In March, a high-speed cylindrical object roughly 0.7 kilograms in mass shot through the roof of a Naples, Florida, home, smashing through a ceiling and punching through a floor.
NASA later confirmed that the object was an item from the International Space Station – a small leftover from a discarded, multi-ton pallet let loose some three years earlier.
That multi-ton Exposed Pallet 9 (EP9) hardware was loaded with 2,631 kilograms (5,800 pounds) of spent nickel-hydrogen batteries. The pallet itself had been ferried to the ISS via a Japanese cargo ship carrying high-tech lithium-ion battery Orbital Replacement Units, swapping those for the old nickel-hydrogen batteries that got dumped into space.
Dispatched to wander through space over the years, EP9 and the collection of spent batteries were meant to meet their fiery finale by nose-diving into Earth’s atmosphere, but at least one fragment survived the journey.
That occurrence and the following confirmation that the errant object was, indeed, an old ISS battery-related part, has spun up worrisome views regarding the escalation of human-made space debris plummeting to Earth in an uncontrolled manner.
Debris assessment
There was a bit of detective work in appraising the pedigree of the Florida object.
Joshua Finch, a Kennedy Space Center spokesperson, provided a NASA statement on the matter to SpaceNews.
“The NASA Kennedy team initially evaluated the photos from the homeowner and noticed key features still present on the debris similar to a stanchion from the NASA flight support equipment used to mount the batteries on the cargo pallet,” the NASA statement explains.
In order to determine the origin of the debris, the team looked at configuration and shipping documentation for the battery flight support equipment sent by the agency to Japan for installation to the exposed pallet that was lofted in 2020 via the HTV-9 Japanese cargo ship.
“This research yielded the correct part number of the stanchion, and, when reviewed, the engineering drawings confirmed the same key features found on the images,” said NASA.
A new battery stanchion was obtained from the space station parts inventory and a comparison made with the debris for a positive visual confirmation, NASA added.
“The team also had the NASA Kennedy metrology and chemistry labs evaluate the debris to determine dimensional and material properties and compare the results to the engineering drawings. Finally, X-ray equipment and dimensional analysis confirmed all properties of the debris matched the engineering drawings for a space station main battery stanchion, most likely used on HTV-9,” the NASA statement concluded.
Wanted: data exchange
“I am quite sure that there are more surviving fragments,” said Tobias Lips, managing director of Hyperschall Technologie Göttingen in Bovenden, Germany. As a specialist in reentry analysis, he simulated the fall of the ISS pallet of batteries days before the actual reentry event.
“But some of them might have fallen into the ocean before reaching the coast of Florida,” Lips said. Some pieces, however, might have landed on solid ground just to be overlooked as typical terrestrial debris, Lips added. “Imagine you seeing such a piece on a street. What would you think?”
Lips said that he is hoping for (but has yet to see) some international cooperation, such as agreeing on what modeling tools to use, and exchanging data
Risky reentries
“Companies and governments continue to abandon objects in orbit instead of responsibly disposing of them using controlled reentries,” said Ewan Wright, a Ph.D. candidate at the University of British Columbia and junior fellow of the Outer Space Institute. “In any other industry this abandonment would be illegal, but because it’s in space it’s out of sight and mind … until it crashes down again.”
“In this instance someone’s home was hit, with someone inside. The consequences could have been much worse,” Wright said. “Similarly risky re-entries occur weekly, meaning the chance of someone somewhere getting hit is considerable.”
Researchers are still unsure exactly how space debris burns up in Earth’s atmosphere, Wright said, as illustrated by the ISS battery episode. “In this case, NASA models were wrong. With more satellites and rockets launched each year, the potential consequences of this uncertainty are growing,” he said.
Dragon trunk fragments
The Florida impact may not be as rare an event as it seems, as more space debris seems to have hot-footed its way onto terra firma even more recently.
The latest incident, on May 21, happened within The Glamping Collective, a secluded 160 acre mountaintop site that features travel and leisure outdoor structures near Clyde, North Carolina. A grounds worker at the site reported finding a large object, now thought to be fragments of the jettisoned trunk associated with the SpaceX Dragon Crew-7 mission.
Space object tracker Jonathan McDowell had earlier posted via X that the SpaceX trunk reentered the atmosphere over Birmingham, Alabama. Given its northeast track, potential debris could have fallen in Tennessee, western Virginia and West Virginia, he said.
SpaceX trunk clutter has also been found in Australia and Canada.
Increasingly common event
The problem of incoming space rubbish isn’t going to disappear any time soon. In fact, the problem appears to be getting worse, experts told SpaceNews.
Tommaso Sgobba, the executive director of the International Association for the Advancement of Space Safety, told SpaceNews that the rule currently governing uncontrolled reentry — what he termed the 10-4/event rule dictating that “uncontrolled reentry is allowed if the probability of casualties on ground is less than 1 in 10,000 reentries” — is “obsolete because it refers to a time when reentries were a rare event.”
“Uncontrolled reentries must be forbidden,” Sgobba, who formerly led the European Space Agency’s Independent Safety Office, added.
Sgobba said that the risk debris poses for the ground population depends on the kinetic energy and composition of the falling object, as well as population density. He added in an email that he supports banning uncontrolled reentry unless the probability of risk is less than one in 100,000. Large and light debris both pose a minor risk on ground, he said — even a 300 gram piece of debris would be considered catastrophic for an airplane in flight.
Carmen Pardini of the Space Flight Dynamics Laboratory, Institute of Information Science and Technologies in the National Research Council, Pisa, Italy, has recently published papers focused on uncontrolled reentries, with a particular focus on mitigating the risks posed from their fall to Earth. “According to our analyses over several decades, the overall risk represented by uncontrolled reentries is increasing,” Pardini told SpaceNews.
Moreover, the situation is changing fast.
“In the coming years, in fact, while the casualty expectancy of orbital stages might remain basically stable, or slightly increasing, that of satellites might progressively increase by a factor of 20 or more,” Pardini said. “It is therefore necessary to take effective mitigation measures as soon as possible, for instance [by] requiring the generalized adoption of controlled de-orbiting for large orbital stages, satellites and discarded payloads.”
The problem must be addressed now, said Pardini, while new launchers and large constellations of low-orbit satellites are being developed and deployed, “otherwise the situation is likely to spiral out of control within a decade.”
This article first appeared in the June 2024 issue of SpaceNews Magazine.
