Yesterday I created an exoplanet on Space Engine, and then started to imagine how life could be possible on that little rock.

I started to think about bacterial cells / archaea, anaerobic organisms living under the ice.

And after that, right now, I am having a bigger question: How humans could start a colony here with realistic "hard science" technologies ?

The planet looks like an ice world, the average temperature is under 0, even if some places should be above that..

The parent star is a G7.2V, 0.7 times brighter than the sun and with roughly the same mass.

Planet specs:

Name: Marpal c

Class: Temperate rocky world

Diameter: 6224.8 km

Mass: 0.1242 Earth mass

ESI: 0.824

Orbital period: 283.355 days

Rotation period: 11h 36m 45s

Axial tilt: 4° 15'39"88

Age: 1.730 x 10^9 years

Gravity: 0.52 G

Atmosphere composition: 98.2% Co2, 1.63% N2, 0.131% of H2O

Atmosphere pressure: 0.0979 atm

Average temperature: -8.601 °C

Density: 5.9 g/cm3

Marpal c

For this scenario we could use 1000 colonists, they will have modern tech and of course a generation ship able to reach that planet (let's say, 10 light years away from us), something able to keep them alive and to reach 10-15% of the speed of light (Project Orion like)..

And finally, they had knowledge about the planet before arriving (they used probes for analysing the world)

  • 4
    $\begingroup$ Stack Exchange sites are not forums. $\endgroup$ – Renan Nov 8 '18 at 12:23
  • $\begingroup$ welcome to worldbuilding, please take the tour and visit the help center to get familiar with this site and its policies. Your question is rather fuzzy: please put the relevant information in the text, and ask a single, specific problem which can be measurably answered. $\endgroup$ – L.Dutch - Reinstate Monica Nov 8 '18 at 12:26
  • $\begingroup$ I edited the question so it would be much more understandable, thanks for the advices. $\endgroup$ – Marpal Nov 8 '18 at 12:29
  • $\begingroup$ Please include all details needed to answer in a text form. Reading from screenshots is tiesome, and search can't access text on images. $\endgroup$ – Mołot Nov 8 '18 at 12:35
  • $\begingroup$ I just made a text form about the details,.. Don't hesitate to tell me if others changes / details are required. $\endgroup$ – Marpal Nov 8 '18 at 12:44

While it would be possible to colonize this planet, I don't think that it would be a viable in the long-term, primarily due to a lack of liquid water.

To make things simpler, let's assume that your colonists have the ability to protect themselves from intense UV radiation, subzero temperatures, and low pressure environments. The first thing that they will need then is to establish a sustainable supply of oxygen and water. While it is possible to sustain themselves for a while with water filters and CO2 scrubbers, that will not last for the length of time and population increase that will come with establishing a colony.

Oxygen can be produced in one of two ways: through a chemical reaction or a synthetic reaction. A chemical reaction would involve using manufactured chemicals to break the carbon from CO2 and produce pure oxygen. While this method is efficient, the chemicals required may not be readily available on the planet you have described, so their only source would be what they have brought with them, which is in no way viable. Synthetic reactions, on the other hand, use biodegradable reactants and catalysts, a la photosynthesis and chemosynthesis, meaning that they should be more readily available, since foodstuffs and remains can be used to perpetuate the reaction. Of photosynthesis and chemosynthesis, I feel that photosynthesis would be the better option, considering the increased exposure to light.

So, we can have our colonists bring with them a plant specifically modified to be able to withstand high UV exposure, can operate at low temperatures (also high temperatures, since it is likely that the surface of the planet would fluctuate wildly with such a thin atmosphere), and is able to grow in deficient soil. But then we have our biggest issue: liquid water. Since arsenic-based life is incompatible with our current biology, there is not really any way around this problem. With a low atmospheric H2O content, the best method for rectifying this is through aquifers, underground stores of liquid water, but those may or may not exist on this planet, given that we know nothing about its internal geology. So, without any sort of vast array of water, these colonists would struggle with terraforming the planet's surface, unless there is some breakthrough in a synthetic reaction that does not require large amounts of water.

| improve this answer | |
  • $\begingroup$ This planet have some ice lakes on the surface, and the atmosphere have enough pressure for being able to sustain liquid water (above the Armstrong limit / triple point).. But with the UV, i can't tell if long term liquid water could be possible... For the internal geology i'am pretty sure than this planet have active tectonic plates $\endgroup$ – Marpal Nov 8 '18 at 17:35
  • $\begingroup$ Uh? Where does the arsenic come from? $\endgroup$ – GretchenV Nov 9 '18 at 10:57

Not the answer you're looking for? Browse other questions tagged or ask your own question.