Building a test planet takes serious engineering. Researchers at the University of Maryland have constructed a 30-ton sphere that spins at more than 90 mph to generate magnetic fields. The 10-ft.-dia. sphere is filled with 13.5 tons of liquid sodium to mimic the Earth’s liquid-iron center core. A 3.3-ft.- dia. stainless-steel sphere inside the larger one counterrotates to approximate the motion of the planet’s solid iron inner core. The action of Earth’s inner liquid produces a magnetic field that makes compasses work, deflects harmful cosmic rays and protects the planet from solar wind. The field reverses every couple of hundred thousand years. By using a model instead of a computer simulation, scientists hope to determine how these reversals occur and predict the next one.[youtube]http://www.youtube.com/v/bm_iqzmR2cE&hl=en&fs=1&rel=0&color1=0x006699&color2=0x54abd6[/youtube]Stats of SpinLittle Earth: Both spheres are driven by 350-hp electric motors. At full speed the outer sphere spins at 240 rpm; the inner sphere reaches 960 rpm.Dangerous Metal: Sodium is highly conductive and melts more easily than iron, but it can explode if touched by water. (The lab in Maryland has no sprinklers.)Fuel Metal Jacket: The corrugated half-pipes around the sphere are filled with oil, not water or steam, that heats the sodium inside to its melting point, 207.9 F.RELATED STORIES* PM NEWS: Large Hadron Collider to Turn on Sept. 10, Not End World* PLUS: Hurricane Lab Will Simulate 155-mph Storm With “Wall of Wind”* TECH WATCH: 5 Extreme Research Machines You Need to Know* EARLIER: MIT Fights for Clean Power With Holy Grail of FusionJoe PappalardoJoe Pappalardo is a contributing writer at Popular Mechanics and author of the new book, Spaceport Earth: The Reinvention of Spaceflight.
