Almost 6 to 10 percent of abandoned rocket stages left in orbit after space launches have a chance of seriously injuring or even killing someone over the next decade, according to a study led by the University of British Columbia (UBC).

While this would raise the cost of launches, it could potentially save lives if governments took collective action to ensure rocket stages were safely guided back to Earth after their use.   

Are human life losses acceptable as a cost of doing business, or should they be protected when possible? Michael Byers, a UBC Political Science expert, said that we can protect ourselves against this risk.

It is common for rockets to be left unattended in orbit when satellites are launched into space. Those leftover pieces can reenter the atmosphere uncontrollably if they are in a low orbit, potentially hurtling toward the ground in potentially lethal pieces.

In a study using satellite data from over 30 years, researchers found that uncontrolled rocket body re-entries pose a six to ten percent risk to human life in the next decade. In the case of re-entry spreads dangerous debris over a ten meters squared area, each re-entry is likely to result in a casualty.

Due to the distribution of orbits used when launching satellites, rocket bodies are three times more likely to land in Jakarta, Lagos, or Dhaka than in New York, Moscow, or Beijing, despite the north is home to major space-faring nations.

In this study, the risks have been evaluated per launch, which has given people the impression that they can ignore them because they are so small. But the cumulative risk isn't as small.

Even though no casualties have yet been reported, and no mass casualty has occurred, do we wait until that moment and react, particularly when it involves people, or should we take action now?

Several technologies and mission designs are already available that can significantly reduce these risks. For example, engines that reignite and extra fuel can guide rocket parts safely to remote oceans. Multilateral agreements do not require companies to make such changes at the moment.

The authors concluded that national governments with populations at risk should impose re-entries on controlled rockets, create meaningful consequences for non-compliance, and eliminate the risks.