There is a really obvious problem with going to a planet we have deemed "habitable". Even if the temperature is perfect, the air composition is perfect and the terrain is perfect we still have the problem of micro-organisms. If the planet has checked the aforementioned three boxes then it is very likely (in fact almost definite considering there's oxygen) that there will be plenty of micro-organisms around.

We have evolved alongside the micro-organisms on Earth for billions of years and our bodies are naturally built to withstand them. I would hazard a guess that if we encountered alien viruses / bacteria (and possibly a vast array of other unknown types of micro-organisms) we would be royally dissolved.

Is this too big an assumption? If not, what could we do to protect ourselves in a not-too-invasive way? Let's rule out wearing space suits the whole time because that's a boring answer, let alone problematic.

What can we do to acclimatize to an alien environment so that we don't need excessive gear attached to us to live there? Assume any level of tech.

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    $\begingroup$ There are at least two more boxes: radiation level and type and atmospheric pressure. $\endgroup$ Commented Sep 21, 2015 at 14:35
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    $\begingroup$ Yea and gravitational strength, angular velocity, magnetosphere strength etc. I was just being brief. $\endgroup$
    – Varrick
    Commented Sep 21, 2015 at 14:39
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    $\begingroup$ Orson Scott Card's Pathfinder posits that the first step in colonizing an Earthlike would would necessarily be to deliberately engineer an extinction event and wipe out as much of the native life as possible, because it would almost certainly be biologically incompatible with (and highly toxic to) Earth life. $\endgroup$ Commented Sep 21, 2015 at 15:31
  • $\begingroup$ I don't think the bacteria and viruses will be very different from those on Earth given that the conditions are similar. So most probably there won't be problems $\endgroup$
    – ACV
    Commented Sep 22, 2015 at 13:19
  • $\begingroup$ @ACV Please do note that viruses evolve to be accepted by a certain species (and that isn't always perfect - some people are naturally immune to certain strains of viruses). There is no chance that the viruses in the host ecosystem would be able to interface properly with Earth ecosystem cells. And the toxin synthesis processes in the bacteria would be evolved to target the lifeforms in the host ecosystem, not those of Earth. The toxins will likely not work as expected. And finally, we cannot assume that the life will be biologically compatible with us. $\endgroup$
    – rytan451
    Commented Jul 8, 2017 at 9:38

3 Answers 3


You don't really need full organisms to test the conditions of the planet and nanotechnology doesn't have to be the counter-measure either. Bioengineering could do all the work.

Since the colonists would be arriving in space-ships, the ship could have scanners/sensors that would measure and gather the air/soil/water of the planet before the colonists even got out. Then, batches of human tissue (or organs or organ systems or even just cells!) could be grown in labs to act as test cases against the planetary conditions.

Even today, researchers are able to grow tissue in labs without it ever being actually attached to living humans (which has a lot less ethical implications).

Then data about the exposure could be gathered, and the ship could then grow human-friendly m-o's designed to counteract the conditions of the planet, combine them with a new batch of human tissue, gather new data, and then continue iterating until any negative effects were either eliminated or negligible.

These m-o's would then be administered to the colonists and act as an immune system upgrade. Or you could go with gene therapy to change the behavior of white blood cells etc, so that the human immune system could handle the environment with as little change as possible.

Computers could even do simulations based on the data from the new planet and formulate a workable solution based only on those simulations. This would be much faster than the grow/test cycle. Real tissue testing would take place only once the simulations had come up with something, and just to make absolutely sure nothing bad happens.

And if it didn't work with the first iteration, you still have a faster process with simulate/grow/test since the simulate step gets you at least close before you bother growing anything.

All of this could be automated by the ships computer, which would use machine learning algorithms to iterate on the immune solutions.

These ways of doing things are less intrusive, faster, cheaper, more ethical, more "natural" (whatever that means), and less dangerous than using crew members or animals as test subjects or augmenting the crew with "synthetic" technology.

