Can China's space-junk zapping lasers be weaponised to target US satellites?

China wants to use large lasers to shoot down space junk and clear out debris that is potentially dangerous for future satellites. The proposal by engineers from China's Air Force Engineering University made the rounds earlier this week.

While the idea seems a bit fanciful, it is one that could possibly work. In fact, Nasa has been considering the possibility of using a similar method since 1996. However, setting up lasers in the brink of space might come with its own set of problems.

The 2017 US-China Economic and Security Review Commission has warned that China is interested in shooting down American satellites from orbit, according to a report in Popular Mechanics (PM).

The review reportedly pointed out that there are several ways in which this can be accomplished, like by using a suicide satellite to bump into an active one; using electrical jammers, lights, and other ground based interferences; or even by shooting lasers from the ground. China is reported to be working on all of them and more options.

"China has pursued a robust and comprehensive array of counterspace weapons," the report reads. "Including ground-launched anti-satellite (ASAT) missiles, ground-based directed energy weapons, ground-based satellite jammers, computer network operations, and co-orbital ASAT systems."

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The co-orbital ASAT systems is one way to say that the Chinese are working on a satellite with a weapon to shoot down other satellites. This weapon could be a laser, notes PM.

On how the laser would work, the report mentions that the idea of cleaning up space debris is not to blow it up. Lasers cannot really blow anything up in space, and even if it can, blowing up debris in space is a bad idea as it will lead to the formation of smaller and harder to track scattered particles. Invisible particles such as these are extremely difficult to identify and get rid of.

The idea is to heat up one side or corner of the floating debris to an extent that some material gets ejected into space. The heated edge and the force of the ejection will then nudge the junk into Earth, burning it up on re-entry.

China has lasers that can track debris from Earth, but are too weak and operate at up to 40 watts of power. "Although the energy that its lasers emit is currently very low, scaling the power up would not present a difficult technical challenge, and each station might have that capability even now," the report adds.

If the upscaled lasers are pointed at satellites long enough, they can easily fry their circuitry, rendering them useless, especially geosynchronous ones.

While such tactics are possible to carry out from Earth, there is no telling how dangerous such weapons can be in space, right next to important satellites.