Alpha Centauri Has an Earth-Sized Planet

The Bad Astronomer writes "Astronomers have announced that the nearest star system in the sky — Alpha Centauri — has an Earth-sized planet orbiting one of its stars. Alpha Cen is technically a three-star system: a binary composed of two stars very much like the Sun, orbited by a third, a red dwarf, much farther out. Using the Doppler technique (looking for very small changes in the velocities of the stars) astronomers detected a planet orbiting the smaller of the two stars in the binary, Alpha Centauri B. The planet has a mass only 1.13 times that of the Earth, making it one of the smallest yet detected.However, it orbits the star only 6 million kilometers out, so it's far too hot to be habitable. The signal from the planet is extremely weak but solidly detected (PDF), giving astronomers even greater hope of being able to find an Earth-like planet orbiting a star in its habitable zone."

Comments

That sounds really cool

[Anonymous Coward]

Let's use that as a setting for a sci fi movie and waste it on contortionist zombies and scientists who act like complete douchebag morons. Awesome.

Re:That sounds really cool

[jamstar7]

Let's use that as a setting for a sci fi movie and waste it on contortionist zombies and scientists who act like complete douchebag morons. Awesome.

Seriously, dood, you gotta stop writing for SyFy Channel.

Re:That sounds really cool

[MachDelta]

Sounds good. Let's call it... Chiron. Or maybe Manifold 6?
Ooh, ooh, is it going to have telepathic worms?

Re:That sounds really cool

[Anonymous Coward]

We should send seven leaders, who can't agree on anything, on a spaceship to go visit and check the place out.

Re:That sounds really cool

[felixrising]

Let's use that as a setting for a sci fi movie and waste it on contortionist zombies and scientists who act like complete douchebag morons. Awesome.

Did you have a hand in Prometheus?!

Re:That sounds really cool

[pellik]

Let's use that as a setting for a sci fi movie and waste it on contortionist zombies and scientists who act like complete douchebag morons. Awesome.

Seriously, dood, you gotta stop writing for SyFy Channel.

I don't get it. What does his comment have to do with wrestling?

Re:That sounds really cool

[flex941]

There are some "Zombie Originals" too on the channel from time to time when wrestlers rest.

Re:That sounds really cool

[tofarr]

Did anybody ever pick the "Sister Miriam" faction in that game? It always seemed kind of perverse that no matter how far we go, chances are we will still be dragging crap like that with us...

Re:That sounds really cool

[steelyeyedmissileman]

Can we send 546 instead?

Re:That sounds really cool

[MachDelta]

Of course - she was extremely effective at an early blitz campaign where her military bonuses and native anti-spy abilities let her simply crank out military units and push deep into enemy territory before most other factions could mount a reasonable defense. Miriam wasn't really any good at running an economy, or gaining technological superiority, or a numbers advantage (or most other things) on her own - she was good at taking them by force from other players, jumping out to an early lead, and using sheer momentum and decisive military action to carry her to victory.
They were never my preferred faction, but I can't say they weren't an effective one at times.

we already knew this from Star Trek

[Anonymous Coward]

We already know that Zefram Cochrane is going there sometime in the next century to retire and live out his life with a cloud being... probably Apple's iCloud

Re:we already knew this from Star Trek

[Anonymous Coward]

Yeah, and if that wasn't enough there's also this prescient game: http://en.wikipedia.org/wiki/Sid_Meier%27s_Alpha_Centauri

yes yes yes nope

[Anonymous Coward]

Alpha Centauri Planet found. mass similar to earth, .6 million mile radius
Oh wow thats pretty cool. earth size planet maybe theres... nope.

Dear /S/cientists

[DSS11Q13]

how do planets orbit binary star systems? I would think two stars would give the planets erratic orbits that would either send them into one of the suns or shoot them into space.

Re:Dear /S/cientists

[Kaenneth]

Any system of bodies is going to have a center of gravity. My guess (not having read TFA) is that this planet is many times further away from the binary stars than they are to each other.

Re:Dear /S/cientists

[Anonymous Coward]

Close into the binary the field is going to be a bit convoluted, but as you tend to infinite radius the field lines just look like there's one big object at the centre of the system.

Re:Dear /S/cientists

[Anonymous Coward]

Any system of bodies is going to have a center of gravity. My guess (not having read TFA) is that this planet is many times further away from the binary stars than they are to each other.

From the PDF, it seems to be the opposite:

With a separation to its parent star of only 0.04 AU, the planet is orbiting very close to Alpha Centauri B compared to the location of the habitable zone.

Re:Dear /S/cientists

[Anonymous Coward]

Didn't read the summary, either -- it's orbiting one member of the binary, which means it's much closer than the binary separation.

Re:Dear /S/cientists

[Anonymous Coward]

TFS says this planet orbits one of the stars at a distance of 6million km i.e. 1/10 the orbital distance of Mercury. The stars are separated by 200-300 times that distance.

Re:Dear /S/cientists

[harperska]

Having RTFA (I know), this planet is very close in to one of the stars, in this case Alpha Centauri B. There are two possibilities for planets in a binary system, either orbiting close in to one of the stars, or far away from both. I think I remember reading once that Alpha Centauri A and B are far enough apart from each other that there is a good chance that planets in either star's habitable zone would have stable orbits.

Re:Dear /S/cientists

[xigxag]

The planet is 6 million km from B, or roughly 10x closer than Mercury-sun.

A and B are roughly 3.5 billion km from each other, or roughly the Sun-Uranus distance.

So, no.

Re:Dear /S/cientists

[bjorniac]

It's rather the same way the moon orbits the earth. If you have a binary system, a planet can quite happily orbit very close to one of the two stars so long as the distance between the planet and the star it orbits is smaller than the distance between stars. The pair of stars will orbit their mutual center of mass, and the planet will orbit a single star.

Of course, the three body problem is an open question in physics, but if you make the assumption that one of the masses is much smaller than the other two it (which is the case for planets orbiting stars) it becomes quite solvable, especially if you're happy with numerical simulations of orbits.

A similar situation is possible if the planet is a long way from the pair of stars, and would then orbit their center of mass. That isn't the case here, but is certainly a feasible solution to the problem. You only really get orbits that are highly erratic when the planets orbital radius is over a quarter of the distance between the stars.

Throughout this I've assumed equal mass stars. Feel free to put a factor of M1/M2 in front of every distance I gave for non-equal mass stars.

Re:Dear /S/cientists

[Anonymous Coward]

The stars are actually very wide spaced compared to the planet-star system itself. As a result, the planet is well within the gravity well of B. At a minimum AB separation is 11AU - well over 200 times the B-planet separation.

