It is quite recent news that we might have discovered an exoplanet suitable for life orbiting the closest star to the Sun – exciting, isn’t it? Let’s look at the star, the planet and in how long we can (theoretically) be there and have a look with our own eyes.
The star: Proxima Centauri
A red dwarf, at a distance of 4.22 LY from the Sun and mass about 1/8 of our star, too faint to be seen without lenses. It’s in the same system of Alpha Centauri binary star, but quite remote from it (15,000 ± 700 AU). Its age is about 4.85 Gyr, therefore old enough for life to have developed somewhere in a suitable environment.
The planet: Proxima Centauri B
Otherwise said, the (probably) suitable environment. On August 24, 2016, the European Southern Observatory announced its discovery.
“The first hints of a possible planet were spotted back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning. The Pale Red Dot data, when combined with earlier observations made at ESO observatories and elsewhere, revealed the clear signal of a truly exciting result. […] Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance.“
The planet is at least as massive as Earth and may be several times more massive, but its orbital time is only of 11 days.
The biggest obstacle to life on the planet is the brightness of its host star, says Rory Barnes, which works at the University of Washington-based Virtual Planetary Laboratory. “Proxima Centauri, a red dwarf star, is comparatively dim, but wasn’t always so. Proxima’s brightness evolution has been slow and complicated. Stellar evolution models all predict that for the first one billion years Proxima slowly dimmed to its current brightness, which implies that for about the first quarter of a billion years, planet b’s surface would have been too hot for Earth-like conditions. […] Had modern Earth been in such a situation, “it would have become a Venus-like world, in a runaway greenhouse state that can destroy all of the planet’s primordial water, thus extinguishing any chance for life.” (read the whole story here).
Duration of the interstellar travel: about 70,000 years to cover the 40 trillion kilometres, give or take – at least if we use something like Voyager 1 (speed upwards of 62,000 km/h). If we use something like NASA’s Juno probe (the fastest ship ever) we can reach speeds of about 265,000 km/h . Even at that rate, however, it will take about 17,157 years to reach Proxima B. Can we be faster than that? It has been hinted earlier this year we perhaps could – sending superfast miniature probes on a journey that would take only 20-25 years.
According to the Breakthrough Starshot Initiative, it would be possible equipping these probes (“nanocrafts’) with thin sails, that would be propelled by the energy originated from a powerful Earth-based laser – accelerating the tiny ships up to 1/4 of the speed of light -215.85 million km/h. (More details on Space.com).
Amazing, indeed. One of the main problems, however, is the staggering costs – building the full-scale apparatus will be as expensive as the Large Hadron Collider. I hope they have in mind a convincing Kickstarter campaign.