Our Closest Earth-like Planet

In an amazing stroke of cosmic luck, our closest Earth-like planet Proxima b turns out to be orbiting our closest star, Proxima Centauri, only 4.2 lightyears away!

The Kepler space telescope has been expanding our knowledge of exoplanets – planets outside the solar system – for years now. The number of confirmed exoplanets from Kepler now exceeds 3000, and the rate at which our knowledge of these planets is increasing is truly amazing. Kepler is able to give us data on planets thousand of lightyears from our own little corner of the universe.

So it came as a surprise, a number of months ago, when the very closest potentially Earth-like, habitable planet, turned out to be so close. Unlike its very bright neighbours, Alpha and Beta Centauri, which can easily be seen with the naked eye, you need special equipment just to see Proxima Centauri!


Photo: space.com

Proxima Centauri is a red dwarf, one of the most common stars in the universe. In a bit of stellar Karma, it turns out that little stars like Proxima have much longer lifetimes that the bigger, brighter white or blue stars, or even our own yellow star, surviving for trillions of years – plenty of time for life to take hold if the conditions are right.

Astronomers have been trying to unlock Proxima Centauri’s secrets for more than 15 years, using two instruments from the European Southern Observatory in Chile – the Ultraviolet and Visual Echelle Spectrograph (UVES) and the High Accuracy Radial velocity Planet Searcher (HARPS). Both instruments focus on deciphering the star’s ‘wobbles’. So why did it take so long? The detection was made more difficult by sparse data, and the long-term variability of the star itself, which masked the presence of the planet. With new, key observations made in 2016, the astronomers were able to confirm not only Proxima b, but also reveal indications of a possible second planet with an orbital period of between 60 and 500 days also orbiting around Proxima Centauri.

Observations indicate Proxima b is around 1.3 times heavier than Earth, putting it into the rocky planet category. Although the planet is in the habitable zone, it orbits at only around 7.5 million kilometres, completing an orbit every 11.2 Earth days. Due to the closeness to its host planet, astronomers consider it likely that the planet is tidally locked, divided into halves of night and day, and always showing the same face to Proxima Centauri. Earth orbits at 150 million kilometres, much further out from our brighter, hotter sun, but still in our habitable zone. The temperature is right on the planet for surface water to exist, but much depends on the planet’s history. If its star was very active, the water may have been blown away in its early formation, whereas if the planet migrated inward at a later stage, it might be water rich.

So Proxima b’s in the habitable zone, which means it may have surface water, but will it have life? On the pessimistic side, it turns out that Proxima Centauri emits powerful flares and X-ray radiation. That may work to erode the atmosphere of the planet, although we don’t know how much because we don’t know if the exoplanet has a nice, strong magnetic field like Earth that would help to preserve the atmosphere and protect any developing life.

We need to go and have a look. But how to get there?

If we could shrink down to about two inches tall, we could hitch a ride on something like NASA’s New Horizon’s probe, which managed its trip to Pluto in around 9.5 years at around 84,000 km/h. That would get us a sneak peek of Proxima b in around 54,400 years. Hmmn. Or maybe the hotshot Juno probe that reached a whopping 265,000 km/h? That would cut the trip to 17,157 years.

One option is to accelerate a small probe with solar sails to relativistic speeds using a high powered laser. Just such a thing has been proposed by the Breakthrough Starshot initiative. For around $18 billion we could build a system that would send wafer-thin probes to Proxima Centauri. The Earth-based laser would accelerate the probes to around 20 percent the speed of light (215.85 million km/h). That would get the tiny probes to Proxima Centauri in 20 to 25 years. What these small probes could tell us will rely very much on how powerful their miniaturized instruments were, and of course scientists being able to conceive a way for a targeted message to reach Earth with the data.

It’s exciting that we have an Earth-like planet so close to our solar system. How we get there is one thing, but if human history tells us anything, once we want to go there – we will find a way.

My novel, The Tau Ceti Diversion, a story about our search for new planets to colonise outside our solar system, and is now available on Amazon! Read more about what happens in the story here!

Check out the free chapter download!

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Going Faster Than Light

Going faster than light is the Holy Grail of space travel, and is often depicted in science fiction. It seems as easy as flicking the switch to jolt the ship into Hyperspace. I mean, it worked for Han Solo, right?

It was Einstein who first postulated the idea that the speed of light is constant in any “frame of reference”. Basically, no matter how fast you were going, light would always be moving away from you at the same speed. As counter-intuitive as this was, his theories of special relativity and general relativity have been borne out by direct observation and experiment.

