Why Bother Sending Humans?

In conversations with people who profess interest in a human future in space I frequently find the thinking muddy on the fundamental question of ‘why?’ Of course there are many reasons space is important and what works for each of us boils down to some subjective preferences. That said, some reasons are better than others. I’d like to directly call out a few categories of justification for human space exploration/settlement I don’t like and then describe some I do.

Crewed space flight for purposes of near term economic gain, the production of spin off technology, and keeping people in Florida and Alabama employed, all suck. These, and their variations, fall into a basket of parochial benefits I find depressing. I think people who like space feel they need to make these arguments for the benefit of people who are ambivalent about it; not because these actually stand as arguments. They pops up a lot in political dialogue. I’ve always found this line of reasoning, as many arguments which are made explicitly for third party consumption, weak to the point of disingenuous.

The second category of argument I don’t like is anything based on scientific exploration. Don’t get me wrong, I love me some space science. I was a technician in an astrobiology lab at NASA Ames for ~5 years. But it’s simply not the case that humans are necessary. Robotic exploration of the solar system is nowhere near the point of diminishing returns. Sure, crew add flexibility to a mission, but they also increase cost by orders of magnitude. As a casus belli for pushing humanity into space it’s very weak and will basically never scale. Also, it's counterproductive to scientific progress to shoehorn humans into missions unless they add massive value. With the possible exception of early years of the ISS, I think crewed space missions have categorically slowed progress in our scientific understanding of the solar system by diverting funds from robotic and remote sensing missions. Scientific understanding of space is a prerequisite to sending people to space, but it's counterproductive to confuse ends and means.

The last category I’ll be critical of is the argument from existential risk. Of the justifications I dislike, I find it the least offensive. Its problem is that space settlement is simply not the best investment we could make to reduce risk. Humanity faces a lot of problems which could kill us off. Because we haven't killed ourselves off yet it is hard to know how to weigh risks against one another. But, if you had a dollar to spend, would you invest in diplomacy to mitigate the risk of nuclear war, public health to mitigate pandemic risks, or building a Mars colony?

The Mars colony is going to take decades (minimum) and many billions of dollars to be independent of Earth and thus an actual hedge. Alternatively, many small investments can lead to near term and noticeable reductions in the likelihood of us killing ourselves off. In a world of limited resources it's hard to make the argument that Mars should be prioritized highly.

A redeeming part of this argument is that the right amount to spend on a Mars colony is very likely not zero. Space settlement is a long haul, but if it works, it’s a very powerful way to mitigate catastrophe. My takeaway is that building a self sustaining branch of humanity in space simply needs to be much cheaper for investment on risk grounds to make sense.

Now, on to the reasons I like for humanity to go to space! Each of these might deserve their own essay, but I’ll present them in short and in no particular order.

- Humanity’s status quo is a death sentence via the accumulation of existential risk. But Earth is too important to use as a laboratory for the significant technical and societal long shots we need to experiment with but which themselves impose large risks. Space offers the elbow room and isolation to safely manage the added danger of transformative change while keeping the nucleus of humanity safe.

- A society of a trillion humans could live at western levels of consumption until the sun burns out consuming the material resources of the solar system. There is a lot of stuff out there.

- Preserving life and biological diversity on Earth is a moral and aesthetic good. I think it follows that spreading life to lifeless places is also a good. A good which has the potential to result in far more life/diversity than Earth could ever support.

- Humanity is rapidly homogenizing in many ways (linguistically, culturally, technologically, biologically etc). Significant differentiation is a response to necessity and isolation. Space can provide the environmental driver, and distance, necessary for new modes of human being and action to emerge which can then inform the wider human project.

Looking at it after writing it down, the first and the fourth may be the same argument. I have a background in biology and evolutionary theory which I think you’ll see has has informed my views. Personally, I also find “Space is cool. And if you don’t think so, fuck you” a deeply compelling argument. However, it lies in a category of subjective aesthetics beyond my ability to justify in rhetoric. Let me know if you have any thoughts!