L. Calcada / N. Risinger / ESO

An artist's conception shows the planet orbiting Alpha Centauri B, a member of the triple-star system that's closest to Earth. Alpha Centauri B is the most brilliant object in the sky, with Alpha Centauri A at lower left and our own sun visible as a bright speck at upper right.

Chances are that no one alive today will ever travel to Alpha Centauri B b, the boiling-hot, Earth-scale planet detected a mere 4.37 light-years away, but that doesn't mean we have to put off planning for the trip. Even though this particular planet isn't habitable, there might well be more than one reason to take a close look at the star system.

"If you have one planet that's stable there, there's a good chance that there are other planets, too. That would be really exciting, to have it so close, even though it's really far away," said Dirk Schulze-Makuch, an astrobiologist at Washington State University who's a co-author of the e-book "How to Develop the Solar System and Beyond." 

So how can it be done?

As the late science-fiction novelist Douglas Adams once said, space is vastly, hugely, mind-bogglingly big. That definitely applies to the distance between the sun and its closest stellar neighbors in the Alpha Centauri triple-star system. The fastest spaceship ever launched, NASA's New Horizons probe, will require nine years to get to the dwarf planet Pluto — and Alpha Centauri is more than 6,500 times farther away.

The twin Voyager spacecraft are just now approaching the edge of our own solar system, 35 years after they were launched, but at their current velocity it would take them 70,000 years or so to go as far out as Alpha Centauri.

The only hope is that next-generation propulsion technologies could raise the top speed and reduce the travel time to the scale of a civilization's lifetime, if not an individual's lifetime. And that's not easy. "The amount of energy that's needed is usually the part that catches people by surprise," said Marc Millis, founder of the Tau Zero Foundation and a visiting scholar at the Ohio Aerospace Institute.

Forget about warp drive: For now, let's talk about physics we actually understand. Because of the way propulsive energy scales in relation to distance, you'd need an engine a million times more powerful than Voyager's to bring the travel time to Alpha Centauri down to a human time scale, Millis said. That's such a tall order that even Kim Stanley Robinson, who writes about routine interplanetary travel in his latest novel, "2312," has pooh-poohed the whole idea of interstellar flight.

"'Beyond the solar system' is too far away," Robinson told Space.com in May. "It's a joke and a waste of time to think about starships or inhabiting the galaxy. It's a systemic lie that science fiction tells the world that the galaxy is within our reach."

Lasers or nukes?
Schulze-Makuch, however, hasn't given up hope. He notes that interstellar propulsion was one of the big themes at the Defense Advanced Research Project's 100 Year Starship Symposium. "It was pretty clear that we can get up to 10 percent of light velocity, using solar sails. You'd have to wait quite a while, but you're constantly accelerating," he said.

Millis agreed that light-sail technology was one of the most widely suggested avenues for interstellar flight. Such a space-sailing spaceship would be propelled by the pressure of photons — perhaps from the sun, but more likely from a super-powerful laser aimed at the sail from a station on Earth. Another avenue might be to use nuclear fission or plasma drives to blast the starship outward at an accelerating pace.

Assuming that it's possible to get to 10 percent of light speed, Millis said the first traveler to Alpha Centauri would almost certainly be a camera-equipped robotic probe. "At our level of prowess, including the things we think we can do but haven't really tried, a probe is about the only thing you can send," he said. The electronics would have to be robust enough to survive somewhere between 45 and 200 years of traveling — which Millis thinks is within the bounds of believability.

When will humans go?
The first intelligent entities to travel from Earth to other stars will probably be artificial androids built to last for centuries. If it ever gets to the point that humans journey to other stars, they would almost certainly have to live for generations within a huge, self-sustaining habitat.

One of the most popular options is to hollow out an asteroid, place an artificial ecosystem inside it, give it enough of a spin to provide artificial gravity, and somehow send it speeding on its way. Such a concept has been around since the 1960s, and in the novel "2312," Robinson fills the skies with such craft to carry his characters from destinations ranging from Mercury to Pluto and beyond.

