Photonic Propulsion : The Electromagnetic Acceleration

 

 

What is Photonic Propulsion?

There have been all types of buzz lately about some new space tech that would send a spacecraft to Mars in 3 days, and may be even getting spaceships to exo-planets that are light-years away which kind of seems like something out of a fantasy novel. But a group of researchers from the University of California, United States of America is functioning on a new way to travel in space known as Photonic Propulsion also called as Laser Propulsion. Laser propulsion is a form of beam-powered propulsion where the energy source is a remote (usually ground-based) laser system and separate from the reaction mass. This form of propulsion differs from a conventional chemical rocket where both energy and reaction mass come from the solid or liquid propellants carried on board the vehicle. 

Illustration : Laser Propulsion

 

Electromagnetic Acceleration

It might use an enormous set of lasers to push ships along and if it works, it could eventually be wont to explore other star systems but that is a big if. The project is called DEEP-IN, and its goal is to use electromagnetic acceleration to get ships close to the speed of sunshine; fast enough that interstellar travel could actually make sense. These days, our spaceships use chemical acceleration. In other words, they burn fuel and they are fast. They’re just not fast enough to visit other stars in any reasonable amount of your time, which is where electromagnetic acceleration comes in. Instead of using energy to push itself forward, a DEEP-IN spaceship would use the energy from electromagnetic radiation. More specifically the energy from huge set of lasers would be powered by sunlight. That laser array technology may be a whole project all by itself, called the Directed Energy System for Targeting of Asteroids and exploRation, or DE-STAR, and being developed by an equivalent research team. And as you might have noticed from the first part of that acronym, DE-STAR would be a laser system with multiple uses. Like destructive uses.

DE-STAR

DE-STAR is especially being designed to guard Earth both by diverting asteroids that are headed for us, and by vaporizing space debris. This photon-driven propulsion thing is just a bonus, a pretty huge one. It’s supported the thought that light features a lot of pushing power, which comes from its momentum. We might not feel that push from just walking around on Earth, but an enormous reflector screen in space does feel it. That’s the science behind solar sails, and we’ve already built spaceships that use them.

When the photons in light encounter a solar sail, their momentum is transferred and therefore the spacecraft is propelled forward a little bit. DE-STAR’s lasers would offer much light that we could use to require the solar sails concept one step further, and start building spacecraft that use laser sails. We know, solar sails are limited, because the sunshine coming from the sun only comes with so many photons. But this laser sail will have a concentrated beam of photons shooting directly at it. It is like the difference between a sprinkler and a fire hydrant. When it gets hit by that beam, the laser sail and anything that happens to be attached to it like a spaceship is going to start zooming through space.

Asteroid Deflection by Lasers

 

Mars in 3 Days?

A ship that used a laser sail wouldn’t have to carry as much fuel, which would mean that it could have a much lower mass. It could, also, in theory, go very, very fast. With an enormous laser array putting out 50-70 Giga watts of power, a 100 kilogram ship about the size of Voyager 1 could travel at around 1.5% of the speed of light nearly 300 times Voyager’s top speed. But there are still challenges to unravel, when it involves making spaceships powered by giant lasers. We could send a smaller probe to Mars in 3 days, or a larger craft on a trip that would take about a month. But we’d need a giant, square laser array that’s 10 kilometers long on each side – which presents some obvious problems. Getting stuff to space is dear, including 100 square kilometers’ worth of high-powered laser equipment. And albeit we did get everything to the proper spot, it might be incredibly difficult to assemble. Building a laser sail for this super-fast trip to Mars would also be tough. According to the researchers, it would have to be only a micron thick that’s a thousandth of a millimeter. But to figure properly, that whisper-thin laser sail would need to weigh about the maximum amount as the spaceship itself. Means that it might need to be an enormous, thin sail, but strong enough to be stable while the ship is moving ridiculously fast. And we even have no idea the way to slow the spacecraft down once it gets to wherever it’s going. So if we’re talking about sending ships to Mars in 3 days, we’re probably getting ahead of ourselves a little bit here.

Research

Really, the primary step to creating this research a reality is building a way smaller set of lasers. The team’s plan assuming NASA chooses to move forward with their idea is to start with a laser array that’s just one meter square. Then we’d just keep building bigger sets of lasers, until we eventually figured out how to build one that’s 10 kilometers on a side. Then, we could use that to launch what are known as wafer sats. These miniature spacecraft would weigh no quite a gram, but they’d have sensors, a power source, teeny-tiny thrusters, and communications equipment. That giant set of lasers could accelerate these wafer-sats to about 25% of the speed of light, sending them light-years away, where they could tell us all about interstellar space and exoplanets. They might even be able to reach the nearby star system Alpha Centauri only 15 years after they launch. So, there’s still a huge amount of research, technology development, and testing needed before we use lasers to propel any sort of spaceship even a little wafer one. And it’s going to be a very long time before we’re zooming over to Mars in just a few days. But it probably is possible.

 

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