Concerns Over Debris and Space Situational Awareness Abound as Space Activity Ramps Up
Space is getting more crowded, but the growing risk of a satellite colliding with orbital debris is what economists call “a tragedy of the commons” — it’s no one’s job to fix it. At the same time, the way the U.S. government keeps track of all that space junk is being radically shaken up, just as the number of objects in orbit is likely to balloon with the launch of Low-Earth Orbit (LEO) mega-constellations.
That was the alarming picture painted by two sessions at SATELLITE 2020, which examined the problem of space overcrowding and looked at the changes the Trump administration ordered last year — moving the job of tracking objects in orbit from the Department of Defense (DoD) to the Department of Commerce (DoC).
That job is getting harder as space becomes more congested. The latest European Space Agency (ESA) figures show just over 2,200 operational satellites and slightly more dead ones still in orbit. In addition, thousands of additional launches are planned over the next few years as the big LEO constellations come online.
Those satellites will be heading into a very different environment from launches in 2006, when the regulations that govern them were written, said Stephen Earle, the space traffic and Air Force interface lead for the Federal Aviation Administration (FAA). Collision avoidance is much more complicated than it was, he explained, “It’s like merging onto the highway and it gets more and more difficult as space gets more crowded.”
Space Situational Awareness
Earle and other U.S. officials at the Space Policy Roundtable spoke frankly about their concerns that they might not be able to keep proper track of all those objects.
“We've inherited a Space Situational Awareness (SSA) scheme that we have to use, and it's not the best,” Earle said.
SSA is the job of keeping track of all those objects spinning around the earth, their speed and their direction — to ensure they don’t crash into each other. Currently, the U.S. Air Force 18th Space Control Squadron at Vandenberg Air Force Base in California is responsible for providing SSA services like collision warnings to satellite operators around the world. But in 2018, President Trump signed an executive order known as Space Policy Directive 3, transferring that responsibility to the DoC.
The transfer, scheduled to complete by 2024, is an opportunity to modernize SSA provision, the roundtable was told. But the dozen or so responsible officials in the DoC’s Office of Space Commerce face a daunting task as they ramp up to take over.
“We've been trying to define what our ‘to be’ architecture would actually look like,” explained Mark Daley, the office’s deputy director for operations. He said they have also laid out an initial roadmap for stakeholder engagement, including a request for information last year and plans for an industry day.
The Risk of Collision
Keeping track of satellites is hard enough — and about to get much more complex. But, according to the European Space Agency, there are also millions of pieces of orbital debris, ranging from tiny crystals of human urine or flecks of paint to the bus-sized discarded upper stages of launch rockets.
Using statistical modeling, the ESA estimates there are about 34,000 pieces of orbital debris larger than a fist (more than four inches across); and more than 128 million pieces smaller than a bolt (less than a half inch across). But experts say the riskiest debris are the 900,000 pieces estimated between those two size ranges. A piece of debris smaller than a fist is almost impossible to track, but a piece larger than a bolt moving at 17,000 miles per hour can still punch a hole large enough to cripple a satellite.
Tom Stroup, president of the Satellite Industry Association, said during Wednesday’s closing session, What’s the Plan to Prevent Overcrowding in Space, that his member companies see orbital debris as a “very serious issue.” He pointed out that it poses an almost existential threat to the industry, “Because it potentially affects the sustainability of space, the ability to use it in the future.”
“The risk of conjunction is the greatest threat,” he added. Conjunction is when two orbiting bodies get close enough to create a risk of collision. If one of the satellites is live, it can maneuver to avoid the conjunction and eliminate the risk of collision. But when both satellites involved in the conjunction are dead, as nearly happened earlier this year in the skies over Pittsburgh, the world can only cross its fingers and hope.
A major collision like the one narrowly avoided over Pittsburgh, would likely produce a large cloud of additional debris, precipitating a large risk of additional collisions, each producing its own debris cloud.
Indeed, if the initial debris cloud is big enough, there’s a chance that process could scale into the nightmare scenario known as a collisional cascade, in which every collision produces more debris and further collisions. Such a cascade, also referred to as the Kessler syndrome after the NASA scientist who first described it in the 1970’s, would quickly render the orbit in which it happened unusable, according to a NASA analysis.
