Laser-propelled spacecraft to reach Mars in 3 days?

NASA researchers are working on a technology that could harness the power of light and may be the key to cutting down travel time to Mars from months to as little as three days.
Philip Lubin, from the University of California, Santa Barbara, is developing the 'photonic propulsion' system where lasers can propel spacecraft with giant sails to the Red Planet.
The system relies on the momentum of photons - particles of light - to move forward. However, instead of photons from the Sun's rays, Lubin's design would be given a push by giant Earth-based lasers.
In a video for NASA 360, Lubin explained that the technology is very much readily available, and that the system could easily be scaled up.

With our current technology, it is estimated it will take humans around five months to reach Mars, 'ScienceAlert' reported.
"There are recent advances that take this from science fiction to science reality," said Lubin.

"There is no known reason why we can not do this," he said.
When a spacecraft is launched, the thrust comes from burning a chemical, such as rocket fuel. This fuel weighs down the spacecraft.
It is an inefficient system when compared to using 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 wrote in a report describing the technology.

However, electromagnetic acceleration requires complicated and expensive equipment that is not easy to scale up to the size required for space travel.
Despite not having any mass, photons have both energy and momentum, and when they reflect off an object, that momentum is transferred into a little push.
With a large, reflective sail, it is possible to generate enough momentum to gradually accelerate a spacecraft, researchers said.
While the researchers have not yet tried out their system, their calculations show that photonic propulsion could get a 100-kg robotic craft to Mars in just three days.
The system is not designed to send humans across interstellar distances. Instead, Lubin proposes wafer-thin spacecraft that can get close to the speed of light.