EX-Fusion to employ powerful nuclear fusion laser to perform unprecedented task
KAZUKI YOSHIKAWA, Nikkei staff writer
January 14, 2024 23:17 JST
TOKYO – Osaka-based startup EX-Fusion is attempting to accomplish what once seemed impossible – taking out minuscule pieces of space junk with laser beams fired from the ground.
Space debris originates from old satellites and rocket bodies. Smaller fragments materialize when these objects collide in orbit at high speeds, with debris as small as a few millimeters known to have caused problems when they strike spaceships and functioning satellites.
The U.S. military identifies and tracks space junk measuring 10 centimeters or more in size. But with the spread of space-related activities across the globe, there is a growing need to track and remove smaller pieces.
Some are tackling the problem using satellites.
Tokyo startup Astroscale Holdings plans to offer a service that removes relatively large space debris with a dedicated satellite.
Elsewhere in Japan, Sky Perfect JSAT is teaming up with the state-backed research institute Riken plus other partners to develop a satellite-mounted laser that will redirect debris into the Earth’s atmosphere where it will burn up.
EX-Fusion stands apart in that it is taking the ground-based approach, with the startup tapping its arsenal of laser technology originally developed in pursuit of fusion power.
In October, EX-Fusion signed a memorandum of understanding with EOS Space Systems, an Australian contractor that possesses technology used to detect space debris.
EX-Fusion plans to place a high-powered laser inside an observatory operated by EOS Space outside of Canberra. The first phase will be to set up laser technology to track debris measuring less than 10 cm. Pieces of this size have typically been difficult to target from the ground using lasers.
For the second phase, EX-Fusion and EOS Space will attempt to remove the space debris by boosting the power of the laser beams fired from the surface. The idea is to fire the laser intermittently against the debris from the opposing direction of its travel in order to slow it down. With a decreased orbiting speed, the debris will enter the Earth’s atmosphere to burn up.
High-powered lasers are often associated with weapons that blast objects into smithereens. Indeed, the EOS Space group supplies laser weapon systems used to destroy drones.
But lasers designed to remove space debris are completely different from weapon-grade lasers, EOS Space’s executive vice president James Bennett said during a visit to Japan in November.
Current laser weaponry often uses fiber lasers, which are capable of cutting and welding metal and can destroy targets like drones through heat created from continuous firing.
Capturing and removing space junk instead involves diode-pumped solid-state (DPSS) lasers, which are pulsed to apply force to fast-moving debris, stopping it like a brake.
EX-Fusion’s signature laser fusion process also involves DPSS lasers, which strike the surface of a hydrogen fuel pellet just millimeters in diameter, compressing it to trigger a fusion reaction.
“The power of a laser for destroying space junk is an order of magnitude lower than for nuclear fusion, but they share technical challenges such as controlling them via special mirrors,” EX-Fusion CEO Kazuki Matsuo said.
This makes space debris removal a useful test along the path to commercializing the fusion technology.
EX-Fusion’s plan to shoot down space junk from the ground faces development hurdles relating to precision and power. But it has the advantage of allowing for improvements and maintenance to be easily handled on Earth.
The technology could find use in parallel with services for removing larger chunks of debris, handled by companies like Astroscale.