Trouble in orbit: the growing problem of space junk
Forty-five years ago the associate director of science at Nasa's Marshall Space Flight Center, Ernst Stuhlinger, an original member of Wernher von Braun's Operation Paperclip team, was asked by Sister Mary Jucunda, a Zambia-based nun, how he could suggest spending billions of dollars on spaceflight when many children were starving on Earth.
Today, Stuhlinger's response still provides a powerful justification for the costs associated with space research
"It is certainly not by accident that we begin to see the tremendous tasks waiting for us at a time when the young space age has provided us the first good look at our own planet," he said.
Very fortunately though, the space age not only holds out a mirror in which we can see ourselves, it also provides us with the technologies, the challenge, the motivation, and even with the optimism to attack these tasks with confidence."
In the intervening years, the maturing space infrastructure has supported our new and ongoing efforts to tackle global health, hunger, poverty, education, disaster risk reduction, energy security and climate change.
Indeed, we have made great use of Stuhlinger's "mirror" to meet many of society's biggest challenges.
More than 5,000 launches since the start of the space age, each carrying satellites for Earth observation, or communications, for example, have resulted in space becoming increasingly congested and contested.
Now, the US Space Surveillance Network is tracking tens of thousands of objects larger than a tennis ball orbiting above us, and we suspect that there are one hundred million objects larger than 1mm in the environment.
Due to their enormous orbital speed (17,000 mph), each one of these objects carries with it the potential to damage or destroy the satellites that we now depend on.
Red Conjunction
Perhaps the most visible symptoms of the space junk problem are the regular collision avoidance manoeuvres being performed by the International Space Station (ISS), and the increasingly frequent and alarming need for its occupants to "shelter-in-place" when a piece of junk is detected too late for a manoeuvre.
The systems on the ISS that provide vital life support are also responsible for its unique vulnerability to a debris impact - a pressurised module in a vacuum might behave like a balloon if punctured.
The recent "red conjunction" (where a piece of debris comes close enough to pose a threat to the space station) involving a fragment from a Russian satellite on 17 July this year was yet another demonstration of the growing threat from space junk.
Thanks to the hit film "Gravity", and the Oscar-nominated performance of Sandra Bullock, we can now readily appreciate the anxiety that must be felt by the astronauts and cosmonauts aboard the International Space Station whenever they receive such a "red conjunction" call.
In spite of these occurrences, the space station is actually orbiting at an altitude where the number of debris is relatively low.
At higher altitudes the amount of space junk is substantially greater, but only robotic spacecraft are exposed there. Nevertheless, these satellites are some of the most valuable for understanding our planet. Due to this congestion, there is an increasing chance that the space junk population could become self-sustaining.
That is, more junk could be created by collisions than is removed through the natural decay caused by atmospheric drag. Indeed, we already have some experience of this: in February 2009 two relatively small satellites collided over Siberia creating about 2,000 new fragments that could be tracked, with many still orbiting today and regularly passing close to other satellites.
'Super wicked problem'
In 2014, Brian Weedon, a technical adviser for the Secure World Foundation, described space junk as a "super wicked problem." Such problems, he explained, are particularly challenging to solve because time is running out, there is no central authority providing guidance or support, those seeking to solve the problem are also causing the problem, and the solutions are left for future generations to find.
The critical first step in tackling super wicked problems is to expand the group of people who support measures that reduce the risk. Indeed, there are encouraging signs that both old and new space actors understand the need to mitigate negative impacts of their activities in space and to limit the consequences for other space users.
Several companies, including Planet Labs and OneWeb have affirmed their commitment to tackle the space junk problem in the public domain. However, much work is still needed to fully understand the problem, develop technologies (such as e.Deorbit), remove legal and political barriers, and to increase awareness. The Kessler Syndrome remains an ever-present threat.
The space age has enabled global solutions to some of society's biggest challenges, just as Ernst Stuhlinger described in his letter to Sister Mary Jucunda. It has also held out a mirror and shown us that a continuing disregard for the space environment will surely affect our ability to deliver these solutions, with potential consequences for millions of people.
