Alpha Centauri—our first target for interstellar probes?

February 22, 2016 by Tomasz Nowakowski, Astrowatch.net, Universe Today
Alpha Centauri—our first target for interstellar probes?

With the completion of New Horizons' Pluto fly-by, its primary mission, should we now set our sights even higher, ambitiously taking aim at other star systems? If so, Alpha Centauri would probably be considered as the best target for an interstellar spacecraft due to its "proximity" to Earth. This system, consisting of three stars and possible planetary companions, is the nearest to the solar system, located "only" about 4.3 light years from the sun. The problem is that getting there within a human lifetime is still a mission impossible—or is it?

The neighboring system hosts a pair of stars named Alpha Centauri A and Alpha Centauri B. Alpha Centauri C, also known as Proxima Centauri is a small and faint "red dwarf"—a small and relatively cool star – and may be gravitationally bound to the duo. However, what baffles astronomers is the existence of exoplanets in this system. In 2012, the discovery of a planet orbiting Alpha Centauri B was announced, but three years later, new research disproved this theory, calling the previous finding a "ghost in the time series." Moreover, in 2015, another study proposed the existence of an alien world orbiting the "B" star.

Interestingly, the two hypothetical exoplanets would probably be Earth-like if they really exist. This could be another motivator to send spacecraft there. But before any mission concepts are prepared, a deeper look into the system could be very helpful. The obstacle is that we don't currently have a telescope that can directly image a planet in this system.

"This would have to be done from space—even then, it would be hard. We don't have a space telescope that can do this right now, especially for small planets. There are no gas giant planets there. If there were any, we would have detected them," Debra Fischer, astronomer and exoplanet hunter at the Yale University, told Astrowatch.net.

4.3 light-years equals 25 trillion miles, so knowing at least some basic information about this destination is quite essential before embarking on such a demanding trip. Using current technology, a robotic probe sent from Earth would require some 40,000 years to reach Alpha Centauri, making the mission irrelevant.

NASA's New Horizons spacecraft, which is the fastest-moving spacecraft ever launched from Earth, currently travels at about 36,400 mph. If the probe was aimed at the Alpha Centauri system, it take 78,000 years to arrive!

A huge technology advance is required to make interstellar journeys feasible. Unless a new propulsion system can be developed, every interstellar mission concept is doomed to fail.

"Once we have the ability to accelerate a probe to 10 percent the speed of light, that is the first place we'll go! It's the closest star system and therefore a great target," Fischer said.

In the past, project proposals included sending unmanned interstellar spacecraft with a velocity of 4.5 or even 7.1 percent the speed of light. Between 1973 and 1978, a study was conducted by the British Interplanetary Society to send a probe using a fusion rocket that would reach Barnard's Star, located 5.9 light years away. The study, named "Project Daedalus," aimed to develop a spacecraft capable of reaching up to 7.1 percent the speed of light; thus, the entire journey would take only 50 years.

A similar study, "Project Longshot," was developed by the U.S. Naval Academy and NASA, from 1987 to 1988. The project would use a spacecraft powered by nuclear pulse propulsion to reach an average velocity of approximately 30 million mph (4.5 percent the speed of light). That would allow the mission to arrive at Alpha Centauri some 100 years after launch.

There are many concepts and projects tasked with designing a future propulsion system to allow interstellar travel. Contrary to ideas based on conventional propulsion, many concepts include using antimatter rockets, warp drive or wormholes.

A laser-powered interstellar sail ship is an original concept that seems feasible in the near future. It was presented by Geoffrey A. Landis of NASA's Glenn Research Center in 2002. Landis described a starship with a diamond sail a few nanometers thick, powered by solar energy, which could achieve 10 per cent of the speed of light. Using this type of propulsion, it would take 43 years to reach Alpha Centauri, assuming it simply passed through the system. However, slowing down to stop at the neighboring system could increase the trip by up to 100 years. Thus, it would be more appropriate for a fly-by mission performed by an unmanned probe.

When will we be able to develop such a propulsion system allowing travel at around 10 percent the speed of light? That remains in dispute.

"We have to have the probe travel faster than 10 percent the speed of light and we need a high-gain antenna in the outer solar system to pick up the signal that the probe sends back. This is a technology horizon that currently seems far away. 50 years? 100 years? Hard to say!" Fischer said.

Explore further: Hubble's new shot of Proxima Centauri, our nearest neighbor

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antialias_physorg
3.6 / 5 (9) Feb 22, 2016
Using current technology, a robotic probe sent from Earth would require some 40,000 years to reach Alpha Centauri, making the mission irrelevant.

