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 if 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 tweetfrom 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 had the opportunity to speak 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 George Clooney and Sandra Bullock in Gravity was among the most underappreciated global commons 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.
There are some pertinent facts about space debris that demonstrate the pressing danger. Roughly three-quarters of all space debris -- 23,000 items over 10 centimeters across, 300,000 measuring between 1 and 10 centimeters, and over 135,000,000 fragments less than 1 centimeter -- is presently 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.)