Artist’s impression of the planet around Alpha Centauri B. Credit: ESO

We Explored Pluto, Now Let’s Explore The Nearest Star!

Article written: 25 Feb , 2016
Updated: 26 Apr , 2016

On July 14th, 2015, the New Horizons space probe made history when it became the first spacecraft to conduct a flyby of the dwarf planet of Pluto. Since that time, it has been making its way through the Kuiper Belt, on its way to joining Voyager 1 and 2 in interstellar space. With this milestone reached, many are wondering where we should send our spacecraft next.

Naturally, there are those who recommend we set our sights on our nearest star – particularly proponents of interstellar travel and exoplanet hunters. In addition to being Earth’s immediate neighbor, there is the possibility of one or more exoplanets in this system. Confirming the existence of exoplanets would be one of the main reasons to go. But more than that, it would be a major accomplishment!

Located 4.3 light years from Earth, the Alpha Centauri system consists of three stars – Alpha Centauri A, B, and C (aka. Proxima Centauri). For many years now, exoplanet hunters have been divided on the issue of whether or not it has a system of planets. This began in February of 2008, when a team of European observers working at the European Southern Observatory’s La Silla facility in Chile began searching for a possible exoplanet in orbit of Alpha Centauri B – which was designated Alpha Centauri Bb.


Alpha Centauri A and B (shown to scale), and their respective habitable zones (not to scale). Credit: PHL/UPR Arecibo

Using the Doppler spectroscopy method, they recorded measurements of Alpha Centauri B’s radial velocity and color spectrum over a four-year period. They then applied statistical filters to remove known sources of variance to be sure that what they were detecting was indeed a planet, and not background noise.

In October of 2012, in an article submitted to the scientific journal Nature, they officially announced the existence of Alpha Centauri Bb. According to the team, the planet was similar in mass to Earth and orbited Alpha Centauri B within its habitable zone (aka. “Goldilocks zone”). This made it the closest Earth-like exoplanet discovered to date.

However, three years after the announcement, in October 2015, researchers from the University of Oxford published a paper entitled “Ghost in the Time Series” which indicated that there were flaws in the original analysis. According to the paper, the signal that was observed by the ESO team naturally arose from the “window function” of the original data – aka. it was a ghost signal.

However, in March of 2015, the same scientific team published a paper that proposed the existence of other alien world orbiting Alpha Centauri B. Using data from the Hubble Space Telescope, they discovered evidence of a possible transit in front of the B star. If confirmed, this planet would be called Alpha Centauri Bc, and is apparently located too close to its parent star to support life.

Artist's concept of Dawn above Ceres around the time it was captured into orbit by the dwarf planet in early March. Since its arrival, the spacecraft turned around to point the blue glow of its ion engine in the opposite direction. Image credit: NASA/JPL

Artist’s concept of Dawn above Ceres. Since its arrival, the spacecraft turned around to point the blue glow of its ion engine in the opposite direction. Image credit: NASA/JPL

Hence why scientists like Dr. Debra Fischer – a professor of astronomy at Yale University, and a member of the Planetary Society who has discovered hundreds of exoplanets – are advocating for a mission to the Alpha Centauri system. As she told Universe Today via email:

“The Kepler mission demonstrated that almost every star has planets and we have found planets orbiting stars that are in binary systems not too different from Alpha Centauri. It’s a good bet that there are planets there that we just have not been able to find yet, given current precision… It will likely take a spacecraft in a low Earth orbit with sufficient measurement precision to detect small rocky planets in the system.  Once we find them, then we will be highly motivated to send robotic spacecraft to look for life.”

Naturally, sending a spaceship to the nearest star system represents a major challenge. As we explained in a recent article – How Long Would It Take To Get To The Nearest Star? – even with our most advanced technology, it still would take thousands of years to reach Alpha Centauri – between 72,000 and 81,000 to be exact. Considering that 3000 to 4000 generations would pass between launch and arrival, that hardly seems worth it.