Orbit centred on A: https://upload.wikimedia.org/wikipedia/commons/e/ee/Orbit_Alpha_Centauri_AB_arcsec.png

Simulation plus table of info: http://www.solstation.com/orbits/ac-absys.htm

Re:Dear /S/cientists

[wierd_w]

What are the prospects for a single orbiting planet (let's exclude other objects) orbiting both stars in a figure 8 configuration, crossing the barycenter of the star's combined rotations?

(Eg, both stars orbit clockwise as seen from plane of rotation north, and orbit each other in an elipse. A planet orbits first one star, then the other, crossing the barycenter at the period of maximal approach of the two stars, moving from one star to the other like a dance partner in a ballroom routine.)

Assuming that the objects are free from outside gravitational purturbations, are exactly the right distance apart, and that the periodicity of the planet's orbits between the stars is exactly synchronized, would such a system be stable?

Re:Dear /S/cientists

[MyLongNickName]

Not an erratic orbit at all. Picture Jupiter. If it suddenly increased its mass by a factor of 20, it might have enough mass to become a star, but would have virtually no impact on the orbit of Mercury, and very little on Earth or Venus. Just because a body becomes a star does not require planets to orbit both stars. In actuality, all planets orbit the center of mass of the solar system. In our solar system's case that resides inside the sphere of our sun.

Re:Dear /S/cientists

[Vekseid]

It'll get ejected - that configuration isn't stable.

For Alpha Centauri A and B, the 'stable zone' is out to roughly Jupiter's orbit from each star - plenty of room for both to have habitable worlds.

Re:Dear /S/cientists

[confused one]

There have been a number of planets found orbiting binary star systems. Kepler has identified a planet around a star in a binary pair, orbited much further out by another binary pair.

Re:Dear /S/cientists

[wierd_w]

Oh, I understand it would be absurdly touchy, pretty much garanteed to not exist, and almost certainly not stable long term.

We could juice it up a little, and say that there is a very massive object that orbits both stars at a very large radius out, around the combined center of rotation. Say, a class M star, or a brown dwarf. This object will perturb the orbit of the hypothetical figure-8 planet. (We will assume that the planet is very far frrom the parent stars, say jupiter orbit equiv, and that the companion stars are very far apart as well. (The distance between the locked stars at closest approach is slightly greater than the greatest distance of the planet's orbit.) The timing of the 3rd, distant star is such that it provides the nudge to push the planet out of orbit of the first star, and into the orbit of the second. (Let's view it this way: the planet is moving in toward the barycenter clockwise from the northwest quadrant. For visualization purposes, we are locking camera rotation so that both stars are fixed on the X axis and periodically approach and recede each other. The 3rd massive body orbits clockwise, and is say, 5 degrees off the X axis at the point of transit, in the north east quadrant. As the planet transits, it would gain a shitton of momentum, and woult tend to get thrown out like a stone from a sling. However, the location of the 3rd massive object curves the tradjectory, preventing ejection. The planet then orbits the second star eliptically, and rotates much faster on its own axis. As the system returns to the point of closest proximity again, the 3rd object has exchanged places such that it is at the complimentary angle, the planet passes the transit point, is again caught by the gravitational influence of the 3rd star, and forced into orbit with the original partner again. The change in orbital rotation (clockwise-anticlockwise) caused by the figure 8 orbit, causes the rotation of the planet to radically drop, possibly tide locking with the first star. The system then repeats. Orbital momentum of the 3rd star is conserved by the wobble of the system barycenter as the planet enters conjection with each star relative to its location.)

The 3rd star would shepherd the crazy figure8 planet, keeping it from being ejected.

I might pull an orbital simulator and see if this can actually work.

Re:Dear /S/cientists

[Anonymous Coward]

I have a feeling it could work, but as others and you said, it would be highly unlikely. The masses of the three bodies and the distance between the binary entities would need to be just right. Hypothetically speaking, if that could work then you could expand things to a planet and three stars that are equidistant, then four stars and perhaps at some point even accommodate multiple planets. Again, that's merely an idea, not to mention the fact that eventually the stars would be gone, but so will our sun, which our planet orbits. Of course, the greater the complication, the less stable the system as a unit could be. It's still fun to dream, though.

Re:Dear /S/cientists

[Vekseid]

And that's just it - all stars involved are shedding mass in different directions, at varying rates. You might have instances where a single figure-eight of sorts gets performed, but that means there's been a capture and likely a subsequent ejection. But unless you actually want to engineer this somehow, and have a means of keeping it stable (planetary thrusters go!) - it won't be seen. If we ever find something like that the first assumption is going to be aliens having fun, and that's what Occom's razor is going to boil down to.

Re:Dear /S/cientists

[MyLongNickName]

For those who care

Jupiter is about 0.0009 solar masses. Current models of nuclear fusion predict that if an object has mass of about 0.07 solar masses it will begin a fusion reaction. So Jupiter would need to swell to 80 times its current mass.

Re:Dear /S/cientists

[MyLongNickName]

More reading indicates that the center of mass of our solar system can be inside or outside of our solar system depending on the position of Jupiter relative to Saturn. I didn't know this before.... interesting stuff.

Re:Dear /S/cientists

[__aaltlg1547]

Any system of bodies is going to have a center of gravity. My guess (not having read TFA) is that this planet is many times further away from the binary stars than they are to each other.

No, that's not what TFA says. It says it is many times closer to one of the stars than it is to either of the others. The other two stars have only minor effects on its orbit.

Re:Dear /S/cientists

[tyrus568]

I take it you meant inside or outside our sun. I didn't know that either.

Re:Dear /S/cientists

[wonkey_monkey]

My guess is that you didn't read TFS either - the planet is orbiting the smaller of the binary pair.

Re:Dear /S/cientists

[sFurbo]

Either very close to one star (as in this case), so it is, in effect, orbiting one star, of vary far from the star, so it is orbiting the center of mass. I think both could be unstable, but so could any three-body problem, and that hasn't stopped our solar system from existing.

Re:Dear /S/cientists

[cyberdime]

What are the prospects for a single orbiting planet (let's exclude other objects) orbiting both stars in a figure 8 configuration, crossing the barycenter of the star's combined rotations?

Why not just an ellipse? As it nears each star, the planet gets a gravity assist that forces it into an extended comet-like orbit.

Re:Dear /S/cientists

[dotancohen]

What are the prospects for a single orbiting planet (let's exclude other objects) orbiting both stars in a figure 8 configuration, crossing the barycenter of the star's combined rotations?