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    $\begingroup$ This is actually my favorite answer, despite having the least votes. $\endgroup$
    – Varrick
    Commented Sep 22, 2015 at 10:41

Alien viruses would be highly unlikely to be a problem - they are adapted to reprogram the cell mechanisms of their local wildlife and would be unable to affect us.

Micro-organisms though you are absolutely right. We've no idea how they would effect us but there is a long history on earth of bad things happening.

There is actually a fairly high chance that they would find the human body a very inhospitable environment. They have no more idea how to deal with our immune system than ours knows how to deal with them.

On the other hand though they could be a deadly unstoppable pathogen that loves nothing more than nomming down mammalian cells. Until we encounter them there is no way to know what we will meet, and no matter how many planets we visit this one may be the one with the killer lurking in wait.

In order to adapt then the local m-o would need to be studied and then our immune system updated to handle it. This may be as simple as creating vaccines or as complex as specially programmed nano-machines in your blood.

In fact its likely that colonists would have nano-machines in their blood to boost their immune system anyway - at the very least to keep an eye out for bad stuff coming.

  • $\begingroup$ I was going to write the exact same answer, but you beat me to it. Vote up! $\endgroup$ Commented Sep 21, 2015 at 16:55

Test all the things. Assume that the new world is a new class of medicine then use the same kind of testing procedures to determine safety.

Test it and see what happens. Here on earth we use numerous animals as human testing analogs, such as mice, pigs, rats, sheep, dogs, cats, etc. Bringing the larger mammals on a space expedition probably isn't feasible but bringing some rats and mice shouldn't be too much of a burden.

Some rudimentary chemical analysis will indicate if the amino acids used in life on this planet matches our own. Different amino acids will need to be tested for toxicity. This kind of testing can be done on bacteria. If those bacteria die, find out why. If they thrive, find out why. It won't take long to figure out of the alien viruses will interact with Earth biology or not.

Expose a collection of mice to the alien atmosphere and add some soil/biomatter to their food. Watch what happens for a generation or two. If something weird starts happening then you'll know what's going on and can study it. Say the mice exposed to soil from a certain place roll over and die with horrible abdominal pain. Do an autopsy to find out what happened.

If all the animal studies check out, have a crew member volunteer to be the human guinea pig to start acclimatizing to the new biosphere. Even better if you have a cloned, brain dead human to test on first. Keep the test subject in quarantine for weeks or months with full diagnostics on blood work, stool & urine samples and psychological evaluations.

Should the human trials check out then exposing more of the crew or passengers to the new biosphere would be okay. At this point, the safety of humans in the new biosphere has been well established and there shouldn't be any addition precautions required outside the usual "wear gloves when handling body fluids" rules.

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    $\begingroup$ I like the cloned, brain dead human idea. I hope that doesn't make me morally corrupt. $\endgroup$
    – Varrick
    Commented Sep 21, 2015 at 14:15
  • $\begingroup$ @Varrick a brain dead human clone is more ethical because the clone cannot feel pain. It's not human. Maybe grow a clone so it doesn't have a head or something to make it definitely not human. $\endgroup$
    – Green
    Commented Sep 21, 2015 at 14:31
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    $\begingroup$ Yea I know, I just think if we were to grow these on Earth right now, there would be some people who had a problem with it :P $\endgroup$
    – Varrick
    Commented Sep 21, 2015 at 14:34
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    $\begingroup$ @Varrick That they would, but their objections would be on philosophical or theological grounds. Sure there are ethics questions to be worked out too. $\endgroup$
    – Green
    Commented Sep 21, 2015 at 14:36
  • $\begingroup$ Depending on the setting, you might want to use a live human for utilitarian reasons. Suppose you have enough life support for 10 human-shaped objects. You could take 10 humans, which gives you 10 colonists, maybe 9 if a guinea pig dies. You could take 9 humans and a brain-dead clone, which gives you only 9 colonists, even if the guinea pig lives. Granted, this is assuming that you can't make clone them on the spot, and must take the clones with you. $\endgroup$ Commented Sep 21, 2015 at 14:49

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