Lasers Could Destroy Space Debris

More than 500,000 pieces of debris, or “space junk,” are tracked as they orbit the Earth (Source: Nasa)

More than 500,000 pieces of debris, or “space junk,” are tracked as they orbit the Earth (Source: Nasa)

Space debris from completed missions like inactive satel­lites, lens covers, fragments from spaceship disen­gagements pose a serious and ongoing threat to active communi­cation and navi­gation satel­lites used by billions of people on Earth.  A new approach whereby debris orbiting in space could be pushed into the Earth’s atmo­sphere by laser impulses, causing it to burn up.

Pieces even smaller than a smart­phone represent danger to our ability to share information and find our way. While the locations of major space debris are known, fragments smaller than 10 centimeters are difficult to cata­logue, and there are 10 times more small pieces than large ones. Because of their remarkably high speeds of up to 15 kilometers per second small pieces of debris pose a serious threat for space flight and the ope­ration of satel­lites such as those involved in communi­cations and navi­gation.

Stefan Scharring, Jascha Wilken, and Hans-Albert Eckel of the German Aero­space Center DLR describe now a new approach in applying laser-induced damage principles where using high-energy laser pulses modify the orbit of debris and push it into the atmo­sphere, causing it to burn up. In the weightlessness of space, the scien­tists note, “a secondary effect of laser-induced damage, which is not immediately apparent in experiments on Earth”. When part of an object is ablated, or removed, using a laser beam, the recoil transfers momentum to the object. The researchers simulate powerful laser oscil­lations to hazardous materials with the goal of modi­fying the debris’ orbit so that it re-enters and is destroyed by the atmo­sphere.

Similar laser-based concepts to remove space debris have been proposed in the past. However, the other studies have targeted simple geometric shapes such as plates, cubes, spheres, and cylinders that are optimally oriented to the laser source. Scharring and col­leagues point out that the drawback of such studies is that they fail to address geo­metrically complex or irregularly shaped objects and do not account for the random orien­tation of those objects in space.

“Our work consti­tutes the tran­sition from labo­ratory expe­riments with idealized flat targets and optimum laser alignment towards simu­lations of the real world scenario with arbi­trarily shaped debris and limited laser pointing accuracy,” said the scien­tists. “Laser damage is usually considered to be a negative pheno­menon, but this approach considers a signi­ficant positive application of laser-induced damage. The damage produced by laser beams serves a highly useful and positive purpose by cleaning up the space around Earth. The group acknow­ledges that the proposed tech­nique of deor­biting debris piece-by-piece using laser pulses is a small building block of the large-scale effort needed to clean up space, but assert that their modeling shows great poten­tial. (Source: SPIE)

Reference: S. Scharring et al.: Laser-based removal of irregularly shaped space debris, Opt. Eng. 56, 011007 (2016); DOI: 10.1117/1.OE.56.1.011007

Link: Inst. of Technical Physics, Studies and Concepts Group, German Aerospace Center (DLR), Stuttgart, Germany

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