It could take 200 years or more to send out the first true starships — but along the way, there will be plenty of discoveries like this week's detection of Alpha Centauri B b to push us along.

"The roadmap that we have takes a grand perspective, with the objective to scout out our own solar system first, put a permanent human presence on Mars, look at asteroids, and really work first on our own solar system before we take the next step to an extrasolar planet," Schulze-Makuch said.

Will we humans ever get the chance to follow through on that roadmap? Feel free to weigh in with your comments below.

More about planet discoveries:

• In a statement issued today, NASA's associate administrator for science, John Grunsfeld, praised the researchers at the European Southern Observatory who made the Alpha Centauri discovery . "For astronomers, the search for exoplanets helps us understand our place in the universe and determine whether Earth is unique in supporting life or if it is just one member of a large community of habitable worlds," Grunsfeld said. He noted that NASA's Kepler, Hubble and Spitzer missions have contributed to the search for planets beyond our own solar system, and that the James Webb Space Telescope would study exoplanets as well. "NASA is also studying two medium-class exoplanet missions in our Explorer program, and in the spring of 2013 will select one of them to enter development for flight later in the decade," Grunsfeld said. Those missions are known as FINESSE and TESS.
• The Alpha Centauri discovery has turned the spotlight once again on the Exoplanet app for the iPhone, iPad and iTouch, developed by Danish-born astrophysicist Hanno Rein. The app keeps track of more than 800 extrasolar planets, and sends alerts when new discoveries are announced. Believe it or not, more exoplanets have been added to the list since Tuesday's announcement about Alpha Centauri B b. The new entrants include WASP-72b and two worlds detected by the Optical Gravitational Lensing Experiment, or OGLE. These giant planets range from about a tenth of Jupiter's mass to nearly one and a half times Jupiter's mass.

More about interstellar travel:

• Reality check for starships
• Alpha Centauri has closest exoplanet
• Voyager 1 isn't as far out as we thought
• Biggest challenge for interstellar travel? It's us

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

The Pentagon's think tank has selected the group that will manage its "100 Year Starship" project to explore what it would take for a multigenerational mission beyond the solar system, and sources say the leader will be Mae Jemison, who became the first black woman in space in 1992.

In the 20 years since then, Jemison has founded several ventures — including The Jemison Group, a technology design and consulting company; and the Houston-based Dorothy Jemison Foundation for Excellence, which takes on educational projects. Jemison, a 55-year-old Alabama native who has experience as a physician and a Peace Corps worker as well as an astronaut, played a prominent role in facilitating the 100 Year Starship symposium organized by NASA and the Pentagon's Defense Advanced Research Projects Agency in Florida last fall.

One of the follow-ups from that seminar was to be the award of a $500,000 contract from DARPA to continue study of the technological, political and social requirements for ultra-long-term projects such as interstellar space missions. Several ventures put in proposals, and one of the groups that didn't win the contract, the Tau Zero Foundation, said in this week's email update that the contract was going to a team "led by an ex-astronaut."

The BBC identified the ex-astronaut as Jemison, based on the text of an unreleased letter from DARPA. It also reported that Jemison's foundation was teaming up with two other groups, Icarus Interstellar and the Foundation for Enterprise Development.

NASA file

Jemison was the first black woman in space in 1992.

DARPA has not yet publicly announced the selection, and my efforts to contact the agency's representatives have been unsuccessful so far. But after the BBC's story, the report was confirmed on the Centauri Dreams blog by Paul Gilster, who is affiliated with the Tau Zero Foundation. Gilster said Jemison's organization "now takes on the challenge of building a program that can last 100 years, and might one day result in a starship."

Adam Crowl, director of Icarus Interstellar, elaborated in a blog comment:

"... Project Icarus will keep running as it has since 2009, and the end point will be an interstellar probe design, chiefly fusion-propelled in the boost phase. That’s due at some point in 2014.