As with Moore's law we could formulate an estimate that would state "technological advances will lead to a twice as fast propulsion system every X years"

Depending how robust such an estimate is you can then easily calculate the date of launch (when launch date plus flight time gets you the earliest arrival date...possibly when launch date plus flight time plus exploration time plus return trip time gives the earlist date...as there is no real way of transmitting data from Alpha Centauri back to Earth, yet).

Launching right now would be rather pointless because we are still in an era of rapid development of propulsion systems.
vlaaing peerd
5 / 5 (4) Feb 22, 2016

As with Moore's law we could formulate an estimate that would state "technological advances will lead to a twice as fast propulsion system every X years"


Moore's prediction, as I prefer to call it, is very specific about the development of one particular technology and though he is proven right for some time now, it's rather a very good guess than a scientific method.

I don't think it will work for applying it to increasing our space travel speed. It's more a matter of when we will invent the fusion/ion/etc drive. And once it's there, I really think we'll shoot something to a nearby star in a matter of years.
antialias_physorg
3.6 / 5 (9) Feb 22, 2016
It's more a matter of when we will invent the fusion/ion/etc drive.

We'd still be talking of a turnaround time of over 200 years. Even fusion drives will not be fully optimal once invented. You can always plot the increase in efficiency of a technology and make a best estimate when the best time for launch will be. Even if it isn't linear you can see from such a plot when advances taper off and launch then.

Launching when the projected flight time is on the order of hundreds (or thousands) of years is pointless for several other reasons besides flight time. We have no technology that reliably doesn't require servicing for such a duration (Least of all something as complicated as fusion drives). Until we have self servicing tech or AI that can adapt to any kind of servicing task this is a no-go.
chileastro
3.3 / 5 (7) Feb 22, 2016
The Pioneer probes are way out there, moving quite fast for a probe, but it would still take them thousands of years to get to the nearest star. This is like people whose greatest invention is the wheel deciding to build a SR-71 in the next few decades. That's the difference there would need to be.
Mayday
5 / 5 (2) Feb 22, 2016
Hard to believe that the author didn't even mention or reference Mae Jemison and the 100 Year Starship project and annual international symposiums on advancing research on interstellar travel. They have done much to advance the thinking in these areas. I've gone twice and hope to attend again.
matt_s
4.3 / 5 (6) Feb 22, 2016
@anti, I saw an analysis similar to what you're suggesting, but it took the energy necessary to reach a nearby star and compared it to the energy output of the entire human civilization to estimate time frames... let me dig it up here.

Eh, here's the pop sci overview
http://www.popsci...ulations
TechnoCreed
5 / 5 (6) Feb 22, 2016
The Pioneer probes are way out there, moving quite fast for a probe, but it would still take them thousands of years to get to the nearest star. This is like people whose greatest invention is the wheel deciding to build a SR-71 in the next few decades. That's the difference there would need to be.

"On 17 February 1998, Voyager 1's heliocentric radial distance equaled Pioneer 10 at 69.4 AU and thereafter exceeded Pioneer 10 at the rate of 1.02 AU per year." http://www.nasa.g...eer.html

At 134au Voyager 1 the is the farthest human made object. http://voyager.jp...v/where/

eachus
5 / 5 (1) Feb 22, 2016
There is a shortcut, but... Build a (chemical) rocket and use a slingshot maneuver at Jupiter to send it toward the sun. Actually you don't need any oxidizer. When the probe gets near enough to the sun, solar radiation can be used to heat a hydrogen working fluid to rocket exhaust temperatures. Use a magnetic nozzle to get further specific impulse. Even if you have to point the exhaust directly at the sun...

The problem with this approach is you can only get an extra boost that is a fraction of the orbital velocity of the probe when you light it off. Six hundred km/sec is a rough BoE of what can be accomplished--and that takes most of the probes mass as LH2 to throw out the back.

So what good is it? Sending a telescope even a few light-days from Earth, a duplicate of JWST is a good working model lets you measure distances to stars hundreds of light years away directly. Also looking back at the solar system should help in finding Kupier and Oort cloud objects.
wduckss
1 / 5 (1) Feb 22, 2016
No need to go towards the light the lamp. Nearby is Proxima Centauri, which is more likely for finding a planets suitable for life.
The binary system leads to a turbulent and dynamic geological processes of the planets in the system.
Speed is possible with new thinking a significant increase.
Mark Thomas
3.3 / 5 (6) Feb 22, 2016
While we are obviously not ready to launch a probe to Alpha Centauri just yet, thinking about it reminds us that telescopes are going to be where the action is for a long time. It would be incredibly helpful to know exactly what is next door in the Alpha Centauri system. While a number of space and ground based telescopes will try to answer this question, the proposed ATLAST space telescope might be the tool to do this. ATLAST is envisioned as a NASA flagship mission of the 2025 – 2035 period, and in one form, could characterize the atmosphere and surface of an Earth-sized exoplanet in the Habitable Zone of long-lived stars at distances up to 140 light years. http://arxiv.org/...1.3841v1
baudrunner
1 / 5 (2) Feb 22, 2016
We need something other than rocket propulsion for that. They are just too inefficient.

