Paying for Space Settlement

Bold visions for the human settlement of Mars, and perhaps beyond, would require unprecedented technical management over successive generations. Space settlement can also only succeed with an uninterrupted and sufficient supply of resources, as the unique dangers of space would make food, water, and even breathable air scarce and expensive resources. Gradually building the infrastructure of a permanent space settlement would also be costly, and unlikely to provide any direct financial benefits to investors in a timely manner.

I recently published a chapter titled “Can deep altruism sustain space settlement?” in the book The Human Factor in a Mission to Mars. In this chapter I explore the idea of “deep altruism,” where a donor is concerned not with benefits to themselves or kin but to distant future descendants for whom they may have no direct connection. Similar to a time capsule or other grand construction or big science projects in human history, space settlement may provide benefits to the distant future that are not easily identifiable today. Wealthy individuals, foundations, and corporations interested in the permanent human settlement of space may find the idea of investing in humanity’s long-term future to be valuable and worthwhile, even if the return on investment is not immediately obvious.

Commercial interests will likely be an important factor as space industries expand. But investment in space infrastructure out of deep altruism can complement market forces in establishing a sustainable human presence in space.

More on Mars Climate Cycles

Fluvial features on Mars seem to indicate that liquid water once flowed on the surface, yet climate theorists remain divided among how the red planet was able to sustain warm enough conditions in the distant past when the sun was fainter. Popular ideas include a dense greenhouse atmosphere of carbon dioxide, hydrogen, and other gases permitted a lengthy period of warmth. Another option suggests that periodic impacts caused enough warming to carve the features in a shorter time.

My co-authors and I have argued in previous papers that climate cycles on early Mars could have been driven by oscillations in the carbonate-silicate cycle, which would have provided transient warming from the accumulation of greenhouse gases by volcanoes and subsequent loss by weathering. In a new paper, we respond to a critique of the limit cycle hypothesis in our “Reply to Shaw.”

We acknowledge that the biggest obstacle to any explanation for warming early Mars with carbon dioxide is their ultimate fate: are there carbonate rocks buried underneath the martian regolith? If not, where did all the carbon dioxide go? Even so, we maintain that the early Mars climate cycle hypothesis remains consistent with observable geologic evidence and could have played at least a partial role in providing warm conditions on early Mars.

Climate Cycles on Early Mars

Mars today shows evidence of flowing water in its past from the presence of delta basins, canyons, and surface mineralogy. The remaining water on Mars today seems to be locked up in ice, but at some point in the early history of the solar system, Mars had flowing rivers, lakes, and even oceans.

The problem with this idea of a warm and wet early Mars is that the sun was fainter in the past, thereby providing even less energy than today to help thaw a frozen planet. One possibility is that early Mars had a much thicker greenhouse atmosphere than today, which could have provided enough additional warming to melt the ice. However, many climate models struggle to provide sufficient warming, even with a dense carbon dioxide atmosphere. Another option is that episodes of volcanic eruptions of meteor impacts could have temporarily warmed Mars long enough for water to flow and carve the fluvial features we see today. However, this type of episodic warming may not provide enough rainfall to carve the martian valleys observed today.

In a recent paper published in Earth and Planetary Science Letters, titled “Climate cycling on early Mars caused by the carbonate-silicate cycle,” my co-authors and I propose that climate cycling between warm and glacial states could have occurred on early Mars, driven by the carbonate-silicate cycle as we discuss in a previous study. For early Mars, the accumulation of greenhouse gases may have risen and fallen in episodic cycles, providing punctuated periods of warmth for carving the martian valleys. Our proposed hypothesis combines the notion of enhanced greenhouse warming with episodic warming, which can potentially be tested by future exploration of the martian surface.

Colonizing Mars

National space agencies and private corporations have declared plans to send humans to the red planet, with longer-term planets of settlement and resource extraction likely to follow. Such actions may conflict with the Outer Space Treaty of 1967, which currently prohibits any sovereign claims in space.

In a recent Space Policy paper written by Sara Bruhns and myself, titled “A pragmatic approach to sovereignty on Mars,” we develop a practical approach toward allowing the settlement of space and use of its resources through a “bounded first possession” model with a required planetary park system. We suggest that exclusive economic claims could be made without establishing sovereignty on Mars, and we propose a model for management and conflict resolution on Mars that build upon lessons from history. We also recommend revisions to the Outer Space Treaty to resolve the current ambiguity of how nations, corporations, and individuals can use the resources of space.