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Defending against space debris

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On Oct. 19, a walnut farmer 200 miles south of Stanford found a distinctly foreign object smack in the middle of his field. Bulbous, broken and charred, the roughly spherical hunk of metal had clearly not fallen off one of his nearby trees. The farmer finally found his answer after calling the local sheriff’s office, who then alerted the Vandenberg Air Force Base: the object was most likely a fuel tank from a defunct Iridium satellite.

As one of the largest commercial constellations in the world, Iridium has been the victim of destructive accidents before. In 2009, Iridium 33 collided with a defunct Russian satellite. That collision, which occurred over northern Siberia, quickly created the second largest orbital debris cloud in history.

More Debris

Although most of us don’t need to worry about the dangers of raining debris quite yet, mitigation of space debris remains a large obstacle to new satellite constellations, especially with mega-constellations of small satellites on the technical horizon. Many industry actors, from DARPA to the FCC, have attempted to address the impending danger of the Kessler Syndrome, where the density of objects in orbit prevents space travel completely. Postulated by NASA scientist Donald Kessler in 1978, this event is caused by repeated space collisions creating more and more wreckage, leading to the exponential growth of space debris. Multiple solutions have been suggested, from limiting satellite life to 25 years to keeping a low altitude “buffer zone” where satellites would have to prove their functionality before boosting up to operational orbits.

Other professionals suggest that the onus rests on industry to address these future problems. Fred Kennedy, the director of the DARPA Tactical Technology Office, explicitly pushed responsibility to launchers and operators, saying, “if the industry is putting up a thousand satellites, they have to figure this out.” DARPA has broadly concluded that the only sustainable long-term solution is self-policing.

What About Satellite Tracking?

In their attempts create hardware-based answers to debris, both DARPA and the FCC ignore the most useful method for addressing satellite collision right now: accurate and publicly available spacecraft observation. Although publicizing accurate satellite locations presents a significant security risk, the government should definitely invest further in rapid, precise measurement of space body movements. Afterwards, the government must weigh the benefit of orbital collision avoidance with the potential harm to national security of publicizing real time satellite tracking data to find the most appropriate solution that serves both the commercial and the military sectors.

Fortunately, this idea is not new. Space Directive 3, issued by the administration in June, directs the government to create a On-Orbit Collision Avoidance Support Service, which would provide a “timely warning of potential collisions … essential to preserving the safety of space activities for all.” This stipulation exists in a crowded field of executive directions on the topic of space policy, and must be given more attention. In terms of technical applicability and monetary investment, the combination of more accurate observation and satellite orbital agility presents a far easier solution than active satellite cleanup. Besides, it also avoids the legal challenges that any active measure would face from foreign governments and the 1967 Outer Space Treaty.

Ultimately, as with any tragedy-of-the-commons scenario, the issue of satellite debris will come to a disastrous conclusion. It is the responsibility of the federal government to lead the world in supporting a financially reasonable and technically feasible solution. Although many steps are being taken to address debris, improved observation and commercial-government cooperation is the most appropriate method to safeguard the American public and ensure the future of space exploration.

 

Contact Andrew Gatherer at gatherer ‘at’ stanford.edu.