An asteroid at least 500 feet long will make a rare close pass by Earth next week, but there is no chance of an impact, scientists reported Thursday. The object, known as 2007 TU24, is expected to whiz by Earth on Tuesday with its closest approach at 334,000 miles, or about 1.4 times the distance of Earth to the moon. The nighttime encounter should be bright enough for medium-sized telescopes to get a glimpse, said Don Yeomans, manager of the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory, which tracks potentially dangerous space rocks. However, next week's asteroid pass "has no chance of hitting, or affecting, Earth," Yeomans said. An actual collision of a similar-sized object with Earth occurs on average every 37,000 years. Spotted last October by the NASA-funded Catalina Sky Survey in Arizona, 2007 TU24 is estimated to be between 500 feet and 2,000 feet long. The next time an asteroid this size will fly this close to Earth will be in 2027. Scientists plan to point the Goldstone radar telescope in California and the Arecibo radar telescope in Puerto Rico at the asteroid and observe its path before and after its closest approach to Earth. Researchers will use instruments to measure its rotation and composition. The 2007 TU24 rendezvous comes a day before another asteroid is projected to pass close to Mars. Scientists have effectively ruled out a collision between the Red Planet and the asteroid 2007 WD5, estimating it will pass at a distance of more than 16,000 miles from the Martian surface. Initial observations of the Mars-bound asteroid put the odds of an impact at 1 in 25, but scientists later dropped the odds to 1 in 10,000.