Just about all of us use GPS data on a daily basis, with signals pinging from our smart phones through our networks to global satellites. The clocks on those GPS satellites all run slower than those on Earth, a direct prediction of relativity, and corrections are used on a routine basis to bring them into line with their “stationary” counterparts. Astronomers also routinely use Einstein’s predicted ‘gravity lensing’ to make observations of the universe, and have used this technique to pin down the enigmatic ‘dark matter’ that makes up so much of our universe.

So if Einstein’s predictions tell us we can’t go faster than the speed of light, is that it for our desire to go speeding through the Universe in our faster-than-light spaceship? Interestingly enough, not necessarily. . .

There are two potential loopholes than emerge from Einstein’s work, and both of them have to do with the way spacetime can fold up. The ‘warp drive’ and the more familiar idea of wormholes.

The warp drive, originally a concept from science fiction, is familiar from just about every episode of Star Trek. The idea for the warp drive is that spacetime would be expanded behind the spaceship, and compressed in front of it, to such a degree that the ship would seem to flash through vast distances in moments. The ship itself would not actually be moving, but be inside a ‘warp bubble’. This is a pretty exotic solution of Einstein’s equations, but physicists have shown that it is possible – at least mathematically. Despite moving so fast, the astronauts would not be subject to any inertial effects because they are not actually moving. They would, however, be in a state of ‘free fall’, due to the angle of folded space in front of them. Some people have questioned whether our warp drive pilots would get cooked by intense, blue-shifted light, but the jury seems to be still out on that one.

The warp drive has been dubbed the Alcubierre drive, after the physicist who first proposed this solution. Believe it or not, the theory was evolved by Alcubierre in response to the use of the warp drive on Star Trek. The travellers on the warp drive capable ship would be cut off from the outside universe, riding on a ‘wave’ of compressed space, along a corridor or warped space-time that would probably have to be constructed in advance, like some sort of cosmic superhighway. Alcubierre himself muses “We would need a series of generators of exotic matter along the way, like a highway, that manipulates space for you in a synchronized way”.

The graphic below gives a 2-dimensional representation of the spacetime around the ‘warp bubble’, stretched to create a gradient pushing the ship forward. Just don’t try to leave the bubble – you would get ripped apart.

Alcubierre space time

To make the Alcubierre drive work we need a pretty exotic fuel – either negative matter or negative energy to be precise. Now that’s negative matter – as apposed to dark matter (which is invisible but has weight) or antimatter (positive energy but reversed charge). Both dark matter and anti-matter have been proven to exist. So far there is no proof that negative matter exists. If it did, it would fall up rather than down, and would have left any solar system long ago (being repelled by ordinary matter) and be drifting out in the middle of nowhere somewhere. So finding negative matter is going to be hard, but perhaps possible using gravity lensing techniques.

Negative energy, though – believe it or not – has been demonstrated by experiment.

In the experiment, two plates in a vacuum, positioned very close together, experience a net movement toward each other because of the ‘pressure’ difference of virtual particles being created at the quantum level around and between the plates. These are electron-antielectron pairs that burst out of nowhere for incredibly brief periods of time, then disappear as they collide (preserving the average energy stat). As brief as their appearance is, the particles create a real effect. That ‘pressure’ causes the predicted movement in the plates, and that equates to a net amount of energy. Since that energy is coming from ‘nowhere’ (and energy must be conserved) to make the whole system balance the plates have a net negative energy left between them. And how much? The effect, called the Casimir effect, was measured in the laboratory in 1996 at Los Alamos. The attractive force is the equivalent to 1/30,000 of the weight of an ant. We would need a lot more than that!

As a civilization, we are a long way from any faster than light travel, even if it is possible. It’s true that Einstein’s equations give solutions that show the possibility of both the warp drive and even wormhole travel, but are these real possibilities, or mere mathematical curiosities? If it is possible, we would need an awesome amount of energy. It’s estimated that to keep a transversable wormhole open wide enough to allow human travellers to pass through, you might need as much as a Jupiter mass of negative energy. That’s clearly well beyond us now.

That doesn’t mean we can’t reach the stars, just that we can’t get there quickly!

Fusion drives, or even antimatter drives, or a combination of the two, will enable us to construct starships that could travel at respectable fractions of the speed of light.

In my novel, The Tau Ceti Diversion, the starship Starburst uses a fusion drive, assisted by an antimatter ‘burst’ to reach a new solar system and look for planets to colonize. Much of the action in the book takes place on planet tidally locked to Tau Ceti, some 12 lightyears away.

The novel was officially launched on 1st September 2016, and is available in both electronic and print formats! Grab a copy!

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