I asked this very question not long ago:
http://physics.stackexchange.com/questions/31201/might-a-planet-perform-figure-8-orbits-around-two-stars

Re:Dear /S/cientists

[Tastecicles]

All bodies in all solar systems orbit a common centre of gravity - which is not necessarily even within the central star. As planetary systems go, those in binary systems orbit the barycentre of the stellar system, unless they orbit too close to either of the stars in which case it becomes a Lorentzian body, which then orbits both stars in a semi-chaotic orbit describing a figure-8 of varying distance from both stars, with both stars becoming orbital axes.

Re:Dear /S/cientists

[Anonymous Coward]

If that comment were true, then Jupiter or Saturn having any moons would be an impossibility...

Re:Dear /S/cientists

[smooth wombat]

As a follow up to your input, would it be possible for a planet to have a figure 8 orbit around a binary star system? i.e. the planet has such a highly elliptical orbit that it goes part way around one star but is then sent off on a trajectory which allows it to be "captured" by the second star but is again flung out on a reverse trajectory to be "captured" by the first star?

Just a thought question.

Re:Dear /S/cientists

[halltk1983]

Even the moons?

Re:Dear /S/cientists

[bjorniac]

A figure-8 is quite hard to find, since the symmetries involved would require almost perfectly equal masses between the stars and perfectly circular orbits of the stars. (This is from memory running simulations a long while back). However it is certainly possible to have a planet be orbiting one star for a few loops and then be captured by the other, orbit it a few times and keep getting passed back and forth.

The basic condition you need for this is for the planet to have enough energy to get over the maximum between the two gravity wells of the stars. If you think of kinetic and potential energy being like those of a ball rolling on a set of hills, you'd say that the ball is either trapped between two peaks or not. However with this case it would appear that the hills themselves are moving, so the "hump" between them will grow and shrink with time, sometimes letting the ball pass between valleys, sometimes trapping it in a single valley for a few cycles.

What's really remarkable is that this is all do-able without too much technical knowledge. You'd need:

About a second year undergrad level of physics - You could do it with Newtonian mechanics, but Lagrangians make it a LOT easier);

A bit of programming technique (two days or so with MATLAB and you'll get the basics of ODE solvers).

A LOT of patience :)

As an aside, you could just grab the game "Osmos" which has a lovely set of orbital levels that basically implement this :) I strongly suspect whoever was involved with it was well educated in physics, as finding the stable orbits they have requires an understanding of conservation laws and use of a symplectic integrator (eg Verlet's algorithm) to implement time updates, instead of just using Newton's method.

Re:Dear /S/cientists

[Anonymous Coward]

If you really want to juice it up a little, just decree that hot blue anthropomorphic babes live there.

Re:Dear /S/cientists

[Anonymous Coward]

Holy smokes, everyone is making this far too complicated. A planet can orbit a binary star like satellites can orbit our earth and be minimally affected by the moon. Same orders of magnitude.

Re:Dear /S/cientists

[mcgrew]

Having RTFA (I know), this planet is very close in to one of the stars, in this case Alpha Centauri B.

I wonder if there is another planet around A cen B slightly closer to it than Earth is from the sun? We may find life on our nearest neighbor star system. If such a planet exists, but is yet undiscovered, can we name it Tattooine?

Re:Dear /S/cientists

[MyLongNickName]

Yes... I was clearly posting too late at night.

Re:Dear /S/cientists

[Tastecicles]

the Earth/Moon system shares a common barycentre which lies somewhat off the centre of Earth's core - in effect, both bodies orbit a point in space rather than the Moon orbiting Earth.

Re:Dear /S/cientists

[RockDoctor]

You can name it anything you want, but the people who get to decide the official name are the discoverers (with some restrictions, probably from IAU). So if you really want to name the (putative) planet "Tattoo Ine" like something out of Star Trek, you'd better get started on your post-doctoral work in planet discovery.

(I'm not sure what the actual naming rules for "popular" names for extra-solar planets are ; the formal names are the likes of "Alpha Cen Bb". It may be that there are no rules for "popular" names. I'm projecting from the rules for minor planets, which seems reasonable.)

Re:Dear /S/cientists

[RockDoctor]

There has been a fair amount of work done on this. Your summary covers the main points.

Paul Wiegert (http://www.astro.uwo.ca/~wiegert/) did some of the work 15-odd years ago. Some of the earlier work is online at http://www.astro.uwo.ca/~wiegert/papers/1997AJ.113.1445.pdf.

Re:Dear /S/cientists

[Anonymous Coward]

Both of your posts here have been very interesting to read. Thanks for your expertise!

Re:Dear /S/cientists

[mcgrew]

I can't name it anything, but can hope that whoever discovers it was a Star Wars (not Star Trek) fan.

I'd leave well enough alone!

[p51d007]

If somehow we "made contact" with some "ET" type, and they had the means to get here "quickly", you think they would come in friendship? LOL, probably blow us up like the Klingons, Borg or some other crap. Just leave things alone will ya?

Re:I'd leave well enough alone!

[MyLongNickName]

Why is this modded down? Stephen Hawking would agree.

Re:I'd leave well enough alone!

[Anonymous Coward]

If aliens exist nearby and they're sufficiently advanced for rapid interstellar travel and thus pose a threat, then they already know about us.

Re:I'd leave well enough alone!

[sakari]

If somehow we "made contact" with some "ET" type, and they had the means to get here "quickly", you think they would come
in friendship? LOL, probably blow us up like the Klingons, Borg or some other crap. Just leave things alone will ya?

That's what the television and movies tell you, don't they? Do you ever wonder why most of them tell that ETs are here to attack us ?
To keep us in Fear and to believe that if someone would come here, this would be automatically justify a reason for us to attack them.

Think about how the US & Hollywood portrays terrorists in movies, TV -series and mainstream news. Same thing with Extraterrestrial Life.

Oh, and btw. Imagine, that if there are civilizations out there who are _exponentially_ more evolved, have the capability to understand 100,000,000 times more of every aspect of technology and life, why would they travel here slowly ? They would have most probably already mastered Quantum Teleportation and other technologies we are still dabbling around with, and therefore would already know how to transfer themselves physically to our realms if needed.

And if a lifeform has gained such high insights into life itself, it would have already meant that they had gone through the phase of understanding that killing themselves and others is not the way. So why would such a race attack us ?

And now, if there is a race that wants us as their slaves, wouldn't they just infiltrate themselves into our society instead of attacking directly? What's the point of just killing everyone and taking the planet ? Any race that could come from such far distances would have to technologically and socially so much more advanced, they must have thought about more advanced tactics also.

