orbital debris cropped photo

By Dale Skran

A term you will hear in many modern space discussions is “space sustainability.” Few space-related terms are used to mean such a wide variety of completely different things, which can be extremely confusing for the “unschooled.” Making matters worse, the same person or organization may use the term in different contexts to mean different things, so it is not easy to associate a particular meaning with a particular group. Thus, I’ll be saying things like “most often, when you hear space sustainability from a NASA employee, they mean X,” but in some contexts other NASA employees or even the same person may mean something completely different.

However, most often when a NASA representative refers to “sustainability” in space they are referring to “budgetary” or “programmatic” sustainability. There are a variety of aspects to this characteristic, but they include:

  • The budget requirements for a particular program are not excessive relative to the value of the program as perceived by the President and Congress.
  • The budget does not require too great a proportion of the NASA’s overall funds such that other programs would push back, either internally within NASA, or via public pressure on Congress.
  • The program has strong political support in Congress, and especially in the two Appropriations Committees.
  • The program employs a sufficiently large number of people at as many NASA centers as possible, and especially in those NASA centers that are located in states that are often decisive in Presidential contests.
  • The program enjoys significant “stakeholder” support, either with scientific groups or with traditional NASA contractors.
  • The program is sufficiently aligned with U.S. national space policy and grand military strategy that there will not be pushback from the Pentagon, the White House, or Congress.

Thus, a NASA program such as the Space Launch System is “sustainable” in this sense since it rates highly in most of the aspects listed above. A $500 Billion “Apollo to Mars” program tends to get into trouble with the first two bullets, which is a major reason why NASA is so reluctant to provide a firm budget for a crewed mission to Mars. Although this may not be initially obvious, large investments in scientific research in space are aligned with U.S. national space policy and military strategy, since this research provides many benefits to the U.S., including so-called “soft power.”

When people from the National Space Society, commercial space firms, or venture capitalists investing in space talk about “space sustainability,” they frequently are referring to “economic” or “commercial” sustainability.  Characteristics of this kind of sustainability include:

  • The risks associated with the project are sufficiently low that investors will put in money that could alternatively be used to fund a wide variety of Earthly enterprises.
  • The risks associated with the enterprise are low enough that employees can be hired to work at companies engaged in project.
  • Once the product is developed and operating in space, it is possible to build a growing and profitable business around the new technology.
  • There are no regulatory barriers, including excessive taxation, that operate to prevent the enterprise from becoming successful.
  • Whatever new technology is required is at a sufficiently high Technology Readiness Level (TRL) level that the amount of funds that can be raised by venture capital, i.e., tens to hundreds of millions, are sufficient to bring the enterprise to success.
  • Even if the system, i.e., weather satellites or location services, is currently funded all or in part by the government, it is so valuable that if the government lost interest private money could be found to continue the service.

As can immediately been seen “NASA budget sustainability” and “economic sustainability” for a space project are night and day different. Projects like NASA’s Space Launch System (SLS) are light years from economic sustainability but are still sustainable from a budgetary view. The development of new private launch vehicles appears to have reached the point of economic sustainability, with successful private companies dominating the launch market, and many more companies racing to develop new launch vehicles, many of which, once developed, will be clearly superior to anything NASA has ever flown to date.

It is worth mentioning that the test of economic sustainability should not be applied to everything NASA does. There is no purely economic case for the James Webb Space Telescope, but it is a wonderful device that will enrich the lives of every human on Earth.

A third use of the term “space sustainability” can be associated with groups like the Secure World Foundation (SWF). SWF defines space sustainability as the ability of all humanity to continue to use outer space for peaceful purposes and socioeconomic benefit over the long term. The particular focus of SWF includes the following concerns:

  • Space debris, whether arising from accident, weapons testing, or conflict.
  • Space weather, and especially the concern that natural events might be confused with hostile action.
  • Radio frequency interference.

