Astronomers with the Pale Red Dot Project have announced the discovery of an Earth-like planet orbiting Proxima Centauri, the star closest to Earth. The newfound planet, currently called "Proxima b", has the fortune of being 1.3 times the mass of the Earth, and orbits within the star’s Goldilocks Zone, meaning that it is just the right size and temperature to host liquid water, one of the requirements for life as we know it.
A red dwarf star that orbits the slightly further away stellar pairing of Alpha Centauri A and B, Proxima Centauri is so-named because it is, at the relatively short distance of 4.25 light-years away, the closest star to Earth (aside from the Sun, of course). This puts this planet within reach of a number of research programs, including being directly photographed by the James Webb Space Telescope, due to be launched in 2018.
Otherwise, there is still a great deal that we don’t know about Proxima b, as its existence has only been confirmed indirectly, through a minute wobble it causes in its star’s rotation. Further study of the planet will reveal more information, such as whether or not it has an atmosphere, what that atmosphere is composed of, potential weather patterns, and the length of its day, just to scratch the surface.
Proxima b’s proximity also makes it a prime candidate as a destination for the Project Starshot program, a space exploration initiative started by Russian billionaire Yuri Milner, with the aim of sending miniature,laser-propelled probes to neighboring star systems at 20 percent of the speed of light. At that speed, a space probe could reach Proxima Centauri in a little over 20 years, allowing researchers remote access to another solar system within our lifetime.
A quicker alternative to reaching Proxima b might lie in an abandoned spaceflight concept called "Project Orion": started in 1958, research was conducted into the development of an interstellar spacecraft that would be powered by a series of small nuclear bombs detonated behind the craft. The ship itself would be protected by a "pusher-plate" that would absorb the energy of the detonations, propelling the craft forward at an acceleration of 1 gravity — aside from making the craft substantially faster than conventional rockets, this would also provide any astronauts onboard with a source of artificial gravity to work in.
This project was cancelled after the Partial Test Ban Treaty of 1963, effectively banning above-ground nuclear testing, meaning that testing the technology for Orion’s engines would be illegal. The concept of such a nuclear-propelled craft was revisited in the mid-70s by the British Interplanetary Society in Project Daedalus, upgrading the craft’s concept to use nuclear fusion (Orion only envisioned fission reactions being used), and adding a magnetic ramscoop to gather hydrogen fuel for the engine.
Using a propulsion method such as this, Proxima Centuari could potentially be reached by a spacecraft in a little over half a decade: at one g of acceleration (9.8 m/s2), it would take the craft only 354 days to reach the speed of light; the craft then travels at (or very near) light speed for 3.25 years, then decelerates for a year at one g, to slow down so that it doesn’t whiz past its target.
Interestingly, while everyone on Earth would have to wait roughly five and a quarter years for the craft to make the trip, relativistic effects on the ship would make the trip appear to only be about two years long to any astronauts on board: as they approach light speed, time on the ship would still appear to be normal, but the distance to their destination would appear to shrink until they hit the speed of light, where that distance would suddenly be zero.
And all of this with 1950s technology.
Essentially, this effect would also mean that any point in the universe is roughly 2 years away for potential relativistic astronauts — albeit with the stipulation that the full travel time would sill be observed for those of us left behind…
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