Though I have been involved in space science and exploration for nearly 15 years, I only recently came to appreciate that space is an extension of the terrestrial wilderness that I love to explore. Last year, I was enjoying an evening soak in a natural hot spring, melting the soreness away after a long hike in mountainous central Idaho. Reclined against a rock, I faced upward at the clear night sky. As my eyes adjusted to the inky blackness, I noticed a satellite. Then a couple minutes later, another. A few minutes later, a third. They seemed to be in a formation. Oh—I was seeing SpaceX’s Starlink constellation.

Just a decade earlier I had a similar experience searching for satellites while deep in the woods of northern California. At the time, spotting a satellite required a lot more patience. Since then, the night sky has gotten noticeably more crowded, largely due to the rapid growth of the commercial space sector. Is this level of growth sustainable? As chief scientist at an engineering firm specializing in space and sustainability systems, and as a human who enjoys the serenity of the wilderness, I feel obligated to grapple with this question.

But what does “sustainability” really mean? Even in the terrestrial context, its definition can be nebulous. I have heard the term used to refer to both the responsible use of nature (conservation) and the protection of nature from use (preservation). These are two very different approaches to land and natural resource management. From the perspective of preservation, nature should be protected from human activity. I am particularly sympathetic to this view while located in natural hot springs, miles from other people.

person hiking in mountains — *Backpacking to the next hot spring (Credit: Elizabeth Frank)*

However, there is a problem with the logic of preservation: it romanticizes nature by presuming that humans are not a part of it. The fatal flaw with this reasoning is eloquently described by William Cronon in his essay, “The Trouble with Wilderness”:

“Wilderness embodies a dualistic vision in which the human is entirely outside the natural. If we allow ourselves to believe that nature, to be true, must also be wild, then our very presence in nature represents its fall. The place where we are is the place where nature is not…We thereby leave ourselves little hope of discovering what an ethical, sustainable, honorable human place in nature might actually look like.”

This passage rattled me. I realized that if we accept the argument that wilderness is natural and humans and their cities are unnatural, then a logical conclusion is that to “save the planet,” we must rid it of humanity. No one would argue that that is the proper course of action.

Furthermore, preservation ignores the fact that humans have already shaped landscapes over millennia, even before the Industrial Revolution—from Native Americans setting fires in the West as a form of land management to Vikings cutting down the forests of Iceland to the aqueducts of ancient civilizations. Preservation also prioritizes nature over the well-being and dignity of the millions of humans in poverty around the world. Cronon writes, “if we set too high a stock on wilderness, too many other corners of the earth become less than natural and too many other people become less than human, thereby giving us permission not to care much about their suffering or fate.” This tension is typified in the loss of Great Ape habitats in central Africa due to the slash-and-burn agriculture techniques of impoverished subsistence farmers. Preservation would prioritize gorillas over humans; conservation accounts for the rights of both.

Thus, I believe that any definition of sustainability must err on the side of conservation. This is not an original thought: the 1969 U.S. National Environmental Policy Act (NEPA) stated that the goal of sustainability is to “create and maintain conditions, under which humans and nature can exist in productive harmony, that permit fulfilling the social, economic, and other requirements of present and future generations.” Importantly, this definition captures that for an activity to be considered sustainable, it must acknowledge that both humans and nature have the right to flourish, now and in the future.

Nature also includes space, from low-Earth orbit to the surfaces of other bodies in our solar system. As humans explore and expand our use of space, we must also reckon with what sustainability means for environments beyond Earth. I believe there are four key ways in which space and sustainability intersect, and I will explore each of them in a series of forthcoming blog posts:

Monitoring Earth’s changing climates from space
Maintaining sustainable space environments
Addressing the environmental & social impacts of space exploration on Earth
Using lessons from space exploration to tackle climate change on Earth

*Smoky skies and charred pine trees in central Idaho (Credit: Elizabeth Frank)*

A nuanced examination of this overarching topic feels increasingly urgent as the impacts of climate change bear down on us all. To get to that Idaho hot spring, I had hiked through the charred remains of a forest from a fire a few years prior; the air was smoky from an active fire on the other side of the state. An increase in the frequency, intensity, and size of forest fires in the Western U.S. is just one of many indicators of human-caused climate change. As we extend our presence to other planetary bodies, we must learn from our mistakes that have so adversely impacted Earth lest we repeat them elsewhere in the solar system.