"Icarus Interstellar is a broader banner for a whole group of interstellar related research projects, Project Icarus being just one, which will be producing designs and doing basic research with the common goal of building the technical foundation required for eventual successful interstellar flight.

"Now in light of this news, we’ll be under the banner of the 100 Year Starship Organization, which covers more than just the technical aspects. Each of the triad came to our happy union with different strengths and emphases – Mae Jemison’s organization covering education and broader social goals, the Foundation for Enterprise Development covering innovative organization and operational approaches, and Icarus Interstellar covering the technical aspects. Together we’ll be working towards an organization that will last 100 years and produce a viable interstellar technology, with benefits for all humankind."

The $500,000 DARPA grant is intended to serve as seed money for the 100 Year Starship Organization. Meanwhile, the founder of Tau Zero, former NASA researcher Marc Millis, suggested in his email update that Tau Zero would lower its profile:

"It is too soon to know how this selection will affect Tau Zero's goal to rigorously and impartially guide progress toward interstellar flight.  With insufficient funding to go around, I feel that it would be a disservice to the community for Tau Zero to attempt to compete with this new organization, especially considering that this new organization now has significantly more than an order of magnitude more funding. I hope they serve the community well."

Millis said Centauri Dreams would "continue to operate as an impartial and articulate news source and discussion forum on all things interstellar."

Courtesy of Adrian Mann

An artist's impression shows the Icarus starship accelerating past Jupiter, gaining a valuable boost in speed with the help of the gas giant's gravity, slingshotting it toward its interstellar destination.

Jemison has made a name for herself not only as the first black woman in space, but also as the first real-life astronaut to appear on a "Star Trek" episode. How big of a role will she and her partners play in turning the "Star Trek" vision into reality, and on what time scale? Feel free to weigh in with your comments below.

Update for 9 p.m. ET Jan. 9: DARPA confirmed the selection of Jemison's foundation in a brief statement attributed to Paul Eremenko, DARPA program manager, but indicated that the deal was not yet completely done:

"We can confirm that the Dorothy Jemison Foundation for Excellence has been selected for negotiation for a grant award for the 100 Year Starship effort. We have no further comment until the grant is awarded."

More about interstellar flight:

• Reality check for starships
• Billionaires wanted for starship plan
• Visionaries ponder 100-year starship
• Sex poses big challenge for interstellar travel
• Destination for first starship? Someplace that's livable
• The best options for flying to faraway stars

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

Les Bossinas / NASA

An artist's conception shows a starship entering a wormhole to travel to a distant galaxy.

Last month's "100-Year Starship" conference, backed by NASA and the Pentagon's Defense Advanced Research Projects Agency, threw a huge spotlight on the idea of sending spacecraft far beyond our solar system — but how realistic is that idea? Check out what one of the world's top experts on the subject has to say on "Virtually Speaking Science."

Marc Millis, the researcher behind NASA's Breakthrough Propulsion Physics Project and the nonprofit Tau Zero Foundation, was my guest on tonight's show, which is available as a podcast via BlogTalkRadio and iTunes.

Millis estimates that it'll take 200 years to get in position for the first missions to stars beyond our own, but he says there are lots of small steps we can take starting tomorrow to "chip away" at the challenge. Experiments with solar sails have already started, and Millis says the next step there is to figure out the business case for more ambitious light-powered trips.

There are all sorts of potential breakthroughs to consider: Could the recent reports of faster-than-light neutrinos point to a way to break the speed limit set by special relativity? Could laser experiments let scientists warp the fabric of space-time on a small scale? "What creates the properties of an inertial frame, and how does that relate to space travel?" Millis asked.

Is it worth spending money on precursor missions — for example, sending a "Super-Hubble" space telescope beyond the edge of our solar system to look outward, and inward? "What would it take to do that? How much would it cost?" Millis said.

Here's an edited transcript of my pre-show Q&A with Millis:

Cosmic Log: More people are aware that interstellar flight is on the agenda, in part because of the 100-Year Starship conference. So is anyone building a starship anytime soon? What's the next step?