  And maybe this has already happened, and we are living in such a society where we are slaves to some certain bloodlines who are in contact with these beings .. think about kings & queens, why are always the same f*ckers in control and most of the society feels like slaves to them ? Think about this possibility.

Oh yeah, and one more thing, we already are in contact with ETs and Aliens, and have been for so long time already. Our society has suppressed this information for so long to keep us blinded from the truth. The communication happens telepathically and during meditative states of mind, or during dreams. Research the subject, the information is out there.

Re:I'd leave well enough alone!

[mcgrew]

Our society has suppressed this information for so long to keep us blinded from the truth. The communication happens telepathically and during meditative states of mind, or during dreams.

WTF, slashdot? That's insightful??? Prove telepathy exists, prove that the "telepathic" subject actually had contact, prove it wasn't a stupid dream, do it with the scientific method and you could have a point. But you see, you can no more prove that than you can prove that sentience exists.

This was NOT the least bit insightful, rather Sakari has shown evidence of schitzophrenia in himself. Dude, see a mental health professional; I've known a few folks with your disease and the drugs do indeed work. Unfortunately, the symptoms of the disease keep the sufferer from taking his medication.

At least, lay off the coke and acid, dude, because you've gone off the deep end.

Re:I'd leave well enough alone!

[Anonymous Coward]

Stephen Hawking is an intelligent man and a great physicist, but his assumptions on the topic of xenopsychology are no more valid than anybody else's. He presumes danger to Earth from extraterrestrial contact because he assumes the ET's desires are similar to ours (i.e. a planet with a biosphere).

In my opinion this is far from certain; if the ET civilization is accustomed to spaceflight, they would find it more convenient to harvest material resources from asteroids and moons due to shallower gravity wells and lack of contamination by living organisms. Exposure to Earth's biosphere could well be hazardous to them, and in the very least it's unlikely they could eat Earth organisms due to unrelated biochemistry. Farming their own would, again, probably be easier in greenhouses on a moon where they wouldn't be under constant assault by Earth's micro-organisms or affected by weather, and could be launched into space with less cost.

Sterilizing the entire Earth to make way for their "terraforming" it for their purposes is somewhat feasible, but does not become more probable by us contacting them. In this case they would detect Earth as a colonization candidate by measuring Earth's mass, temperature and atmospheric chemistry from a distance. If anything, our signals might arouse their curiosity and make them *not* launch their automatic sterilization/terraforming fleet until they have investigated us further. If they have ethical qualms about exterminating intelligent life, or if they are concerned about resistance by such, again signaling our existence can only be beneficial to us: if they see a desirable planet that nobody intelligent appears to be using, that would obviously be a better target than a planet with potentially dangerous intelligences.

Re:I'd leave well enough alone!

[MyLongNickName]

While you have a very intelligent post, I think you have missed the point of my post. What I am disagreeing with is the modding down of the post. A downmod isn't a way of saying "I don't agree with your point".

Re:I'd leave well enough alone!

[Anonymous Coward]

And if a lifeform has gained such high insights into life itself, it would have already meant that they had gone through the phase of understanding that killing themselves and others is not the way. So why would such a race attack us ?

Or their insights could tell them the opposite. That life is purely disposable and, presumably with that level of technology, easily replaceable.

Quite a discovery...

[buckeyeguy]

... considering that if the distance estimate is right, its orbit is 1/10 that of Mercury. Better put on the SPF 1million if you go out on that rock.

Re:Quite a discovery...

[confused one]

If it's that close, it's likely tidally locked, or at least have a very slow rotation as does Mercury; so, the "dark side" should stay icy.

Re:Quite a discovery...

[NeMon'ess]

Exactly. What is the temperature on the side away from the sun? I'm guessing the atmosphere has been blown away by stellar wind. If not the convection could make it a furnace anyway.

Re:Quite a discovery...

[confused one]

Well, there might be a thin atmosphere composed of stuff boiling off the star facing side.

Apparently there's a message there...

[Gort65]

...for us about some space bypass or something. Seems important for some reason.

Temperature = 1500K

[kf6auf]

That sounds really cool. Or hot since, unfortunately, the close proximity to its star means that it probably has a surface temperature of 1500 K.

I guess I'd be more interested in a different-sized planet a bit further away from its star.

Re:Temperature = 1500K

[Anonymous Coward]

Well, then, get to work finding one and quit whining on Slashdot.

Re:Temperature = 1500K

[harperska]

What makes this a big deal, is that prior to this it was an open question whether the Alpha Centauri system could support planets orbiting the individual stars or not. Now that it has been shown that planets can orbit the individual stars in this system, as opposed to orbiting outside both stars around the common center of gravity as is the case for most planets in binary systems, the probability of their being more planets including possible ones in the habitable zones of the stars just got a whole lot bigger.

Re:Temperature = 1500K

[v.dog]

Then they really are the real small furry creatures.

Re:Temperature = 1500K

[IrquiM]

That's only ~1227C - that's not even enough to melt Manganese

Re:Temperature = 1500K

[Anonymous Coward]

Forget whether there's a planet in the habitable zone or not. Alpha Centauri is relatively close (4.37 light years - 41.3 trillion km) - use the planets for resources to engineer the first extrasolar starbase that orbits in the center of the habitable zone.

High temperatures like that may be suitable for thermopiles to run mass drivers on the surface of these planets, especially if there's no atmosphere. By the time we have the technology to do this, it may be possible to synthesize water, carbon, and nitrogen from just hydrogen by using fusion. Hydrogen fuses to Helium and Helium is the fuel for the carbon cycle. Since hydrogen is abundant, locating heavier elements like iron, sodium, potassium, silicon, uranium, etc. will be more important than finding water.

1500K is cool when compared to the melting point of tungsten (3683K). Before this is discounted as impossible due to temperature, consider that Mercury has surface ice.

At the very least, we need to send a high-speed probe using nuclear propulsion. Uranium has an energy density about 1 million times larger than hydrogen. Even if only 0.1% of the energy gets translated to motion, that would make it possible to send a probe at 17,000 km/sec (5% of c). At that speed, it would take about 80 years before data from the system got here. Hopefully, there's a way to make it more efficient so it could go 25% of c. Then the mission length would be under 20 years.

Re:Temperature = 1500K

[shiftless]

Well it's a dry heat.

On track for the 2154 colonization

[Anonymous Coward]

From the Star Trek Database: Sol's closest stellar neighbor, a trinary that is only 4.3 lightyears away from Earth. One of its components' habitable planets was already colonized by Earth humans in 2154--possibly the planet where warp-drive inventor Zefram Cochrane took up residence later in life.

