Debris poses a clear, present and growing danger to space operations. The latest wake-up call to take steps to address this danger was provided by the Feb. 10 collision between a dead Cosmos satellite and a revenue-producing Iridium satellite. This dreaded event may have produced the second worst debris field in the history of the space age. Debris travels at 10 times the speed of a rifle bullet at altitudes where hundreds of satellites used for intelligence gathering, personal communications and Earth observation operate. If a single piece of debris the size of a child’s marble strikes one of these satellites, the international space station or the space shuttle it would strike with the equivalent force of a 1 ton safe dropped from a five-story building.

Some debris is inevitably released during every space launch. Extremely large spikes in space debris have been caused by space weapon tests designed to kill satellites on impact. In 1985, the administration of then U.S. President Ronald Reagan carried out a destructive anti-satellite weapon test, turning an aging weather satellite into 300 pieces of trackable debris. One lethal debris fragment from this test came within a mile of the newly launched international space station – 14 years later. It took 19 years for the debris caused by this test to burn out of the Earth’s atmosphere. After this experience, the Pentagon lost enthusiasm for debris-producing anti-satellite weapon tests.

By far, the worst man-made debris field in the history of the space age was caused by the 2007 Chinese anti-satellite test, which produced approximately 2,000 trackable pieces of lethal debris. Because the Chinese test was carried out at more than twice the altitude of the 1985 U.S. test, its debris field will pose a space hazard for a century or more. Even tiny pieces of debris can be worrisome because they can’t be tracked and because they can penetrate the thin outer skin of vulnerable satellites. The Chinese test is estimated to have produced approximately 40,000 debris fragments or larger. The windows on the space shuttle have needed to be changed more than 70 times because of tiny debris hits.

We depend on satellites for personal, national and economic security. Without them, police, fire fighters and first responders would be hampered in reaching their destinations; troops in harm’s way would be less able to defend themselves; and intelligence gathering would be seriously constrained. No nation benefits more from space or has more to lose if space becomes a shooting gallery than the United States. What, then, is the most appropriate strategy to ensure that essential satellites will be available when needed? There is no simple or complete solution to the satellite vulnerability problem. We can, however, take several steps to reduce the likelihood that satellites will be attacked.

Because so many existing weapons can be adapted for use as anti-satellite weapons, deterrence helps explain why no satellites have been attacked thus far in crises or warfare. But deterrence based on mutual vulnerability is, at best, an incomplete remedy. Protecting satellites against some man- made and natural hazards can be marginally improved when projected benefits exceed costs. In addition, the can choose to deploy larger numbers of less capable satellites, rather than investing in a small number of hugely expensive ones. Wise, diversified investments in space can make surprise attacks against satellites – a “space

Maintaining the world’s strongest military also helps dissuade other countries from attacking satellites.

Diplomacy can also play a useful role in improving the survivability of life-saving satellites. Since space debris poses a greatly increased hazard to satellite operations, and since destructive anti- satellite tests are a major contributor to space debris, a formal agreement that bans the testing and use of destructive methods against space objects would be a welcome step. A sharply focused, verifiable treaty banning a clear and present danger would be far better than the unverifiable treaty now advocated by and , which is focused on preventing the deployment of weapons in space. Pending the conclusion of negotiations banning the testing and use of destructive methods against space objects, responsible spacefaring nations should pledge not to conduct destructive anti-satellite tests.

Another approach we endorse is a Code of Conduct that sets norms of responsible behavior and proscribes irresponsible acts, such as debris-causing anti-satellite tests. Either way, if seeks to rule out destructive tests in space, there are no guarantees of good behavior by others. Therefore, restraint should be accompanied by a hedging strategy to encourage similar restraint by others.

The personal security of citizens, as well as their economic and national security, requires that essential satellites be available whenever needed. Foreign governments have similar requirements. The challenge facing spacefaring nations is how to align space diplomacy with these common interests, despite mistrust over motives and the capabilities major powers possess to damage satellites. A sharply focused ban on further destructive tests of anti-satellite weapons and a Code of Conduct could serve the interests of all countries that rely on space.

Ashley Tellis is a senior associate at the Carnegie Endowment; Michael Krepon is co- founder of the Stimson Center and author of “Better Safe than Sorry, The Ironies of Living with the Bomb” (2009).