Image: Warp Drive
Alexandre Szames  /  Antigravite
A warp drive works by creating folds in the underlying fabric of spacetime, as shown in this artistic concept created by Alexandre Szames. The concept is based on theories proposed by physicist Richard Obousy.
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updated 10/21/2010 3:51:26 PM ET 2010-10-21T19:51:26

Just last month, scientists announced the discovery of the first possibly habitable planet, orbiting a star 20 light-years from Earth. That's relatively close in astronomical terms, but beyond today's reach.

Estimates based on three key factors — finances, technologies and energy sources — all come to the same conclusion: The first missions to others stars will not be possible for another two centuries.

While that's a sobering answer, it's not the last word on the topic. Volunteers at the Tau Zero Foundation, the nonprofit organization I founded, are working to improve humanity's prospects in the decades ahead.

Interstellar flight is quite possible in principle, whether it's launching a probe to Alpha Centauri or sending a colony ship out of the solar system. The catch is that it takes a lot of work to pull it off. Global commitments beyond historical precedents would be needed. Sending spacecraft to other stars is as much a sociological challenge as a technical challenge.

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The technical progress being made toward interstellar flights was one of the topics discussed two weeks ago at the 61st International Astronautical Congress in Prague. Almost 3,000 professionals from the aerospace community gathered in Prague, the Czech capital, to bring each other up to day on the latest developments in space exploration.

Most of the discussions were about current space missions and the rise of commercial launch services, but there were also sessions on interstellar precursor missions, advanced space propulsion and the search for extraterrestrial intelligence. A few of the researchers in attendance are already making progress on meeting the challenges of interstellar flight. Here's a quick scan of that progress:

Solar sails:
Simple in principle, solar sails are large sheets of ultra-thin materials that are pushed by sunlight. Successful flight tests occurred this summer with Japan's Ikaros spacecraft. For interstellar missions, however, the sails would have to be at least thousands of times larger, and it would still take thousands of years to reach other stars. Using beamed power could reduce the requirements for sail size and travel time, but building those beaming systems would require global commitments.

Rockets work by blasting propellant rearward to push a spacecraft forward. If you want to go farther and faster, or send a bigger payload, you'll need more propellant ... and then you'll need even more propellant to propel that extra propellant.  It adds up exponentially to the point where interstellar rockets are astronomically difficult (and in some configurations, flatly impossible).

An international team of volunteers is pushing interstellar rocketry to its edge.  Finishing the first year of a five year study, this "Project Icarus" is a sequel to the 1970s-era "Project Daedalus," designed at creating a fusion-based interstellar probe. This study aims to deliver realistic estimates of what such technology could accomplish, along with estimates of what other milestones would be needed to make it happen — such as making the business case for extracting helium-3 from the atmosphere of Uranus, and building the communication network for deep-space exploration.  By reaching beyond the near-term horizons, such work sets the stage for a new wave of advancements to follow.

Precursor missions:
With actual interstellar flight still so daunting, numerous ideas are being discussed for smaller, learning missions.  These include missions through the heliopause, where our solar system meets with the galactic background, and missions far enough out to study the gravitational lensing of our own sun. Even now, NASA's Voyager 1 and 2 spacecraft are on their way through the heliopause. Among the mission concepts being considered for solar gravitational lensing are FOCAL and TAU.

Beyond technology by advancing physics:
Rockets and space sails operate within the laws of physics that we already understand, but their ultimate performance falls far short of timely missions.  This brings us to the next ambition — exploring the realm of unfinished physics in search for spaceflight breakthroughs.

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A book about these prospects, "Frontiers of Propulsion Science," was published last year by the American Institute for Aeronautics and Astronautics. It's not light reading. Weighing in at 730 pages, this technical volume is aimed at professional researchers and graduate students. But the basic concepts for breakthrough propulsion are easily understood by anyone who's watched "Star Trek."

