Does space need air traffic control?

As more countries race to launch satellites and manned craft, some warn of a space jam.

from the March 14, 2008 edition

Page 2 of 2

Page 1 | 2

Meanwhile, the risks to orbital regions are growing. Experts cite China's antisatellite test last year as one example. The target, a one-ton weather satellite, circled Earth in a region where other weather, remote-sensing, and spy satellites commonly roam. Its destruction generated an estimated 900 pieces of debris that will remain in orbit for up to a century.

By some estimates, it would take only 10 to 12 such "tests" to render the region useless to everybody. Remaining debris from the satellite the US Navy shot down late last month, by contrast, will be gone in a matter of months since the Navy's missile hit it at a lower altitude.

One challenge to setting up a more effective system is agreeing on a definition of where traditional air space, with its national sovereignty, leaves off, and outer space, a global commons, begins. By tradition, the boundary is 100 kilometers up, or some 62 miles. But there is no legal or scientific definition to support that, analysts say. Most spacefaring nations buy into this working definition. But in 1976 a handful of countries that lie along the equator signed the Bogota Declaration, which asserts that their "airspace" – hence their sovereignty – reaches all the way up to the geosynchronous-orbit slots some 22,300 miles directly over their countries.

A system to avoid collisions

Sorting through this and other issues including national security will be challenging, acknowledges Theresa Hitchens, director of the Center for Defense Information in Washington. She says a new aerospace traffic-management scheme should include mandatory notification and consultation when a satellite operator – government or private – plans maneuvers. In addition, countries need to establish an international database on satellite and debris orbits. Currently, the US Air Force has an exhaustive database, but getting information from the Air Force can be slow and its budget for data-sharing waxes and wanes. Countries should also be required to send out a global notice when they plan to place their satellites into graveyard orbits or allow them to reenter Earth's atmosphere and burn up, she adds.

"The real crucial thing is some system for collision avoidance and a process to ensure that people don't run into each other," she says. It may look like space leaves plenty of room to maneuver, but objects are moving so fast that once they swing into sight, it's too late.

To be sure, some efforts at sharing data and coordinating activities are appearing now, although on an ad-hoc basis. Ms. Hitchens notes that when China sent up its Taikonauts, for instance, the US Air Force shared its orbital-debris data with the Chinese.

Tentative cooperation

Moreover, with this shuttle mission and the arrival of Japan's space-station hardware – as well as the launch of Europe's first automated cargo ship – six control centers in five countries are linked for the first time to coordinate activities around the space station. In the private sector, several of the world's major commercial satellite operators, including companies such as Inmarsat, Intelsat, Loral, and Eutelsat, reportedly have been working over the past 18 months to develop ways their operators can exchange data on orbits and maneuvers without exposing trade secrets.

Such approaches may serve as valuable proving grounds for more effective aerospace traffic-management techniques. "The technical issues are not difficult," says Baseley-Walker. "The key issues are political."

1 | Page 2