This question links to an article describing a ground-based laser designed for shooting down orbiting space debris:
"The scientists intend to use the massive soon-to-be-built telescope at the Altay Optical-Laser Center and convert it into a laser cannon," a source from Roscosmos told Sputnik News.
On June 11, researchers at the Scientific and Industrial Corporation "Precision Instrument Systems" (NPK SPP), a group within the Russian space agency Roscosmos, announced the creation of a laser cannon that will shoot down space debris that is currently orbiting the Earth.
How is this supposed to work? Would shooting things in orbit not simply break them into smaller (less easily trackable) things which are still in orbit?
The article claims the space junk will just be vaporized:
The cannon will follow a process known as "laser ablation" to shoot down space debris. Energy from the cannon will heat space junk with a beam, which will then vaporize it. As a result, the space junk will evaporate.
emphasis mine
But surely that will just create lots more < 1cm particles to worry about?
@Chris Stratton mentions the Wikipedia article on laser brooms in the comments, which describes a different mechanism for space junk removal:
The ablating material imparts a small thrust that lowers its orbital perigee into the upper atmosphere, thereby increasing drag so that its remaining orbital life is short.
and
Other funded research into this area refutes NASA's claim and demonstrates the precise physics involved, which shows that space debris is re-entered regardless of the direction of laser illumination.
But I'm still not sure I'm convinced. I think I get how pushing an object "up" would cause the other side of its orbit to lower, but if the object were tumbling (or was induced into a tumble due to being shot with a laser), wouldn't the direction of the ablative thrust end up going off in random directions? Also, how small must the bits of ablated matter providing the thrust be to avoid becoming a problem themselves?