By the time the film “Gravity” won seven Academy Awards in March, casual viewers probably knew it as much for its arresting visual imagery as for its lengthy list of technical errors. Amplified by the Twitter feed of celeb astrophysicist Neil deGrasse Tyson, space watchers identified problems with Sandra Bullock’s hair (why wouldn’t it float in a zero-G environment), and why would the Hubble telescope and International Space Station have the same sight lines (given they are over 100 miles apart). However, the one tweet from deGrasse Tyson that got overlooked was that the movie was plausible: “The film ‘Gravity’ depicts a scenario of catastrophic satellite destruction that can actually happen.”

The problem of orbital space debris is one that I focused on for a new Council on Foreign Relations report on “Dangerous Space Incidents.” Over the past nine months, I have spoken with many U.S. government officials and staffers, and non-governmental experts, who work on national security space issues. One repeated concern was that the sort of space debris that threatened Bullock and George Clooney in “Gravity” was among the most underappreciated challenges facing the world. Moreover, because the United States remains the predominant actor in space — with 43 percent of active satellites and 75 percent of global space funding — it has the most to lose from a space domain further littered with space debris.


Some pertinent facts about space debris demonstrate the pressing danger. Roughly three-quarters of all space debris — 23,000 items over 10 centimeters across (almost 4 inches), 300,000 measuring between 1 and 10 centimeters, and over 135,000,000 fragments less than 1 centimeter — is found in low earth orbit (LEO), the area extending from 99 to 1,200 miles above the Earth. Traveling at an average speed of 18,000 miles per hour, even small pieces of debris can damage or destroy satellites and spacecraft.

At that speed, even a half-inch piece of debris would have the kinetic force of a bowling ball thrown 300 miles per hour, as NASA describes it. (This is one thing “Gravity” gets very wrong: The actors would not have been able to see the debris moving toward them.)

The problem is that space debris tends to hang around. At lower altitudes, it can be pulled by the Earth’s gravity within years and burn up upon re-entering the atmosphere. Higher up, it can remain for decades or centuries and collide with other pieces of debris or spacecraft, thus exponentially creating more debris in a process known as the Kessler Syndrome. In 2011, the National Research Council estimated that portions of the space debris environment already had reached this “tipping point,” with enough in orbit to continually collide and create even more debris.

Debris poses the most acute threat to critical U.S. space assets that reside in LEO, where, not coincidently, half of the world’s 1,100 active satellites reside, including many essential for U.S. government and military missions. Satellites where the greatest amount of LEO space debris exists (at an altitude of 370-620 miles about the Earth), include: The Air Force’s ORS-1, used for reconnaissance of Afghanistan and Central Asia; the Missile Defense Agency’s NFIRED, which gathers high resolution data to help validate boost phase intercept simulations; dozens of remote-sensing satellites operated by U.S. intelligence agencies; and the Iridium constellations of 66 communications satellites that provide global data transfer and encrypted voice communications for U.S. military and intelligence agencies.

Historically, space debris had been produced in small amounts from human activity, including the upper stages of launch vehicles, disabled spacecraft, dead batteries, solid rocket motor waste, and refuse from human missions. But while it took 40 years to produce the first 10,000 pieces of softball-sized debris, it required less than a decade for the next 13,000. This recent increase was partly because of two worrying incidents in particular, which, according to NASA, combined to increase the number of total space objects by over 60 percent.


The first resulted from human error or negligence. In February 2009, an active U.S. Iridium communication satellite and a defunct Russian satellite, which were predicted to pass each other 1,900 feet apart, unexpectedly collided 500 miles above Siberia. This event unintentionally caused two objects in space to break up into 2,100 pieces, each larger than 10 centimeters.

The second was an act of human malevolence. In January 2007, China conducted a direct ascent anti-satellite test (ASAT) against its defunct Fengyun-1C weather satellite, which instantly created 4,500 pieces of space debris, some 3,000 of which remain in orbit. There is disagreement about why China might have done this, and who authorized it, given that it was a self-inflicted harm, since 65 percent of China’s 107 functioning satellites reside in LEO.

