Messenger, Nasa's pioneering spacecraft, ended its four-year study of the planet Mercury by crashing into the planet's surface. Flight controllers at the Johns Hopkins University
Applied Physics Lab, Maryland had earlier estimated that Messenger, travelling @ 14,000 kmph, would hit the ground near Mercury's north pole. Messenger, without any fuel, fought the downward push of the sun's gravity until it hit the planet's surface, thereby creating a 16 meter-crater into Mercury's face.
During its final weeks, Messenger relayed more details about the innermost planet of the solar system, which has patches of ice inside some craters, despite its sizzling location, which is more than twice as close to the sun as the Earth. Messenger (Mercury Surface, Space Environment, Geochemistry, and Ranging craft) made the first close-up studies of Mercury since NASA's Mariner 10 spacecraft flew by the planet thrice in the mid-1970s. It arrived at Mercury in 2011 after a winding six-year journey.
During its orbits, Messenger detected potassium, sulphur and other volatiles on the planet's surface that should have evaporated due to the planet's high temperature. Mercury's average surface temperature is 167 degrees Celsius, with daytime highs of 427 degrees Celsius. It also confirmed the existence of ices and other materials, possibly even carbon-based organics, on the craters where sunlight never shines. It also found evidence of past volcanic activity and some signs that the dense and shrinking planet has a .