WASHINGTON: As America moves beyond Earth’s orbit and expands operations to the Moon, space operators face the specter of the same crowding and pollution problems now bedeviling current space operations in orbits that are even more fragile, a new Aerospace Corporation study warns.

Further, if many countries rapidly expand their commercial and military cislunar operations — as that region of space is known —  without sufficient forethought about how to manage space traffic and access to limited orbits this could raise risks for military conflict.

“Failure to conduct sustainable and transparent operations in an environment with a growing number of players may lead to conflict if careless behavior or unannounced proximity operations are interpreted as hostile acts,” James Vedda, one of the Aerospace authors, told Breaking D in an email today.

As Breaking D readers know, national security space leaders are more and more preoccupied with cislunar space — seeing it as a future area of global competition, particularly with China. DoD has myriad new efforts aimed at developing technologies to expand military uses of cislunar space, including by Air Force Research Laboratory’s Space Vehicles Directorate; DARPA’s nuclear-powered rocket project called Demonstration Rocket for Agile Cislunar Operations (DRACO); and the Space Development Agency’s (albeit financially constrained) interest in developing satellites for space domain awareness capabilities to monitor future activities by potential adversaries (read Chinese) around the Moon.

The new study, “Cislunar Stewardship: Planning for sustainability and international cooperation,” was authored by Vedda and George Pollock of Aerospace’s Center for Space Policy and Strategy. Aerospace Corporation is a federally funded research and development center (FFRDC) working closely with Air Force, and now Space Force.

It explains that by mid-century many nations will be undertaking familiar missions such as communications and intelligence, surveillance and reconnaissance in cislunar space, but also for new types of activities potentially including asteroid mining, on-orbit gas stations for spacecraft, and even space-based manufacturing facilities.

The expected boom in cislunar operations, Aerospace finds, means the United States and other spacefaring nations should start developing both technical and regulatory measures to avoid future disasters. This includes figuring out how debris mitigation would work in cislunar orbits, policy changes that would allow third-party debris removal, and international agreements for space traffic management.

The study, aimed primarily at policymakers, is both a technical primer on the potential uses of cislunar space and a call to early action to ensure its future sustainability:

As cislunar activity grows, a policy framework should be developed to promote the sustainability of operations in these locations. Motivated by lessons learned in space operations thus far, this paper discusses the need to extend best practices for debris mitigation (preventing its accumulation) to cislunar space lest we create a space debris mess in this valuable regime.

Additionally, current international policy prevents spacefaring nations from removing space debris left by other actors. Significant policy adjustments are needed if debris remediation (removal of nonfunctional and potentially dangerous objects from useful orbits) is to become an effective complement to debris mitigation in cases where mitigation is not completely effective.

Beyond the extension of current practices, significant future work remains in characterizing new orbital environments, monitoring their evolving use, and determining appropriate sustainability practices.”

Cislunar Space: Why Does It Matter?

There is no legal definition of cislunar space, but in general it refers to the orbits between Geosynchronous Orbit — 36,000 kilometers above the Earth — and the Moon. Some definitions include orbits slightly beyond the Moon as well.

DARPA’s DRACO nuclear-powered rocket for cislunar operations

The study authors say that it is “reasonable” to expect that in the near- to medium-term “a greater variety of cislunar orbits will be used for an assortment of space applications, including communications, navigation, space domain awareness, scientific remote sensing, and human exploration.” And in addition to simply expanding the frontiers for these current space activities, cislunar orbit could host new types of space applications:

  • Next-generation multi-purpose orbiting platforms for use as labs, manufacturing facilities, and habitats
  • Propellant storage depots
  • Research outposts on the moon
  • Extraction, processing, and use of extraterrestrial resources
  • Training and support for deep space missions

Of particular value to both commercial and military operations could be the physically limited — and potentially environmentally fragile — orbits that comprise “relatively stable gravitational points” — called Lagrange or libration points — where spacecraft can essentially ‘hover’ without the expenditure of much if any fuel to maintain their position. These orbits may even see “aggregation of space structures into industrial parks,” Aerospace finds.

Cislunar Lagrange points, Aerospace Corp. image

How Is Cislunar Different?

Just as the laws of physics mean that the operating environment of GEO differs widely from that of lower orbits (for example, objects travel slower in GEO than in Low Earth Orbit (LEO) where they zip around at bullet speed of some 7.8 kilometers per second), the complex physics of various cislunar regions will mean operating there will be different.

For example, Aerospace explains: “Sunlight is essentially perpetual, with rare passages through Earth’s or the moon’s shadow. The radiation environment is more intense than LEO, since cislunar orbits are largely outside of Earth’s magnetic bubble.” This means that electricity supplied by solar panels could be more easily supplied; other types of systems might degrade faster due to radiation.

Further, the study notes, “the volume of cislunar space is vastly larger and distances from Earth-based sensors much farther, so the tracking of objects is much more difficult. Similarly, the relative speed of an encounter with a neighboring cislunar object will be different than in other orbit regimes.”

Indeed, the study adds, many cislunar orbits will take days, not hours, to circumnavigate, and the volume of space traveled will be larger than, for example, LEO — where congestion and the ever-increasing amount of space junk already are raising risks to satellites.  So, while some cislunar orbits might take longer to build up a dangerous density of space junk, Aerospace cautions that we should learn from experience in GEO where operators also thought that physics would mean satellites are relatively safe from possible collisions, only to find that over time that assumption has been proven wrong.

“We should learn from the early missions to GEO with respect to disposal practices. Early GEO satellites often were disposed in place, leaving the orbital inclination to drift, which has resulted in twice daily passages of the GEO belt to this day, decades after their retirement,” the study warns. Had the US and other nations moved earlier to begin disposing satellites above the active GEO belt, as is current practice, “far fewer wayward dead satellite would transit the highly valuable GEO belt today.”

The orbits at the Lagrange Points, moreover, because they are relatively stable, face the specter of becoming debris dumps — kind of like the Great Pacific Garbage Patch of swirling plastic waste. “Their natural mission utility will attract increasing use, and the complex dynamical behavior motivates a rigorous approach to traffic management, including debris mitigation and remediation,” the study recommends.

What To Do?

A first step, according to the study, is to learn from the past.

“As activity increases in cislunar space, established and emerging spacefarers should employ lessons learned from operations in LEO and GEO to be better caretakers of valuable orbits,” Vedda says.

Scientists will need to undertake a good deal of work to characterize the physical nature of various usable cislunar orbits in order to adept debris mitigation practices, the study says.

Then, space operators need to do a better job of following those practices. As I reported in May, NASA has found that most space operators fail to follow even the most basic of current debris mitigation best practices recommended by the United Nations, expert bodies and the US government.  Orbital Debris Mitigation Standard Procedures. 

“Today, that means better adherence to mitigation practices,” Vedda says. “Eventually, it will include active remediation, which will require expanded monitoring and tracking, coordination of proximity operations, and reconsideration of international law regarding salvage in space.”

Unfortunately, at this point, there is little effort — and less agreement — about how this new frontier for space operations should be managed. And while current treaties and agreements in general apply to all of space, the study points out, “there is no agreement, for example, on how multiple operators will share orbits around Lagrange points.”

“It would be an unsound practice to wait—as we did in the early space age—until the most valuable orbits become crowded before we define protected regions, devise space traffic management protocols, and establish norms for debris mitigation and disposal practices,” the study concludes.