Summary : The problem of orbiting space debris was dramatised in the Oscar-winning film Gravity. Photograph: Sportsphoto Ltd/Allstar/Universal Pictures
Space debris, as a pressing problem for humanity, has had its moment. For an hour-and-a-half it threatened to kill Sandra Bullock in Gravity, a movie that won enough statuettes to clutter low Earth orbit. Now people working on the real-life problem of space debris would like to extend the public attention created by the movie.
Space experts testifying on Friday at a US House of Representatives hearing entitled “Space Traffic Management: How to Prevent a Real Life Gravity” warned that space activities – including both human travel and the dependable operation of satellites – will become increasingly dangerous if new rules are not put in place to control debris.
Foremost on the panel’s agenda was a request by the Federal Aviation Administration for additional authority over commercial satellite operators, including the authority to order evasive action to avoid collisions. No US agency currently holds such authority, and it is unclear what agency could hold an authority that would apply worldwide.
The witnesses described space as a frazzled frontier, in which more than 60 countries, dozens of companies and “a multitude” of educational and nonprofit organisations are now operating satellites – with zero universal oversight.
“As the barriers to access space are lowered, the number of actors is expected to increase, and our ability to carry out our missions will become progressively more difficult,” said Lieutenant General John W Raymond, commander of the Pentagon’s joint functional component command for space.
Two events in the last decade (not counting Gravity) have driven calls for new controls on space junk. In 2007, China shot one of its own weather satellites out of orbit in an explosion that created thousands of pieces of debris. Two years later, in what is known as the Iridium-Kosmos collision, a private US satellite collided with a defunct Russian satellite, notwithstanding calculations that the two would miss. The result was the biggest single creation of space debris ever, generating an estimated 2,000 of the 23,000 tracked objects in orbit.
“The 2009 Iridium-Kosmos collision was a watershed event,” said George Zamka, a former astronaut and an administrator with the FAA, which currently has authority only over space launches and atmospheric re-entry. “The accident brought to light that more work needs to be done to ensure the safe separation of space objects.”
The duty of tracking space debris and warning of potential collisions currently falls to the defence department, which maintains 21 sensors globally, catalogues all debris and publishes partial information on the website space-track.org. The Pentagon supplies additional debris-tracking information through a subscription service to 41 companies and five countries, Raymond said.
“Several” collision avoidance manoeuvres involving debris with the space shuttle and the International Space Station have been conducted during the past 10 years, according to Nasa. But the Pentagon cannot order a private US company, such as Iridium, or a foreign company to take the expensive step of changing the orbit of a satellite. And neither, for now, can the FAA. No practical technology has been developed to dispose of the debris.
Zamka, the FAA administrator, acknowledged that any decision to order evasive action would be fraught with cost considerations and the inherent difficulty of predicting the probability of collision between two relatively small objects 800km up in the air.
“The request to have the ability to have an operator be forced to move, that can be done in a number of ways,” said Zamka. “Earlier is better, earlier interaction – perhaps agree with the operator as part of the licensing process what the critieria would be for which they’d move. And then probably best of all would be an industry-based consensus on what is the agreeable time to effect a move. Because all of these things involve probabilities, and a lot of expense for the operator, frankly.”
In his testimony, Zamka shared a dramatic personal anecdote illustrating the threat of space debris. “During my two space missions, we flew upside down and backwards to protect our shuttle windows from orbital debris,” he said. “And even then we had debris strikes and cracks in our windows from very small debris strikes.”