Lockheed Martin Corp. on Wednesday said its engineers had made a breakthrough in the race to build a nuclear fusion reactor.The company’s secretive research unit, Skunk Works, claims thatwithin a decadeit’ll develop and deploy a nuclear fusion reactor that’s powerfulenough to light over 80,000 homes, yet small enough to fit in the back of a truck. If the company succeeds, it would mark a major milestone in mankind’s pursuit of a viable nuclear fusion power source.Nuclear Fusion’s AllureIn case you haven’t heard, nuclear fusion is kind of a big deal. Rather than splitting atoms apart, like our current nuclear fission reactors, fusion melds two atoms into one releasing an enormous amount of energy. Fusion reactions are emission-less, sparing the planet nuclear waste from fission reactors, and the heavy carbon emissions spewed by coal-powered plants. Best of all, the reactions are fueled byhydrogen isotopes that are practically in infinite supply in the planet’s oceans.Earlier this year, scientists at Lawrence Livermore National Laboratory, a massive fusion research facility in California, announced they had produced afusion reaction that yielded more energythan went into it. That breakthrough occurred in a firing chamber the size of a small house.Lean, Mean Fusion Reaction MachineLockheed’s scientists believe they can exponentially scale down the size of a reactor by with improved magnets. Fusion reactions occur within a firing chamber where two atoms are smashed together. The collision produces intense heat — fusion, after all, is what powers the sun — that needs to be controlled to keep the reactor from being destroyed.Powerful magnets keep superheated ions suspended in place within the chamber, which prevents them from destroying the reactor walls. Lockheed’s reactor utilizes a higher fraction of the magnetic field pressure within the firing chamber, allowing for more control of the reaction while also reducing its size.Lockheed’s engineers say the small size of their proposed reactor will let them build and test prototypes in a shorter timeframe, which makes them hopeful they’ll find a successfuldesign within the decade. The truck-sized reactors could someday be installed in ships that could travel the seas indefinitely, or power airplanes for over a year of continuous flight on just a few bottles of fuel. In a promotional video (above), Lockheed engineer Tom McGuire said the pint-sized reactors could power cities and homes within 20 years.A Bit of SkepticismIf you think Lockheed’s nuclear fusion reactor sounds a little too good to be true, you have plenty of company. Since the announcement Wednesday, scientists have tempered Lockheed’s high hopes with a dose of reality. For one, the reactor hasn’t been built yet.“Some key parts of the prototype are theoretical and not yet proven,” Nathan Gilliland, CEO of Canadian fusion company General Fusion, toldWiredThursday.