Cleaning Up Our Mess in Space

In “A Montreal Protocol for Space Junk?” (Issues, Spring 2022), Stephen J. Garber and Lisa Ruth Rand correctly recognize the challenges to pursuing remediation for removing space debris despite the obvious use for the technology. Remediation alone is difficult to incentivize. Despite lowered costs to access space, the incentive to remove debris remains outweighed by the cost of a dedicated remediation mission.

An alternative approach to remediation is to focus on the creative combination of multiple objectives in a single mission. The companies Northrop Grumman and Intelsat recently accomplished two satellite-servicing missions, to extend the operational life and reposition the Intelsat satellites. Similarly, NASA is developing a spacecraft called OSAM-1 (short for On-orbit Servicing, Assembly, and Manufacturing 1) that is designed to test on-orbit refueling of satellites. OSAM-1 (formerly called Restore-L) is intended to refuel the Earth-observing satellite Landsat-7, for mission extension purposes and to demonstrate a repair capability.

Mission extension is a significant driver toward servicing a satellite. There exists a common tension between using limited fuel resources for mission extension vs. removing the satellite from orbit within 25 years of mission completion (known as the “25-year rule”). Private satellites are held accountable by regulators to meet the 25-year rule. However, public goods such as NASA’s satellites are pressured to maximize the utility of their highly valued and well-utilized science missions, particularly when a replacement satellite is delayed.

The current culture focused on near-term science does not necessarily align with the concept of timely disposal. A combined mission extension and disposal mission may offer a solution to this tension. In the case of Landsat, retaining operational continuity is key to achieving science objectives. Thus, a comfortable overlap between the operational Landsat and the developing replacement Landsat mission is often desired.

Technologies for remediation, or satellite servicing, have potential applications in the public and private sectors as well as the civilian and defense sectors. However, no one entity wants to get stuck with the bill for developing a service and sustaining that service. Creative public-private partnerships that meet the needs of nongovernment entities, rather than bespoke solutions, may serve well in this situation. In this manner, the government can encourage the development of an industrial base and be one of many customers.

It is important to remember that remediation is part of a multipronged approach. Debris mitigation continues to serve space sustainability well, but has limitations. Unplanned incidents on orbit will inevitably occur. Having an alternative solution available to support those unexpected accidents is a valuable addition to the suite of technologies that will support space sustainability.

Marissa Herron

Stephen J. Garber and Lisa Ruth Rand make the argument that orbital debris is a form of pollution and that it is constructive to examine past efforts to address global pollution. The authors logically turn to a successful international treaty, the Montreal Protocol on Substances That Deplete the Ozone Layer, adopted in 1987.

How successful is the Montreal Protocol? The United Nations Environment Program recently reported that signatory countries, or “Parties,” have phased out 98% of ozone-depleting substances globally compared with 1990 levels. Without the Protocol, ozone depletion would have increased tenfold by 2050. On a human scale, this would have resulted in millions of additional cases of melanoma, other cancers, and eye cataracts.

The authors highlight lessons learned from the Montreal Protocol that could apply to the planet’s burgeoning space debris problem, including:

• Developing consensus on the existence of the problem;
• Emphasizing government-led international collaboration to find solutions;
• Devising incentives or financial assistance (“carrots”) for developing countries and punitive measures (“sticks”) for developed countries;
• Evolving regulatory flexibility to align with new discoveries; and
• Emphasizing the risks posed by inaction.

Emphasizing the risks of inaction is key. What would happen if Earth’s orbital regime reaches a point of no return? While there appears to be a consensus that orbital debris proliferation is a problem, we need to do more to broaden awareness.The value of space extends to all countries. Even those countries without operational satellites will benefit from space services such as increased connectivity, geolocation capabilities, and access to satellite imagery.

Over 50 countries now own and operate space assets. However, equity in space assets is not distributed evenly. Citigroup recently estimated that the space economy would generate over $1 trillion in annual sales by 2040, up from around $370 billion in 2020, but wealthier spacefaring countries are the most invested and stand to benefit the most from the expanding space economy.

Thirty-five years ago, the architects of the Montreal Protocol navigated a dire situation—a thinning ozone layer—and planned a course of action that addressed a diverse range of stakeholders with varying degrees of resources. Now the planet is facing a dangerously congested orbital environment. But the financial consequences will not be felt equally across the planet. The higher-income world has more “skin in the game,” or equity in space-based assets, and therefore more to lose if a worsening space debris cascade threatens the long-term viability of satellites. Following the spirit of the Montreal protocol, more affluent spacefaring countries should lead while the smaller, less-invested countries should be given incentives to follow as debris mitigation policies continue to take shape.

As the ecologist Garrett Hardin noted over 50 years ago, “Freedom in a commons brings ruin to all.” If we are on the brink of a tragedy of the commons in space, now is the time for the space sector to learn from successful international cooperation efforts—and the Montreal Protocol provides a shining example.

Karen L. Jones

Stephen J. Garber and Lisa Ruth Rand provide a well-supported article regarding the extent of space debris and the potential application of that international agreement for controlling terrestrial pollution to controlling the risk of collisions with debris in space. They eloquently identify the three key aspects for controlling the debris population: debris mitigation, space traffic management, and debris remediation. I would like to focus on a specific attribute of the Montreal Protocol discussed and the most critical, and difficult, means to manage debris growth: debris remediation.

Debris remediation is primarily the act of removing massive derelict objects (e.g., abandoned rocket bodies and nonoperational payloads) from orbit to eliminate the possibility of future massive debris-generating collision events. A paper completed in 2019 by 19 scientists from around the world identified the top 50 statistically most concerning objects in low Earth orbit (LEO). Leading the list were 18 SL-16 rocket bodies launched by Russia primarily in the 1990s and left in a tight 40-kilometer-wide band centered around 840 km altitude, where they routinely cross orbital paths with each other, debris from the 2007 Chinese antisatellite test, and defunct US payloads and debris related to their demise. This combination has created a uniquely bad neighborhood in LEO. These objects were deposited primarily by the three major space powers—the United States, China, and the Russian Federation—before the turn of the century. For perspective, if two SL-16s were to collide, this event could singlehandedly double the debris population in LEO (i.e., add up to 15,000 large fragments).

Garber and Rand call for leadership. Indeed, leadership is critical to control the debris population in LEO and catalyze the debris remediation industry. Just as government investment has catalyzed the now largely commercial fields of space-based Earth imagery, global space-based communications, and satellite launch, development and deployment of debris remediation solutions cannot be borne solely by the emerging commercial ventures. Conversely, an investment by the government entities that are responsible for the decades of debris deposition on orbit is needed.

Darren McKnight