Artist's impression of Alpha Centauri. Credit: ESO/L. Calçada/N. Risinger (skysurvey.org)
It all seems so easy in science fiction. Climb into a starship, pull a lever and the next thing you know, you're halfway across the galaxy and looking at another M-class (habitable) planet. If only real life was as fun and easy as "Star Trek." In reality, however, getting out of the solar system takes a
time. Look at the case of Voyager 1. It took the better part of 35 years for it to get out of the solar system using chemical fuels and some gravity assists from the giant planets.MORE: Is Hawking's Interstellar 'Starshot' Possible?
Philip Lubin, a researcher at the University of California, Santa Barbara's Experimental Cosmology Group, has NASA fundingas well as several papers
published figuring out how to breach the interstellar problem. He also wrote a recent paper outlining aroadmap to interstellar flight
and is a member of the advisory committee for therecently announced "Breakthrough: Starshot" initiative
. While his ideas are being tested out in the lab, he figures he can possibly get a mission out the door in 20 to 30 years that would be a precursor to interstellar flight.
Artist's impression of the ion engines on the Dawn spacecraft. Credit: NASA/JPL
The main ways we propel spacecraft these days are through chemical propulsion (fuel), solar propulsion (the sun), nuclear propulsion (radioactivity) and ion propulsion (using the pressure of charged particles). These are all adequate to get through the solar system, especially in the cases where engineers use gravity assists to get the spacecraft where it needs to go. For example, the aforementioned Voyager 1 spacecraft flew by Jupiter, Uranus, Saturn and Neptune to speed its way out of the sun's heliosphere. Outside the solar system, however? Not possible in a human lifetime.MORE: Hawking Backs Project to Launch Probe to Nearby Star
"If it takes a second to go from here to the nearest star, or a year to get to the nearest star, we're okay with it," Lubin told Discovery News. "If it's 600,000 years, however, it's more for somebody else."
A lab demonstration of the laser spectrometer used in the Mars Curiosity rover. Credit: NASA/JPL-Caltech
In computing, we're used to speed advances being made very quickly, Lubin said. Semiconductor speeds tend to double their capacity in 1.5 to 2 years, for example. While rocketry isn't proceeding quite that fast, Lubin said he has identified a promising technology that could at least move little, wafer-thin spacecraft at reasonably fast speeds. As technology progresses, Lubin said he is confident the spacecraft could go even faster than what we would imagine today.GALLERY: Icarus Interstellar: Visions of Our Starship Future
His vision involves using a directed energy system -- a laser -- to use the force of light to move the spacecraft. The benefits are that it doesn't require fuel (which can be exhausted) or the sun (which is too dim far out in the solar system). The laser pack to move the spacecraft can also be jettisoned when no longer needed; one possibility is it could be parked somewhere in space for other spacecraft to use.
The Cray XE6 supercomputer. Credit: Lawrence Berkeley Nat'l Lab - Roy Kaltschmidt, photographer
Lubin compares his laser idea to a supercomputer. Supercomputers use parallel computer processing from several processors. (On a small scale, we see this in home computers that have, say a dual core or quad core processor). "Instead of one gigantic cylinder, if you will, you have a lot of processors running in parallel, making a faster computer work with a lot of smaller computers," Lubin said. The lasers would work in a similar fashion. Lubin says that several relatively modest lasers could be made to work synchronously, with their beams working in phase with each other. This allows a small push from one laser to become a very big push using several lasers. A tiny spacecraft could thus be propelled to incredible speeds, perhaps going as fast as 20 percent of the speed of light. This makes the nearest star system -- Alpha Centauri, four light years away -- accessible in 20 years. More details are described in this description of hisNASA Innovative Advanced Concepts proposal from 2015.
Kepler-186f, an Earth-sized planet in the habitable zone. Credit: NASA Ames/SETI Institute/JPL-Caltech
While Alpha Centauri is relatively close to Earth, many of the exoplanet systems viewed by the Kepler space telescope are hundreds or thousands of light-years away. It still would be prohibitively long to get to these systems, but Lubin says he isn't giving up hope. Advances in lasers could arrive that we can't even envision today. (A similar example would be how the computer chip revolutionized the speed and size of computers, compared to the old vacuum-tube specimens that took up entire laboratory rooms in the 1960s).MORE: 'Firefly' Starship to Blaze a Trail to Alpha Centauri?
If it is possible to get out to a Kepler-distance planet, Lubin cautions there would be one last limitation: relativity. If it took even a second to get to a Kepler planet that is 2,000 light-years away, and another second to come back, it would arrive at an Earth that had progressed by 2,000 years -- plus two seconds. The civilization that sent it off may not even be around when the spacecraft comes back. Lubin isn't sure how to answer all these sociological questions yet, but says that in the meantime, lasers do offer the potential to move very fast compared to what we have today.