Reaching the stars, or reducing our travel time to Mars and other planets, will require a method of travel that can approach relativistic speeds. Currently, missions launched during the most optimal launch windows, which occur every two years, take several months to reach the Red Planet. However, NASA researchers are working on a new laser technology that could send spacecraft to Mars in just three days.
The theoretical “photonic propulsion” system relies on the momentum of photons — particles of light — to move forward. Instead of using photons from the Sun’s rays, NASA scientist Philip Lubin’s design uses a push from giant Earth-based lasers to push spacecraft to incredible speeds. Although they have no mass, light particles have energy and momentum; when they are reflected off an object, their momentum creates a small push. Therefore, by using a large, reflective sail, it should be possible to generate enough momentum to gradually accelerate a spacecraft.
The proposed system isn’t designed to send humans across interstellar distances. Lubin, a professor at the University of California Santa Barbara, instead proposes wafer-thin spacecraft that can get close to the speed of light.
“There are recent advances that take this from science fiction to science reality. There is no known reason why we cannot do this,” Lubin says. His calculations predict that photonic propulsion could get a “100-kiolgram robotic craft to Mars in three days” at 30 percent the speed of light. A larger craft designed to carry passengers would take about a month to get there, which is still one-fifth of the time it would take NASA’s Space Launch System (SLS) — “the world’s most powerful rocket” currently in production — to carry astronauts “into deep space” in 2018.
“Electromagnetic acceleration is only limited by the speed of light, while chemical systems are limited to the energy of chemical processes,” Lubin explains. As an added benefit, since very little fuel would be required on the craft itself, weight and cost would be kept to a minimum.
Over long distances, where the spacecraft has more time to speed up, photonic propulsion could eventually take us outside the Solar System to neighboring star systems.
“It is time to begin this inevitable journey beyond our home,” Lubin says in his paper “A Roadmap to Interstellar Flight,” submitted to the Journal of the British Interplanetary Society in April 2015.
- NASA 360 video (2:06 min) developed from a live recording at the 2015 NASA Innovative Advanced Concepts (NIAC) Fall Symposium in October, 2015
- Directed Propulsion for Interstellar Exploration complete 24-minute video
- A Roadmap to Interstellar Flight, Philip Lubin, UC Santa Barbara Physics Department, submitted to JBIS April 2015
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