If it were possible to move a spacecraft without propellant, the energy requirements drop exponentially. This is where notions of manipulating gravity or inertia come into play.  Such advances would also ultimately allow zero-gravity hotel rooms on Earth as well as crew cabins with artificial gravity for long-duration space missions, plus any number of other revolutionary advancements.

This might sound like science fiction, but the subject has matured to where several rigorous investigations have commenced, but mostly at the level of asking the right questions, with a few embarking on experiments. The key issues involve unsolved questions about the origin of inertial frames, the interactions of matter and energy when moving through those frames, and the coupling of gravity with the other fundamental forces.

Beyond the speed of light:
Before 1988, traversable wormholes were considered merely make-believe. And before 1994, warp drives were seen as impossible science-fiction plot devices. These challenges have now matured into normal scientific discourse and even appear as homework problems in general-relativity textbooks.

Rather than attempting to break the light speed limit through spacetime, these theoretical approaches manipulate spacetime itself to create shortcuts (wormholes) or to move 'bubbles' of spacetime (warp drives). The rate at which spacetime can move is inferred from the faster-than-light expansion that physicists say occurred just after the big bang.

The contentious issues are the implications of time travel, the magnitude of energy required, and the assertion that the energy must be "negative." Although negative energy states are observed in nature, there are unresolved debates regarding how much energy these states can hold, and for how long. Another recent conclusion is that wormholes appear to be theoretically more energy-efficient than warp drives.

To clarify a common misunderstanding, the category of space drives is distinct from the notions of faster-than-light space warping. As an analogy, consider moving an automobile across a landscape. The space-warping theories would move whole sections of the landscape to carry the automobile toward the desired destination. This requires substantial energy expenditures, but also opens the way for creating faster-than-light pathways.

The space drive perspectives, on the other hand, consider how the automobile might move under its own power relative to that landscape, in a way analogous to tires pushing against the ground. The energy requirements are minimal, but travel is limited to less than light speed.

Regardless of whether such abilities are achievable, pursuing interstellar flight adds another perspective for advancing technology and solving the lingering mysteries of physics. In addition to the unsolved connections between gravity and the other fundamental forces, cosmological observations have presented us with the mysteries of dark matter and dark energy, plus anomalies surrounding the trajectories of deep space probes.

Quantum physics — which is profoundly useful on extremely small scales — has not yet been successfully extended to cosmological scales. There is plenty of physics yet to be discovered.

Keeping up:
If you are interested in such activities, stay tuned to the "Centauri Dreams" news blog. This blog is part of the Tau Zero Foundation — a volunteer network of more than four dozen researchers, educators and journalists who collaborate on the methods, lessons and inspirations of interstellar flight. We hope the work of our nonprofit foundation will pave the way to eventually reach other habitable worlds, and you can contribute as well.

Marc Millis is the founder and president of the Tau Zero Foundation, and the former head of NASA's Breakthrough Propulsion Physics program.

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Explainer: 10 pieces of Star Trek tech

  • Paramount Pictures

    The latest reboot of the Star Trek franchise follows the story of a young James Kirk on his way to becoming captain of the Starship Enterprise. The movie gives Trekkies a fresh dose of fictional high-tech wizardry. But is any of this possible in the real world? Click the "Next" arrow above to see how 10 pieces of Trek tech, from teleportation to warp drive, are faring here on Earth.

    -- By John Roach, MSNBC contributor

  • Teleportation: a work in progress

    Ray Strange  /  AFP via Getty Images file

    "Beam me up, Scotty!" Oh, how easy travel would be if the technology existed to disintegrate our bodies in one place and nearly instantaneously make them reappear at our destination. Unfortunately, that kind of teleportation remains firmly fixed in the realm of Star Trek fiction. However, scientists are meeting with some success as they try to teleport messages encoded in beams of light across table-length distances, such as this experiment from 2002. More recent advances include teleporting information from one trapped atom to another.

  • Tricorder-like device scans for cancer

    Boris Rubinsky et al.