Re:On track for the 2154 colonization

[Teancum]

Of course many thought we as a species would have established permanent bases on the Moon and even a manned spaceflight mission to.... Saturn. (or was that Jupiter?)

I'd personally put the likelihood of anybody from the Earth ever getting to the Alpha Centauri system or for that matter any star within about 15 light years of the Earth no earlier than the year 2500 A.D., if even that early. That even is assuming we find an Earth-sized planet in a habitable zone of a star with liquid water oceans anywhere within that range.

There might be an unmanned space probe that will be sent to one of these stellar systems by 2154 (not to arrive at that time... just get sent by some future successor to NASA). If it takes a century or two to make the trip, that wouldn't be a big deal. Hopefully successful nuclear fusion reactors will finally be a proven technology by that year.

Heil Sid Meier

[vgerclover]

When can we start travelling over there?

We have to establish colonies with factions fighting each other!

Re:Heil Sid Meier

[philcheesesteak]

Within this decade, if we send space priests. I coincidentally started reading that book today; quite good so far.

Re:Heil Sid Meier

[cashman73]

We better get moving! It's already 2012 and the game ends in 2050!

Re:Heil Sid Meier

[EnsilZah]

Sorry, travel has been indefinitely postponed due to a copyright dispute.

Re:Heil Sid Meier

[cbhacking]

Err what? The game *starts* in 2100 (the Unity launches in 2060 and spends 40 years in transit). You may be thinking of one of the earlier Civ games. Alpha Centauri, depending on difficulty level, ends (you reach "mandatory retirement age") on 2300, 2400, or 2500. Each turn is one year, unlike typical Civ games.

Re:Heil Sid Meier

[Anonymous Coward]

The colony in Alpha Centauri is that of the victorious nation in civilization who sent the spaceship.

Re:Heil Sid Meier

[Anonymous Coward]

Yeah, he's thinking of civ, where one of the victory conditions is to send a colony ship to alpha centauri with time to reach it prior to the end date (which again varies with difficulty).

Unfortunately

[AndyKron]

Unfortunately the United States can't even get off the planet anymore, and musicians out bid the USA for seats on the Russian rocket.

Re:Unfortunately

[Anonymous Coward]

Almost as if manned space was never more than a stunt in the first place. Thanks, predictor of the WWW and all around genius for pointing that out 65 years ago.

Re:Unfortunately

[murdocj]

Not unfortunate, just a recognition of reality. At this moment in time, the science return for sending unmanned probes / orbiters / rovers vastly exceeds the return on sending humans. We'll continue to develop space capability and at some point it may make sense to send humans to Mars ... or maybe not.

And please do NOT invoke the whole "omg we have to get off this rock" argument. If an asteroid impact blew most of Earth's atmosphere and water into space and annihilated 99.999% of the species, Earth would STILL be easier to live on than Mars.

Re:Unfortunately

[Anonymous Coward]

Calling that an "argument" is giving it far too much credit. "Adolescent angsty drivel" is more like it.

Re:Unfortunately

[Hal_Porter]

He failed to predict the danger of Nazi WMD though, and allowed a "missile gap" to develop

http://en.wikipedia.org/wiki/Vannevar_Bush

The German V-1 flying bomb demonstrated a serious omission in OSRD's portfolio: guided missiles. While the OSRD had some success developing unguided rockets, it had nothing comparable to the V-1, the V-2 or the Henschel Hs 293 air-to-ship gliding guided bomb. Although the United States trailed the Germans and Japanese in several areas, this represented an entire field that had been left to the enemy. Bush did not seek the advice of Dr. Robert H. Goddard. Goddard would come to be regarded as America's pioneer of rocketry, but many contemporaries regarded him as a crank. Before the war, Bush had gone on the record as saying, "I don't understand how a serious scientist or engineer can play around with rockets", but in May 1944, he was forced to travel to London to warn General Dwight Eisenhower of the danger posed by the V-1 and V-2. Bush could only recommend that the launch sites be bombed, which was done.

Not a mistake his rather unjustly maligned namesake would have made.

Re:Unfortunately

[Tubal-Cain]

Unfortunately the United States can't even get off the planet anymore...

Sure we can.

Re:Unfortunately

[Anonymous Coward]

I think the official stance is "omg we have to get off this rock and other people should be forced to pay for it".

Re:Unfortunately

[Anonymous Coward]

If an asteroid impact blew most of Earth's atmosphere and water into space and annihilated 99.999% of the species, Earth would STILL be easier to live on than Mars.

With the exception that there wouldn't be an Earth that sends a supply vessel over every two years.

Re:Unfortunately

[Anonymous Coward]

The "science return" isn't a scalar quantity. Unmanned missions mostly advance physics and astronomy, while manned missions advance a much more diverse set. Take a look, when you design spaceships for humans, the spin-off technologies are more useful for humans.

Learning about the universe is great, but tax dollars should probably be spent on things that benefit people more than probes. The populace seems to agree with this sentiment, as NASA gets less and less funding the fewer manned missions they do. Furthermore, the gains from unmanned probes will be easier and cheaper to acquire when we have a decent presence in space and don't have to burn millions of dollars fighting Earth's gravity. Knowing the composition of rocks on Mars is really cool, but doesn't have a practical use that necessitates learning about it now VS bringing some back after humans land there (i.e. what we did with moon rocks).

Re:Unfortunately

[DahGhostfacedFiddlah]

But if an asteroid impact blows most of earth's atmosphere and water into space, and we haven't had practice setting up a self-sustaining system on Mars - what chance do we have on earth?

Re:Unfortunately

[Mad Marlin]

I really think the reason we have such stalled space progress is because of NASA. I don't mean to go all libertarian, but I do think that NASA suffers from a lot of the worst problems of any large governmental body, and that has suffocated space research.

Re:Unfortunately

[murdocj]

One of the "arguments" for going to Mars is to survive AFTER an asteroid hits Earth. Not too many supply ships going to arrive on Mars in that case.

Re:Unfortunately

[murdocj]

We aren't going to figure out how to set up a self-sustaining system on Mars. It's not like we can fly there and find the Martian plants that produce oxygen in the secret underground caverns (although I have to admit, that would be very cool). The technology and systems to do a self-sustaining environment would be built & tested on Earth.

Re:Unfortunately

[DahGhostfacedFiddlah]

That's fair, but I don't see it happening without a concrete goal to get us there. I'd be happy with plans for a moon/asteroid belt/Mars colony, as long as we're taking the long view and asking how to build a self-sustaining space colony with minimal materials.

