21 February 2023

Where does space begin? Chinese spy balloon highlights legal fuzziness of ‘near space’

Lauren Morello

The Chinese spy balloon the U.S. shot down earlier this month highlights a curious gap in international relations: There is no widely accepted definition of where a country’s sovereign airspace ends and space begins.

Whether and how that threshold is ever defined could change how craft like planes, balloons and drones operate in “near space,” which is a vast layer sandwiched between the altitudes where commercial jets fly and the lowest band of satellites orbit the Earth. Various legal treaties establish space as free for use by all, while international agreements and customary law give nations control over their own airspace.

What was once a philosophical debate about the concept of near space has become more relevant as countries develop and deploy more craft capable of operating in or passing through this zone, from an ever-growing number of commercial rockets to the uncrewed vehicles known as high-altitude pseudo-satellites.

“You’re not really supposed to fly over another country without their permission,” said Scott Anderson, a former U.S. diplomat who is now a visiting fellow at the Brookings Institution. “It’s worth noting that there’s no agreement around where the vertical limit of that is.” In the simplest terms, he added, “we know it stops somewhere short of outer space, because there’s a whole separate set of legal norms and treaties that govern outer space.”

When news of the Chinese balloon broke in early February, U.S. Defense officials said it was traveling over Montana at an altitude of roughly 60,000 feet. That’s the ceiling of the airspace monitored by the Federal Aviation Administration and a height that most countries accept to be within a nation’s sovereign airspace. But as the balloon headed toward the East Coast, where it was eventually shot down off the coast of South Carolina, it lofted as high as 65,000 feet, edging ever so slightly closer toward a legal gray zone.

“We know from the Chicago Convention of 1944 that a nation has sovereignty over all of its airspace, and we know from the Outer Space Treaty of 1967 that nobody can claim territory in [outer] space,” said Michelle Hanlon, co-director of the Air and Space Law Program at the University of Mississippi. “The question — and this is a can that has been kicked down the road since the 1950s — is where space begins.”

Drawing a line

One of the best-known definitions of the boundary between Earth’s atmosphere and space is the Kármán line, established in the 1960s and located 100 kilometers (62 miles) above Earth. Named after Hungarian physicist Theodore von Kármán, it is the standard used by the World Air Sports Federation for record-keeping purposes.

The United States has its own standard of 50 miles (80 km), set out in federal law and used by both the Defense Department and NASA. At its highest reaches, above the airspace where civilian planes and jets fly under the watchful eye of the FAA, military, scientific and commercial aircraft operate under what’s known as a “due regard” standard. That means aircraft “need to pay attention to what’s going on, but it doesn’t mean they can fly with impunity over sovereign countries,” said Scott Pace, director of the Space Policy Institute at George Washington University. It’s a common international stance, not just in the U.S., he noted, pointing to the well-known 1960 incident in which the Soviet Union shot down an American U-2 spy plane flown by Francis Gary Powers as it flew 80,000 feet over the USSR.

Countries including Australia, Denmark and Kazakhstan have adopted the Kármán line equivalent of 62 miles (100 km) for space’s lower bound — but they still assert their authority over that threshold, Hanlon noted. “All of these national rules are very careful to say with respect to national activities, ‘This is where we are going to decide where space begins,’” she said.

Meanwhile, the United Nations has studied the issue for years without any firm decisions, through its Committee on the Peaceful Uses of Outer Space. (Yes, that’s an actual committee.) “The U.N. has a working group that has been meeting every year since the committee was formed in 1958,” Hanlon said. “There has not been a consensus reached on where air ends and space begins.”

In a less serious way, billionaires have waded into the debate in recent years — albeit for personal bragging rights. In 2021, space entrepreneurs Jeff Bezos (of Blue Origin) and Richard Branson (of Virgin Galactic) participated in competing high-altitude flights just days apart. A top Blue Origin official publicly questioned whether Branson had actually reached space, since unlike Bezos he had not crossed the Kármán line.

Sky’s the limit

Putting aside bickering billionaires, experts on space policy and law are divided on whether new rules or definitions for near space are needed.

“Some lawyers would like to have things cleaner, but most people really don’t see the point — whether the benefit you’d get out of it would be worthwhile,” Pace said. High-altitude balloons and military spy planes, such as U.S. SR-71s or U-2s, fly above airspace monitored by air traffic controllers but are able to operate safely under the “due regard” standard, he noted, and nations generally respect each others’ airspace rights.

In many ways, the situation in the skies resembles the legal regime governing the world’s oceans. Customary maritime law and the U.N. Convention on the Law of the Sea set boundaries that become more restrictive as you transition from the high seas toward a nation’s territory.

President Joe Biden said Thursday that Secretary of State Antony Blinken would work with other countries to create new international norms for activities in the highest reaches of the atmosphere. But for many countries, the current vague definition of near space is actually an advantage — one they appear loathe to give up by taking a hard line on where sovereign airspace ends or where space starts.

“Nobody who is working or spying in or using this space wants to define it, for much like the reason President Eisenhower didn’t object to Sputnik,” Hanlon said. “No one wants to be the first to say, ‘No you can’t,’ because they want to do it also.”

Hanlon believes this may help explain one aspect of the recent spy balloon saga. Although China criticized the United States’ characterization of its wayward balloon as a tool of espionage, it didn’t make any legal arguments about whether the U.S. had the right to shoot the object down. Rather, Hanlon noted, the Chinese government said it was a weather balloon and accused the U.S. of conducting its own balloon surveillance of China.

Still, she is pleased that the White House is putting together a task force to study sightings of anomalous airborne objects — including any in near space — and any safety or security risks they may pose. Countries “should be talking to each other about the technology that we have, so we can look at the lights in the sky and say, ‘This is the new technology we’re testing,” she added. “It would be really sad if we shot down a UAP [unidentified aerial phenomenon] that was alien and was just here to say, ‘Look at us!’”

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