Getting to Mars in three days isn't rocket science--it's laser science.
A recent research paper from University of Santa Barbara professor Philip Lubin outlines how laser propulsion could help send spacecraft at speeds that would leave the fastest rockets in the world in the dust. NASA is so interested in the technology that its Innovative Advanced Concepts program gave Lubin one of its 15 grants last year for "visionary" projects, Christian Science Monitor reports. If the technology proves feasable, it's possible that private space companies like Richard Branson's Virgin Galactic, Jeff Bezos' Blue Origin, and Elon Musk's SpaceX may even help commercialize laser propulsion
Here's how it works (in plain English): NASA would launch a conventional rocket carrying a spacecraft that, once in orbit, would open a large reflective sail. By shooting lasers from Earth onto the sail, the spacecraft could be "pushed" through the zero-friction environment of space at speeds approaching one-third the speed of light. A 220 lb. probe could get to Mars in roughly 72 hours, while a heavier spaceship carrying astronauts could make the trip in around a month, according to Lubin's research. This compares to the current technology that can send a small spacecraft to Mars in about five months.
The main reason humans are proposing alternatives to rocket-powered space travel is that with existing propulsion technology it would take 10 millennium to reach even the closest stars, Lubin writes. "We have to radically rethink our strategy or give up our dreams of reaching the stars, or wait for technology that does not exist," he states in the paper.
Lubin's project, called Directed Propulsion for Interstellar Exploration, or DEEP IN, would likely take "decades" to develop before it's ready for space travel, Popular Mechanics reports. Among the challenges facing laser-propulsion space travel are avoiding crashes with debris in space, and slowing the vessel down after reaching speeds of roughly 2 million miles per hour. Despite the challenges, Lubin writes that scientists have "no known reason why we cannot do this."
For more on how laser-propulsion works, check out the video from NASA, below.