The bottom line is, we don't know just how rare intelligent life is in the universe, and I'd hate to see it disappear.

Re:Unfortunately

[murdocj]

I would hate to see us disappear too. But I'd like to see a clear link between spending massive amounts of money on a self-sustaining Mars colony and the survival of the human race. For example, enumerating the top threats to humanity (nuclear war, nearby supernova explosion, asteroid impact, bio-warfare, civilization collapse due to resource exhaustion, etc) and some explanation as to how a Mars colony is the most practical solution to these problems. Right now, I'm not seeing it.

Don't get me wrong, I love space exploration, I'm insanely jealous of these billionaires who can actually just pony up $$$ or rubles or whatever and buy their way to the ISS, but I can't justify the immense cost of a Mars colony on the basis of human survival. I'd love to see some compelling argument for human space exploration, but it's going to have be more concrete than the old "Columbus sailed the ocean blue and look what happened".

Re:Unfortunately

[RockDoctor]

Mars is a poor choice of places to go. Medium-size asteroids would be much simpler to colonise, multiple times. (Re-form the exterior to form a structural shell with adequate radiation shielding ; spin ; fill with gas ; inhabit. When living room gets tight, terraform another asteroid.) It wouldn't be Earth, it wouldn't be very Earth-like, but it'd be easier by several orders of magnitude than terraforming Mars (if that were possible without effectively rebuilding it completely, which as a geologist, I rather doubt).

Who knows better?

[TheRealMindChild]

Using the Doppler technique (looking for very small changes in the velocities of the stars) astronomers detected a planet orbiting the smaller of the two stars in the binary

I understand how the Doppler effect actually works, I don't understand how it works on a scale of this magnitude, with one or two sources of reference and data that has been determined "scrubbable" (as in, "static noise", or data that doesn't belong in the analysis). How exactly is the speculation even tied to something worth a story?

Re:Who knows better?

[tp1024]

> How exactly is the speculation even tied to something worth a story?

It is tied to something worth a story by a scientific paper linked in the fucking article.

Re:Who knows better?

[Anonymous Coward]

Spectroscopy, especially of atomic lines, is a really precise science and can measure and account for very small changes in velocity. Too bad Mössbauer spectroscopy isn't usable in astronomy, as with an undergrad lab setup you can measure Doppler shift of a couple mm/s for gamma rays...

Re:Uh oh...

[Anonymous Coward]

lol, anonymous thinks the universe is twice as big as the solar system.

Man will never fly, and only a fool would think it possible to walk on the moon.

Sure

[viperidaenz]

A very close and very fast orbit produces weak but detectable movements of its star. But what if the planet were moving much slower and was much further away? Would that not mean the star would move even less, and slower as well? How does this give more hope to detecting planets in the habitable zone? Its 25x closer to its star than Earth. It's also 13% heavier than Earth and Alpha Centauri B is 9% lighter than the Sun. If my napkin calculations are correct, this planet has ~700x more gravitational effect on its star than Earth has on ours.

Re:Sure

[RockDoctor]

Well done, you've realised the basic difficulties of using the Doppler method for small planets in (relatively) distant orbits.

But the techniques are getting better. And the "transit" method (OGLE, Kepler projects) has different constraints.

Obligatory:

[Anonymous Coward]

This IS Beta Centauri Five!!! Beta Centauri Six exploded, six months after we were left here. The orbit of the planet shifted. ADMIRAL Kirk never came back to check on our progress...

Or...

So, found an Earth-sized planet, did you? Real close too, neh? When are you leaving?

Re:Obligatory:

[Geoffrey.landis]

This IS Beta Centauri Five!!! Beta Centauri Six exploded, six months after we were left here. The orbit of the planet shifted. ADMIRAL Kirk never came back to check on our progress...

Amusing, but, no, Alpha Centauri B is not Beta Centauri. Beta Centauri is a completely different star, about 300 light years away.

http://www.astro.wisc.edu/~dolan/constellations/hr/5267.html

Re:Uh oh...

[Anonymous Coward]

Man doesn't fly. We build machines that we sit inside of that can fly. Please describe the machinery required to traverse four light years of space, with absolutely no resources available from Earth once it's on its way, and is 100% fail safe and will get there either within a useful human lifespan, or describe a way to (on top of the machine from step 1) slow down life processes reversibly and safely.

That's the thing with all your "man will never fly" quotes. Someone BUILT a machine, using real materials, real energy sources and real engineering with a few YEARS.

Since the moon shots, the space loon brigade has had DECADES to show us something, ANYTHING, that manned space makes a shred of sense.

That's the thing. You think that because someone was wrong, you think anyone who predicts a negative outcome is wrong. But you skip the tiny little detail of you know, BUILDING what it is you claim is possible.

By your logic, any prediction that sounds wrong to you, for whatever reason, can be discarded.

Man will never extend his lifespan.

UVB x 3

[dimethylxanthine]

I wonder what factor protection they use over there. Oh wait, it's only 6 Mkm away from Cen B.

Understatement of the Year

[BlackGriffen]

"it's far too hot to be habitable."

That's an understatement. From the ArsTechnica article on the alpha Centauri planet:

"But don't start building the colony ship just yet. With a 3.3 day orbit, the planet is only 0.04 Astronomical Units (1 AU is the typical distance from the Earth to the Sun). That makes this planet blazingly hot, at about 1,500 Kelvin."

Re:Understatement of the Year

[Anonymous Coward]

If calling 1,500 kelvins "far too hot to be habitable" is the understatement of the year, then I'll call it merely "too hot to be habitable" and win the award!

Re:Understatement of the Year

[T.E.D.]

Nah. It's just a wee bit balmy.

Re:Uh oh...

[Anonymous Coward]

to traverse four light years of space

It simply needs to be long-lasting, and repairable en-route.

with absolutely no resources available from Earth once it's on its way

Make it big, contains adequate resources to support itself indefinately. An ecosystem.

and is 100% fail safe

Why? Nothing else we do is 100% fail safe. There is always risk.

and will get there either within a useful human lifespan or slow down life processes reversibly and safely.

Why? A generational ship is not a new concept.

And us space bloggers feel like chumps

[Nyrath the nearly wi]

Space bloggers (like me) who are signed up with the ESO news feed got word of this overnight. But the story was under embargo. You do not break the story until the embargo lifts or the ESO and Nature magazine gets very angry at you.

But some loud-mouth in Croatia violated the embargo. We were patiently waiting for the embargo to lift, biting our collective tongues, when mouthy jumped the gun.