Even reckoning for the fastest speed ever achieved by a spacecraft – 240,000 km/hr (150,000 miles/hr), which was accomplished by the Helios 2 probe in the late 1970s – the trip would still take a whopping 19,000 years. In order to make this trip is a single lifetime, during which the spacecraft could reach Alpha Centauri and radio back its findings, something new and experimental would need to be developed.

Weighing in at 60,000 tons when fully fuelled, Daedalus would dwarf even the Saturn V rocket. Credit: Adrian Mann

Weighing in at 60,000 tons when fully fuelled, Daedalus would dwarf even the Saturn V rocket. Credit: Adrian Mann

For decades now, ideas ranging from nuclear-thermal propulsion and solar sails have been considered, and some of these proposals are within the realm of possibility. At the more radical end of things, concepts such as nuclear-pulse spacecraft (i.e. Project Orion), fusion containment (i.e. Project Daedalus, shown above) and fusion ramjets have been suggested – ideas that, while possible, would be incredibly expensive to build.

And whereas some of these concepts are feasible in the near-term (and using current technology) others are still very much in the theoretical phase, like the Alcubierre “Warp” Drive. Others still, such as the Radio Frequency Cavity Thruster (aka. the Cannae, or EM Drive), have been tested, but not to satisfaction of many in the scientific community.

But as Fischer explains, these sorts of challenges have not stopped us before. And there are several options on the table, the development of which could have beneficial applications here on Earth.

“When you study the energy requirements, it is a daunting goal,” she said. “But needing to beat the odds has never stopped us before. We would need to figure out how to accelerate a swarm of networked robotic spacecraft so that they can reach this star system in something like 40 years. “We will have to build receivers with the sensitivity to pick up messages from the Alpha Cen bots. The pathway to solving those questions will have technology spinoffs as impactful as cell phones, lap tops, or GPS.”

The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA

The distance between our Sun and Alpha Centauri (and all that lies in between) using a logarithmic scale. Credit: NASA

Regardless of the destination, any bold new step in the field of space exploration will have to involve serious planning and careful consideration. Now that we have effectively explored the Solar System, reaching beyond will be a major challenge. But as the history of space exploration teaches us, accepting a major challenge is a great way to bring out the very best in us.

Even when the goal seems insurmountable at first glance, working towards it can lead to many great and interesting breakthroughs, some of which have far-reaching benefits. As Fischer added, setting Alpha Centauri as our next goal is every bit as ambitious as our ancestors decision to go to the Moon, and offers similar rewards.

“The exploration of Alpha Centauri is a grand vision for humanity,” she said. “In the 1960’s, we sent Apollo missions to explore the moon, and humanity just took another big leap with the New Horizons mission, traveling to the outermost reaches of our solar system. Sending a mission to Alpha Centauri could be the next big stepping stone.”

Here’s hoping some of our more radical ideas start bearing fruit in the coming years. Otherwise, any missions to Alpha Centauri will be very “slow boat” in nature, and I for one would like to live to see what’s really there!

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17 Responses

  1. Patreon
    Hematite says

    I wonder if the same physical process that allows the tip of a whip to exceed the speed of sound as a wave accelerates down the ever narrowing whip could somehow be used to accelerate a space probe. It would likely take a really long and strong whip to get to something like 0.1xlight speed.

  2. InTheory says

    Considering the extremely slow rate of data received from New Horizons, devising new methods of communications will be just as important as any other aspect of a project of this magnitude.

    We’re probably hundreds of years away from having the technology to do this properly. Until then we should concentrate on building bigger and better telescopes and just learn to be happy with observational data collected by them.

    We’ll get there, just not anytime soon.

    • CoacervateDroplet says

      Have you looked into this problem beyond the Horizon technical limitations? How does your comment help us>

      My father once quoted to me that the meaning of life is to plant a tree knowing that you will not live to enjoy its shade. I’m 62. Lets get planting now for our children’s children’s children. They will so pleased with us.

