The missing ingredient for assigning fault in space


If a driver were to veer from the street and drive into me while I’m running in my neighborhood, that person — and possibly the person’s employer — could be held financially or even criminally liable by a court for injuring me, regardless of intention.

The caveat is that in order to win, I must prove cause and effect, and for that I need evidence that’s complete enough to meet the standard of doubt required by the court.

Assume that witnesses saw the driver look at a cellphone (which I’ve personally witnessed while running) and then veer. Cellphone text records then show that the driver was actively texting at the time. For this evidence to be complete, two criteria must be met: (a) Deduction is possible — the driver was looking down at the cellphone, and this avoidable distraction caused the driver to lose focus and hit me. The driver should not have been operating a motor vehicle while texting. And (b) no evidence refutes this conclusion — witnesses did not report seeing a child chasing a ball toward the car or a baby carriage rolling away from a parent or anything that would justify the driver veering into me on the sidewalk.

Unfortunately, for events in near-Earth orbit, we’re still quite far from the ability to attribute fault as efficiently as we can on land, not because we lack legal instruments to make claims but because by and large, we lack evidence that is complete.

Incomplete evidence can lead to chaos and confusion in outer space. When a space traffic information provider or satellite operator sounds the alarm about a potential on-orbit collision, we can’t blindly trust them and act on their data, assuming this to be truth. Maneuvering to get out of the way of a fictitious event may actually put the satellite into harm’s way instead.

Conflicting evidence is a problem in determining real from false alarms. At least several times over the last decade, one group or another has warned of a possible impending collision, while another group has concluded that there was no risk. In such cases, one group’s null hypothesis, or default belief, was that a collision is likely and more evidence would be needed to determine this was not the case. On the flip side, the other group’s null hypothesis was the opposite.

In cases where a collision did not occur, that does not necessarily mean that a group or agency that discounted the collision risk had adequate evidence to do so. “Absence of evidence is not evidence of absence,” according to a line attributed to cosmologist Martin Rees and made famous by Carl Sagan. When two entities have opposing null hypotheses and incomplete evidence, their decisions can also be opposite of each other. This situation introduces otherwise avoidable operational risk and results in operational costs.

The problem of incomplete evidence comes up in other scenarios as well. Intentionally blowing up one of your satellites in space and creating a cloud of space debris can have long-lasting consequences. A satellite operator who loses a spacecraft to a collision with debris and an astronaut who has to defer a critical spacewalk and seek shelter have each experienced what the lawyers call “harmful interference.” Such deliberate and irresponsible acts should result in some form of compensation for the victims. However, no single entity has a complete set of data or evidence to prove that such evasive maneuvers were necessary.

Last November, the International Space Station performed a propulsive maneuver to avert the risk of colliding with a piece of debris from an anti-satellite test that China performed in 2007. This maneuver was a unilateral decision based on a perception of impending harm, rather than on a complete set of evidence available to and trusted by all space operators.

Having a pool of multiple independent sources of information available to all space operators would allow them to draw conclusions based on the same body of evidence and then compare notes before expending fuel and time on maneuvers that might themselves invite risk. As long as conclusions are drawn from different evidence, it is impossible to separate real from false alarms. Even if this aggregate pool of evidence fails to meet completeness, actions of operators could at least be coordinated and consistent, leading to improved predictability. That is a goal we must strive to achieve for space safety and long-term sustainability.

United Nations treaties and conventions, such as the 1971 Convention on International Liability for Damage Caused by Space Objects, provide a framework for signatories to raise concerns and make formal complaints about the actions of other governments and the corporations based in their jurisdictions. However, just because a government complains does not guarantee that its concern is quantifiably real or justified. This “you said, I said” environment can lead to undesirable geopolitical escalation between countries.

In December, China raised a complaint in a note verbale, a kind of diplomatic message, to the U.N. secretary general, saying on two occasions it had to maneuver its space station with three taikonauts aboard to avoid risk of colliding with a growing number of SpaceX Starlink satellites. The United States, citing evidence from U.S. Space Command, responded to the U.N. that there was no risk of collision between Starlinks and the Chinese space station in either of these events. Neither party provided evidence that could be scrutinized or combined to draw consistent conclusions. No third party independently confirmed or refuted either side’s claims. This lack of common ground won’t suffice for a species that intends to peacefully spread its existence into space.

To be sure, having evidence that meets the criteria of being complete may never be obtainable for a large number of potential events in space. However, it is possible for humanity to develop and deploy a framework that provides a widely accessible and curated set of joint, multisource evidence from which all interested parties could draw consistent conclusions. This consistency would be a step toward improving space safety and ensuring the long-term sustainability of the orbital environment for free and unhindered peaceful use of outer space. 

Related Topics

Space safety

Moriba Jah

About Moriba Jah

Moriba Jah is an astrodynamicist, space environmentalist and associate professor of aerospace engineering and engineering mechanics at the University of Texas at Austin. An AIAA fellow, he’s also chief scientist of startup Privateer Space and hosts the monthly webcast “Moriba’s Vox Populi” on SpaceWatch.global.

The missing ingredient for assigning fault in space