WAILEA, Hawaii — The growing number of satellites in orbit is leading to calls to develop formal “right of way” rules, although there is no consensus on what those rules should be and how they should be established.
Several close approaches of satellites in recent years, in some cases exacerbated by disagreements or communications breakdowns between satellite operators, demonstrate the lack of guidelines today and the need to develop them as megaconstellations proliferate.
“For right of way, the regulatory framework is please don’t crash your satellite, and really please don’t crash it into somebody else,” Ruth Stilwell, executive director of Aerospace Policy Solutions, said during a panel at the Advanced Maui Optical and Space Surveillance Technologies, or AMOS, Conference here Sept. 16.
It’s unlikely, she said, there will be an “uber authority” managing space traffic globally and coordinating satellite maneuvers. The alternative is a self-organized network of satellite operators that agree upon standards for determining which satellite has the right of way.
There has already been some progress on this front with agreements between satellite operators. In March, NASA and SpaceX signed an agreement whereby SpaceX agreed to move its satellites should they come close to a NASA spacecraft.
“Bilateral agreements are necessary and problematic,” Stilwell said. The details of those agreements, while effective between the operators, “doesn’t create a standard throughout the community, so we need more visiblity into willingness and desire to reach that standard so we can self-organize.”
She compared that to the self-organization in pedestrian traffic, where people traditionally give way to the right when someone approaches. However, that may not work in an international setting, like an airport, where others are used to giving way to the left. “We have concepts of right of way, principles for safety, but they’re dependent on having enough information about each other,” she said. “That includes a reasonable expectation of what the other actors will do as well as a knowledge about their health, ability and capability.”
Satellite operators are still working out what sort of priority rules should be in place to determine who would maneuver in a case where two satellites both can do so. David Goldstein, principal guidance, navigation and control engineer at SpaceX, suggested that one such rule be that satellites raising their orbits be required to maneuver around satellites in operational orbits they’re passing through.
Maneuvers come at a cost to satellite operators, expending propellant that affects their lifetime and perhaps causing them to temporarily interrupt service. That can create an incentive for satellite operators not to act, forcing the other operator to move its satellite.
“It can create an incentive for others to behave badly because they can avoid those certain costs. It’s another aspect why building norms of behavior is so important,” said Zack Donohew, a scholar in residence at the University of Colorado Boulder’s Leeds School of Business. He called for finding ways of “social disapprobation” for those bad actors.
“This is an opportunity for the United States and its allies to take the lead on that,” he said, though mechanisms like the Space Sustainability Rating being developed by an international consortium.
Even partial solutions could be helpful. In a separate presentation at AMOS Sept. 15, Mariel Borowitz of the Georgia Institute of Technology discussed ongoing work to examine the effectiveness of various right of way approaches for space traffic management, modeling them based on the current orbital population. The study looked at both the effectiveness of those potential rules as well as their overall efficiency.
The research showed that a “U.S.-only” system could still have a significant impact on reducing risks of satellite collisions, getting around the complications of establishing an international space traffic management regime. “We’re finding some initial support for this idea of the U.S. as a first mover,” she said. “From an effectiveness standpoint, that seems like it could make a difference.”
During the AMOS panel, Stilwell compared the Kessler Syndrome, an exponential growth in orbital debris caused by a chain reaction of collisions, to the threshold of a two-degree Celsius increase in global temperatures above which there could be catastrophic impacts on the planet’s climate.
“We can debate the horribleness of the result, but the fact is a lot of bad things can happen along the way,” she said. “It doesn’t really matter when or if there’s a Kessler Syndrome. We have a problem today that is a result of congestion and debris generation in space that we need to address.”