupiter and Saturn lie low in the southeast before dawn. The Moon will be Full, and eclipsed on the 26th.