  3. CoacervateDroplet says

    Thank you for this exciting piece. I literally got a chill just thinking about it.

    Matt, do you have a website? Have you written any books? I need them! If I could make a wish it would be that you and Paul Gilster at collaborated on a book about our nearest star system. I’m not an astrophysicist so all the technical papers are difficult to read let alone find. You guys would make a great team for the masses! We’ve got to get people onboard if this thing is to fly.

    Also, IF LENR turns out to be real, could it be applied to propulsion? would that make continuous acceleration/decelation travel possible?

    I always look for your top quality writing.

  4. dimobi says

    Why is Alpha Centauri called a system of three stars? What does a star system mean?

    • Patreon
      Hematite says

      A star system is what they call two or more stars orbiting around their mutual center of mass. Most of the time the brighter star in the system is called “alpha”, and the next brightest, “beta” and so on. The Centaurus system has three stars: Alpha and Beta Centauri are relatively close to each other, while the third star, Proxima Centauri (normally it would be gamma but it gets its name for being closets to the sun) is a red dwarf star that orbits the other two at a distance.

  5. Patreon
    Cyrus says

    Hey Matt,

    When are we going to be able to get telescopes trained on this place so that we can figure out the planet situation? A.k.a. are James Webb or the Transiting Exoplanet Survey Satellite going to be able to satisfy our thirst for galactic buddies? And if not, why not? What kinds of telescopes do we need to figure out if the closest star system to us has planets?


    • Good question. And that is certainly the hope. My belief is that they will greatly add to our catalog of exoplanets, and help us refine our knowledge of them to the point that we are far more certain which ones are habitable and which ones are not. However, they will be just another step in a long series of experiments that will bring us incrementally closer to knowing what we want about our stellar neighbors. I honestly think we will not be satisfied until we can send a probe to Alpha Centauri, hopefully one which can utilize quantum entanglements and/or superposition to send messages back at FTL speeds (though I hear this may be a pipe dream due to “decoherence”)

      • Patreon
        Cyrus says

        I don’t mind waiting the 4 years for the transmissions, but we should figure that FTL stuff out soon rather than later.

  6. Bob Andersson says

    For the cost of one interstellar probe consider what size and capability one could engineer into a “space telescope”. Instant results once it’s commissioned and, even better, it wouldn’t be restricted to “visiting” a single star. Do you remember the 1997 film Contact? Baby steps…

  7. Patreon
    LordJohn says

    Well the next best thing we can do is improve our imaging. The article

    shows a way that we might see things better. Also do look up thwe British Interplanetary Society’s study on a stapship Project Daedalus. Also check out Starwisp.

    Yes people have been thinking already – we now just have more to encourage ideas and the like.

  8. Patreon
    LordJohn says

    Well the next best thing we can do is improve our imaging. The article shows a way that we might see things better. Also do look up thwe British Interplanetary Society’s study on a stapship Project Daedalus. Also check out Starwisp. Yes people have been thinking already – we now just have more to encourage ideas and the like.

  9. Zoutsteen says

    “Human … phone … home”

  10. SteveZodiac says

    You wouldn’t all be so keen if you’d read The Three Body problem by Cixin Liu!

  11. Snerdguy says

    Technology has to evolve with advancement building on advancement. Right now, we still rely mostly on technology from hundred years ago to put objects and people into space. There are a number of theories for better propulsion systems. But, they are probably generations from being practical. What needs our focus right now is the Internet. It’s going to be the resource that allows scientists to work together to develop new technologies. But, in the US, the Internet has become overcrowded and stagnant. A lot of our population still can’t get high speed Internet and even those that can find it to be frustratingly slow and unreliable. A project as massive as Interstellar travel will need worldwide participation and everybody will need to be connected. So, advancing the Internet is the first step toward reaching the stars and keeping science moving.

  12. sangos says

    The first step is to map out the system with telescopes. Lets get that accomplished before worrying about the centauri probes, propulsion and what not. Gotta do it in steps to achieve the goal.

Comments are closed.