In his memoir, former Secretary of Defense Robert Gates wrote about the test: “We would later conclude that this action had been taken by the People’s Liberation Army (PLA) without the knowledge of the civilian leadership in Beijing.” Meanwhile, Gregory Kulacki and Foreign Policy contributor Jeffrey Lewis had earlier determined: “Multiple sources confirm these (PLA) managers did not make the decision to test by themselves. The decision was carefully vetted. … An internal report laying out the pros and cons worked its way up the bureaucracy for review and comment before finally being put before the ultimate decision makers.”

The lack of transparency into who authorized the test, and whether they knew that it would create such debris, raises the troubling prospect of what might precipitate similar space events conducted by China.

When U.S. intelligence agencies picked up evidence of the 2007 test and notified the Bush administration, the White House considered asking China to refrain, but ultimately chose to do nothing, fully expecting that the intercept attempt would fail — as previous tests had in 2005 and 2006. According the diplomatic cables leaked by Wikileaks, soon after the debris-causing 2007 test, Chinese officials assured their American counterparts that they would conduct no additional ASAT tests. China, however, did conduct similar intercept tests in 2010 and 2013, under the guise of hit-to-kill mid-course missile defense tests.

More ominously, former Air Force officer and space expert Brian Weeden determined that, in May 2013, China tested the rocket component of a new direct ascent ASAT weapons system derived from a road-mobile ballistic missile — representing a significant development in China’s capabilities.

The reason that U.S. officials are particularly worried about the methodical and incremental escalation of China’s potentially debris-creating ASAT capabilities is that it bears similarities to the timeline of U.S. and Soviet ASAT weapons testing that dates back to the 1960s. Indeed, this makes it difficult for Washington to tell Beijing to refrain from an activity that it conducted extensively in the past, particularly given the immense secrecy that shrouds U.S. military space activities. However, should China — or other space-faring countries, such as North Korea, Iran, or India — conduct one or more mass-debris creating ASAT tests, certain high-demand portions of LEO could be nearly uninhabitable.


One of those activities is well known, and serves to mitigate the global commons challenge of space debris. The U.S. Strategic Command’s Joint Space Operations Center (JSpOC), which tracks space objects over 10 centimeters, has formal agreements with 41 commercial space operators and five countries (France, Italy, Japan, Australia and Canada) to provide conjunction assessment notifications when it is predicted that one of their space systems could collide with existing debris.

JSpOC also has a little-known informal mechanism, via the State Department, by which Russia and China are provided conjunction notifications. China, for example, has been warned hundreds of times in advance of when its satellites are predicted to collide with other satellites or space debris, including the orbiting junk created by its own ASAT test in 2007.

JSpOC provides over 10,000 such warnings of potential collisions each year, at no charge. In an April House hearing, Rep. Jim Cooper, D-Tenn., asked the interesting question of: “Is it appropriate — possible to even charge for those calls on a subscription basis, because that’s an incredibly valuable service we’re offering to the world for free?” Putting tight Pentagon budgets aside, Lt. Gen. John Raymond answered: “It’s in our best interest as well for a safe, secure operating environment, and we do that for the world and for ourselves at the same time.”

The bad news is that while JSpOC can predict, with good accuracy, when softball-sized debris will collide with something else, there remains no practical or cost-effective way to remove debris from orbit. Under the current space regime as defined by the Outer Space Treaty of 1967, “States shall be responsible for their national activities in outer space, whether carried on by governmental or non-governmental entities.”

Launching states own and are liable for whatever they place in space. While outer space is a domain open to all countries, no country or international institution possesses the sovereign authority or responsibility for regulating space. Therefore, any efforts to remove space debris must be agreed upon by the international community.

The United States can take steps to prevent and mitigate the consequences of debris-causing incidents in space. In fact, the United States has a unique obligation to do so as it relies heavily on space and has unmatched space situational awareness. Specifically, the Obama administration should upgrade the JSpOC space fence or radars and sensors to better predict debris collisions, expand the scope and number of data-sharing agreements with countries and commercial space operators, test and develop space debris removal techniques through collaboration with other spacefaring nations, and work with Congress to repeal the 2011 provision that prevents Chinese officials or experts from visiting NASA’s facilities in order to allow for bilateral civilian cooperation on space.

To better ensure Washington’s continued access to space as China, North Korea, Iran and others, advance their capabilities, the United States must intensify its efforts to prevent dangerous incidents, or else forsake its role in shaping rules of the road for space.

Micah Zenko is a fellow with the Center for Preventive Action at the Council on Foreign Relations. He wrote this column for Foreign Policy magazine.

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.