We’ve achieved space exploration on an unimaginable scale compared to 100 years ago. But despite these advances, one thing is clear that a major setback going forward is the slowness of our space craft. Although we can accelerate particles to near the speed of light in a laboratory setting, our fastest vessels can barely get to 3% of that. Just getting to Mars would take nearly 5 months. Additionally, decelerating and landing is also a challenge.
NASA scientist Philip Lubin has proposed a possible answer in this video for NASA 360. He describes a system called ‘photonic propulsion’ that could get us to Mars in only three days. The design is more or less a giant Earth or near Earth based laser designed to push a spacecraft to incredible speeds.
Photonic propulsion, as it is properly known, is a theoretical system that would use particles of light to propel objects through space. Though particles of light have no mass, they do have energy and momentum — and it’s this energy that, when reflected off an object, is transferred into a push. With a large, reflective sail, Lubin suggests, it would be “possible to generate enough momentum to accelerate a spacecraft” via lasers pulsing light from the surface of the Earth.
This could, he says, get a “100 kilogram robotic craft to Mars in three days”. A craft occupied by humans would take slightly longer — but at a month, it would still be significantly shorter than current transit estimates
The added benefit is that very little fuel would be required on board the craft itself — keeping weight, and cost, to a minimum
If this sounds familiar you may recall Bill Nye’s much ballyhooed solar sail, that uses the power of Solar rays. Nye’s ‘photonic propulsion’ system also relies on the momentum of photons. It may sound a bit mind stretching, but the video on the next page describes how this can be achieved.
Current rocket technology generates thrust from burning a chemicals used as fuel source. In addition to adding great weight, it’s also incredibly inefficient when compared to electromagnetic acceleration, which employs light or other electromagnetic radiation to accelerate objects.
“Electromagnetic acceleration is only limited by the speed of light while chemical systems are limited to the energy of chemical processes,” Lubin mentions in a paper on the technology. But it hasn’t been scaled up to the size needed for space travel.
While Lubin and his team haven’t yet tried out their system, their calculations show that photonic propulsion could get a 100-kg robotic craft to Mars in just three days.
A larger craft, like the kind humans might travel in, would take around a month to get there – one-fifth of the time it would take the Space Launch System (SLS), the world’s most powerful rocket currently being developed to take us to Mars.
Lubin also explains that in the 10 minutes it will take to get the SLS into orbit, photonic propulsion could propel a spacecraft to an unheard-of 30 percent the speed of light – and it would also use a similar amount of chemical energy (50 to 100 gigawatts) to do so.
But the real benefit of photonic propulsion comes over longer distances, where the spacecraft has more time to speed up, and could eventually take us outside our Solar System and to neighbouring stars.
Source: Science Alert
But it doesn’t solve the problem of human interstellar travel. Lubin notes that the system works best on unmanned “wafer thin” spaceships, saying robots are better suited to explore deep space. It may be the most efficient way to scout out nearby solar systems for potentially habitable exoplanets.
Lubin has received a proof-of-concept grant from NASA showing that photonic propulsion for space travel is viable, so we may start seeing some reports soon. In the meantime, check out the video below by NASA 360 for more info and some nice illustrations of the technology.