Another big question that we have to prepare for during space colonization is that a species might change very quickly once on the new planet. Ecologists are realizing this now because recent research shows that evolution can happen quickly ... An example of the rapid evolution of species we can see occurs on the Galapagos Islands, where the birds change and interbreed, and species disappear and appear.

So even if we bring one species that we've figured out does something, it might change completely within a couple of generations. Ecologists don't even know how many species there are on earth, much less the general rules of how species interact and respond to each other, nor how this changes over time. Ecosystem studies are useful because ecology is just starting to ask these questions. And while we're waiting for space colonization, this ecological knowledge might help us survive on the earth!

I'm going to assume that we find a new planet without an ecosystem already on it. Thus, in order to live in space we will have to build something from scratch with species we bring us.

Scientists are realizing that it's more and more difficult to make an ecosystem from nothing, and to know how exactly the new ecosystem might work. There are just so many details and parts in an ecosystem that we don't understand yet. Let's say we decide to bring a specific useful insect because it pollinates coffee plants. Then we also have to bring the parasitoid bug that kills our bug, otherwise there would be too many of our bug. And to make sure that there aren't too few bugs, we have to bring the parasitoid that kills the parasitoid that, in turn, kills our bug. But the situation gets even more complicated, because we also have to think about the parasitoid that kills the parasitoid that kills the parasitoid that kills our bug!

Science doesn't (yet) understand these connections between species, but we are trying. We are now trying to use DNA barcoding to identify all parasitoids that live on spruce budworm. Think of Biosphere 2 , which gave us many ecological lessons and surprises!

3D printing and the rocket engine are the two inventions that will eventually enable space settlement. With 3D printing, you can cut that supply chain and make all the spare parts you need locally ... A colony cannot survive if it is dependent upon a supply chain from Earth. We must mine asteroids for their raw materials (making solar arrays, colony structural materials, etc from the raw materials in Near Earth Asteroids). Mine comets for water. Water is for drinking, bathing, radiation shielding ctrolyzing into hydrogen and oxygen for rocket propellant and for use in fuel cells.

As far as technologies needed for a pathway that leads to Mars, We assessed 10 high priority areas in terms of the technical challenges. The 10 high priority areas are: Mars Entry, Descent and Landing (EDL), Radiation Safety, In-Space Propulsion and Power, Heavy Lift Launch Vehicles, Planetary Ascent Propulsion, Environmental Control and Life Support System (ECLSS), Habitats, Extravehicular Activity (EVA) Suits, Crew Health, and In-Situ Resource Utilization (ISRU - using the Mars atmosphere as a raw material).

Before humans start living in space on a regular basis, there's a lot of basic science and political agendas that need to advance. We talked to scientists and experts about the fundamental things they think we should do right now if we want to have a space colony in the next 100 years.