We got an email from the ESO about an hour ago that said:

"I just spoke to the Head of Press at Nature, Ruth Francis, and we have agreed to LIFT THE EMBARGO on the Alpha Cen story IMMEDIATELY due to an unfortunate leak. You may run your stories."

Nature and ESO lift exoplanet embargo early following coverage by Croatian news outlet

Re:And us space bloggers feel like chumps

[Anonymous Coward]

Why did they even have the embargo ? The news wasn't really that much of a big deal and they could have just come out with it without all the cloak and dagger stuff..

The way it was handled made it seem like they were going to announce definite proof of life whereas this is just meh.... whatever.

Power source [Re:Uh oh...]

[Geoffrey.landis]

to traverse four light years of space

It simply needs to be long-lasting, and repairable en-route.

with absolutely no resources available from Earth once it's on its way

Make it big, contains adequate resources to support itself indefinately. An ecosystem.

The hard resource is energy. What's the power supply for a very very long voyage?

We really need fusion for this.

Re:Power source [Re:Uh oh...]

[Anonymous Coward]

We send an unmanned ship carrying all of human knowledge, a few robots, a bunch of DNA samples and the equipment needed to grow clones. We might not be able to do it now, but it's likely that we could in time.

Footfall time

[Dave Emami]

Here come the baby elephants.

Re:Footfall time

[RockDoctor]

It's been a few years since I last read that one ; I don't think that the pink elephants in platform-soled shoes came from the Centauris.

Re:Footfall time

[RockDoctor]

I sit corrected. It was Alpha Centauri.

There Could Be Habitable Planets Also

[crunchygranola]

It is entirely possible that there are undiscovered planets in the habitable zone. It is the planets closest to the star with the shortest orbital periods that are the easiest to discover, either because generate frequent perturbations that can be detected in the data set, or are the most likely to cross the stellar disk (when using the brightness fluctuation method).

Re:There Could Be Habitable Planets Also

[__aaltlg1547]

It is entirely possible that there are undiscovered planets in the habitable zone. It is the planets closest to the star with the shortest orbital periods that are the easiest to discover, either because generate frequent perturbations that can be detected in the data set, or are the most likely to cross the stellar disk (when using the brightness fluctuation method).

Then sign me up! If there's a star in the habitable zone, we'll colonize it when we get there. If there's not, we should have advanced enough technology by that time to move the planet we've already discovered anywhere we want it.

Re:There Could Be Habitable Planets Also

[wonkey_monkey]

If there's not, we should have advanced enough technology by that time to move the planet we've already discovered anywhere we want it.

Yeah, but they've been saying planet-moving technology is five years away since the 60s.

Re:There Could Be Habitable Planets Also

[RockDoctor]

You want to colonize a star. Fine. Go ahead. Don't forget to leave the mike on "transmit" as you land, I'd like a soundtrack for the nursery.

Re:Uh oh...

[harperska]

Then, there is this:

http://science.slashdot.org/story/12/09/17/2229257/warp-drive-might-be-less-impossible-than-previously-thought

But what we want too know is ...

[Anonymous Coward]

Does it have fungus and mind worms?

Rings Around Uranus?

[Anonymous Coward]

Hey Bad Astronomer: someone told me that there are rings around Uranus.

Is this true? If so, I suggest that you make an appointment to see the doctor!

*Snigger*

Re:Uh oh...

[jamstar7]

Since the moon shots, the space loon brigade has had DECADES to show us something, ANYTHING, that manned space makes a shred of sense.

And every time we come up with something, the JOEs shoot it down by saying 'We can't do that now, therefore we'll never be able to do it so don't even bother getting out of bed'. And Congress seems to listen to the JOEs, especially when they can game the system to pump and dump 'development money' into their districts as purest pork without having to come up with anything tangible with the money, rinse and repeat.

Doudoune Moncler France

[Anonymous Coward]

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OF course

[Anonymous Coward]

There is nothing to say there isn't an earth mass planet in the Goldilocks zone of either star. We just don't have the tech to be able to detect it yet.

To: Centauri Prime. Attn: Londo Mollari

[snap2grid]

We no longer need to develop the not-quite-impossible-anymore warp drive. Just wait to buy jump gate technology from our good and dear friends.

Re:Frist stoP?!

[Hal_Porter]

"The Narwhal bacons at midnight?"

Don't worry everybody. I'm just testing to see if it's a feral redditor. If it is I'll have to cut its head off and then burn the body to prevent an infestation.

I'd keep you kids locked up inside until I give the all clear if I were you.

Problem with discovering further-out planets...

[Anonymous Coward]

- the orbital period is way longer (let's say 1 year) ... so I guess you'd need at least 1 year and then some of observation data (albeit with a lower sample rate) to make sure you really found something and it's not a fluke.
- this is even worse if you go for observing passes of the planet in front of it's host star (as the possibility of the pass from our perspective decreases with distance, and also the time between passes increases).

Ah! Home sweet home

[SmallFurryCreature]

Ah! Home sweet home, I do miss it sometimes but the journey back is a pain in the ass.

Re:Uh oh...

[aaaaaaargh!]

Why? A generational ship is not a new concept.

It sucks, though, as it will invariably be overtaken by some dudes in a faster-than-light space yacht who make fun of the ancient crew. At least that's what my sci-fi reading experience tells me. :-)

What's the use

[Rexdude]

We're stuck here for good, destined to just keep looking at extra solar planets via telescope and speculating about whether they could support life as we know it. The nearest star, Proxima Centauri, is 4.3 light years away. The farthest man made object is just roughly 17 light hours from home after 35 years of travel; so forget about sending spaceships physically to the stars unless someone invents warp drive. It's laughable to talk of Alpha Centauri when no one in power is showing interest in returning to the moon, let alone Mars.
And leaving aside that, we're stuck with the reality of NASA facing budget cuts despite its overall budget being a drop in the ocean compared to what's been spent on war in the last 10 years.
Space exploration should've been incremental, start with a lunar refuelling base at the pole where there's water ice that can be broken down into hydrogen and oxygen for rocket fuel, and use that as a staging area for further exploration. Build a spacecraft for travelling to Mars in LEO stage by stage, and send a bunch of robots to assemble a modular base well before the first humans are sent (Kim Stanley Robinson's Mars series describes this approach).

While Curiosity, Opportunity & Spirit are testimony to NASA's engineering prowess, it still can't beat an actual geologist (areologist?) on Mars with a field laboratory who's able to directly analyse rocks and figure out what it was like in the past.

Want some perspective? Just the annual airconditioning budget for the US Army in Iraq/Afghanistan far exceeds that of NASA's.