Whose Cost to Bear?
But the economic ripples from even a single collision could be severe, said Clare Martin, the senior vice president of Programs and Operations for Astroscale U.S. — a company developing techniques for orbital debris removal.
“Even a single collision would have a knock on effect because of how reliant we all are on space,” she said.
And the economic costs of orbital overcrowding are already being felt, according to Benjamin Reed, deputy director of NASA’s Satellite Servicing Projects Division. “It costs … real dollars to make [satellites] trackable, reportable, to have enough fuel to do unplanned maneuvers …to be responsible orbital citizens,” he said. There have been only one or two catastrophic collisions that have destroyed a functioning satellite, he added. “The reason why we have to spend that money to minimize the possibility that there might be more.”
But it will be money well spent, he argued. “Preventing things from crashing is a lot more economically feasible than cleaning up afterwards,” he said. “Orbital mechanics make [clean up] very difficult. The speeds are astronomical, the distances are crazy, lane changes are unbelievably expensive.”
Martin Zhu, an economist with the FAA, pointed out that safely bringing down a post-mission rocket body in orbit could cost as much as $109 million, but to plan the launch so that the upper stages either fall back to earth and burn up on reentry or are boosted to escape velocity and sent into outer space can cost as little as $68,000.
But, in economic terms, the clean up cost is an externality — a cost someone else has to bear. When users of a common resource externalize their costs like that, Zhu explained, it’s called “a tragedy of the commons.”
That suggests that the market cannot solve the problem, and indeed, even Martin, whose company is working to offer debris mitigation services, acknowledged that actually recovering debris from orbit was probably beyond the capability of the private sector.
“Active debris removal is very challenging,” she said, “We see that as being the preserve of the [national space] institutions,” she said.
Astroscale plans to offer satellite operators end of life services, she said, helping deorbit decommissioned satellites. “This is like being almost a tow truck in space,” she said. For the large constellation operators, she suggested, there was an economic case for paying for such services. “What is the risk to you if you have a rate of infant mortality and you leave those dead assets in your constellation?”
Zhu asked, if the market cannot solve the debris problem, who will take the lead? “We need a [regulatory] leader, or for industry to start self-regulating,” he said.
“Regulations are not just restrictive, they are enabling,” he argued, using the example of the road system. “Without traffic regulations, it wouldn’t be safe to drive your car.”
The U.S. produces 44% of satellites, provides 40%-50% of satellite services and has more than 45% of the global launch market, Zhu said, making it the ideal option to regulate the global space industry.
Stroup, the trade association president, gave a note of caution: “We don’t want to pursue a solution that just pushes the problem offshore. We don’t want a regulatory regime that makes it so onerous for those players that they just move out of the country,” he said.
Martin, who previously worked in the satellite manufacturing business, agreed. “What we can’t risk is having different regulations around the world, creating [satellite] flags of convenience, [jurisdictions] where people can go to launch with less regulation,” she said. “You cannot create an uneven playing field because you’ll end up hurting your industry and ultimately the whole economy when the money goes elsewhere.”
“Everyone has to be on the same page if we’re to come up with a sustainable model,” she concluded.
And decommissioned or dead satellites are actually a much smaller issue with orbital debris than the upper stages of booster rockets — which tend to be much larger and heavier than the smallsats dominating the new LEO constellations.
“Post-mission rocket bodies compose 44% of the mass of orbital debris,” said Zhu, pointing out that the launch industry had just been deregulated. “The satellite industry is regulated by the FCC and is required to have [orbital debris] mitigation measures, but the rocket launchers are under DoT’s jurisdiction and there is no [mitigation] requirement in their rules,” he said.
Worse, the risks of collision in orbit require very precise measurements of possible error, but as Earle points out, the different jurisdictions mean “We have an on-orbit asset with an error determined by one party, and a launch vehicle that has an error determined by yet another party.
“It's like using a tape measure, and trying to establish a standard where two different people are holding the ends and they're both moving independently,” said Earle. VS