The Russian probe Phobos 1 imaged a long cylindrical object just before the probe mysteriously stopped transmitting. Long cigar shaped objects have been spotted in the sky before. It's impossible to know how big they were, because it was impossible to know how far away they were. Then, there's that 5 km long object near Izsak crater, on the far side of the moon. It was probably one of those.

So, here's some food for thought. Ever played with one of those gel-capsule like toys with the little ball-bearing inside it? Scale it up to where it's about 5 kilometers long and devise a way to use the momentum of that internal bearing to propel it forward. Just a single rotation of that cylinder will move it forward by five kilometers. If acceleration can be achieved, then we would have a space faring habitat - with gravity, no less, provided by the rotational characteristics of the device.
Osiris1
1 / 5 (2) Feb 23, 2016
:No one seems to want to even think about a warp drive, but THAT is the BEST way to go. Someone even mentioned the idea that the Chinese EmDrive of the next generation of superconducting units could acheive this. Of course our government is verrrry 'mum' about it. One of them might talk but then would have to 'remove the person talked to from society'.Would not put it past the 'guv' to have a working 'stargate'.
antialias_physorg
3 / 5 (6) Feb 23, 2016
No one seems to want to even think about a warp drive, but THAT is the BEST way to go.

Plenty of people are thinking about it. But currently there's a few problems associated with it that we have no clue how to solve (and some issues which may even mean that they are impossible)

So 'best' is a rather relative term. If it could be made to work it would be best. If it can't be made to work it would be worse than getting out and pushing.

The EM drive doesn't seem to work (not surprisingly, as it violates conservation of momentum)
Sonhouse
4 / 5 (1) Feb 23, 2016
One thing about AC, you get three for one, three stars in that triple system withing 1/10th ly and 2 very close to each other. It's a win win situation as to where to go first. The propulsion system is another issue. The actual design for anti matter thrusters is ahead of the design for fusion. If we can get enough anti matter and stored safely, an anti-matter rocket would be relatively easy, at least compared to fusion and it would be a LOT more powerful pound for pound. To get antimatter rockets you just aim the stream of anti stuff to meet the regular stuff and instant energy which can then be used to produce ions shooting out the ass end close to the speed of light. Easy peasy:)
antialias_physorg
3 / 5 (6) Feb 23, 2016
If we can get enough anti matter and stored safely

For these two reasons I don't think it's ahead of fusion. At least we know how to do fusion and are on the way to building real powerplants.
With antimatter we have no clue where to find enough of it or how to store it. Particularly the storage is a problem as the methods that exist require energy. This eats into your antimatter reserve exponentially with trip duration (as you need to spend antimatter to generate power to power the storage cells).

..and, of course, if you have even the most minute failure (on a craft without any maintenance for centuries!) you have just sent the worlds most expensive interstellar bomb.
Mark Thomas
3 / 5 (4) Feb 23, 2016
"No one seems to want to even think about a warp drive, but THAT is the BEST way to go."

Of course! But AAP is right, we don't know enough to even confirm it can or can't be built right now. By analogy, let's say you travelled back in time 300 years and folks back then were begging you for the secrets of flight. You could try to lay out all the details such as metals they hadn't discovered (aluminum), fuels they don't know about and how to refine (jet fuel), the physics involved (Bernoulli Effect, internal combustion, electrical ignition), but they clearly wouldn't be ready. The better approach would be to convince them to relentlessly push and evolve their science and technology. Most importantly, they must dedicate their minds and hearts to boldly go where no one has gone before. With that flight and warp drive will both be assured, or at least we will take it as far as it can go.
Sonhouse
5 / 5 (1) Feb 23, 2016
The amount of antimatter V matter is about 10 billion to 1. That means if you have 1 billion grams of matter floating around in space there should be 1 gram of anti stuff. There is a plan to capture that little bit of antimatter by having this giant chicken wire sphere charged up to around a hundred million volts designed to attract antimatter, what little there is, and collect it inside with magnetic and electric trickery.