Re:What's the use

[ledow]

Let's be honest - Voyager was never intended to be a transport to get to Alpha Centuri. It's designed to be a low-power "poodle-along" slowcoach to get to the outer planets, not to get much further, and to take it slow because it takes DAYS to send back an image that it's captured and anything faster moving wouldn't provide enough useful data.

The problems of scaling up and speeding up aren't insurmountable but are HUGE, I grant you. But considering that 51 years ago no man had ever gone into space whatsoever, that's pretty quick progress to keep an eye on.

And we all KNOW that the space programme is being seriously held back by other matters at the moment and if we *wanted* to we could fund it ten times better (e.g. the US pays more to air-condition its military facilities in the Middle East than NASA's entire budget, for instance).

So, even being conservative, if we assume there's a proper incentive (i.e. there's a habitable planet on our closest star), some funding appears for it, we can use vaguely modern technology and have the aim to just "get there" and take a photo of it (not even land necessarily), and let's say that in 30 years we launch something towards it (non-human-bearing) that's capable of moving at 10 times Voyager's speed.

That's a launch in 2040-ish - long enough away to seem futuristic even to use, and long enough way that our technology now would appear then to be like 1980's technology does to us now (when computers BARELY entering a handful of MHz and coming into homes - your top-of-the-range PC would be the equivalent of a ZX Spectrum in 2040).

Then we're honestly talking contact with an extra-solar planet sometime this century. That's a HUGE step. Much larger than setting foot on the moon or doing whatever on Mars. That's something completely outside the Solar System which is a scale never before imagined compared to all previous human endeavours (except, possibly, Voyager by then).

That's pretty damn close, and pretty damn good, and pretty damn realistic, and pretty damn achievable, and pretty damn likely I could even be around to see it happen (depending on what happens with medical science in that time), but certainly my children or (absolute worst-case) grand-children would definitely see it.

Colonising it? Terraforming it? Stripping it of resources? We can do all that to Mars etc. in the meantime if we really want, to get the hang of it. But we could easily make physical contact with any planet on Alpha Centauri that's in a safe-enough orbit, take photos of the star and planets directly, etc. before my daughter pops her clogs.

That's pretty damn impressive.

That's not news, ...

[gauthamg]

... Asimov said so years ago! http://en.wikipedia.org/wiki/Foundation_and_Earth#Part_VI:_Alpha

Finally my ships are not going there in vain

[tequila_j]

I am glad to know that all the ships that I ve sent all these years are really going somewhere..

Win

[Anonymous Coward]

So the nation that first is able to send a space ship there with a colony wins?

Re:Frist stoP?!

[Anonymous Coward]

Implying slashdotters are significantly better?

Hurr, in soviet russia, linux put beowulf cluster on you.

Re:Uh oh...

[dywolf]

Idiom crits your language skill for 9999 damage. You have lost all knowledge of English and are reduced to grunting and pointing.

Re:Frist stoP?!

[Hal_Porter]

Well we need to put them in the oven too as weev memorably said of bloggers, but for some reason I get modded down here whenever I say that.

Next, we find the earthlike planets there

[whitroth]

Especially Rann. Now, *where* did I put my red flight suit and rocket packs?

                  mark "Alanna's waiting for me...."

Re:Uh oh...

[shiftless]

Please describe the machinery required to traverse four light years of space, with absolutely no resources available from Earth once it's on its way, and is 100% fail safe and will get there either within a useful human lifespan, or describe a way to (on top of the machine from step 1) slow down life processes reversibly and safely.

Warp drives. DUH. If that doesn't work then just reverse the polarity, or invert the modulation to the phase coils. Make sure you realign the sensor array first so you don't cause a cascade overload in the resonance dampers.

Nearest?

[Anonymous Coward]

I thought that award went to "Proxima Centauri"?

Re:Nearest?

[RockDoctor]

Proxima Centauri is a red dwarf which is (probably) in distant (IIRC about 15000 AU?) orbit around the Alpha Centauri A and Alpha Centauri B stars (orbiting each other at about 300 AU separation).

There is a moderate possibility that Proxima Cent is not actually in orbit around Alpha Centauri A and B, but with around 10 other stars in the same area of the sky having similar proper motions, then they probably constitute a "moving group" of common origin.

We must colonize it!

[Arancaytar]

Quick, gather seven intelligent, ruthless leaders with widely disparate ideologies and barely restrained hostility toward each other, then put them on course for the planet.

Technology development needed [Re: Power source]

[Geoffrey.landis]

We send an unmanned ship carrying all of human knowledge, a few robots, a bunch of DNA samples and the equipment needed to grow clones.

Well, that has been proposed-- for that matter, by me http://web.archive.org/web/20100409080615/http://www.space.com/scienceastronomy/generalscience/star_voyage_020319-1.html
(although I'm by no means the first)

We might not be able to do it now, but it's likely that we could in time.

Yes, quite a bit of technology development needed.

Of course, it's the planet Rann.

[tripwire45]

An earth-sized planet around Alpha Centuri. That's old news. I was reading about Adam Strange's adventures on Rann since the early 1960s: http://en.wikipedia.org/wiki/Adam_Strange

Re:Uh oh...

[RockDoctor]

Please describe the machinery required to traverse four light years of space, with absolutely no resources available from Earth once it's on its way,

With the currently plausible technology, it'd have to be a generation ship. We'd need them for exploring and fully utilising the Solar System, so by the time that we're in a position to seriously consider expanding to Alpha Centauri, we'll have generations of experience with them.

and is 100% fail safe

An unnecessary constraint. you only need to persuade the first generation of pilots, engineers, life-support specialists etc that they've got an adequate likelhood of surviving to their (natural) death on board. The offspring won't have any choice about it - they won't have the delta-V and energy to turn round without spending years in orbit near a star ... i.e. the Alpha Centauri system.

and will get there either within a useful human lifespan,

See previous comment. If you're effectively taking your family and all you really care about with you, on a on-way trip, then it doesn't necessarily have to be completed in your life span. Just set up the system so that the next generation onboard have no option but to continue with the mission that you signed up to. It's as dirty a trick as that played on pretty much all the children of the (European) settlers of America and Australia. [SOB]

In reality, quite likely the appropriate crew for the first inter-stellar voyage will have been living on "generation ships" working the outer reaches of the Solar System for several generations. So, the shock of reaching adolescence and finding out that you really don't have the choice of taming horses on the Argentine Pampas won't exactly be a new situation.

or describe a way to (on top of the machine from step 1) slow down life processes reversibly and safely.

Unnecessary. It may not be impossible, but the absence of such a technology isn't exactly a show-stopper.