Is it possible for an alien organism to survive on earth?

Question

Let's assume that our intelligent alien organism is living on an earth like planet with an atmosphere but higher gravity. Its world is on the verge of doom. Somehow it could make it to earth with a spaceship. Here are some facts of the home world and our alien organism:

• gravity is around 3G - 4G
• atmosphere is breathable (let's say it's like our air for the simplicity of this question)
• blood-like-system transporting oxygen to the organs but with the ability to control its own blood pressure
• can also control its own heartbeat frequency (is able to sustain a heartbeat frequency that is up to 3 times higher compared to a human and also able to reduce it to a minimum to keep its organ to work)

QUESTION:

Can this organism survive on earth without a pressure suit?

I've read these questions but they don't answer my question
How long can humans survive in increased gravity?
Would a species evolved for very high environmental pressure necessarily die in lower pressures?

Answer 1

TL;DR: The Alien could probably survive for a while without a pressure suit but would definitely suffer long term side effects.

The gravity issue is a problem. Astronauts in space suffer issues of losing the calcium in their bones after long periods of weightlessness, which weakens the bones and would make them brittle and prone to breaking. The gravity of earth being 3 to 4 times less than that of the Alien's home planet could induce the same effects in the aliens, causing long term irreparable damage.

RonJohn's answer about high altitude got me thinking, so I did some research. High altitude is rough on humans because initially there is a stark increase in breathing, and heart-rate in an attempt to compensate for sparseness of oxygen in the air. For obvious reasons, this doesn't do so well for humans who suffer from Hypoxia at higher altitudes without breathing tanks and masks.

For your alien, who can safely increase their blood pressure and heart rate, this might not be an issue as they would be able to get the oxygen that they need without suffering strain on their body the way humans do. After a time, the Alien would likely acclimatize to the earth's atmosphere, and while they wouldn't necessarily have the strength or endurance that they had on their home planet, they would most likely be able to survive

References:

https://www.space.com/23017-weightlessness.html https://www2.palomar.edu/anthro/adapt/adapt_3.htm

Edit: I reworked my answer to conform better with site guidelines. Thanks for the heads up Frostfyre.

Answer 2

Is it possible for an alien organism to survive on earth?

Flip the question around: what would stop them from living on Earth (ignoring us trying to kill them), since if they don't die they -- by definition -- survive.

1. Lack of food. (Maybe their biology is sufficiently different that Earth material is toxic and their native seeds won't grow.)
2. Disease. (Maybe -- by some miracle, and convergent evolution -- they can eat our food. But -- in a reverse Colombian Exchange -- our diseases are unknown to them, and are sufficiently virulent that they die before they can create vaccines and cures.)
3. Temperature: their world is much colder than Earth, so they experience what it would be like if the temperature was 180 degrees F. This ties in with Item #1, since their plants would die, too.

You'd think, though, that any species smart enough to develop interstellar travel would have thought of that in advance.

EDIT: If their home world has air pressure 4x higher than Earth's, then they'd experience Earth like we experience the altitude around 9,800 meters (32,000 feet). So, they'd definitely need oxygen bottles, as we do when climbing Mt. Everest.

Answer 3

I have some objections to your basic premise, and you may want to describe the alien society in a way to show reasons why my objections don't apply to the situation in your story, which thus will be highly unusual and unexpected.

I find the premise that the alien world would be more advanced than 21st century Earth for many hundreds, thousands, or millions of years, but never bother to explore or colonize their own or other star systems, and then suddenly develop interstellar travel when their home world is threatened, and seek to migrate to Earth, is deeply flawed. I always hated it when pulp-era science fiction stories used that plot, and I don't see much use for it in 2018.

If the aliens are anything like Earthlings they would gradually explore and colonize other planets in their solar system, and build space habitats, and eventually have thousands of times as many people living in space as on the home planet. So if a disaster threatens their home planet, the population of it can seek refuge elsewhere in their solar system.

