A focused beam of particles and photons could propel us to Proxima Centauri

Getting to Proxima Centauri b will require a lot of new technology, but there are increasingly exciting reasons to do so. Public and private efforts are beginning to seriously look for ways to make it happen, but until now, there has been one significant roadblock to the journey – pushback.

To solve this problem, Christopher Limbach, now a professor at the University of Michigan, is working on a new type of beam propulsion that uses both a particle beam and a laser to overcome that technology’s biggest weakness.

Let’s first look at why conventional propulsion systems wouldn’t work to get a spacecraft to Proxima b. Conventional rockets are out of the question, as their fuel is too heavy and burns too quickly to get a probe close to the speed it would need to reach Proxima b. Conventional solar sails also fail because once they are far enough from the sun, only minimal thrust is given to them.

Other non-conventional solutions may work, such as nuclear propulsion or ion drives. However, they fall victim to the tyranny of the rocket equation – since they have to carry their own fuel, they have to carry more mass to go faster, thus eliminating much of this benefit.

This leaves beam thrust – essentially creating a giant beam in space that continues to push a spacecraft with a manifold on it, which can continue to push the entire time the spacecraft is on its way to its destination. her. Typically, there are two types of beams used in these systems – particle beams and light beams. However, each has a weakness – diffraction.

Both light and particle beams tend to spread over long distances, making them much less effective at focusing on a single small object that may be light years away. Even lasers, if allowed to be pointed too far, eventually dissipate into unusable light. However, there is a way around this.

Recently, optics research has developed a way to combine particle and laser beams that eliminates all diffraction and beam spreading when both are used simultaneously. This would allow a beam thruster system to continue focusing its beam in exactly the right place without slowly losing its thrust as the probe moves further away.

Dr. Limbach used this fundamental technology to develop what he calls PROCSIMA, a new propulsion method that used a combined coherent particle motion system and laser beam.

Calculations by Dr. Limbach and his associate, Dr. Ken Hara, now a professor at Stanford, show that it is possible to make a coherent beam that can effectively extend to Proxima b while diffracting only to about 10 m, at least in theory.

According to their calculations, a 5g probe like the one the Breakthrough Initiatives project is working on could be pushed up to 10% of the speed of light, allowing it to reach Proxima b in 43 years.

Alternatively, they also calculated that a much larger probe of about 1 kg could reach the system in about 57 years. This would allow for a much more exciting payload, even if the probe zoomed through the Proxima Centauri system at a significant fraction of the speed of light.

There is still some work to be done, including developing things like cold atom particle sources and improving the functionality of the beam systems.

However, so far, the project has not been supported by another grant, although Dr. Limbach at UM continues to work on similar ideas, such as a nanoNewton propulsion system. Development continues on a star-shooting method to eventually get a probe to another star, and it looks like, for better or worse, beam propulsion is how we’ll get there.