Millis: No one's building a starship anytime soon, although a lot of people would like to attempt that. The workshop had about 1,000 people there. It was open to the public, and I was glad to see some very intelligent questions from the public. It was an introductory look at not only the technology, but also some of the social issues, and how you would do financing.

The next step by DARPA is that there's a competition out to award the remaining funds of about $500,000 [out of an original $1 million] as seed money to whoever can suggest the best organizational structure to carry forward with the 100-Year Starship image. That will be an organization that will work for at least a century to develop the technology and financing to ultimately enable starships.

Q: Do you see Tau Zero as that organization?

A: Tau Zero is making a proposal. To gauge our chances, I would have to know what all the other competitors are proposing, and that's hard to do.

Q: Could it be that the social issues are actually more challenging than the technological issues?

A: Theoretically, it would be possible to send a probe to the nearest neighboring star in less than a century, so you could actually get your data back. But the required expense is beyond what I think our society could commit to right now.

Q: What's the ballpark figure for the cost?

A: There isn't one, because it's so beyond what we can do.

Based on the progression of society ... if we don't change anything that we're doing, it looks as if it might take another two centuries to have an interstellar probe that's fast enough to complete a mission within a human lifespan. Not that there's people on board, but that the people who launched the mission could get the data back before they retire. We have a long way to go.

The important issue to figure out today is to make sure we have a sane comparison of the real challenges and the real state of the art, so we're proceeding wisely here. Then, from that, ask, "OK, if that's where we are, what can we start tomorrow to chip away at those issues?" We can't build the starship tomorrow, but we can identify the correct questions to ask, and begin seeking answers to those questions. When it looks more promising, and the advancements are there, fine.

On the social issues ... when you think of leaving the planet, and representing Earth, that requires a high degree of political will and collaboration. I don't consider that impossible, and things are certainly looking up in terms of nations collaborating on major space topics. But I don't know how long it will take to really bring this collaboration to bear. Now this doesn't preclude any one sufficiently able and wealthy team from launching their own mission, on their own. Would that be ethical or not?

Then, suppose we did identify a habitable planet. Is it really ours to consider colonizing?

There are a lot of huge questions: What's the optimal population for an interstellar trip? What are the governance models? What's the meaning of life? When you start thinking about "world ships," where we're sending people instead of just robotic probes, that provides a venue that's far enough out that you can rationally discuss these questions. It's an interesting opportunity that we really haven't tapped into yet.

Q: I guess one of those big questions would be, "Why travel to other star systems?" How would you answer that one?

A: The ultimate, highest-priority benefit of star flight is the survival of the human species beyond the fate of our own solar system and our home planet. In the meantime, the progress we make to try to turn all this stuff into a reality will result in profound improvements in energy conversion, transportation, self-supporting life support — things that would be very useful for life on Earth. And then there's the social aspect. This effort can give us hope for a better future, expand our opportunities — and hopefully give people a frontier to conquer, rather than being left with no option other than to conquer each other.

More about interstellar flight:

• The best options for flying to other stars
• Billionaires wanted for starship plan
• Sex poses big challenge for interstellar travel

Podcasts from 'Virtually Speaking Science':

• Download tonight's hourlong show from BlogTalkRadio or iTunes
• Sean Carroll on the puzzling frontiers of physics
• Rand Simberg on the private-enterprise vision for spaceflight
• Martin Hoffert on the future of energy policy
• George Djorgovski on science in virtual worlds
• Alan Stern on suborbital research and NASA's mission to Pluto
• Col. 'Coyote' Smith on the outlook for space solar power
• Tim Pickens on rocket ventures and the Google Lunar X Prize

Last update: 10:30 p.m. ET Nov. 2.

Many thanks to the Meta Institute for Computational Astrophysics for co-sponsoring tonight's Second Life talk at the Stella Nova auditorium.

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding me to your Google+ circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.