When you look at how far we have come in space exploration, interstellar travel is one area that has made the least advances. What’s to blame? In short, our spacecrafts are too slow, even though we can send particles close to the speed of light, our spacecrafts are struggling to get even beyond 3 percent of that.
NASA currently estimates that with current technology it would still take humans close to five months to reach Mars, and that’s on a good day. But don’t despair, a scientist at NASA now believes he can reduce the trip to just three days.
Philip Lubin from the University of California, Santa Barbara and Directed Energy Propulsion for Interstellar Exploration project (DEEP IN) is proposing a system of lasers could propel a spacecraft with giant sails to the Red Planet.
This is similar to Bill Nye’s solar sail. The “photonic propulsion” system uses the momentum of photons — particles of light — to move forward. But instead of photons from the sun’s rays, Lubin’s design would be given a push by giant lasers to gain incredible speeds.
Lubin said at the 2015 NASA Innovative Advanced Concept Fall Symposium in October, 2015:
“There are recent advances that take this from science fiction to science reality, there is no known reason why we cannot do this, except for NASA budget reasons.”
How does it work?
Current rocket propulsion-systems are fuel-based, and because spaceships are heavy, a large volume of fuel is required to move them. So, not only does it weigh down the spacecraft, it’s also an extremely ineffective system when you compare it to electromagnetic acceleration.
Lubin wrote in his paper called “A Roadmap to Interstellar Flight:”
“Electromagnetic acceleration is only limited by the speed of light while chemical systems are limited to the energy of chemical processes.”
However, electromagnetic acceleration in the lab is relatively straightforward, it necessitates a lot of complex and costly equipment. It requires a ring of superconducting magnets that make up the Large Hadron Collider, which hasn’t been easy to scale up to the size that would be required for space travel.
Another contender for a propulsion system is the “impossible” EM Drive, which has received a lot of media attention for supposedly achieving electromagnetic acceleration. However, scientists are still struggling to figure out how it works, or even prove that it wasn’t an experimental anomaly.
Now, photonic propulsion on the other hand has the theory to support it, and works regardless of scale.
Watch NASA 360 as Professor Philip Lubin explains:
How does ‘photonic propulsion’ work?
It is a hypothetical system that uses particles of light to propel objects. Although these particles have no mass, they do, however, have energy and momentum. Lubin suggests that if reflected off an object, this energy and momentum could be transferred into a push.
By using a large reflective sail, Lubin suggests it would be “possible to generate enough momentum to accelerate a spacecraft” by the use of lasers pulsing light from a powerful laser in orbit around earth. The technology that would be needed already exists, Lubin said, although it would be a massive project to build such a device in orbit.
“The mass in orbit [would be] about a hundred times the International Space Station mass,” he said. “So it’s significant, but it’s not, you know, completely crazy.”
However, Lubin and his team have not tried this theory out yet, but they believe that they could get a “100 kilogram robotic craft to Mars in three days.” A spacecraft occupied by humans would take a little longer; current estimates are at a month.
This works out to be approximately one-fifth of the time it would take the Space Launch System (SLS), which is currently in development, and will be the world’s most powerful rocket.
Lubin explains in the video from NASA 360 that during the 10 minutes SLS would take to get into orbit, the “photonic propulsion” system would have to propel a spacecraft to an unheard-of 30 percent the speed of light — and it would use a similar amount of chemical energy (50 to 100 gigawatts) to do so.
This, however, is not the true benefit. The “photonic propulsion” really shines over longer distances. This is where the spacecraft has more time to speed up, and may possibly take us outside our own solar system.
Now, just to make it clear, the system was not designed to send humans across the solar system. The system would work best on unmanned spaceships, Lubin says, adding that robots (AI) are better equipped to explore deep space. To do this Lubin proposes to build wafer-thin spacecraft that would be able to achieve, or get close to, the speed of light.
Now, to be able to send AI through our solar systems so rapidly still has “huge benefits.” If this was to work it may be possible to explore potentially habitable planets outside our solar system.
However, there will be new technical problems to resolve, like communicating with the craft. Our nearest neighbouring star, Alpha Centauri, which is a distance of four light years, would pose significant technical problems.
Lubin wrote in his paper:
“The human factor of exploring the nearest stars and exoplanets would be a profound voyage for humanity, one whose non-scientific implications would be enormous.
“It is time to begin this inevitable journey beyond our home.”