And they would eventually also explore and colonize other star systems. And thus if a disaster threatens their entire home solar system, the population of the home system can seek refuge in already colonized solar systems and explored but as yet un colonized systems. And unless they have a faster-than-light drive their star ships will have to keep them alive for decades, centuries, or millennia, and they will have a proven ability to create livable environments in outer space - their star ships will be more or less artificial space habitats with interstellar drives attached. So they won't have much need to experiment with how well they can survive on Earth if the conditions on Earth are only partially in their comfort or survival zones.

So you might want to consider those reasons why your premise is so improbable and come up with reasons why my objections to it do not apply.

For example, maybe the aliens only have 21st century technology but do have psychic powers, that enable them to locate the borderline habitable planet Earth and teleport themselves to Earth with just the clothes on their backs (if they have backs) and a few tools they can carry.

Answer 4

Unfortunately it would likely not survive

We live in a literal soup of life. Not just us, plants and animals, but bacteria, viruses, viroids, as well as Archaea, protists, and fungus.

Every cubic centimetre of our atmosphere contains innumerable fungus spores, bacteria and other growths, waiting to spawn.

All animal life on earth has grown resistant (through complex defence mechanisms tailored to these organisms) and these will quickly infiltrate the alien's body, either on the surface or inside it. It would not have the defence that would resist these, likely it would only have defence for its own microbial soup on its home planet.

This could happen quite quickly, and in fact faster than you think. If you imagine how fast mould spores, bacteria or fungus grows in moist warm dark environments this is a good indicator.

Also, keep in mind that the events leading up to our own evolution are quite random. Presumably your alien's planet had a Great Oxygenation Event (or it wouldn't be breathing oxygen), but there are countless other variables that could be completely different other than the gravity difference you describe, some of them would be:

• Atmospheric composition - although you state it may be 'breathable', we have a certain proportion of C02, nitrogen and other gases which change radically over the millennia. If your alien has evolved in a certain compositional environment it is unlikely to be identical, and more likely than not harmful. In particular also artificial chemicals in the air (pollution) could interfere with respiratory systems.
• Temperature - even on our planet we have a strong temperature variance - does your alien require a constant temperature? How resistant is it to hot/cold?
• Radiation - although we have our magnetic field and atmosphere, there are still sources of low-level radiation that surround us (in particular artificial, or even from granite and other sources). How tolerant is your alien? What about UV tolerance - would its skin be resistant to our level of UV radiation from the sun?
• Even things we don't think of as harmful, such as sound, light, or water / humidity - these things more likely than not will be different on the aliens planet and again, it will not be a good result for its biology.

Of course the alien might be tolerant to many things, but it would only be tolerant to things found on its home planet, which would not be the same as here. Therefore it is likely that our environment will be quite hostile to it.

Answer 5

Yes... or No.

Its your alien, so you should decide what range of atmospheres it can survive in. We can't tell you what your fictional alien can withstand.

Humans can survive in atmospheres with a certain range of O2 and atmospheric pressure. That does not mean that aliens must also have a similar range. Perhaps theirs is far wider. Or narrower. If you want the alien to be able to survive, just say they can.

Answer 6

So I did some digging on the atmosphere issues... Assuming this Alien does not stray far from sea level, it could survive. But higher elevations are going to start causing problems. The Atmosphere pressure at sea level is 150 mm Hg... at 4000 meters this falls to 70 mm Hg. It's a survivable level... at 8000+ meters you enter the Death Zone... the height at which nothing living in the Himalayas exists... humans do go up here to climb Everest and the ilk without back up oxygen, but it's very dangerous to do so. Air pressure here is 35 mm hg. This is 23.333% of Sea Level pressure.

If we say that alien's sea level is 3 times the pressure of ours, than our sea level should be survivable. Though an increase to 4 times our pressure puts your alien at just on the read line for long term survival... he'll have some time, but not much of it.