We have landfills in space, but we don’t have to
By Moriba Jah|February 2023
If you feel like rocket stages and dead satellites are crashing back to Earth with increasing frequency, you are right. Most recently, NASA’s Earth Radiation Budget Satellite, an environmental spacecraft retired in 2005 and left in orbit, reentered the atmosphere in January. There was a 1-in-9,400 chance of a surviving piece harming someone, NASA said, according to Space News. In November, a 22-metric-ton Chinese rocket plunged back to Earth, also with large parts surviving reentry, but they happened to impact somewhere in the South Pacific Ocean.
Today, even if no one launched another satellite, many anthropogenic space objects are adrift in low-Earth orbit and will eventually reenter, and the problem is compounding. The root cause remains our stubborn tendency to continue to treat LEO like an open landfill of abandoned space hardware.
Until last September, the best attempt to keep the problem from getting even worse was a 20-year-old United Nations guideline, so called because it is nonbinding. This guideline urges space operators to ensure that their used rockets and defunct satellites will fall from orbit within 25 years of the end of their missions. A slight improvement came in September, when the U.S. Federal Communications Commission published a rule requiring U.S. licensed satellite operators, or those abroad seeking to enter the U.S. market, to ensure that their objects will burn up within five years after the end of their operations.
This rule and the international guideline it is intended to replace in the U.S. are deficient, mainly because the “disposal” they speak of can be an uncontrolled one. Disposal is defined as simply ending the potential for the object to interfere with space operations and activities. We can see the deficiency demonstrated clearly in the case of NASA’s environmental satellite: It reentered 17 years after its retirement, well within the guideline, and yet its debris still posed a risk to us on the ground, however small. The fact that it entered over the Bering Sea and injured no one was just luck, luck that someday will run out.
Right now, the options for LEO operators are too broad: An object can be left at an altitude that ensures it will reenter within 25 years, and therefore meet the U.N. guidance; an object can be left in a graveyard orbit above LEO, but below geosynchronous Earth orbit, while somehow avoiding the medium-Earth orbital regime populated by the GPS constellation and other navigation satellites; or an object can be moved to a graveyard orbit above GEO.
None of those options is satisfactory. Let’s dissect this a bit. When objects reenter naturally, there is a higher chance that some part of their mass will survive the process and reach the surface, potentially in a populated area. That’s because the angle of reentry is shallower and the heating rate and dynamic pressure that the object experiences are also less than if forced to reenter with intention and planning. The generally adopted threshold for concern about the risk of human casualty by most space agencies is a 1-in-10,000 chance of someone being killed, formally called the probability of expected casualties. That risk, however small, is unacceptable. We should not accept, as a part of normal space operations and business, expected casualties from reentries if we can control them. We wouldn’t build a highway overpass and accept that one in 10,000 drivers will be killed by a piece falling from it. Leaving objects in a graveyard orbit is the equivalent of dumping them into a landfill, but worse. Imagine a landfill of objects that move around in ways that even the most skilled astrodynamicists or advanced software have trouble predicting because of a paucity of measurements and vast number of variables. Objects in graveyard orbits should never fall back to Earth or into the LEO regime, but just like with a landfill, there can be unanticipated consequences. Put simply, we’re leaving trash out in the hopes that in the near term it won’t risk space operations and activities, but for the long term, who knows?
Because we began launching stuff into space back with Sputnik in 1957 and Explorer 1 in 1958, but did not formally begin addressing the fate of the things we launch until 2001 when the 25-year guideline was published (NASA’s 1995 guidelines for mitigating debris from its own missions being an exception), there are many thousands of objects, large ones too, that were abandoned on orbit without a disposal plan. Yes, I used the word abandoned. Counting on Mother Nature to dispose of an object is tantamount to abandoning it. The 25-year guideline and the FCC’s five-year rule should be supplemented by one or more laws that require spacecraft and rocket stages to be disposed of responsibly, whether by the operator or by a third party. These objects should be deorbited in a controlled manner, or better yet, brought home or taken to an orbital facility for recycling, because recycling or reuse could be built into the design if we wanted to. Designing satellites and rockets for reuse and recycling is called Extended Producer Responsibility, within waste management processes. Doing so would address the threat to space sustainability, which I define as humanity’s ability to utilize orbital space as a finite resource, free and unhindered in perpetuity.
The United States considers itself the leader in space. Establishing proper disposal techniques by law would provide incentives for others around the world to join in creating a thriving, circular economy in space. A circular space economy prioritizes the prevention of pollution through reuse and recyclability, followed by active disposal for those things that can’t be reused or recycled. The United States already has a company with recyclable rockets: SpaceX. Bravo! Now we need recyclable and reusable satellites. That’s critical, because even with the 25-year guideline and the five-year rule, the debris problem continues to compound.
Therefore, as we begin to recycle and reuse, we also need to shift to active cleanup. It would be nice if there were a list of space objects that all space actors agree should be removed first, based on risk. Today, the best we have is a loose collection of recommendations from the scientific community.
It’s time for us to abandon abandonment.