Hypothetical Space Shuttle at Epsilon Eridani. Credit for base image: NASA

Once again I have drifted off thinking about the size and scale of space–the things in it and the distances between them–and once again have brought pen and paper, math, and a spreadsheet to bear on the question: are the stars in our destiny, or is the notion of physically reaching them (in person, at least) beyond the available realities?

With all of the science fiction stories devised to get their characters to other stars not only within their lifetimes, but sometimes within a few paltry days, it’s easy to think of interstellar travel as something we might eventually get around to, given the technology, time, and money. We just need to figure out how warp drive or hyperspace work, and how to exploit them, and we’re off!

But putting teleportation and wormhole expressways and their ilk on the shelf labeled, “Cool, but probably just fancy” for a moment, what are the Newtonian-Einsteinian requirements to get us to, say, the nearest known extrasolar planet, which orbits the star Epsilon Eridani, 10.4 light years away from us? It’s a gas giant planet larger than Jupiter and orbits well beyond its star’s habitable zone, but it’s a planet after all, and we star-seekers just love planets.

Now the math that will get us there. I had to assume a mass for our would-be starship, conservatively chosen as 2000 metric tons, or about the weight of the Space Shuttle. In reality that’s far too small a ship for any human interstellar journey, unless the crew are all frozen. And keep in mind, my calculation does not take into account the weight of any fuel we need to carry with us. I’m also choosing a top cruising (coasting) speed of one-tenth the speed of light, or 30,000 kilometers per second. A tenth light speed is pretty darned fast, but not so fast that we need to worry much about relativistic mass—that is, the increase in the spaceship’s effective mass when traveling a significant fraction of the speed of light.

If our engines can produce thrust sufficient to accelerate our 2000 ton spaceship at a rate of “1 gee”, or one Earth-gravity equivalent (~10 meters per second, per second), then to achieve a velocity of one-tenth light speed we’ll need to run those engines for about 35 days, non-stop. We should assume our engines are powered by nuclear fusion or even antimatter reaction (possible future technologies that today present technical challenges, but which aren’t on that shelf of sci-fi fancy).

The energy required for this 1-gee, 35-day engine burn of our 2000 ton spaceship is about 900,000,000,000,000 (yes, 900 trillion) MegaJoules, or 250 trillion kilowatt-hours. That’s the same amount of energy required to launch 20 million normal Space Shuttle flights to low Earth orbit, or almost twice the world’s annual energy consumption. And that’s just to get this little ship accelerated to cruising speed. We’d need another like amount of energy to slow it down to its destination in the Epsilon Eridani system.

As for how long the trip would take, forgetting the 35 days spent getting up to speed and the 35 days spent slowing down again, traveling 10.4 light years at one-tenth the speed of light would take 104 years, one way. (Although, moving at a tenth light speed, the trip would only feel like 103.5 years due to relativistic effects.)

What about the weight of fuel required to do the job? Forget normal rocket fuel; we’d need the energy contained in about 20 billion tons of it just to get to cruising speed—and that doesn’t take into account the mass of the fuel itself, which would also need to be accelerated. Two-thousand ton spacecraft + 20 billion tons of fuel = not practical.

If our engine is powered by hydrogen fusion, we may only need about 3000 tons of fuel (and I’m assuming our fuel is also our propellant—the mass we need to fling out of the engine to accelerate the ship by reaction force; probably not a conservative assumption, in reality).

And if we could use antimatter as our fuel, as does the Starship Enterprise, releasing energy by mixing equal parts antimatter with normal matter, we could carry in our fuel tanks as little as 5 tons of the stuff (plus, I think, 5 tons of normal matter to react with) to achieve cruising speed.

And of course double the fuel amounts if you plan to come to a stop at your destination, 104 years from now.

In summary: tiny cramped ship, 20 tons of antimatter/matter fuel to pack the necessary 500 trillion kilowatt-hours of energy, and 104 years to delivery you to the fabulous Epsilon Eridani system with its one known super-Jupiter sized planet. Anyone interested? Or should we leave space travel to the robot crowd….

Governor Schwarzenegger, clad in a pink tie– an odd sartorial choice for dedicating this giant hulk of a building housing 500 trillion watt laser housed within– nevertheless succeeded in channeling at least some of his Hollywood days. When they originally visited the facility last November, "we were so excited that we said, 'We'll be back.'"

The project's goal is to focus 192 laser beams onto a BB-sized capsule of hydrogen fuel in order to heat it to the point of ignition, that is, to achieve a nuclear fusion reaction where more energy comes out of the capsule than is put in. Fusion is the common process for creating energy in the Sun, and has been demonstrated on Earth both in the apocalyptic specter of thermonuclear weapons and in the more hope-inspiring form of plasma reactors such as those at the Joint European Torus (JET) in Britain. However, ignition has yet to be demonstrated, as JET requires a constant influx of energy greater than anything it is capable of producing. If all goes well within the next several months, ignition could be achieved at NIF as early as 2010.