For instance, the amount of antimatter needed to launch the space shuttle would be measured in milligrams so you can see we wouldn't need a whole lot of the stuff. I don't think we will ever be able to create anti stuff on Earth, I think it will take some kind of capture method like the big chicken wire idea in space to get usable amounts.

Once we actually have a gram or so, the actual rocket is not that big an engineering project.
baudrunner
1.5 / 5 (2) Feb 23, 2016
An anti-matter drive would require an anti-matter production facility on board. This requires a re-think on the method of production, because current methods are hopelessly inefficient and expensive. So that kind of propulsion, and Warp drive, are yet in the realm of sci-fi, and not likely to be realized in the foreseeable future.

I think we need to think BIG.
baudrunner
1 / 5 (2) Feb 23, 2016
Then of course there is the space elevator. First step, build the elevator. Second, assemble massive fuel tanks in orbit. Third, fuel the tanks from Earth using the elevator, either by delivery, or directly by a super long fuel line, highly unlikely unless some genius figures out a way to overcome the obvious.
pnyikos
3 / 5 (2) Feb 23, 2016
How soon we forget even such widely distributed articles such as the one published a year or two ago in _National Geographic_! It gave four ways of reaching for the stars, the first of which used technology well within reach: exploding hydrogen bombs behind a spaceship with a "pusher plate" at the back and giant shock absorbers.

Back in the 1970's there was even a project sponsored by the Air Force called "Project Orion" that aimed towards the production of such a ship. It was envisioned for manned missions to the outer planets, but the costs for an instrumental flyby would be much smaller.

Freeman Dyson published a lot of details for an interstellar probe of this nature in:

"Interstellar Transport," Physics Today, October 1968, pp. 41-45.

Among the details is a design that would reach a speed of 1 parsec per century; so a flyby of Alpha Centauri would take about a century and a half.
Mark Thomas
2 / 5 (3) Feb 23, 2016
For a world still not ready for nuclear thermal rockets, and unable to create fusion rockets, it is going to be a real stretch to get behind Antimatter Catalyzed (initiated) Micro Fission/Fusion(ACMF). However, if we decided that we absolutely must have a probe reach Alpha Centauri by the end of the century, this would be our best bet.

http://www.nss.or...sion.pdf
antialias_physorg
3.7 / 5 (6) Feb 24, 2016
An anti-matter drive would require an anti-matter production facility on board.

Erm...let me get this straight: You are suggesting a facility that creates that which you then destroy in order to get the energy to move the craft?.

I hate to tell you this, but have you heard of this niggling thing called "conservation of energy"?
(Read: yours is the dumbest idea that has been posted on physorg for quite some time. And given some of the posters on here that is a pretty neat trick.)

I think we need to think BIG.

You should start with the 'think' part...never mind the 'big'.

Then of course there is the space elevator. First step, build the elevator. Second, assemble massive fuel tanks in orbit.

First step: do magic.
Second step: have infinte amounts of cash
Great ideas (/sarcasm)

(BTW: If we could get loads of antimatter then a space elevator really isn't necessary anymore)
baudrunner
1 / 5 (3) Feb 24, 2016
I hate to tell you this, but have you heard of this niggling thing called "conservation of energy"?
(Read: yours is the dumbest idea that has been posted on physorg for quite some time. And given some of the posters on here that is a pretty neat trick.)
I didn't propose that idea. If you would hone your reading comprehension skills, you would realize that what I said was pretty much an invalidation of the anti-matter propulsion concept.

You are just an ignorant, simple-minded troll who seeks only to criticize and attack posters. Go away. Bother somebody else.
javjav
3 / 5 (2) Feb 25, 2016
An anti-matter drive would require an anti-matter production facility on board.
(Read: yours is the dumbest idea that has been posted on physorg for quite some time. And given some of the posters on here that is a pretty neat trick.)
I agree, I vote it number one.

Regarding interstellar probes, I think no technology is ready or nearly ready for this. Meanwhile it is better to invest in bigger and more advanced telescopes, as we are seeing real progress and very interesting advances in this area. There are new concepts that could image exoplanets directly. Even if expensive, they are technically possible or not very far. Does anybody now what happened with the Focus project? ( to send a telescope to 150 AU, to the focal distance of the sun for its usage as a gravitational lense ... )
javjav
3 / 5 (2) Feb 25, 2016
Sorry, 550 AU, not 150.
eltodesukane
not rated yet Mar 16, 2016
I favor other priorities.
Following New Horizons' flyby of the dwarf planet Pluto, we should do similar missions to Uranus and its moons, and to Neptune and its moons. It's a shame that 39 years after the launch of the Voyager missions in 1977, we are still waiting for the next mission to Uranus and Neptune.

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