New research by Nicholas L. Johnson and J.C. Liou of NASA’s Johnson Space Center in Houston makes clear that the proliferation of potentially hazardous orbital junk is a problem that is only going to get worse in the years ahead.
Perhaps most troubling was their conclusion that even if all launch activity were halted today, space debris levels would remain constant for about 50 years — and then increase as existing pieces of orbital junk collide or explode into still more pieces.
If there is good news, it is that steps have been taken in recent years to address the problem. The Inter-Agency Space Debris Coordination Committee, which includes most of the world’s major space agencies, in 2002 published voluntary procedural and technical guidelines designed to minimize the creation of space junk. But adherence is not universal, even among some committee members. Mr. Johnson noted, for example, that Ukraine’s Tsyklon rocket, while little used these days, still features an upper stage that is prone to exploding after a number of years in space. It is, in effect, an orbital time bomb.
More recently, the U.S. Federal Communications Commission adopted stricter licensing rules that require applicants to submit debris-mitigation plans, such as boosting satellites reaching the end of their service lives up and out of the geostationary arc, a finite piece of orbital real estate where most communications satellites operate.
But given the conclusion by Mssrs. Johnson and Liou that even a complete cessation of space activity will not prevent the proliferation of debris in the years ahead, more needs to be done. But just what that might be is far from clear, since no one has come up with a cost-effective way to dispose of the some of the larger man-made objects that today clog near-Earth space.
Although the chances of an in-orbit collision involving an operational spacecraft are still relatively small, they are growing. If current trends continue, it is only a matter of time before orbital debris becomes a significant constraining factor in space activity. To cite just one example, shielding to protect crew-carrying space vehicles against a potentially fatal debris impact will necessarily drive up their weight and cost.
With so much at stake, research into affordable means or orbital-debris removal — studies have suggested that ground-based lasers might be able to do the job — should be accorded a higher priority by all spacefaring nations. Given what is known about the threat today, there can be little excuse for waiting until there is a catastrophic collision involving an operational spacecraft.