Even though scientists can not yet predict exactly how close it will approach, they are certain it will come no closer than 6,800 kilometres from the surface of Earth.Although it’s too early to predict exactly how near it will come to Earth, scientists are confident it will come no closer than 4,200 miles (6,800km) from the planet’s surface.The asteroid last whipped by Earth in 2012 at about one-fourth the distance to the moon.For the first time, NASA will use an actual space rock for an observational campaign to test NASA’s network of observatories and scientists who work with planetary defense. Now NASA scientists are excited they’ll finally get to test out some of their defence systems with an upcoming asteroid fly-by in October. NASA’s planetary defense system is created to protect the Earth from potential asteroid impacts, and this is the best time to see if the system works.2012 TC4 is about 30mts across, and will become the test subject for a new detection and tracking network developed to assess the level of threat posed by rogue asteroids. “This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination, and worldwide communications”, concurred Vishnu Reddy, leader of the 2012 TC4 observation campaign.An asteroid, as big as a Boeing 737 passenger plane, had a near miss with the Earth but remained completely undetected until three days after its closest approach. “This will be a team effort more than a dozen observatories, universities and laboratories around the world, so that we will all be able to understand the strengths and weaknesses of our planetary protection”, says Vishnu Reddy, a member of the Department for coordinating planetary defense (PDCO).That working together takes in places across the Earth, and so it’s important to see how well they can track the asteroid and communicate it as it passes.Details on what this system actually entails are unclear, but it will test “precise orbit determination” and “international communications”, according to NASA.Scientists from NASA’s Centre for Near-Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory (JPL) in California, have determined that while at closest approach, asteroid 2012 TC4 will pass no closer than 6,800 km from the Earth – it will more likely pass much farther away, as far as 270,000 km, or two-thirds of the distance from the Earth to the Moon. ‘It will be incumbent upon the observatories to get a fix on the asteroid as it approaches, and work together to obtain follow-up observations than make more refined asteroid orbit determinations possible’.