These issues are of the greatest salience with regard to Earth orbits. However, as space development proceeds, similar issues will arise throughout cislunar space and on the Moon. With regard to the Moon in particular, concern exists with regard to:

  • The possible desecration of lunar heritage sites such as the area where Apollo 11 landed.
  • The generation of orbital debris clouds caused by the backwash as rockets land and take off.
  • The possibility of a “Moon Rush” in which faux scientific missions are used to control access to resources with limited geographic distribution.

It should be noted that the SWF mission is based on the assumption that space will be developed, and not kept as a scientific preserve for all time. Instead, the goal of space sustainability is to ensure that how we use the resources of space does not prevent others from similar use, nor lead to a degradation of the space environment that precludes any use of space resources. NSS shares these concerns, and has been especially active in the area of space debris. On December 31, 2021, NSS joined voices around the world in condemning a Russian ASAT test. A complete description of NSS positions and activities related to space debris can be found on the NSS website Orbital Debris page. Given the nascent state of true commercial space enterprises, NSS has a crucial role in ensuring that the long-term use of space is sustainable in this sense, but also that the means used to ensure this sustainability are not so onerous as to prevent space development from happening.

A possible source of additional confusion lies in that fact that the SWF usage of “space sustainability” is more or less synonymous with “sustainable space development.” However, when the UN uses the term “development,” they have in mind much more than economic development. With a look back to colonial exploitation of developing countries, the UN has a strong focus on ensuring that economic development is beneficial and fair to the population of those countries. The environmental concerns of the UN are also for the most part with respect to impact on the population of developing countries.

In space, there are no indigenous populations to exploit, or to harm via pollution. Thus, the major concern of sustainable space development is that the fashion in which development occurs does not cause excessive harm to those engaged in scientific or commercial activity in space, either in the short or the long run. To put this more concretely, when SpaceX lands a Starship on the Moon, the blast debris should not damage a Blue Origin oxygen refinery. Of course, all space exploration and development require alteration of the pristine environment, so the notion of keeping space as a permanent park is fundamentally incompatible with a human future in space.

An additional concern related to sustainable space development focuses on the small number of resources in space that are limited in abundance and/or not renewable. Most space resources, including for example solar energy, oxygen on the Moon, iron in asteroids, and so on are either renewable or abundant on such a scale that large scale use does not create any issues with regard to fairness to those who are not first to exploit the resource. However, in cases such as lunar water or particular orbital locations, either the resource is “fossil” or is limited by the laws of physics. In such cases, a system of resource reservation for latecomers should protect the incentive for early developers to invest in space development while allowing others to have access to a fair share in the future. Attempts to reserve a resource for a purported “best use” are problematic, since the “best use” will likely rapidly evolve as we expand into space.

A final and radically different meaning of “space sustainability” requires consideration, since it is largely opposed to the three kinds of space sustainability discussed above, all of which are based, to varying degrees, on the idea that humanity has a future in space that includes exploration, the development of space resources to meet human needs, and at least in the long run growing communities of humans living permanently in space.  In this differing vision, “…a sustainable approach to space would treat the Moon, Mars, and other worlds like UN World Heritage Sites or US National Parks.” This particular source amplifies on this vision, adding “A new regime that preserves the beauty of space for everyone will need to prioritize scientific research and public access to its benefits. International agreements could demarcate limited space zones for particular kinds of commercial activity. Sustainable, egalitarian operations in space would focus on social equity, environmental conservation, workers’ rights and balanced economic benefits. Many more people would have access to the benefits of space, not dependent on the beneficence of a few billionaires; decisions would be similarly democratic and consultative. Those who flout the norms, arming the atmosphere, polluting the night sky or defacing the Moon, would lose their access.” (I hope “arming the atmosphere” is a typo — leaving out an “h”.)