    Star Trek fans know tricorders as familiar handheld devices that scan unfamiliar planets (and organisms). Real-world citizens, too, are becoming familiar with a host of futuristic gizmos that do everything from reading a critter's DNA to scanning patients for cancerous tumors, as shown in this side-by-side comparison of a fictional tricorder (left) and a medical scan of simulated breast tumor displayed on a cell phone.

  • Deflector shield envisioned for Mars missions

    Ruth Bamford And John Bradford

    A so-called deflector shield surrounds the Starship Enterprise, protecting the spacecraft and its crew from lethal doses of radiation. Lab experiments now suggest that a portable magnetic shield could protect real-life astronauts on a mission to Mars. The shield would force harmful particles to curve around the ship. The engineering details remain to be worked out, and for now, the shield protects only against particles from the solar wind. Gamma rays and X-rays would remain a threat. An artistic depiction of the technology deployed on the Enterprise is shown here.

  • U.S. Air Force develops PHaSER

    Image: PHaSER
    U.s. Air Force

    The weapon of choice for Trekkies is the phaser, a device that directs an adjustable beam of energy at its target. The phaser is capable of a range of effects, from a momentary stun to instant obliteration. The U.S. Air Force has developed its own prototype device with the Star Trek moniker PHaSER (Personal Halting and Stimulation Response). The hefty gunlike device was originally developed to blind an attacker temporarily. A second laser has since been added capable of heating up skin.

  • Holodeck tech emerging

    Tom Uhlman  /  AP

    Starfleet members seeking knowledge or fun can step into holodecks to experience an interactive virtual reality eerily close to life itself. Similar technologies are beginning to emerge in the real world, including this 3-D lab at Wright State University in Ohio, where businesses can use the technology to speed up and improve the designs of products. An energy company is using it to enhance their search for oil. Other firms are embracing advances in video and audio technology to make telepresence, or videoconferencing, more realistic. The most lifelike experiences, however, remain in science fiction.

  • Tractor beam manipulates cells on a chip


    In Star Trek, tractor beams are used by starships and space stations to control the movement of objects usually to pull them in closer, tow them along, or push them away. Researchers at the Massachusetts Institute of Technology have used a tractor beam of light to pick up, hold and move around individual cells on the surface of a microchip. To demonstrate the technology, the researchers moved around and held in place 16 E. coli cells to spell out MIT, as shown in this image.

  • Cell phones are pretty good communicators

    Apple Inc. via AP

    Trek-style communicators are those little devices, handheld or sometimes worn as a badge, that allow Starfleet members to speak to others in different parts of the ship or different parts of a planet. Modern-day cell phones, including the iPhone shown here, just might wow even the likes of Captain Kirk.

  • Universal translators making strides


    In Star Trek, language is seldom a barrier thanks to universal translators, devices that allow people of different tongues to converse. Communication among cultures in the real world remains a challenge, but basic words and phrases are no longer stumbling blocks, thanks to gadgets such as the translator from iTRAVL shown here. Speak into the device, and it will translate the word or phrase and speak it aloud.

  • Cloaking devices coming out of hiding

    Naomi Halas, Rice University |

    Cloaking devices are rampant in science fiction, from Star Trek to Harry Potter but they are no longer confined to the imagination. Real-world scientists are creating new materials that manipulate wavelengths of light in ways that can hide objects from detection. This graphic shows the basic design of a 3-D metamaterial lined with nanocups that redirect the flow of light that hits it, making the object invisible.

  • Warp drive? Don't bet on it

    Les Bossinas  /  NASA

    The Enterprise can travel faster than light via something called warp drive — essentially, a device that warps the space-time continuum around a starship. Many scientists have batted around ideas about how to achieve blistering speeds in real life, but most experts have concluded that, at least for now, warping the fabric of space is beyond human understanding of the laws of physics. Among the difficulties is harnessing the energy required to kick-start the propulsion.


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