For all of these exciting aspirations and promise of new technology, the press' reaction to NIF throughout the twelve years of its construction has been often lukewarm, and at worst scornful. Some of this has been deserved, and it is certainly true that the facility's $3.5 billion dollar construction cost is a hard price tag to swallow.

However, NIF is a worthy scientific cause and might well turn out to be an excellent investment. To put things a little bit into perspective, other large science projects are similarly expensive. The Large Hadron Collider (LHC) at CERN and the Hubble Space Telescope have both been estimated at about $6 billion. Dianne Feinstein argued in the past (and reminded the audience at Friday's dedication) that Enron needlessly cost $9 billion during the California Energy Crisis. Put another way, with $9 billion you could (a) experience rolling blackouts while Enron power traders cheer for wildfires ravaging your countryside, or (b) assemble the world's most powerful laser and use it to bring the nation to the brink of being able to replicate, in a controlled manner, the sorts of reactions that power the Sun. Twice.

The physics promise of the NIF, meanwhile, is truly fascinating on all three fronts of NIF's stated goals: energy production, basic research, and national security.

Fission reactors, which extract atomic energy from the splitting of large atoms such as uranium, have been a viable source of energy since 1954. However, the waste they produce remains radioactive for thousands of years. Potential fusion plants, on the other hand, would operate by an altogether different mechanism: the merging of much smaller hydrogen atoms. Radioactive byproducts are still generated, but the timescale for their radioactivity is shorter, on the order of 10 to 20 years.

A significant line of inquiry has already been pursued toward commercially viable nuclear fusion at JET and its planned successor, ITER. Such experiments employ powerful magnetic fields to maintain hydrogen plasma in a confined space and heat it to the point of fusion as it soars around inside a doughnut-shaped ring.

NIF serves as a valuable compliment to these magnetic confinement experiments. Instead of forcing a fusion reaction to perpetuate using costly magnetic fields, the NIF laser will attempt to blast its fuel with so much energy in such a short time period that the fuel will have no time to expand before it undergoes fusion. "If it works, developments at NIF would entirely reshape the dialogue on nuclear fusion energy," said Brian MacGowan, a NIF Program Director.

Even the most optimistic estimates place the viability of these types of energy sources 20 years into the future. NIF itself will never be able to function as a power generator even if all experiments performed at the facility proceed exactly as planned. The raw potential for such power extraction is nevertheless tantalizing.

Additionally, there is basic research potential for NIF beyond fusion power. Stars are typically easy to observe from a distance but inevitably too far away and too inhospitable to explore up close. A miniaturized version of the reaction as created in the NIF target bay could provide an interesting model system. There is no way to tell, but it could be that hand in hand with this ability comes a better understanding of some of the deepest outstanding questions in physics as well, such as the nature of dark energy and dark matter.

NIF also offers a unique way for the U.S. to test the effects of nuclear weapons without violating the Comprehensive Nuclear Test Ban Treaty. NNSA Administrator Tom D'Agostino noted at the dedication that, particularly as the United States' nuclear arsenal ages, this will provide the U.S. with invaluable data.

We may emerge from this economic crisis a poorer, humbler country. Still, I hope that we are not yet so humble that we have lost the ability to dream big, and not yet so poor that we can no longer actively pursue at least a few of those dreams.

37.679754 -121.698912

Inside the National Ignition Facility.

So in a nutshell, what is fusion? And how do lasers work? Why are you asking me? I was the kid who always struggled with math and would get hives on the eve of a high school science test.

Luckily, there are some darn good teachers out there and we were fortunate enough to feature one of them in our story. Richard Muller is a professor of physics at the University of California and has also become something of a web phenomenon. Thousands of "students" all over the world have viewed his lecture series titled "Physics for Future Presidents" on YouTube and Cal's own website.

Muller designed this class to "stress conceptual understanding rather than math, with applications to current events." As he told us, "imagine looking out on your classroom and picturing out there is the future president of the United States. What do you want that person to know?" What comes out is an explanation of the physics of energy, nuclear weapons, radioactivity, relativity and the universe– all explained in a way that the physics-challenged, like myself or maybe a future president, can understand.

Watch the "Super Laser at the National Ignition Facility" TV Story online, as well as find additional links and resources.

Chris Bauer is a Segment Producer for television on QUEST.

37.679754 -121.698912

You may listen to the "Super Laser" radio report online, as well as find additional links and resources. Also don't miss our behind-the-scenes photos for this report.

Amy Standen is a Reporter for QUEST and Radio News at KQED-FM.

latitude: 37.6871, longitude: -121.697