Although there are certainly some useful ideas in this approach to space sustainability, in practice it may amount to a new kind of colonialism, which while claiming to protect space from rogue billionaires, will actually enforce a narrow set of Earthly laws on anyone living in space, assuming humans are even allowed to live in space. It is a vision in which space communities lack basic property rights and rights of self-governance, and, sadly, may lead to the kind of Earth-Space warfare depicted in The Expanse. The most probable outcome, however, is that space exploration would be limited by rising costs, and space development would either not occur at all, or would be of such a limited nature that space settlements never become a reality.

As a final note, some authors organize definitions of space sustainability differently than I have above. Such discussions can lead to a constructive dialog about how to best discuss this complex topic, but don’t fundamentally alter the nature of the definitions.

NSS seeks to balance these potentially conflicting visions of space sustainability while staying focused on a basic truth: We are just getting started in space. The main challenge facing this generation is to make the first truly economically self-sustaining steps into space. These steps need to break free from government-funded programs with a limiting mission focus and short-term budget planning. They need to avoid self-inflicted harm from space debris and other challenges of this nature. But most importantly, and the most challenging, they need to happen at all, which requires bedrock economic sustainability.

If it is not possible for those who are investing their treasure and lives in building our future in space to profit from the risks they are taking, we literally have no future in space beyond the expensive robotic probes we already have. And to afford a future in space with thriving human communities expanding throughout the solar system, we need economic development in space at least one order of magnitude beyond the current “space economy.” The good news is that this vibrant space economy promises vast benefits to all of humanity without an onerous regime like the “Moon Treaty”/Moon Agreement being followed. But that is a topic for a future blog post!

© 2022 Dale Skran


Picture of National Space Society

National Space Society

2 thoughts on “NEWSPACE BASICS: What is Space Sustainability?”

  1. This is a great summary. There is one aspect of sustainability that is implied by (and required for) economic sustainability that perhaps should get more direct mention. That is active pursuit of In Situ Resource Utilization (ISRU). That includes developing and using the resources available in space, and I would also emphasize its use for agriculture. This is obviously necessary for economic feasibility, and also for risk reduction, avoiding deaths when politics or Earth catastrophes prevent timely deliveries of key items. You could think of that more as part of the “how” to achieve sustainability than the goal, but it emphasizes where research and development dollars need to be spent. NASA does fund a lot of small scale research projects in these areas, including small scale field trials like MOXIE, but has no plans to actually use any of it in major manned missions.

    I think of this as emphasizing the underlying science and engineering development work that has to be done, so that the economic benefits follow. As an example, think of the development of steam engines. Once the idea was started, it was easy to say that we needed to emphasize the economic feasibility of steam engines to encourage their use. But how? Early steam engines were very inefficient. The way to make those improved economics actually happen was to focus on developing the underlying scientific ideas of thermodynamics (along with a steady stream of small hacks based on experience), and using that to engineer better engines. A virtuous cycle arose, where the scientific principles suggested how to make engineering improvements, the improvements were made, which provided more data and led to further improvements in the scientific understanding, etc.

  2. The Outer Space Treaty sought to block conflicting claims to large tracts of land on celestial bodies to prevent conflicts over the disputed lands. Using the concept of the celestial bodies being owned by all nations gives us the use of resources found on celestial bodies. The way I view this is that space and the celestial bodies in space are International Territory and not subject to exclusive use by any one country but the resources of space are available to all countries. Habitats do not enclose International territory but rather displace it so within the habitat the laws that govern the habitat are those of the Nation who claim the Habitat. A key issue that must be resolved is the expectation of each nation to the non-interference of their activities in international territory. The simpliest way to accomplish this is to recognize that a portion of the International territory would be governed by the Nation which occupies that land. So the Nation does not only control its habitats but the land surrounding the habitats out to a modest distance such as 500 meters. The problem that many would have with this is that it would appear to be a territorial claim. A key difference is that the area is assigned by an International body rather than by one nations’ threatening action and the area is still open to other Nations but their activities would now be under the governing Nation’s control.


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