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The science instruments aboard NASA's New Horizons spacecraft wererunning at full tilt, with cameras snapping images, sensorsscanning the space environment and the communications systemtrading radio signals with ground stations on Earth. No matter thatthe target of this activity - the Pluto system - was still aboutthree years and 850 million miles away. On May 29-30, New Horizons"thought" it was July 14, 2015, and carried out the most intensesegment of its Pluto flyby as part of the mission's first onboardencounter simulation. The simulation was conducted at a distance of 23 astronomical unitsfrom the Sun - 23 times the distance between Earth and the Sun.When the real encounter happens in 2015, Pluto will be 33 AU fromthe Sun. The New Horizons team has been "scripting" the Pluto flyby for thepast several years, building on the experience and success of thespacecraft's 2007 flight through the Jupiter system. This weekmarked the first real test of that code on the spacecraft, in anenvironment New Horizons operators can't fully duplicate on theircomputers. Last week, mission operators at the Johns Hopkins Applied PhysicsLaboratory in Maryland transmitted the 9,675 commands into NewHorizons' computers that guide all activities for the very day thespacecraft is closest to Pluto and its moons - about 22 hours ofactivity in all. "We're really testing the things we can't simulate on the groundvery well, such as the actual slewing - the movement of thespacecraft to point the science instruments - directed by theguidance and control system," says Alice Bowman, New Horizonsmission operations manager at APL. "We'll also look hard at those slews to make sure there was enoughtime between the end of one observation and the start of another." The simulation started with a system-health check-in through NASA'sDeep Space Network; New Horizons then turned from Earth and towardthe spot where it was programmed to find Pluto. A few hours laterthe spacecraft turned back to Earth, sent a quick burst ofhousekeeping data to let operators know it was OK, then returned tothe encounter. All told, the script called for 77 separate observations, with asmany as four science instruments observing at the same time. Thesimulation ended just before 2 p.m. EDT on May 30. With the instruments aiming at empty space where Pluto and itsvarious moons will be on July 14, 2015, the data New Horizons sendsback over the next few weeks might have little science value - butfrom it the team will know whether the sequences went off asplanned and the spacecraft pointed in the right directions. "From what we've already seen, we have a good idea that thespacecraft did what it was supposed to do," Bowman says. "This first mission sim both retired a lot of risks by showing theactual spacecraft can handle the pace of activity we plan at Pluto,and it prepared the way for a more extensive, nine-day Plutoencounter sim next year," says New Horizons Principal InvestigatorAlan Stern, of the Southwest Research Institute. New Horizons is about midway through its annual systems andinstrument payload checkout, having been roused from hibernation onApril 30. It's currently humming through space at more than 34,000 miles(nearly 55,000 kilometers) per hour, between the orbits of Uranusand Neptune, about 2 billion miles (3.3 billion kilometers) fromEarth. The team will ease New Horizons back into electronic slumberin early July. I am an expert from protectivephonecovers.com, while we provides the quality product, such as Blackberry Protective Case Manufacturer , Samsung Protective Case, iPhone4 Leather Cases,and more.
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