NASA-funded researchers are proposing to clean up Earth’s orbital environment by using a ground-based laser to “nudge the debris off course,” as Nature News reports. The proposal is still very much at the concept stage, but some experts are already expressing concern that such “space broom” systems could double as space weapons.
“Scientists at NASA have considered using a ground-based laser to mitigate debris collisions before. However, in their ‘laser broom’ concept, a powerful, megawatt-class laser would vaporize the surface of a piece of debris that is heading for another, causing the debris to recoil out of harm’s way. But critics argued that the laser could be used as a weapon, as it could easily damage an enemy’s active satellites. Indeed, both the United States and China have in the past 15 years been accused of testing the ability of ground-based lasers to ‘dazzle’ satellites and render them inoperable.
“Now, James Mason, a NASA contractor at the Universities Space Research Association in Moffett Field, California, and his colleagues have come up with a variation on the laser broom concept that they claim is unlikely to be useful as a weapon. In a paper … Mason and colleagues suggest using a medium-powered laser of 5–10 kilowatts to illuminate debris with light a few times more intense than sunlight, imparting just enough momentum to nudge the debris off course. ‘We think this scheme is potentially one of the least-threatening ways to solve a problem that has to be addressed,’ says Mason.”
Space debris experts were quick to point out problems with the concept.
“All the experts in space debris contacted by Nature said that the new proposal is feasible, but still has problems. ‘It’ll be ineffective against dense objects that are too heavy to move, ‘ says William Priedhorsky of Los Alamos National Laboratory in New Mexico. ‘To use a medical analogy, they propose not to cure the disease, but to manage it.’
“And some are concerned that the laser could still be used to push enemy satellites out of orbit. Christophe Bonnal, a debris expert at the French space agency CNES, doesn’t buy the researchers’ claim that the laser’s power would be too low for anti-satellite uses. ‘Let’s be logical,’ he says. ‘If the power is low, you’ll have no effect on the debris.’
But Hugh Lewis, an engineer at the Southampton University, U.K., ‘cautiously’ welcomes the idea. ‘Any method that aims to address the growing debris problem should be taken seriously, I think,’ he says.